Document text
MHI
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FM 4-117
FM 4-117
COAST ARTILLERY
FIELD MANUAL
j-
BARRAGE BALLOON
OPERATION OF MATERIEL AND
EMPLOYMENT OF PERSONNEL
UNITED STATES
GOVERNMENT PRINTING OFFICE
WASHINGTON : 1942
For sale by the Superintendent of Documents, Washington, D. C.
WAR DEPARTMENT,
Washington, June 1, 1942.
FM 4-117, Coast Artillery Field Manual, Barrage Balloon,
Operation of Materiel and Employment of Personnel, is pub-
lished for the information and guidance of all concerned.
[A. G. 062.11 (3-16-42).]
By order of the Secretary of War:
G. C. MARSHALL,
Chief of Staff.
Official :
J. A. ULIO,
Major General ,
The Adjutant General.
Distribution:
IBn and H 4 (5) ; IC 4 (25) .
(For explanation of symbols see FM 21-6.)
n
TABLE OF CONTENTS
PART ONE, Fundamentals. Paragraphs Page
Chapter 1. General 1-4 1
Chapter 2. Aerostatics.
Section I. Balloon types 5-7 3
II. Volume, pressure height, and
lift 8-12 5
III. Calculating inflation and
IV. Operating ceiling, limited op-
erating ceiling, and maxi-
weigh-off 13-15 13
mum altitudes for day and
night flying 16-18 21
V. Superheat 19-21 23
VI. Other effects on lift 22-24 28
VII. Topping-up 25-26 28
VIII. Other considerations 27-28 29
Chapter 3. Meteorology.
Section I. Influence of weather on bar-
rage balloons 29-36 32
II. Weather section 37-42 36
III. Form of hourly observations,
pilot balloon observations,
and weather messages 43-45 40
PART TWO. Personnel. ,
Chapter 1. Selection - 46-47 43
Chapter 2. Training.
Section I. Individual training 48-59 45
II. Unit or crew training 60-62 49
Chapter 3. Inspections 63-64 51
PART THREE. Operation of materiel.
Chapter 1. Hydrogen generating plant.
I. Equipment and operation 65-68 55
II. Field location 69 63
III. Personnel 70-72 64
IV. Gas purity 73-74 65
Chapter 2. Safety precautions in manufactur-
ing and handling hydrogen.
Section I. General 75-76 67
II. Manufacture 77 69
III. Handling, storing, and trans-
porting cylinders 78-80 71
IV, Inflation 81 74
V. Deflation 82-83 74
VI. Typical accidents 84 76
Chapter 3. Helium purification plant 85-88 77
Chapter 4. Air inflation, inspection, and
deflation 89-93 ’ 79
Chapter 5. Transferring hydrogen from one
balloon to another 94-95 83
Chapter 6. Maintenance and repair 96-104 85
Appendix. List of references 94
Index 95
III
FM 4-117
1-4
COAST ARTILLERY FIELD MANUAL
BARRAGE BALLOON
OPERATION OF MATERIEL AND EMPLOYMENT OF
PERSONNEL
PART ONE
FUNDAMENTALS
CHAPTER 1
GENERAL
■ 1. Scope. — This manual is designed for use by barrage
balloon units as a guide in the selection and training of per-
sonnel and the operation of materiel. The instructions given
may be applied with slight modifications to any type of ma-
teriel used by barrage balloon units. Instructions given
regarding operation of materiel will be confined, in general,
to operation other than at the balloon sites. Instructions con-
cerning the operation of materiel at balloon sites may be
found in FM 4-108.
fl 2. References. — This manual should be studied in conjunc-
tion with the references listed in the appendix.
B 3. General Problems. — The mission of a balloon barrage
is actually to destroy hostile aircraft which hit the balloon
anchoring cables and attached lethal devices, and to present
the psychological threat of destruction. In order that the
barrage may accomplish its mission, barrage balloon units
must keep balloons flying in sufficient numbers, in such
patterns, and at such altitudes as to present the maximum
probability of destruction. In addition to the maintenance,
repair, and operation of barrage balloon materiel, barrage
balloon units must make regular local weather forecasts, and
must store and transport large quantities of inflation gas.
It may also be necessary for units to generate inflation gas
if commercial sources of supply are not available.
B 4. Materiel. — a. Special materiel and supplies for a bal-
loon barrage include the following:
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COAST ARTILLERY FIELD MANUAL
(1) Balloons.
(2) Winches.
(3) Cables.
(4) Lethal devices.
(5) Inflation gas.
(6) Gas generating equipment.
(a) Semimobile or mobile hydrogen generating unit.
( b ) Gas generating materials.
(c) High pressure manifold.
(7) Gas handling equipment.
(a) Cylinders.
( b ) Inflation manifold.
(c) Inflation tube.
( d ) Thimble and tie-off cord.
(e) Manometer and tube.
(/) Purity testing apparatus.
(8) Mooring and bedding-down equipment.
(a) Screw pickets.
(b) Ground cable.
(c) Ground rigging.
( d ) Ground cloth.
(e) Sandbags.
(9) Boats and equipment for water-borne sites.
(10) Material for platform installations in marshy areas
and shallow water positions; and material for installations on
roof tops.
(11) Air blower and exhauster.
(12) Balloon nurse bags.
(13) Weather station equipment.
b. The communication equipment used for operational con-
trol of the balloons is standard and similar to that used by
other arms.
2
BARRAGE BALLOON
5-6
CHAPTER 2
AEROSTATICS
Paragraphs
Section I. Balloon types 5-7
II. Volume, pressure height, and lift 8-12
III. Calculating inflation and weigh-off 13-15
IV. Operating ceiling, limited operating ceiling, and
maximum altitudes for day and night flyings __ 16-18
V. Superheat 19-21
VI. Other effects on lift 22-24
VII. Topping-up 25-26
VIII. Other considerations 27-28
Section I
BALLOON TYPES
■ 5. General. — Gas, being a compressible fluid, must expand
on rising in the air to a region of lower atmospheric pressure,
and must contract when lowered to a region of greater atmos-
pheric pressure. In barrage balloons, some provision must
be made for this expansion and contraction as the balloon
is raised and lowered. In the present barrage balloons, both
the ballonet and dilatable principles are used.
■ 6. Ballonet. — a. Principles of operation . — A cross section
of the ballonet type balloon is shown diagrammatically in
figure 1. The envelope is divided into two compartments, the
upper compartment for gas and the lower for air. The two
compartments are separated by a light fabric diaphragm,
which is treated to render it impermeable to gas and air.
The air compartment is provided with an air exhaust valve
and an air scoop. The air scoop is equipped with a check
valve which allows air to enter the air compartment, but
prevents it from being exhausted through the air scoop.
As the balloon rises and the gas expands, due to a decreasing
atmospheric pressure, the diaphragm is forced downward by
the expanding gas, and air is forced out of the air com-
partment through the air exhaust valve. The diaphragm is
forced downward through positions 2 and 3 until all air
is exhausted and the balloon is full of gas. The external
shape of the balloon does not change. A gas safety valve is
provided in the envelope of the gas compartment to relieve
3
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COAST ARTILLERY FIELD MANUAL
any additional gas pressure. The altitude at which the
balloon begins to valve gas is known as the pressure height.
When the balloon is lowered and the gas contracts, due to
an increasing atmospheric pressure, the diaphragm is forced
upward and the air compartment is again filled with air
entering through the air scoop.
b. Internal gas pressure of ballonet balloons . — Some bal-
lonet balloons are designed to operate with internal gas
pressure sufficient to resist external wind pressure. These
balloons also have gas-inflated fins, and internal gas pressure
is required to extend the tail surfaces. Other ballonet bal-
loons are designed to operate with practically no internal gas
pressure, the internal gas pressure being just sufficient to
GAS VALVE
AIR EXHAUST VALVE
AIR INTAKE VALVE
Figure 1 .* — Cross section of ballonet balloon.
maintain the shape of the balloon. The design of the latter
balloon is such that it is not affected seriously by external
wind pressures. This balloon has air-inflated fins.
■ 7. Dilatable. — A cross section of the dilatable type balloon
is shown diagrammatically in figure 2. This type balloon is
rigged with elastic cords in the interior of the envelope.
As the balloon rises and the gas expands, the cords are
stretched and the balloon is dilated to the position indicated
by the dotted lines. To prevent the balloon from bursting,
a gas safety valve is provided to valve gas when a certain
internal pressure is reached. The valve setting is determined
by the strength of the fabric. When the balloon begins to
valve gas, the pressure height of the balloon has been reached.
4
BARRAGE BALLOON 7-8
As the balloon is lowered and the gas contracts, the elastic
cords draw the balloon back to the original shape. If gas has
been valved, the original shape may not be recovered. Dilat-
able balloons need a sufficient internal gas pressure to resist
external wind pressure. They also have gas-inflated fins,
and require internal gas pressure to extend the tail surfaces.
Section II
VOLUME, PRESSURE HEIGHT, AND LIFT
■ 8. Minimum Volume. — a. Definition . — Minimum volume of
a barrage balloon is the least volume to which the balloon
may be inflated for safe operation. The minimum volume of
GAS VALVE
Figure 2. — Cross section of dilatable balloon.
balloons which require a certain internal gas pressure (di-
latable balloons and some ballonet balloons) is the volume
of gas needed to produce the required internal pressure.
The minimum volume of ballonet ballons which require no
certain internal gas pressure is the volume of gas required
to give the balloon proper shape.
b. Methods for determining minimum volume . — Methods
for determining whether a balloon is inflated to minimum
volume will be described in various standing operating pro-
cedures issued for the different types of balloons in use.
For dilatable balloons, the standard operating procedure will
usually prescribe the minimum pressure to be maintained.
The internal pressure needed for safe operation will be pre-
scribed by the manufacturer, but it may be necessary to
5
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COAST ARTILLERY FIELD MANUAL
vary this pressure (as determined by experience) in accord-
ance with the external wind pressures encountered in dif-
ferent regions. After a dilatable balloon is inflated to mini-
mum pressure, the volume of gas in the balloon may be
determined through use of methods similar to those described
in paragraph 10. For ballonet balloons, the standard operat-
ing procedure may prescribe the number of cubic feet of gas
required for minimum volume. This will be determined from
data furnished by the manufacturer. If the number of cubic
feet of gas is prescribed, the volume of gas in a balloon
is determined by the weigh-off method described in para-
graph 10a. For ballonet balloons, the standard operating
procedure may also describe the position of the diaphragm
when the balloon contains the minimum volume of gas. If
this is done, a visual inspection of the diaphragm will dis-
close approximately whether the balloon is inflated to mini-
mum volume.
c. Changes due to stretch. — As a balloon ages, the envelope
and expansion cords (in the case of a dilatable balloon) will
become permanently stretched, which will increase minimum
volume. The standard operating procedure should prescribe
the volume that should be allowed for stretch after a certain
period of operation.
d. Minimum percent of fullness. — The minimum percent of
fullness of a barrage balloon is the minimum volume divided
by the gross volume of the balloon. As a balloon ages and
stretch occurs, the minimum percent of fullness increases,
since the volume of gas necessary to produce minimum vol-
ume increases more rapidly than does the gross volume.
■ 9. Pressure Height. — a. General . — The pressure height of
a balloon is the altitude at which the balloon begins to valve
gas. If a balloon ascends above pressure height, it will lose
gas. Pressure height is affected by the percent of fullness of
a balloon at the ground and by the atmospheric temperature.
h. Percent of fullness. — The percent of fullness of a balloon
at the ground has a direct effect on the pressure height of
the balloon For example, a balloon that is 60 percent full
at the ground will have more room for the gas to expand
before it begins to valve, and will therefore have a greater
pressure height than would the balloon if it were 70 percent
6
BARRAGE BALLOON
9
full at the ground. The percent of fullness of a balloon is
determined by dividing the volume of gas actually present
in the balloon by the gross volume of the balloon. The per-
Figure 3. — Pressure height.
cent of fullness may also be determined by dividing the lift
produced by the gas present in the balloon by the maximum
lift, as shown in table I. A chart showing the pressure
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COAST ARTILLERY FIELD MANUAL
heights for various percentages of fullness is shown in figure
3. This chart is correct for any balloon.
c. Atmospheric temperature . — Gas expands more per unit
increase in altitude at a low atmospheric temperature, than
it does at a high atmospheric temperature. This is due to
the fact that atmospheric pressure decreases more per unit
increase in altitude at a low temperature than it does at
a higher temperature. It follows, therefore, that for a given
percent of fullness at the ground, the pressure height of a
balloon will be less at a low atmospheric temperature than
it will at a higher atmospheric temperature. For example,
a balloon 80 percent full at the ground will have a pressure
height of 6,600 at 0° F., and will have a pressure height of
8,300 feet at 100° F., as shown in figure 3.
d. Effect of raising a balloon above pressure height. — If a
balloon filled to a certain percent of fullness is raised above
pressure height it will valve gas, and will contain less than the
original percent of fullness when returned to the ground. If
the percent of fullness of the balloon upon being returned to
the ground is less than the minimum percent of fullness pre-
scribed for safe operation, the danger of break- away or dam-
age to the balloon will be greatly increased. Figure 4 illus-
trates the effect of raising a balloon above its pressure height.
In this case, the balloon was inflated to minimum volume,
which was determined to be 79.3 percent of fullness at the
ground. If it were permitted to ascend to 9,000 feet at 50° F., it
would valve gas above its pressure height of 7,500 feet. When
lowered to 1,400 feet it would be back to minimum percent of
fullness, and when lowered to the ground it would be only 76
percent full, which would be less than the minimum percent
of fullness. In the illustration, it is assumed that no change
in atmospheric temperature occurred at the ground, and that
superheat (sec. V) did hot develop.
e. Effect of minimum percent of fullness on pressure
height. — From the discussion above, it may be seen that the
maximum pressure height at which a balloon may be flown
with safety is governed by the minimum percent of fullness.
If the balloon is filled with a greater volume of gas than the
minimum percent of fullness, the pressure height will be re-
duced accordingly, but in no case should a balloon be flown
8
BARRAGE BALLOON
9
above the pressure height for minimum percent of fullness.
As a balloon ages and stretch occurs, the minimum percent
of fullness is increased, and therefore the maximum pressure
height at which the balloon may be flown with safety is
Figure 4. — Effect of raising a balloon above pressure height.
9
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COAST ARTILLERY FIELD MANUAL
decreased considerably. This is particularly true of dilatable
balloons.
■ 10. Determining Volume. — Two methods of determining
the volume of gas in a balloon are discussed below:
a. Weigh-off method . — The gross lift of a balloon may be
determined by adding the weight of the balloon and ballast
to the weigh-off (par. 12a). The volume of hydrogen in the
balloon may then be computed through the use of the follow-
ing formula:
V=81.24 LT
YP
where V=volume of gas in cubic feet contained in the balloon.
L= gross lift of the balloon as determined by weigh-off.
P= atmospheric pressure in inches of mercury.
T=atmospheric temperature (absolute) in degrees
Fahrenheit.
F=gas purity expressed as a whole number, not as a
percent.
The following formula is used to determine the volume of
helium :
F=87.65 LT
YP
This method is the most accurate available, but to avoid dy-
namic lift it is necessary that little or no ground wind (not
more than 15 mph) exist when the balloon is weighed-off.
b. Groove depth method. — (1) By measuring the depth of
the groove between two lobes of a dilatable balloon at a cer-
tain point and referring to the proper chart, the approximate
volume of gas in the balloon may be determined. The point
at which the measurement is to be taken is marked on the
balloon and the chart is furnished by the manufacturer. The
method of taking the measurement is shown diagrammatically
in figure 5. As the balloon ages, the chart for volume as de-
termined by groove depth becomes inaccurate due to fabric
stretch, and a flat percentage correction is necessary.
(2) A method similar to (1) above has been proposed for
ballonet balloons. In this method, the height of the dia-
phragm as shown diagrammatically in figure 6 is estimated
10
BARRAGE BALLOON
10-11
and reference is made to the proper chart to determine the
approximate volume.
(3) The methods discussed in (1) and (2) above are only
proposed methods, and more complete instructions may be
contained in standard operating procedures issued for various
balloons.
■ 11. Static Lift. — Static lift is the lift produced by the gas
in the balloon. Dynamic lift, produced by the kiting action
of the balloon due to the wind, is not used to supplement
static lift at the present time. To reach a given height, a
balloon must be inflated with a sufficient volume of gas to lift
the balloon, trim ballast, cable, lethal devices (if provided).
READ GROOVE DEPTH
ON YARDSTICK
BALL OF CORD
HOLD YARDSTICK
PERPENDICULAR TO CORD
PULL CORD ACROSS LOWER
LOBE WITH BALLOON FREE
OF GROUND
Figure 5. — Method for measuring groove depth.
and other appurtenances attached to the cable, to this height
statically. (See lines 6 to 14, table I.) A free lift may also
be added, (as determined by experience) to insure adequate
cable tension for better flying performance and proper func-
tioning of the lethal devices, and to compensate for changing
atmospheric conditions, such as a drop in temperature. The
number of cylinders of gas needed to produce the static lift
required is determined by the methods discussed in section
III. Since it is unlikely that all cylinders will be filled to the
specified pressure, and since some valves may have leaked,
it is always necessary to check the static lift of the balloon
11
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COAST ARTILLERY FIELD MANUAL
before ascension is made, either by weighing-off the balloon
or by actually measuring the volume.
■ 12. Checking Static Lift. — a . Weigh-off. — To check the
lift of the balloon by the weigh-off, a number of sandbags
equal in weight to the required net lift of the balloon are
hung on the junction assembly grommets. Sandbags should
weigh 33 y 3 pounds each. If the wind is blowing, dynamic lift
due to the wind may be partially eliminated by allowing the
balloon to drift with the wind. If the balloon just lifts the
sandbags, it is sufficiently inflated. Net lift required is the
APPENOIX
Figure 6. — Method for estimating diaphragm height.
sum of the weights of the cable for the altitude desired, the
attached lethal devices, and other appurtenances, plus a free
lift if desired. The net lift to be used will be greater than that
required if superheat (sec. V) is present at the time of
weigh-off, or if the minimum volume produces a greater lift
than that needed to reach the required altitude. If the balloon
will not lift the sandbags hung on the junction assembly
grommets, the actual net lift may be determined by removing
the sandbags one at a time until the balloon will lift those
remaining. The sandbags remaining are then counted, and
the number is multiplied by the weight of each sandbag to give
12
BARRAGE BALLOON
12-13
the net lift. Sufficient gas must then be added to give the
net lift desired. Gross lift is determined by adding the net
lift to the weight of the balloon and trim ballast. If a tension
meter is provided, the net lift may be more conveniently deter-
mined by attaching the balloon to the flying cable and reading
the tension on the cable while the balloon is flying as close as
possible to the ground. The tension reading will be equal
to the net lift, except for any dynamic lift which may exist.
In the absence of superheat it is preferable to check the bal-
loon by weigh-off . This may be done any time between sunset
and sunrise, after the superheat acquired during the day has
disappeared.
b. Measuring volume . — If the balloon cannot be weighed-
off satisfactorily due to the wind or other conditions, the lift
may be checked by a method involving the actual measure-
ment of the volume of gas in the balloon. The volume of
hydrogen or helium required to produce the desired gross
lift is first calculated by the use of the formulas given in
paragraph 10a. The volume of gas in the balloon is then
measured through use of some method similar to those dis-
cussed in paragraph 10b, and this volume is compared with
the calculated volume required.- If the volume of gas in the
balloon is less than the calculated volume required, addi-
tional gas must be injected. If superheat is present when
the volume is measured, a correction for the additional volume
due to superheat must be made (see sec. V).
Section III
CALCULATING INFLATION AND WEIGH-OFF
■ 13. Appoximate Methods. — The following approximate
methods may be used to determine the volume of gas needed
to inflate a balloon if it is not desired actually to calculate
the volume required. The results will not be as accurate as
the results of calculations discussed later in this section, but
will be definitely superior to guess work.
a. Dilatable balloon . — The principal requirement for infla-
tion of a dilatable balloon is minimum pressure. If the
balloon is inflated to minimum pressure, the lift will usually
be greater than the lift required, and it will not be necessary
460655 ° — 42 -
-2
13
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COAST ARTILLERY FIELD MANUAL
to inject a volume of gas greater than that required to
produce minimum pressure. An experienced balloon chief
will usually know the approximate number of cylinders of
gas required to give minimum pressure. After the balloon
is inflated to minimum pressure, the net lift should be checked
by weigh-off and more gas should be added if needed to
produce the net lift required.
b. Ballonet balloon . — The approximate number of cylinders
of gas needed to inflate a ballonet balloon may be deter-
mined by dividing the gross lift required (see lines 6 to 14,
table I) by the average lift per cylinder. Lift of the gas
contained in a standard hydrogen cylinder may be consid-
ered as about 13 pounds, and that of the gas contained in a
standard helium cylinder, about 11.8 pounds. After the com-
puted number of cylinders of gas have been injected, the
balloon must be weighed off to determine whether it has
sufficient lift. If the balloon will not lift the number of
sandbags required, three cylinders of gas should be added
for each sandbag that the balloon will not lift. Minimum
volume must then be checked by a visual inspection of the
diaphragm, as prescribed by the standing operating procedure
in effect for the balloon. If the diaphragm is extended above
the limits described, additional gas must be injected to
produce minimum volume.
■ 14. Calculations. — a. Gas requirements . — The gas re-
quirements of balloons are determined by the following
factors:
(1) The balloon must contain a sufficient volume of gas
to provide the static lift required to reach the altitude
desired.
(2) The balloon must contain at least the minimum volume
of gas.
(3) There should be as little gas in the balloon as possible
at the ground, consistent with the above, in order that the
pressure height will be as great as possible.
b. Form . — The number of cylinders of gas needed for
inflation, and the weigh-off for checking the inflation, are
calculated on lines 1 to 29 of table I. The pressure height
for the percent of fullness to which the balloon is inflated
is calculated on lines 30 to 34. If, in order to give minimum
14
BARRAGE BALLOON
14
volume, the balloon is inflated to a greater volume than that
required to reach H (line 8), the height attainable with the
minimum volume of gas without valving is calculated on lines
35 to 41. All of the above calculations are made at the
balloon site. Operating ceiling and the maximum altitudes
for day and night flying without valving are calculated by
higher headquarters on lines 42 to 58 of the form. These
calculations are made before assigning H. The lift per
cylinder of gas may be calculated on lines 59 to 64.
Table I . — Inflation and ceiling calculations
DATA AND LIFT
1. P (atmospheric pressure) . - SO. 8 in. Hg.
2. t (atmospheric temperature) 40 ° F.
3. T (460 plus t) A 500° F. Abs.
4. dT (superheat) 25° F.
5. Y (gas purity) 98
6. Weight per 1,000 ft. of cable 88 lb.
7. w (cable weight per 1,000 ft. of alt.) (line 6 divided by .93) 91.7 lb./ft.
8. II (operating altitude) 5.400 ft.
9. Weight of balloon 8701b.
10. Weight of ballast . ... 60 lb.
11. Weight of lethal devices and other appurtenances attached to
cable-— : 40 lb.
12. Free lift 1501b.
13. Cable weight. 495 lb.
( line 7 X line 8\
L000 )
14. Lift required 1,635 lb.
(sum of lines 9 to 13)
15. K (constant for calculating maximum lift) 0.01281
(for hydrogen, use ... 0. 01231)
(for helium, use .. 0.01141)
16. Balloon type Dilatable
17. V (gross volume) 30,600 cu. ft
18. L' (maximum lift at ground) 2,2301 b.
/ PYKV __ lines 1 X 5 X 15 X 17 \
\ T line 3 /
19. F m (minimum percent of fullness) 77%
20. Minimum lift 1,717 lb.
(line 18 X line 19)
21. L (lift to be used) 1,717 lb.
(enter line 14 or 20, whiche ver is greater)
15
14
COAST ARTILLERY FIELD MANUAL
Table I . — Inflation and ceilint/ calculations — Continued
NUMBER OF CYLINDERS REQUIRED
22. to (lift per cylinder)
(from line 64 or known)
23. Number of cylinders required for inflation,
x loo = — — x ioo)
(—
\Yl „
lines 5 X 22
WEIGH-OFF
13 lb.
136
24. C (constant for superheat correction)
(for hydrogen, use 108)
(for helium, use 116)
25. L (enter line 21) — —
26. dL (superheat correction)
I dTL C = lines 4X21X24 \
\ T Y lines 3X5 /
27. Total gross lift
(sum of lines 25 and 26)
28. Weight of balloon and ballast '
(sum of lines 9 and 10)
29. Weigh-off -
(line 27 less line 28)
PRESSURE HEIGHT
30. L (enter line 21)
31 . dL t (superheat correction) —
fdTL = line 4Xline 2l \
V T line 3 /
32. L plus dL, (sum of lines 30 and 31).
33. F (percent of fullness) —
/ L plus dL, _ line 32\
\ V line 18/
108
Night
1, 717
0
1, 717
960
767
Night
1,717
0
1,717
77
Day
1,717 lb.
95 lb.
1 , 812 lb.
950 lb.
862 lb.
Day
1, 717 lb.
86 lb.
1, 80S lb.
80.9 %
34. Pressure height 8, 360 6, 780 ft.
(enter chart with line 33;
Note. — When either value of line 34 is less than line 8 anc^—
a. Line 21 is the same as line 20, the altitudes shown on line 34 are the maximum
attainable without valving.
h. Line 21 exceeds line 20, a smaller value for H of line 8 should be determined;
unless the first column, line 34, exceeds line 8 and attainment of H at night with
sacrifice of day altitude is desired.
16
BARRAGE BALLOON
14
Table I . — Inflation and ceiling calculations — Continued
ATTAINABLE HEIGHT (OPTIONAL)
Note— E xcess lift (effective day and night) and superheat buoyancy (effective
during the day) permit the following altitudes to be attained with the quantity of gas
used without valving:
Niyht Day
35. Excess lift 88 88 lb.
(line 21 less line 14)
36. dL (superheat correction) 0 5511).
(enter line 26)
37. Total excess lift 88 /7? lb.
(sum of lines 35 and 36)
38. Additional altitude 896 1,988 ft.
/ lOOOXline 37 \
\ line 7 )
39. II (line 8) - - 5, 400 5,400 ft.
40. Sum of lines 38 and 39 6,895 7,888 ft.
41. Height attainable without valving 6, 895 6 , 780 ft.
(enter line 34 or line 40, whichever is. smaller)
OPERATING CEILING
42. Pressure height for Em.. 8,350 ft.
(enter chart with line 19)
43. Superheat correction 1,5401 1.
(80 F dT — SOXline 19Xline 4)
44. Daytime pressure height for F m ... 6,810 ft.
(line 42 less line 43)
45. F' for H — 84.5%.
(enter chart with line 8)
46. U F/ (line 18Xlinc 45).. 1,884 lb.
47. Lift required (enter line 14) 1,635 lb.
48. Line 46 less line 47 (plus or minus) ~h849 lb.
49. 0.026 V (0.026Xline 18) 58.0 lb. /ft.
50. w (enter line 7).... - 91.7 Ib./ft.
51. Sum of lines 49 and 50 149.7 lb./ft.
52. Operating ceiling — H (plus or minus) . +1,563 ft.
\w plus 0.026 L' /
x 1,000)
\line 51 J
53. H (enter line 8) - - - - . 5,400 ft.
54. Operating ceiling - - 7,068 ft.
(algebraic sum of lines 52 and 53)
55. Superheat correction - -578 ft.
(30 F d l^SOXline 33Xline 4)
(Use night percent of fullness; if
unknown, use line 19 instead of line 33)
17
14
COAST ARTILLERY FIELD MANUAL
Table I . — Inflation and ceiling calculations — Continued
OPERATING CEILING — Continued
56. Limited operating ceiling 6,485 tt.
(line 54 less line 55)
57. Maximum altitude to be assigned for inflation: Maximum altitude
for night flying 6,485 ft.
58. Maximum altude for daytime flying 6,485 ft.
Note.— a. If line 54 exceeds line 42, enter line 42 in line 57 and enter line 44 in line 58.
b. If line 44 exceeds line 56, enter line 56 in lines 57 and 58.
c. If neither a nor b apply, determine line 41 (night flying) for inflation to minimum
fullness and enter result in line 57; enter line 44 in line 58.
LIFT PER CYLINDER
Note.— If lift per cylinder is known, enter lift on line 22 directly. If lift is unknown
use following lines, suitable for a cylinder of 1 .528 cu. ft. capacity.
59. P' (gage pressure of cylinder) 2,000 lb./sq. in.
60. V (temperature at which P’ determined) „ 68° F.
61. T’ (4G0 plus /') — 528 °F. Abs.
62 * ( For hydrogen: 3.02— j
V ?V __._D.44 lb.
^ For helium: 2.70— J
63. Constant 1 .56 lb.
64. l 0 (lift per cyl. for 100% purity) IS. 00 lb.
(sum of lines 62 and 63)
c. Data and lift (lines 1 to 21). — Atmospheric pressure (P)
and temperature (£) are furnished by the weather section of
the barrage. (It is more desirable to read the temperature at
the balloon site if a thermometer is available.) Superheat
idT) is determined as described in paragraph 19. Gas purity
(Y) is determined by the gas workers, and is used in the form
as a whole number and not as a percent. Thus, 98 percent
purity is expressed by the number 98. Cable weight per 1,000
feet is .furnished by the manufacturer, and the cable weight
per 1,000 feet altitude is computed as shown on line 7. This
computation takes cable sag into account. Operating alti-
tude (H) is assigned by higher headquarters. The weight and
type of balloon are painted on the nose of the balloon. The
ballast is weighed when it is placed in the ballast pockets.
Weight of lethal devices and other appurtenances attached
to the cable is furnished by the manufacturer. Free lift may
be added if desired (as determined by experience) to insure
adequate cable tension for better flying performance and
18
BARRAGE BALLOON
14
proper functioning of the lethal devices, and to compensate
for changing atmospheric conditions, such as a drop in tem-
perature. Cable weight for the operating altitude is de-
termined by multiplying the operating altitude by the cable
weight per 1,000 feet altitude, and dividing by 1,000. The sum
of the weights. of the balloon, ballast, lethal devices, free lift,
and cable is equal to the gross lift required. Gross volume of
the balloon is obtained from the manual for balloon operation
issued by the manufacturer. Maximum lift at the ground
(L') is determined by the use of the formula shown on line
18. Minimum percent of fullness ( Fm ) is determined by
dividing the minimum volume (par. 8) by the gross volume.
Minimum lift is determined by multiplying the maximum lift
by the minimum percent of fullness. If the minimum lift is
greater than the lift required, the minimum lift is used, since
the balloon must be filled at least to minimum percent of
fullness.
d . Number of cylinders required (lines 22 and 23) . — The lift
per cylinder of gas (h) may be known from information fur-
nished by the battalion gas' service section. If not known it
may be calculated on lines 59 to 64. The pressure of the
cylinder (P') and the temperature at which the pressure was
measured (l') are determined by the gas workers at the in-
flation site. The temperature used must be the temperature
at which the pressure was measured. Pressure and tempera-
ture readings should be taken on one out of every 12 cylinders
(approximately), and the average lift per cylinder of this
sample is used in making the calculation. If the cylinders
are used within several days after being charged, the pres-
sure and temperature at the time they were charged may be
used. If facilities for measuring the pressure and tempera-
ture are not available, a lift of 13 pounds per cylinder of hy-
drogen and 11.8 pounds per cylinder of helium may be used.
After the lift per cylinder has been determined, the number of
cylinders required is determined as shown on line 23.
e. Weigh-off (lines 24 to 29) . — To determine whether the
balloon has sufficient lift after inflation, it must be weighed-
off (par. 12a). If superheat (sec. V) is present at the time of
the weigh-off, a correction for the additional lift due to super-
heat must be added to L, since the balloon must be inflated
to fly with or without superheat. The correction for addl-
19
14-15 COAST ARTILLERY FIELD MANUAL
tional lift due to superheat ( dL ) is computed as shown on
line 26. The weight of the balloon and ballast is subtracted
from the total gross lift to give the net lift or weigh -off which
the balloon should have in order to be sufficiently inflated.
The night value is used whenever the balloon is weighed off
in the absence of superheat.
1. Pressure height (lines 30 to 34) .—Although the operating
altitude ( H ) assigned by higher headquarters will normally
be within the pressure height of the balloon, changes in
atmospheric pressure, temperature, and gas purity since
the operating ceiling was assigned, may have altered the
volume of gas required for inflation, and therefore the pres-
sure height will be altered. It is desirable, therefore, to
determine the pressure height for the actual percent of
fullness after inflation. If superheat is present, a correction
for the increase in lift due to superheat must be added to
L. This correction is calculated as shown on line 31. The
percent of fullness is then determined as shown on line 33,
and the pressure height for this .percent of fullness is read
from the chart shown in figure 3. At all times when super-
heat is not present, the night pressure height is used. If
the pressure height for either day or night operation is less
than the assigned operating altitude and line 21 is the same
as line 20 (indicating that the balloon must be filled to
the minimum percent of fullness) , the pressure heights shown
on line 34 are the maximum altitudes attainable without
waiving gas. If either value of line 34 is less than line 8,
and line 21 exceeds line 20 (indicating that the balloon must
be filled to more than the minimum percent of fullness), a
smaller value for H must be determined and lines 13, 14,
and 21 to 34 must be . recalculated. Higher headquarters
should be so informed. The new value for H may be deter-
mined on lines 42 to 58. If only the first column of line 34
is greater than line 8, H may be reached at night without
valving gas, but altitude must be sacrificed in the daytime
to conform with the pressure height shown in the second
column, line 34.
■ 15. Calculating Attainable Height (lines 35 to 41) . — If line
21 exceeds line 14 (indicating that the minimum percent of
fullnes to which the balloon must be filled results in more lift
20
BARRAGE BALLOON
15-17
than is required to reach H) the balloon will be able to sup-
port more cable than necessary to reach H. Superheat buoy-
ancy also permits more cable to be lifted. The altitude at-
tainable with the volume of gas used without valving may
be calculated on lines 35 to 41. The excess static lift of
the balloon is determined by subtracting the lift required
to reach H from the lift produced by the minimum volume of
, gas. If superheat is present or will be present when the bal-
loon is being flown, the additional lift due to superheat is
added to give the total excess lift. The additional altitude
attainable (ignoring pressure height) is determined by use
of the formula shown on line 38. If the sum of H and the
additional altitude is less than pressure height (line 34) , this
sum is the height attainable without valving; otherwise, the
pressure height should be entered on line 41.
Section IV
OPERATING CEILING, LIMITED OPERATING CEILING,
AND MAXIMUM ALTITUDES FOR DAY AND NIGHT
FLYING
■ 16. General. — The operating ceiling of a barrage balloon is
the maximum altitude to which the balloon will lift the
anchoring cable and attached lethal devices and other appur-
tenances statically, and still maintain a cable tension at the
winch equal to the free lift. It may or may not be greater
than the pressure height for minimum percent of fullness.
The limited operating ceiling of a balloon is the altitude for a
certain volume of gas that cannot be exceeded at night because
of lack of lift, and cannot be exceeded in the daytime when
superheat is present because to do so would result in a loss
of gas by valving, the altitude being the same for both day
and night operation. The maximum altitudes which may be
assigned for inflation and for day and night operation without
valving gas are limited by the operating ceiling, and by the
pressure height for minimum percent of fullness. A further
discussion of limited operating ceiling and maximum altitudes
for day and night flying will be found in section V.
■ 17. Calculations. — In order accurately to assign the altitude
for inflation (H) and the altitudes for day and night flying
21
17
COAST ARTILLERY FIELD MANUAL
to the various balloons in the barrage, higher headquarters
must calculate the maximum altitudes which may be attained
without valving gas and then make assignments which are
within these altitudes. These calculations may be made on
lines 1 to 21 and lines 42 to 58 of table I. To begin the calcula-
tions, a value must be assumed for H and entered on line 8.
(A plus or minus correction for this assumed value will be
determined later.) Lines 1 to 21 are completed as described
in paragraph 14c, and lines 42 to 58 are completed as described
below. Lines 42 to 44 are not necessary for calculating the
operating ceiling, but are necessary for determining the maxi-
mum altitudes fpr day and night flying. The pressure height
for minimum percent of fullness ( Fm ) is read from the chart
shown in figure 3. If it is expected that superheat will be
present during the day, a correction for the effect of superheat
must be made as shown on line 43, and this correction must
be subtracted from the pressure height for Fm. The percent
of fullness (F') for the assumed altitude (H) is obtained from
the chart shown in figure 3, and the lift for this percent of
fullness is determined as shown on line 46. The lift required
to reach H is subtracted from line 46 to give the excess lift,
which is entered as a plus or minus quantity on line 48. If
line 47 is greater than line 46, line 48 is negative. The amount
that the assumed H must be increased or reduced to give the
operating ceiling (operating ceiling minus H ) is calculated as
shown on lines 49 to 52. Line 52 bears the same algebraic
sign as line 48. Line 52, when added algebraically to the
assumed H will give the operating ceiling for the balloon.
The limited operating ceiling may then be determined by
correcting for superheat for daytime operation, as shown on
lines 55 and 56. The altitudes to be assigned for inflation ( H )
and the maximum altitude for day and night flying are
entered on lines 57 and 58 as follows:
a. If the operating ceiling exceeds the pressure height for
Fm, the pressure height for Fm is assigned for inflation. The
pressure height for Fm is the maximum altitude for night
operation. The daytime pressure height for Fm is the maxi-
mum altitude for daytime operation when superheat is
present.
b. If the daytime pressure height for Fm is greater than
the limited operating ceiling, the limited operating ceiling or
22
BARRAGE BALLOON
17-19
a lesser value may be assigned for inflation. The limited
operating ceiling is the maximum altitude that may be as-
signed for day and night operation. The altitudes assigned
for inflation and for day and night operation will be the
same.
c. If neither a nor b above is true, which will be seldom
(meaning that the limited operating ceiling is greater than
the daytime pressure height for Fm and the pressure height
for F m is greater than the operating ceiling), the balloon
should be inflated to minimum fullness and the altitude at-
tainable for night flying must be calculated on lines 35 to
41. The maximum altitude for daytime flying will be the
daytime pressure height for Fm.
■ 18. Effect of Atmospheric Density’ on Operating Ceil-
ing. — As the atmospheric density at the ascension point de-
creases, the lift per unit* volume of the gas in a balloon
decreases, and therefore the operating ceiling is decreased.
Density of the atmosphere decreases with altitude above sea
level. Therefore, as the altitude of the ascension point above
sea level is increased, the operating ceiling above the ascen-
sion point is decreased. Density of the atmosphere also de-
creases with an increase in temperature. Therefore, the op-
erating ceiling of a balloon will be decreased in regions of
prevailing high temperatures. Correction for atmospheric
density is automatically made on the computation form, and
no separate correction is necessary.
Section V
SUPERHEAT
■ 19. General. — a . Determining superheat . — Superheat is the
increase in temperature of the gas in a balloon above that
of the surrounding air due to the effect of the rays of the
sun on the balloon fabric. It is expressed in degrees Fahren-
heit. The amount of superheat present in a balloon may be
measured by a thermometer in the balloon envelope, or may
be estimated, based on experience and records of superheat
acquired under the same or similar climatic conditions. Rec-
ords of superheat acquired may be compiled by calculating the
superheat by weigh-off and then recording the superheat,
23
19-20
COAST ARTILLERY FIELD MANUAL
together with the atmospheric temperature. Superheat may
be calculated by weighing-off the balloon with and without
superheat, and then using the formula:
dT=D . TY
LC
where
dT=superheat in degrees Fahrenheit.
D=the difference in weigh-off of a balloon when super-
heat is present' and the same balloon without
superheat.
T^atmospheric temperature (absolute) in degrees
Fahrenheit.
Y=gas purity expressed as a whole number, not as a
percent.
Z,=the gross lift of the balloon without superheat.
C=constant, which for hydrogen is 108 and for helium
is 116.
b. Superheat effects . — An understanding of the effects of
superheat is important in barrage balloon work. Due to
the expansion of gas caused by the heating, the gas in a
balloon will have greater volume and lift when superheat
is present, but this volume and lift will disappear when super-
heat disappears. The additional lift and volume must be
considered in checking the lift of the balloon by weigh-off
or volume measurement methods. The additional volume
will also affect pressure heights determined without taking
superheat into account. Therefore, corrections for the effect
of superheat must be made.
■ 20. Superheat Corrections. — a. Weigh-off . — To determine
the weigh-off when superheat is present, the additional lift
due to superheat must be added to the weigh-off calculated
without superheat. This additional lift is determined by the
formula:
dL—dT LC
YT
where
dL=the additional lift in pounds due to superheat.
dT ~ superheat in degrees Fahrenheit.
L=the lift of the balloon without superheat.
24
BARRAGE BALLOON
20
C=constant, which for hydrogen is 108 and for helium
116.
y=gas purity expressed as a whole number, not as a
percent.
T=atmospheric temperature (absolute) in degrees
Fahrenheit.
b. Volume measurement . — To determine the volume of a
balloon when superheat is present, the additional volume due
to superheat must be added to the volume without superheat.
This additional volume is determined by the formula:
dV=FV . dT
T
where
dV~ the additional volume in cubic feet due to superheat.
FV=the volume of the balloon without superheat.
dT=the superheat in degrees Fahrenheit.
T= the atmospheric temperature (absolute) in degrees
Fahrenheit.
c. Pressure height. — Since superheat causes expansion of
gas in a balloon, the pressure height for a certain volume of
gas will be reduced when superheat is present. In order
that the balloon may be flown at the maximum altitudes
without valving both day and night, certain compensations
for the effect of superheat upon pressure height must be
made. These compensations may be made by reducing the
altitude of the balloon in the daytime when superheat is
present, by reducing the volume of gas used for inflation (but
not below minimum volume) , or by a combination of the two.
(1) Reduction in daytime altitude. — This method is used
when it is desired to attain the greatest altitude at night, but
considerable altitude is sacrificed during the daytime when
superheat is present. This method must be used whenever
the operating ceiling is greater than the pressure height for
minimum volume, because the balloon should not be inflated
with less than the minimum volume of gas. In this case, the
balloon is inflated to minimum volume and is flown at the
pressure height for minimum volume at night. During the
day when superheat occurs, the gas in the balloon will expand
and the balloon must be lowered to the daytime pressure
height for the minimum volume of gas. Daytime pressure
25
20
COAST ARTILLERY FIELD MANUAL
height is determined by subtracting a correction for super-
heat from the pressure height for minimum volume without
superheat. The superheat correction is determined as follows :
F dT
Reduction in feet altitude=-=r
xLi
where F— the percent of fullness at the ground without super-
heat.
dT— superheat in degrees Fahrenheit.
T=atmospheric temperature (absolute) in degrees
Fahrenheit.
if=the change in air density corresponding to a change
in altitude of 1 foot, expressed as a fraction of
the ground density. For the range of altitudes
encountered with low-altitude balloons,
if =.0000245 to .000027.
For an average value of 50° F. and .0000245 for K, the
approximate rule is:
Reduction in feet altitude=80 F dT
(2) Reduction of gas content . — When feasible, it may be
more desirable to reduce the gas content of the balloon below
the volume required to reach operating ceiling (but not below
minimum volume) and fly the balloon at the same altitude
both day and night. This altitude is known as the limited
operating ceiling, since it cannot be exceeded at night be-
cause of lack of lift and cannot be exceeded in the daytime
when superheat is present without valving gas. The amount
of gas to be used for inflation is the volume required to lift
the balloon to the limited operating ceiling without super-
heat. The limited operating ceiling is determined by first
calculating the operating ceiling and then subtracting the
superheat correction. The superheat correction is determined
by the formula—
F dT
Reduction m feet altitude^ J~K+w)’t
where ^
F=the percent of fullness at the ground without super-
heat—
dT=superheat in degrees Fahrenheit.
K — the same as explained in (1) above.
26
BARRAGE BALLOON
20-21
u?=the cable weight per foot of altitude.
Z/=the maximum gross lift of the balloon at the ground.
2 T =atmospheric temperature (absolute) in degrees
Fahrenheit.
Using average values for the above, an approximate rule is:
Reduction in feet altitude=30 F dT
The method described in this paragraph is applicable only
if the limited operating ceiling calculated in this way is
below the daytime pressure height for minimum volume.
(3) Combined reduction in altitude and reduction in gas
volume . — It sometimes happens that the limited operating
ceiling is abpve the daytime pressure height for minimum per-
cent of fullness. In this case, the balloon could be lowered
in the daytime as described in (1) above, but a greater day-
time altitude without valving may be attained by a combina-
tion of the two methods described above. The balloon is
inflated to minimum volume and is flown during the daytime
at the daytime pressure height for minimum percent of
fullness. The altitude attainable at night is determined on
line 41 of table I.
■ 21. Other Considerations. — As shown in the preceding
paragraph, a balloon may be filled with the minimum volume
of gas and flown at the maximum height attainable with
this volume of gas at night. In the daytime, when superheat
is present, the additional lift produced by superheat may be
used to lift the balloon above the altitude otherwise attainable
with the volume of gas used. When superheat is used to
produce this additional altitude during the day, it must be
reasonably certain that the superheat will continue through-
out the day. The appearance of clouds, which would reduce
superheat, would cause a loss in lift and a consequent re-
duction in altitude. This would cause a sag in the cable,
which if not removed, would impair the flying performance
of the balloon and functioning of the lethal devices, and
might cause the cable to become entangled in surrounding
obstructions.
27
22-25 COAST ARTILLERY FIELD MANUAL
Section VI
OTHER EFFECTS ON LIFT
■ 22. Loss of Gas. — -The lift of a balloon does not change
materially between the ground and operating altitude (except
for gain due to superheat) , provided no gas is valved. In order
to insure that the balloon will maintain its lift, and also to
insure that the balloon will have minimum volume when
lowered, every effort should be made to avoid valving gas by
keeping the balloon within pressure height. Loss of gas by
valving will not produce a loss in lift until the gas contracts
as the superheat disappears or until the balloon is lowered
to a region of greater pressure.
■ 23. Superpressure. — Super pressure is the difference in
pressure between the pressure of the gas in a balloon and
atmospheric pressure. The amount of superpressure in a
balloon reaches a maximum when the balloon is 100 percent
full. Gas under pressure weighs more (has a greater density)
than gas not under pressure, and therefore the useful lift per
unit volume is less. It follows that a balloon with superpres-
sure will have a smaller lift than the same balloon without
superpressure. A superpressure of 3 inches of water will
reduce the lift of a balloon less than 1 percent at 9,000 feet
altitude. This effect is small enough to neglect in all barrage
balloon work.
■ 24. Humidity. — The lift of a balloon is determined by the
weight of the air displaced. Humid air weighs less per unit
volume than dry air, and therefore a balloon will have less
lift in humid than in dry air. An increase of 50 percent rela-
tive humidity will decrease the lift of a balloon about 1 per-
cent at the ground. This effect is small enough to neglect in
all barrage balloon work. Constants in the equation given in
this manual and the pressure height chart of figure 3 are
based upon an average humidity of 60 percent at 50° F.
Section VII
TOPPING-UP
■ 25. General. — An inflated balloon may lose gas by valving
or leakage through the envelope. This gas must be replaced
28
BARRAGE BALLOON
25-27
if sufficient pressure and lift are to be maintained. Replace-
ment of this gas is called topping-up. The volume of gas to
be added is determined by weigh-off or volume measurement.
In order to avoid the effects of superheat, balloons are ordi-
narily weighed -off and topped up between sunset and sunrise
or when there is no superheat. If superheat is present, a
correction must be made for the effect of superheat as
discussed in section V.
■ 26. Topping -up Gas. — As shown in the computation in
table I, in some instances a balloon may have more than
sufficient lift to reach a given altitude. In that particular
illustration, the balloon has more than sufficient lift to reach
the operating altitude of 5,400 feet, and the gas which pro-
duces the additional lift is needed only to maintain minimum
volume. This balloon, with a minimum volume ( FV ) of 23,500
cubic feet, could be inflated with 22,400 cubic feet of hydrogen
and 1,100 feet of marsh gas and still reach 5,400 feet. Hence,
marsh gas would be very satisfactory for topping -up this
balloon. If desired, the actual altitude attainable after marsh
gas had been used for topping-up could be calculated on
table I by entering on lines 5 the estimated purity of the gas
in the balloon after topping-up. Coal gas may also be used
as a topping-up gas. In localities where hydrogen is difficult
to obtain, it may be practicable to resort to the use of marsh,
coal, or other locally available gas for topping-up.
Section vm
OTHER CONSIDERATIONS
■ 27, When to Deflate Due to Leakage. — If a balloon is kept
below pressure height so that no gas is valved, an excessive
loss of lift indicates that gas is being lost through leakage.
Gas leakage produces a decrease in pressure, which may lead
to poor flying performance caused by inadequately inflated
fins and nose-cupping. Therefore, the number of pounds of
lift loss is an indication as to whether such erratic perform-
ance may be expected. When the lift loss becomes abnor-
mally high, the balloon should be deflated, air inflated, in-
spected, and repaired. To determine when the balloon should
be deflated, a record should be kept (preferably by the platoon
460655° — 42 3 29
27-28
COAST ARTILLERY FIELD MANUAL
chief) showing the pounds of lift loss of each balloon as
determined by weigh-off. An example of such a record is
shown below:
WEIGH-OFF RECORD BALLOON NO.
1
Date
Weigh -oil
after
previous
topping-up ^
Present
weigh-off
before
topping-up
Lift loss
Remarks
Pounds
Pounds
Pounds
Feb.
1 i
600
567
33
Feb.
2
600
600
0
Did not. top-up.
Feb.
3 1
600
567
33
Feb.
4
600
533
67
Feb.
5
600
567
33
Feb.
6
- 600 1
567
33
Feb.
7
600
400
200
Believe gas valved.
Feb.
8
600
600
'' 0
/ Value doubtful. Wind affected
\ weigh-off.
Feb.
ft
600
533
67
Feb.
io !
600
567
33
Feb.
11 1
600
533
67
Feb.
12
600
500
100
Feb.
13
600
500
100
Recommend deflation.
Feb.
14
600
!
467
1 133 |
Deflation ordered.
It should be remembered that as a balloon ages and perma-
nent stretch occurs, (particularly in a dilatable balloon) the
pressure height for minimum percent of fullness is reduced,
and the balloon must be lowered accordingly or gas will be
valved and this record will be of no value.
■ 28. Aerodynamics. — a. Angle of trim. — The flying perform-
ance of a balloon is very dependent upon the attainment of
the proper angle of trim, as prescribed by the manufacturer’s
specifications or by standard operating procedure. If the
adjustment of the rigging is improper, so that the balloon will
fly with less than the proper angle of trim, the balloon is sure
to dive. On the other hand, if the adjustment of the rigging
will permit the balloon to fly with more than the proper angle
of trim, a high dynamic lift and great cable tension will result,
and the danger of loss of the balloon due to cable breakage
30
BARRAGE BALLOON
28
will be greatly Increased. The rigging should be checked at
every opportunity to Insure that the balloon will fly with the
correct angle of trim.
b. Kiting . — Dynamic lift due to kiting action of the balloon
produced by the wind will ordinarily not be used to increase
operating ceiling of the present balloons, except in special
situations. Kiting may be used to advantage in areas of
steady prevailing winds to maintain the altitude of a ballonet
type balloon which is carrying heavy cable and does not require
a certain internal pressure. In making use of kiting, the
responsible officer should insure that the balloon lifts the extra
cable payed out and does not drift away from the ascension
point without increasing in altitude. A balloon especially
designed to be lifted by the wind would have an extra large
air chamber to provide for a greater pressure height.
31
29-31
COAST ARTILLERY FIELD MANUAL
CHAPTER 3
METEOROLOGY
s Paragraphs
Section I. Influence of weather on barrage balloons 29-36
II. Weiather section 37-42
III. Form of hourly observations, pilot balloon obser-
vations, and weather messages 43-45
Section I
INFLUENCE OF WEATHER ON BARRAGE BALLOONS
■ 29. Weather Elements. — The weather elements which
must be considered in barrage balloon operations are light-
ning, wind, clouds, fog, ice, snow, rainfall, and sunshine.
■ 30. Lightning. — -Lightning tears and ignites balloons. Bal-
loons have been destroyed under conditions when there
was no actual lightning discharge to earth, and by strokes so
weak that thunder was not heard on the ground. Experience
has shown that there is great danger to balloons in lightning
from all precipitating cumulo-nimbus clouds. It is essential
for weather personnel supplying information to a balloon
barrage to watch the development of cumulo-nimbus and
cumulus clouds and give careful attention to reports of such
clouds.
■ 31. Wind. — Large balloons should withstand a wind speed
of at least 50 miles per hour. In the case of old balloons,
rigging patches may tear off and the envelopes may rip at
lower wind speeds. Gusty winds may cause balloons to yaw
and dive. Such action may break their flying cables. A
barrage normally contains balloons of all ages, and experi-
ence has shown that casualties may be caused by winds of
45 miles per hour, and balloons may be seriously endangered
if the wind speed >is 50 miles per hour or more. A rapid
increase in wind speed or a squall is more dangerous than
a steady wind. A wind of 25 miles per hour is dangerous
when a balloon is being maneuvered near the ground, par-
ticularly on sites surrounded by obstructions which may dam-
age the balloon fabric. If the balloons are kept flying until
the wind at operating altitude is more than 50 miles per
32
BARRAGE BALLOON
31-34
hour, serious losses may be incurred in attempting to bed
down the balloons? It is necessary, therefore, to issue warn-
ings when a wind speed of more than 40 miles per hour is
expected. If balloons are flying during a surface wind of
20 miles per hour which is expected to increase, information
about the possible later development of squalls, gales, light-
ning, and snow or icing conditions should be given as early
as possible. This will enable the barrage commander to
decide whether to bed down the balloons while it is still
practicable to do so or to allow them to remain flying in
the face of adverse conditions.
■ 32. Clouds. — The presence of stratus or strato -cumulus
clouds is of tactical operational importance. If balloons pro-
ject above a cloud layer they indicate the presence of a target
to enemy bombardment aviation. The barrage commander
must decide whether his balloons should or should not be
hidden in the clouds. When the sky is less than six-tenths
covered by clouds over the barrage area, the importance of
concealing balloons in the clouds decreases. The weather
section must keep watch for the development of stratus
and strato- cumulus clouds. All available information as to
height of the upper surface of these clouds, whether the in-
formation is obtained from aircraft observations or by other
means, should be supplied to the barrage headquarters.
■ 33. Fog. — The considerations applying to fog are similar to
those for stratus and strato-cumulus clouds. The barrage
commander requires information as to when fog is expected,
its vertical and horizontal extent, and the time it is expected
to end. In dense fogs, balloons are ordinarily bedded down.
■ 34. Ice, Snow, and Rainfall. — a. Ice and snow. — Glaze is
the type of ice formation most seriously hindering balloon
operation. The weight of the ice so formed may become
sufficient to force the balloon to the ground. Actual inspec-
tion and tests of a balloon during and after a snowstorm
revealed that the flight characteristics of the balloon were
greatly affected by the snow. It was found that ice and
snow had gathered in the corrugations of the fins, in the
grooves, on the metal fittings, on the gas and air valves,
and on the top surface of the balloon. Great difficulty was
33
34 COAST ARTILLERY FIELD MANUAL
encountered in removing the snow. The tests showed the
following:
(1) The balloon fabric may become brittle in temperature
of 32° F. or less, and there is an increased danger of tearing
the fabric.
(2) The load of snow that will accumulate on a balloon
while it is on the ground or in flight in snowy weather will
completely destroy trim and cause the balloon to be tail
heavy.
(3) The weight of the snow will decrease the net lift of the
balloon.. If there is little wind to offset this decrease the
balloon may lose altitude and drag the cable on the ground
unless the winch operator is present at all times to take up
any slack in the cable.
(4) The high angle of trim caused by the heavy tail of the
balloon under ice and snow conditions may, in appreciable
winds, result in a high aerodynamic lift and great cable ten-
sion. Under these conditions, the balloon will behave more
nearly like a kite, and care must be taken to prevent the loss
of the balloon due to cable failure.
(5) Due to the poor flying performance of the balloon
under ice and snow conditions, it is essential that extreme
care be taken in raising or lowering the balloon. The winch
should be operated by an experienced operator. The allow-
able speed in raising or lowering the balloon is greatly reduced
due to the following:
(a) Poor flying performance.
(b) Stiffness of the cable.
(c) Brittleness of the fabric.
id) Slowness of the fabric to become adjusted to changes
in pressure when the balloon is raised or lowered.
(6) When the balloon is flown under snow conditions, it is
necessary to remove the ballast from the tail or adjust the
rigging to compensate for the added weight of the snow on
the fins. As the snow and ice melt and evaporate, it is
necessary to haul down the balloon from time to time to read-
just the trim. If this is not done, the tail will become lighter
and poor trim will result.
(7) If the balloon is bedded down in any position other
than with the nose into the wind, the accumulation of snow
34
BARRAGE BALLOON
34-36
on one side of the balloon will be greater than the other.
This will cause the balloon to list when flying. The same will
result if the sun melts the snow off one side of the balloon
more rapidly than off the other side.
(8) Cold weather may cause both the gas and air valves to
freeze open or shut regardless of whether actual moisture is
present around the valves. Any valve frozen open or shut
must be freed in order to permit proper functioning of the
valve. Danger of valves freezing will be decreased if talc or a
similar substance is used between the valve contacting
surfaces.
(9) Snow blown by the wind may pile up in hard lumps in
the air scoops, and may block the passage of air into air-
inflated fins or into the air chamber of a ballonet balloon.
The effect of this is most serious in ballonet balloons which
do not require a certain internal pressure, since in these
balloons the diaphragm must react quickly on even a slight
change in gas volume in order to maintain the shape of the
balloon.
b. Rainfall . — When rain is falling, the weight of the mois-
ture absorbed by and collected on the fabric will be greater
on the wide tail surfaces than it will on the nose, particularly
of a dilatable balloon. This moisture will affect the angle of
trim of the balloon. Rainfall may have a favorable effect on
well- drained sites by decreasing the danger of fire during
inflation and deflation.
■ 35. Sunshine. — Direct rays of the sun upon a balloon cause
superheating of the gas within the balloon. A discussion of
the effects of superheat may be found in section V, chapter 2.
Bright sunlight also hastens the decomposition of neoprene,
with the formation of hydrochloric acid. The acid causes
deterioration of the fabric used in constructing the balloon,
particularly the outer ply. Small drops of water on the
balloon will concentrate the sunlight and increase this effect,
which may cause the formation of small pinholes in the fabric.
■ 36. Weather References. — Additional weather information
may be found in TM 1-230 and 3-240.
35
37-38
COAST ARTILLERY FIELD MANUAL
Section II
WEATHER SECTION
■ 37. General. — The susceptibility of balloons to weather
conditions makes it necessary that frequent local weather
forecasts be made. The local forecasts must cover the area
in which the barrage is operating, and must be made often
enough to provide the barrage headquarters with all timely
weather information, particularly the wind and lightning
risks and whether or not moisture will be frozen on the
balloons. It will be extremely unwise to rely on the more
general Weather Bureau forecasts, and barrages will fre-
quently operate in localities where such general forecasts are
not available. For these reasons, a weather section is fur-
nished each separate battalion and each barrage balloon
group to provide the necessary forecasts. The weather sec-
tion will also supply battalion and group headquarters with
the atmospheric pressure and temperature readings for use
in making aerostatic calculations, and will supply informa-
tion as to the cloud ceiling and sky condition so that the
barrage commander may determine the extent to which
the clouds may be used to conceal balloons.
■ 38. Personnel. — a. Each balloon barrage maintains a
weather station unless the required weather information is
available from other nearby sources. The personnel and
equipment to operate a weather station are organic within
each separate battalion. When several battalions operate a
barrage, the personnel and equipment from the weather sec-
tions of the separate battalions may be combined to operate
a group weather station.
b . The weather section of the separate barrage balloon bat-
talion is a part of the headquarters battery. It is composed
of the weather officer, who is responsible for the organization,
training, and operation of the weather section. He advises
the battalion commander on all matters pertaining to
weather. He is assisted by the following enlisted personnel,
according to the present tentative Table of Organization :
1 technical sergeant, meteorologist.
1 sergeant, meteorologist.
1 technician, 5th grade, clerk, weather.
1 private, clerk, weather.
36
BARRAGE BALLOON
38-40
3 privates, observers, weather. .
1 private, chauffeur.
1 private, basic.
The weather officer will determine the distribution of duties
among the enlisted personnel.
c. The weather personnel provided for the barrage control
section of each barrage balloon group headquarters battery
consist of-^-
1 master sergeant, meteorologist.
1 technician, 5th grade, meteorologist.
1 technician, 4th grade, clerk, weather.
2 privates, observers, weather.
■ 39. Equipment. — The equipment of the weather station
consists of Signal Corps meteorological kits 6, 7, and 8, plus
two weather teletypes. One teletype will carry schedule A
weather information (hourly reports), and the other will
carry schedule C information (all other weather informa-
tion) .
■ 40. Operation. — a . The weather station will operate on a
24-hour day, 7-day week basis. The weather section will be
divided into watches arranged so that a forecaster will be
on duty at all times. At least two men should be on duty
during periods when adverse weather conditions are expected.
The essential requirements of a balloon barrage weather
station are the ability to issue accurate local weather forecasts
from the basic weather information and to recognize the
weather conditions as they appear.
b . All Weather Bureau teletype reports throughout the
United States are based on eastern standard time. It is
therefore necessary for the barrage weather station to base
its operations on eastern standard time so that all weather
information may be coordinated for issuance to barrage
headquarters.
c. The following observations will be made by the weather
section:
(1) Six-hourly map observations, four times daily; to be
completed by 1:30 and 7:30 AM and PM, EST. These ob-
servations are used in the preparation of weather maps.
(2) Hourly observations, 30 minutes past each hour, for
the purpose of maintaining a constant check on existing
37
40-41
COAST ARTILLERY FIELD MANUAL
weather conditions at the station and determining pressure
and temperature for aerostatic calculations.
(3) Pilot balloon observations (“pibals”) four times daily, to
be completed by 10:00 and 4:00 AM and PM, EST. These
observations are used to determine wind direction and ve-
locity at various levels above the earth’s surface.
(4) Special hourly observations as the weather requires.
(5) Special “pibals” as the weather requires.
d . All observations made by the weather section are for
the use of the barrage, and will not be transmitted on the
teletype circuit unless specifically authorized. All weather
information will be transmitted to the command post of the
barrage and to the command post of each battalion if the
barrage is operated by more than one battalion.
e. The following maps and charts will be made at each
weather station:
(1) Weather maps four times daily, beginning at 7:30 and
1:30 AM and PM, EST, and completed as soon as possible
thereafter.
(2) Upper wind chart, two times daily, beginning as soon as
possible after 6:00 AM and PM, EST.
(3) Adiabatic charts and Rossby diagrams, daily, from any
available radiometrograph reports from nearby weather
stations.
(4) Other maps and charts will be made at the discretion
of the weather officer or at the direction of the commanding
officer.
■ 41. Weather Message. — In general, the following types of
weather messages will be issued by the weather station:
a. Eight-hour weather message . — Four 8-hour weather mes-
sages will be prepared daily so as to be delivered to the
barrage and battalion command posts by 10:00 and 4:00
AM and PM, EST. The weather message will include a
forecast of the wind and lightning risks and other weather
conditions for the ensuing 8-hour period, and a report of
the pilot balloon observation just completed.
h. Daily weather summary . — The daily weather summary
will be issued at 11:00 AM daily, and will cover the weather
for the period “tonight and tomorrow.”
38
BARRAGE BALLOON
41-42
c. Special weather message . — If a previous message is found
to be seriously in error or any weather phenomena has de-
veloped concerning which the barrage should be warned, a
special message will be issued immediately. Special messages
will also be issued to cover certain weather elements upon
request by proper authority, and may be issued at any time.
■ 42. Summary. — The following is a summary of observations
made, records preserved, and information supplied by the
weather station:
a. Observations made. Time completed
6 -hourly map observations. 7:30 and 1:30 AM and PM,
EST.
“Pibals” 10:00 and 4:00 AM and PM,
EST
Special “pibals” As weather requires.
Hourlys 30 minutes past each hour.
Special hourlys — As weather requires.
b. Records preserved at station
6 -hourly map observations.
Hourlys and special hourlys.
“Pibals” and special “pi-
bals” •_
Barograph trace
Upper wind charts
Weather maps
Adiabatic charts
Forecasts and special fore-
casts
Teletype weather reports
c. Information supplied.
8-hour weather message
Daily weather summary
Special forecasts
Hourlys
Special hourlys
Other information
Periods retained
Permanently.
Do.
Do.
Do.
1 year.-
1 year.
1 year.
1 year.
3 months.
Time delivered
10:00 and 4:00 AM and PM,
EST.
11:00 AM, EST.
As required.
30 minutes past each hour.
As required.
When requested.
39
43-45
COAST ARTILLERY FIELD MANUAL
Section HI
FORM OF HOURLY OBSERVATIONS, PILOT BALLOON
OBSERVATIONS, AND WEATHER MESSAGES
■ 43. Hourly Observations. — Hourly observations made by
the barrage weather station are reported to barrage head-
quarters in the following form:
Tyson 08305® 30.05 45 N10
The station (Tyson) and the time on the 24-hour clock (0830)
are given as shown. The figure 5 indicates the cloud ceiling
in hundreds of feet. The symbol © indicates the sky condi-
tion. The symbols used are as follows: clear, meaning that
the sky is less than one-tenth covered with clouds, O I scat-
tered clouds, meaning that the sky is one-tenth to five-tenths
covered with clouds, ®; broken clouds, meaning that the sky
is six-tenths to nine-tenths covered with clouds, (fl) ; and
overcast, meaning that the sky is more than nine-tenths
covered with clouds, ® . The next group of figures 30.05 is
the atmospheric pressure in inches of mercury. The figure 45
indicates the atmospheric temperature in degrees Fahrenheit.
The letter N is the wind direction (expressed as one of the
16 points of the compass) , and the figure 10 following the wind
direction is the wind velocity in miles per hour.
■ 44. Pilot Balloon Observations. — Pilot balloon observa-
tions made by the barrage weather station are reported in the
8-hour weather message in the following form:
Tyson 03 015022 025225 036035 etc.
The station and time of the observation on the 24-hour clock
are given as shown. In the groups of six figures each that
follow, the first two figures are the altitude in thousands of
feet above the surface of the earth, the next two figures are
the wind direction in hundreds of miles measured clockwise
from north, and the next two figures are the wind velocity in
miles per hour.
■ 45. Weather Messages. — a. Eight-hour message. — The
8-hour message will be divided into three paragraphs, as
follows:
40
BARRAGE BALLOON
45
(1) Weather risk classification . — A forecast of the weather
risk classification will be given in each message. Classes of
weather risks to balloons are shown in table II. If the clas-
sification for either wind or lightning is other than class I
the probable time of the risk will be given and a word descrip-
tion will be included if applicable. If upper winds of 50 mph
or more are expected, the elevation at which they are expected
to occur will be given. For forecast purposes, a line squall will
be defined as a front accompanied by surface winds of 25 mph
or more.
(2) “Pibal” — A report of the “pibal” just completed will be
given in the message in the form shown in paragraph 44.
(3) Forecast of other weather elements. — The following
weather elements will be forecast in as near the order listed
as proper wording will permit:
(a) Clouds and ceiling. (Large cumulus or cumulo-nimbus
clouds will be mentioned by name) .
(b) Thunderstorms and precipitation.
(c) Icing conditions and the altitude at which freezing is
occurring.
id) Obstructions to vision and visibility.
(e) Surface wind velocity and direction.
(/) Front and time frontal passage is expected.
( g ) Temperature, if decided change is expected.
Table II. — Classes of weather risks to balloons
Class
Definition
Lightning I
Lightning risk very slight, or there is no lightning risk.
It is expected that over the actual region of the barrage there
will be large cumulus clouds which may develop into cumulo-
nimbus clouds, but that there -will be no actual lightning in
the meteorological vicinity of the barrage.
There is practical certainty that cumulo-nimbus clouds will be
over the barrage area and lightning has been observed in the
meteorological vicinity of the barrage.
All wind conditions except those under wind class III.
Lightning II. .
Lightning III
Wind 1 1
Wind III
Wind at ROH is 50 mph or more; or line squall risk exists.
1 There is no wind class II corresponding tolightning class II.
41
45
COAST ARTILLERY FIELD MANUAL
b. Form . — A sample forecast, illustrating the form to be
used, is given below:
Camp Tyson, Tenn. April 1, 1942, 10:00 AM to 6:00 PM.
Weather class *111 from 1:00 PM to 6:00 PM.
Thunderstorms after 1:00 PM.
Tyson 09 013212
023514
033722
043625
053515
High scattered to broken clouds with large cumulus and
cumulo-nimbus forming at 2,000 to 4,000 feet by 1:00 PM.
Thunderstorms with light to moderate rain after 1:00 PM.
Visibility more than 12 miles except lowering temporarily
during rain. Wind SW 8 to 12 mph increasing to 25 to 30
mph during thunderstorm.
c. Weather summary and special messages . — (1) Sum-
mary . — The daily weather summary will cover expected
weather for the period “tonight and tomorrow” in a general
way. An example of a daily weather summary is given below :
Camp Tyson, Tenn. April 1, 1942.
Tonight and tomorrow — Clear tonight, lowest tempera-
ture about 35°. Increasing cloudiness during day to-
morrow with light rain during afternoon. Wind south
6 to 10 mph.
(2) Special iveather message . — The form for a special mes-
sage will vary considerably depending on circumstances, but
in general should follow the form of other messages.
42
BARRAGE BALLOON
46-47
PART TWO
PERSONNEL
CHAPTER 1
SELECTION
■ 46. Importance. — Barrage balloon units require a large per-
centage of highly-trained specialists. In order that the train-
ing program may produce the greatest possible results, it is
highly important that the men who are to be trained as
specialists be carefully selected.
■ 47. Qualifications. — a. General. — Previous knowledge and
experience in similar or related fields is often the most reliable
basis upon which selection of men to be trained for certain
positions may be made. If a sufficient number of men with
previous knowledge or experience is not available, then those
men possessing the desired mental and physical capabilities
for the various positions should be chosen for training. Vari-
ous tests should be devised for the purpose of discovering the
capabilities desired.
b. Balloon chiefs. — Men selected to be trained as balloon
chiefs must possess initiative, a sense of responsibility, and
the ability to handle men. They should be capable of grasp-
ing the fundamentals of aerostatics, meteorology, and map
reading. Prospective assistant balloon chiefs must have the
same qualifications.
c. Winch operators. — Winch operators should be mechani-
cally inclined, and should have a mechanical background.
Manual dexterity and coordination are- principal prerequisites.
Previous experience in the handling of machines or motor
vehicles is desirable.
d. Gas workers. — Gas workers should have a basic knowl-
edge of the chemistry and physics of gases, and should have
practical working knowledge of machinery. Previous experi-
ence with gas or gas producing and compressing apparatus is
desirable.
e. Riggers. — Men selected to be trained as riggers should be
able to read blueprints and should be manually adept.
43
47
COAST ARTILLERY FIELD MANUAL
/. Communication workers . — Telephone operators should
have good hearing and should be able to speak clearly and
correctly. Telephone and teletype maintenance men should
know the rudiments of electricity and should have had experi-
ence with electrical equipment. Teletype operators should be
able to type at least 30 words per minute, using the touch
system.
g. Weather station personnel . — Men selected to be trained
as weather station personnel should have a basic knowledge
of physics. They should have a fair knowledge of mathe-
matics and some ability as draftsmen.
44
BARRAGE BALLOON
48-50
CHAPTER 2
TRAINING
Paragraphs
Section I. Individual training 48-50
II. Unit or crew training 60-62
Section I
INDIVIDUAL TRAINING
■ 48. General. — The training of personnel is divided into
two phases; individual training, and unit or crew training.
In the first phase, individuals are trained in the technique
of their individual duties. In the second phase, the men of
a unit learn to work together as a team. The responsibility
for the training of personnel lies with the officers who com-
mand the various units. General information on training
plans and methods of instruction may be found in FM 21-5.
■ 49. Indoctrination of Personnel. — Each man in a bar-
rage balloon organization must become imbued with the fact
that barrage balloons are an effective means of defense
against hostile aircraft. Demonstrations of effectiveness may
not be possible under training conditions, but the use of
barrage balloons under war conditions has amply demon-
strated their effectiveness. All personnel must be constantly
indoctrinated by the instructors to have confidence in their
arm.
■ 50. Balloon Chiefs. — The balloon chiefs require careful
training in order to command their units properly. Balloon
chiefs must be thoroughly familiar with the work pertaining
to the inspection, care, and maintenance of the balloon, and
its operation, maneuvering, bedding down, and mooring under
all conditions. They must know in detail the work of every
man in the crew and possess the ability to instruct them.
They must keep records at the balloon sites. Their training
should include the subjects listed below:
a. Aerostatics .—' The balloon chief should understand and be
able to explain —
(1) Static lift of the balloon and how it varies with atmos-
pheric conditions.
460655° — 42 4
45
50-52 COAST ARTILLERY FIELD MANUAL
(2) Methods of determining lift required and weigh-off.
(3) Necessity for maintaining minimum volume and flying
the balloon within pressure height.
b. Aerodynamics . — Balloon chiefs should understand aero-
dynamics sufficiently to enable them to make the proper
adjustments to the angle of trim of a balloon and to react
properly to phenomena involving dynamic lift, weaving,
listing, and diving of a balloon.
c. Meteorology. — Balloon chiefs should understand the gen-
eral formation of the atmosphere and how various kinds of
weather affect the operation of balloons.
d. Map reading. — Balloon chiefs must have a sufficient
knowledge of map reading to —
(1) Guide their units to a position indicated on a map, or
to a position for which the map coordinates are given.
(2) Determine whether a road is too steep for vehicles to
climb.
e. Winches. — Balloon chiefs should know enough about the
operation and functioning of the winch to supervise its op-
eration and routine maintenance.
f. Local defense. — Balloon chiefs command their squads in
action against local attacks by ground troops. They should
be thoroughly schooled in the principles of organizing a posi-
tion for local defense, including defense against parachute
troops and mechanized units.
■ 51. Assistant Balloon Chiefs. — The training of the as-
sistant balloon chiefs should include enough of the details
of each job to enable them to understand and explain it.
The assistant balloon chiefs are second in command at a
balloon site. They are responsible for the functioning of
the crew on one side of the balloon during the time it is
being maneuvered by a balloon crew. They should be trained
to take over the duties of the balloon chief, should this
become necessary.
■ 52. Winch Operators. — Operators selected should be given
theoretical instruction to enable them to understand the
functioning and correlation of the various parts of the winch.
As a first step in practical training and explanation they
should be taught the mechanics of starting, running, and
46
BARRAGE BALLOON
52-54
stopping the winch engine. Intensive practical training in
handling the balloon with the winch and cable should be
started as soon as possible for the purpose of giving the op-
erators experience in handling the balloon under various
conditions of wind and weather. Through practical train-
ing, the operators must learn the best procedure to follow
during emergency conditions, such as how to handle a diving
balloon. Operators must be taught how to maintain the
winch and how to make the repairs they are permitted to
make at the site. Since winch operators also assist the
gas workers, they should have a fundamental knowledge of
handling hydrogen.
■ 53. Chief Gas Workers. — The chief gas workers (sergeants)
should be taught the prescribed methds of —
a. Inspecting and adjusting gas and air valves.
b. Reading manometers, and inspecting and adjusting
manometers and fittings.
c. Preparing and maintaining required records concerning
supply and consumption of gas.
d. Testing gas for purity.
e. Handling hydrogen, including safety precautions and ac-
tion in case of emergency.
/. Handling lethal devices and attaching and detaching
them from the cable.
■ 54. Gas Workers. — a. Inflation and topping-up . — It is im-
portant that gas workers be given sufficient instruction and
drill to make them proficient in the operation of equipment
during inflation and topping-up. They should become espe-
cially familiar with the safety precautions required in han-
dling hydrogen and should be taught to observe these pre-
cautions.
b. Maintaining proper pressure. — The maintenance of pres-
sure within some balloons is of primary importance since ease
of handling these balloons in the air is largely dependent upon
it. It is important that the training of gas workers concern-
ing the use of pressure instruments and the procedure used
in checking pressure be thorough and complete. . Gas workers
should be taught how to improvise a manometer if this be-
comes necessary. They should be taught the prescribed
method of —
47
54-56 COAST ARTILLERY FIELD MANUAL
(1) Attaching and detaching the manometer and taking
readings.
(2) Maintaining proper pressure within the balloon.
(3) Installing and detaching air scoops, air valves, and gas
valves.
(4) Operating and caring for the inflation tube, inflation
manifold, and gas cylinders.
c. Testing gas for purity . — Purity of hydrogen in a bal-
loon must be tested regularly in order to insure that the gas is
not below 85 percent purity. Hydrogen must also be tested for
purity at the time of generation and a purity sample is taken
from each lot of cylinders used for initial inflation. Gas work-
ers must be thoroughly trained in the methods of conducting
the various tests for hydrogen purity and the operation of
equipment involved.
d. Handling lethal devices. — It is the duty of the gas work-
ers to handle all lethal devices at the balloon site and to at-
tach and detach these devices from the cable. They should be
thoroughly trained in the technique of handling lethal devices.
■ 55. Riggers. — Platoon and battery riggers should be trained
in the care and maintenance of all rigging, internal and
external, and the care, maintenance, and patching of balloon
fabric. It is incumbent upon instructors to instill in the
minds of these men the importance of their work. Constant
practice in cordage, fabric repair, and other phases of their
work is necessary for riggers to develop the proficiency
required. Riggers should be taught the prescribed method
of —
a. Determining if a balloon is properly rigged.
h. Making various knots, hitches, splices, and servings.
c. Repairing and maintaining all rigging.
d. Maintaining and patching balloon fabric.
e. Making various types of patches and stitchings.
/. Inspecting rigging and envelope.
g . Forming eyes in and splicing cable.
■ 56. Telephone Operators. — Suggested methods of training
telephone operators are found in FM 4-115, and instruction
in the general procedure for efficient telephone operation as
given in FM 24^-5 should be included.
48
BARRAGE BALLOON
57-61
■ 57. Weather Section. — Personnel of the weather section
must be able to prepare and read weather maps with speed
and accuracy. Constant practice in this type of work is the
chief means for training these men. They must also receive
instruction in methods of operating the various instruments
used in the weather station.
■ 58. Chauffeurs. — While the majority of enlisted men
today have had some experience in driving an automobile,
nevertheless they should first be taught the difference be-
tween a passenger car and the truck they are to operate.
Suggestions for training chauffeurs will be found in PM 4-115.
Care and maintenance of motor vehicles should be included
in the training. Suggestions may be found in PM 25-10.
■ 59. Other Crew Members. — The individual training of
other members of the barrage balloon squad and crew should
include enough practical work in cordage to enable them to
perform efficiently the duties of mooring the balloon and
placing it in flight. If possible, every man should be taught
to operate the winch and telephone and to read the manom-
eter. Every member of a balloon squad will perform duty
as a sentry at the balloon site, and the proper performance
of sentry duty will require that the sentry answer the tele-
phone, receive and record messages, read the manometer,
and often operate the winch. As rapidly as possible, every
man in a balloon crew should be trained to perform all duties
necessary at a balloon site.
Section II
UNIT OR CREW TRAINING
■ 60. Teamwork. — The purpose of unit or crew training is
to develop teamwork in order that the men will be able to
work together efficiently. Teamwork is based on the belief
that the team task can be accomplished, on the knowledge
that the leadership is competent, and in mutual confidence.
■ 61. Method. — If proper individual training has been given,
the most important factor in unit training is practice. Prac-
tice must be provided at regular intervals, and should cover
all the situations the unit is likely to encounter in the field.
49
62 COAST ARTILLERY FIELD MANUAL
■ 62. Security and Protection. — Balloon sites may be sub-
jected to various forms of attack, such as by parachute troops,
mechanized forces, small naval craft, landing parties, and
saboteurs. Balloon squads should be taught to be constantly
on guard against parachute troops and saboteurs. The
ground should be organized for defense at each installation,
and the squads should be taught how the defense is to be
conducted in event of an attack. The squads should also be
given training in defense against mechanized units. (See
PM 5-30, FM 100-5, and Training Circular No. 19, W. D., 1942.)
In the event of a land or airborne attack in force, the defense
plan for the tactical area in which a balloon barrage operates
may provide for the abandonment of barrage balloon opera-
tions and the occupation of ground defense stations by bar-
rage balloon personnel coordinated with respect to other
ground units in the same tactical area. Balloon sites close to
hostile air attack objectives should be provided with shelters
to protect the balloon crews during air bombardment.
50
BARRAGE BALLOON
63
CHAPTER 3
INSPECTIONS
■ 63. General. — a. Barrage balloon inspections are made by
the balloon unit commanders of all ranks or by members of
their staffs. All balloon sites in a battery are inspected by an
officer at least once a week. All sites need not be inspected
the same day, nor is it necessary that a specific day in each
week be set aside for inspection. Such training inspections
as may be desired are conducted concurrently with the bar-
rage balloon inspections.
b. Technical inspections of the condition and functioning
of materiel pertaining to the Ordnance Department, the Sig-
nal Corps, and the Army Air Forces are made periodically by
designated representatives. Battery commanders should fol-
low closely the progress of these inspections, and should bring
to the attention of the inspector deficiencies which cannot be
corrected locally.
c. Tactical and training inspections are a function of com-
mand and are utilized to produce battle efficiency. Tactical
inspections are inspections of the actual solution of tactical,
supply, and communication exercises by tactical units and
individuals. Training inspections comprise observations of
the scheduled drills, exercises, assemblies, and conferences.
Detailed information on tactical and training inspections is
included in AR 265-10.
d. During the training period of a barrage balloon unit, fre-
quent administrative inspections conforming to the provisions
of FM 22-5 and FM 4-120 (with suitable modifications) will
be held.
e. When operating under war conditions, the personnel
comprising barrage balloon units are dispersed and the as-
sembly of units for inspection purposes will be impractical.
However, regularly scheduled formal inspections of sites and
installations must be made to insure high sanitary standards
in connection with latrines, garbage disposal, food handling,
and drinking water; to promote a neat appearance of person-
nel and of their uniforms and equipment; to determine the
state of preservation and thoroughness of maintenance of
51
63-64
COAST ARTILLERY FIELD MANUAL
materiel; and to verify the proper maintenance of records,
reports, and logs.
■ 64. Inspection at a Balloon Site. — a. This paragraph
deals with the formal inspection of the balloon squad and
and balloon materiel at a balloon site. Modification of the
procedure herein outlined may be prescribed by the inspect-
ing officer.
b. During the entire inspection the sentry on duty con-
tinues to perform his regular duties.
c. The balloon squad is formed under arms by the balloon
chief in a single rank, 15 paces in front of the nose of the
balloon and facing the left side of the balloon. On the ap-
proach of the inspecting officer, the squad is called to at-
tention and the balloon chief reports to the inspecting
officer. After the men have been inspected in ranks as
prescribed in FM 22-5, arms are stacked. At the command:
1. Inspection, 2. POSTS, given by the balloon chief, the squad
members take posts as shown in the following table. Assign-
ment of men to positions is made previously by the balloon
chief.
Squad member Post
Balloon chief Accompanies inspecting officer.
Assistant balloon chief. __ Takes post near telephone and
displays records, reports, and
logs.
Chauffeur Takes post at his motor vehicle.
Gas worker Procures the inflation manifold,
inflation tube, and the man-
ometer and displays them for
inspection near the gas cylin-
ders.
One crewman Assists gas worker.
Winch operator Takes post at winch. Removes
winch assembly cover, opens
hood and tool box cover, and
starts winch engine. Procures
blower and places it near the
winch where it may be in-
spected when the winch is in-
spected.
52
BARRAGE BALLOON
64
One crewman Assists winch operator.
Two crewmen Take posts, one on each side of
balloon bed, to perform any
task near the balloon and bed
requested by the inspecting
officer.
Two crewmen Procure and display all service and
repair kits at the balloon site.
Sentry Continues to walk his post.
d. Inspection of quarters, mess facilities, latrines, and other
housekeeping facilities may be made following the inspection
at the balloon site, or the inspection may be made at a
different time.
53
BARRAGE BALLOON
65-66
PART THREE
OPERATION OF MATERIEL
CHAPTER 1
HYDROGEN GENERATING PLANT
Paragraphs
Section' I. Equipment and. operation 65-68
II. Field location 69
ELI. Personnel 70-72
IV. Gas purity 73-74
Section I
EQUIPMENT AND OPERATION
■ 65. General. — Large quantities of inflation gas must' be
made available to the balloon barrage in the field. Barrages
will frequently operate in isolated localities and at great
distances from commercial sources of hydrogen, making sup-
ply from these sources extremely difficult. The use of central
generating plants will generally be found impractical, due
to the amount of transportation required and the time re-
quired to make the inflation gas available to units in the
field. Therefore, each barrage balloon battalion is furnished
with semimobile equipment for gas generation when neces-
sary. Safety precautions to be observed in generating hydro-
gen are discussed in section II, chapter 2. Maintenance and
repair of the hydrogen generating plant are discussed in
paragraph 104.
■ 66. Equipment. — a. General . — The high-pressure hydrogen
generating plant now in use is mounted on a trailer and may
be towed , to its location in the field by a tractor. It is a
self-contained apparatus and is capable of continuous opera-
tion under its own power.
b. Parts of the hydrogen generating plant . — The parts of
the hydrogen generating plant are shown in figure 7.
(1) Generators . — The generators are constructed of drawn
seamless* steel tubing, the outside diameter of which may be
from 14 to 20 inches, and the height of which may be from
6 to 8 feet. Due to the high reaction temperature, the
55
BARRAGE BALLOON
66
generators are equipped with hollow water-cooled heads, and
have water jackets about the walls. Connections are so
arranged that the caustic inlet line, generator purge line,
hydrogen outlet line, and sludge outlet line may be led into
the upper portion of the generator. A removable can, in
which lump ferrosilicon is placed, fits within the generator
so that the generator will not be damaged if the reaction
materials solidify during operation.
(2) Soda mixing tank . — The soda mixing tank is a con-
tainer in which the caustic solution is prepared. In it is
a power-driven agitator which aids in the preparation of the
solution. Beneath the mixing tank, and connected to it^
with proper valves, is a storage reservoir for the caustic
solution. The caustic pump suction line is attached to the
storage reservoir, so that mixing and pumping may be carried
on simultaneously.
(3) Power unit . — The power unit is an internal combustion
gasoline engine. Reduction gears reduce the power take-off
speed to 300 rpm. The clutch is of the friction disk type,
and is hand controlled. The engine supplies power for the
caustic soda tank agitator, cooling fan, water pump, caustic
pump, and a small air compressor. Sufficient power is gen-
erated to run the plant and accessories continuously under
maximum load conditions.
(4) Cooling unit . — The cooling unit consists of steel coils
immersed in water. The hot gas passing through the coils
is reduced in temperature. The water is cooled by a radiator
and power-driven fan.
(5) Caustic pump . — The hydraulic piston type caustic
pump is of high strength steel and is capable of pumping
liquids at a pressure of 3,500 pounds per square inch, although
2,500 pounds per square inch is the maximum pressure en-
countered in the hydrogen generating plant.
(6) Sludge separator . — The sludge separator is a chamber
of extra heavy steel pipe construction. It traps any sludge
which may be carried out of the generator by the hydrogen
gas.
(7) Moisture separator . — The moisture separator is a cham-
ber of extra heavy steel pipe construction. It removes
57
66-67
COAST ARTILLERY FIELD MANUAL
liquids which have been condensed from the hydrogen in the
cooling coils.
(8) Drying cylinder . — The drying cylinder is an extra
heavy steel cylinder filled with potassium hydroxide. It re-
moves all remaining water vapor from the hydrogen.
(9) Hoist . — The generating plant is equipped with a pneu-
matic hoist for removing the generator head and the inside
container.
(10) Water storage tank . — The water storage tank is used
for storing plain water for use in mixing the caustic solution.
(11) Auxiliary water pump. — The auxiliary water pump
is a centrifugal type pump which is used to pump water from
local sources of supply, such as lakes and streams.
(12) Air compressor. — The air compressor is used to com-
press air for operating the pneumatic hoist, operating the
sludge valves, and engaging and disengaging the caustic
pump gears.
(13) Manifold. — The manifold is used for transferring gas
from the generating plant into a number of cylinders simul-
taneously. Empty cylinders can be engaged to the manifold
and full cylinders can be disengaged without shutting off the
flow of gas from the generating plant. The manifold is
equipped with gages for measuring the pressure of the gas
in the cylinders. It is not attached permanently to the
generating plant.
■ 67. Reaction Materials. — a. Ferrosilicon. — (1) Ferrosili-
con is an intimate mixture of silicon and iron, and usually
contains small amounts of other elements as impurities. It
is made in an electric furnace by fusing a mixture of sand,
carbon, and iron or iron oxides, and is hard and brittle. It
may be obtained with varying amounts of silicon, but the
high-pressure hydrogen generating plant uses a mixture con-
taining 85 percent silicon in 2-inch lump size. Ferrosilicon
is shipped and stored in metal containers of 100-pound
capacity.
(2) Ferrosilicon and sodium hydroxide should never be
stored together where there is any possibility that they will
become mixed through the breaking of one or more packages.
Such a mixture would create a fire hazard.
58
BARRAGE BALLOON
67-68
b. Sodium hydroxide err caustic soda. — (1) Caustic soda is
a white solid obtained in flake form for hydrogen generation.
It will absorb moisture from moist air. When it is dissolved
in water, a large amount of heat is produced. Caustic soda
solution is extremely alkaline.
(2) Caustic soda is supplied in metal, airtight containers
of 100- or 400-pound capacity, and should not be exposed to
the atmosphere. Containers should be opened only as the
material is required.
(3) Caustic soda is extremely corrosive, either in the solid
form or in solution. Severe skin burns of blindness may
result from contact with it. Wool and leather clothing is
severely attacked by it.
(4) Caustic soda should always be stored in a dry place
under cover.
c. Water. — (1) Water for the caustic solution may be taken
from any adjacent lake or stream or may be hauled to the
generating plant. A small gasoline-operated water pump is
part of each hydrogen generating plant. A water storage
tank is built in the forward end of the plant.
(2) Water for the cooling system may be obtained from
the same sources as the water for the caustic solution.
Extremely muddy water may tend to clog lines and reduce
pump operating efficiency, and should not be used.
■ 68. Method of Generating Hydrogen. — a. Reaction and
general process. — (1) The ferrosilicon process for producing
hydrogen depends on the reaction between silicon, sodium
hydroxide (caustic soda or NaOH), and water, resulting in
the formation of sodium silicate (water glass) and hydrogen.
The chemical equations for the process are:
2Na0H-bSi+H20=Na2Si03+2H2 (iron acts as a catalyst) ;
and Si+3H20=H2SiC>3-f 2 H 2 (NaOH acts as a catalyst).
(2) The sodium silicate formed by the reaction and the
small particles of iron will settle to the bottom of the genera-
tor, and may be removed by purging the generator through
the purge valve. Sodium silicate, or water glass as it is com-
monly termed, is a heavy, viscous fluid. The greater the
quantity of water contained in the water glass, the more fluid
59
68
COAST ARTILLERY FIELD' MANUAL
the substance. In the absence of water, it becomes very hard
and the later addition of water will not dissolve it.
b. Conditions affecting rate of reactions. — (1) Tempera-
ture. — As the temperature rises, the rate of reaction increases.
Since the reaction itself gives off heat, the total yield of
hydrogen may actually be decreased by a sufficient increase
of temperature; therefore, the temperature is a very important
factor. The heat of the reaction causes the temperature to,
rise at an increasing rate* until it reaches a maximum which
depends on the pressure.
(2) Concentration of sodium hydroxide solution. — The re-
action is slow with a weak solution. As the concentration is
increased, the rate of reaction is increased until a solution of
35 to 40 parts of sodium hydroxide to 100 parts of water is
reached.
(3) Amount of ferrosilicon. — The rate of reaction is di-
rectly proportional to the amount of ferrosilicon present at
any time. The rate of reaction decreases as the ferrosilicon
in the generator is consumed.
(4) Size of ferrosilicon lumps. — The rate of reaction is very
rapid if small particles or lumps are used. If the ferrosilicon
is too fine, the rapid reaction fuses the lumps into a solid mass
that will not be reached by the caustic solution. This mass
may destroy the inner cylinder. If the lump size is too great,
the reaction will not be rapid enough. Maximum size of the
lumps should be 2 inches and the minimum size V 2 inch in
diameter.
(5) Silicon content of ferrosilicon . — The greater the per-
centage of silicon present in the ferrosilicon, up to a maximum
of 90 percent silicon, the greater will be the speed of reaction.
(6) Amount of sodium silicate. — As the reaction proceeds,
the quantity of sodium silicate in the generator increases un-
less it is removed. This sodium silicate will settle to the lower
portion of the generator, and if not removed will retard the
chemical reaction.
c. Operation of high-pressure hydrogen generating plant . —
(1) Charging the generator. — (a) The generator head is re-
moved, and the inside container is filled manually with fer-
rosilicon. The container may or may not be removed from
the generator for this purpose. The head is replaced and all
connections made preparatory to the actual run.
60
BARRAGE BALLOON 68
(b) The caustic soda solution is prepared in the soda mixing
tank. The solution should contain approximately 2.5 pounds
of sodium hydroxide per gallon of water.
(c) Steel hydrogen cylinders are connected to the manifold
for the storage of the hydrogen gas produced.
(d) In order to purge the system of air once operations are
begun, the drain valves beneath sludge separator, moisture
separator, and drying bottles are opened.
(2) Initial steps for operation. — (a) The caustic pump is
placed in operation, with the caustic inlet valve of the genera-
tors open.
(b) The air in the generator is “bled” off through the purge
line by the intermittent “cracking” of the purge valve.
(c) The caustic inlet valve is closed when the solution
covers the f errosilicon. This can be determined by the amount
of moisture given off when the purge valve is opened.
( d ) Water jacket valves are opened to allow the flow of
water about the sides of the generators.
(e) When the generator pressure reaches 2,000 pounds per
square inch, as indicated on the pressure gage, the hydrogen
outlet valve is “cracked” to permit the flow of gas from the
generators through the remainder of the generating plant.
(/) After 15 to 30 seconds of operation, during which time
the system has been purged of air, the drain valves are closed
in the following order: sludge separator, moisture separator,
and drying cylinder.
(3) Hydrogen gas production . — (a) The hydrogen gas out-
let valve is operated so as to maintain a pressure of 2,250 to
2,500 pounds in the generator.
(b) The sludge outlet valve is “cracked” intermittently to
remove the sodium silicate (water glass) formed. The sludge
settling to the lower portions of the ferrosilicon container will
impede or prevent the reaction in that region.
(c) If the pressure falls off, additional caustic solution must
be added. The level of caustic should be maintained at the
dip pipe depth, as determined by “cracking” the purge line
valve.
id) All drain valves in the system should be opened at
approximately 20-minute intervals to remove all accumulated
matter.
61
68
COAST ARTILLERY FIELD MANUAL
(e) Each group of hydrogen cylinders connected to tne
manifold should be filled to a pressure greater than the final
desired pressure, since subsequent cooling of the gas will
reduce the pressure to normal storage pressure. The pressure
to which the cylinders should be filled is determined by the
formula:
where
P'=the pressure to which the cylinders should be filled.
P =the final desired pressure.
T'=the temperature (absolute) of the gas when the
cylinders are filled.
T =the prevailing atmospheric temperature (absolute) .
(/) Operations will be continued until insufficient ferro-
silicon is present in the generator, as indicated by the failure
of the generator to produce sufficient gas to give the required
pressure.
(4) “Blowing down” or shutting off gas generation in order
to recharge the generator . — (a) The valves are adjusted so
that water from the storage tank may be carried by the caustic
pump and line to the generator.
(b) The hydrogen gas outlet valve is closed.
(c) As water is pumped into the generator, the pressure in
the chamber is “bled" through the sludge outlet valve.
( d ) When the generator is filled with water, the water is
allowed to stand so as to dissolve all the remaining sludge
within the generator. The ferrosilicon not consumed is left
in a clean condition and is used again.
( e ) The generator drain valve is opened to allow all water
within the generator to be drained.
(/) The generator head must be removed manually and
preparations begun for recharging.
(gr) If the generator is not recharged, all material left in
the generator should be covered with water to prevent it from
hardening.
(5) General instructions for operations . — (a) The appa-
ratus will usually include two generators, though future
designs may increase that number. Connections are arranged
so that the generators may be operated independently and
simultaneously.
62
BARRAGE BALLOON
68-69
(b) Charging and operation of the generators should be
staggered so that production of hydrogen gas from at least
one chamber will be continuous.
(c) Safety valves are arranged to relieve any excessive pres-
sure which may build up within the system before the strength
limit of the material is reached.
(d) In case of emergency, pressure from either generator
may be released through the sludge outlet, hydrogen outlet,
or generator drain lines.
Section II
FIELD LOCATION
■ 69. General. — a. The high-pressure hydrogen generating
plant, assembled on a trailer unit, will be towed to the
desired location.
b. The actual ground site must be level, within reasonable
limits.
c. Nearby lakes or streams are desirable in order to elimi-
nate the necessity of hauling water for operation.
d. A natural setting which will lend to camouflage is
desirable.
• e . Good transportation facilities must be available, due to
the great quantities of charging materials necessary for large-
scale operations and to the great number of cylinders which
must be moved in and out.
/. The generating plant should be as centrally located as
possible within the units it is to serve.
g . Although it is not absolutely necessary, a 10- by 10- by
10-foot pit should be dug into which the sludge from the
sludge outlet valve may be discharged. Since the sludge
issues from the valve under high pressure, it may spray over
the personnel, generating plant, and nearby buildings and
equipment, unless discharged into a suitable pit. The caus-
tic and sodium silicate contained in the sludge are known
to cause damage to window glass, clothing, and painted sur-
faces. The sludge from the sludge outlet valve may be
led into the pit by means of a pipe furnished with the
generating plant, or by an improvised shield made of sheet
metal.
63
70-72
COAST ARTILLERY FIELD MANUAL
Section in
PERSONNEL
■ 70. Selection. — Men to operate the high-pressure hydro-
gen generating plant should be carefully chosen. Those
chosen must be familiar with the handling of tools, and must
be technically inclined so as to readily acquire knowledge
of the operations. They should not be afraid of working
about a high-pressure and high-temperature apparatus, but
should respect the danger that may be present if the equip-
ment is improperly handled.
■ 71. Size of Crew. — A crew sufficiently large to operate a
high-pressure hydrogen generating plant with two reaction
chambers consists ordinarily of eight men. A crew will be
able to operate the plant for a shift of 8 hours. If the plant
is operated only during the hours of daylight, and sufficient
men are available, it is recommended that the daylight period
be divided between two shifts. Three crews will be needed
to, operate the plant on a 24-hour basis. Duties of the crew
members will include —
a. One man per generator (two to a plant) to handle the
caustic inlet valve, sludge outlet valve, and hydrogen outlet
valve.
b. One man to mix the caustic solution and maintain a
constant supply of the solution on hand.
c. One man in charge of the power plant, caustic pump,
and all connecting apparatus.
d. Two men to connect empty hydrogen cylinders to the
manifold for filling, to disconnect filled cylinders, and to test
the valves for leakage by applying soapy water with a brush.
e. Two relief men who will be capable of taking over any
job on the apparatus as well as aiding where help is needed.
■ 72. Equipment for Personnel. — a. Tools. — A complete set
of tools, including crescent, socket, pipe and special wrenches,
pliers, hammers, etc., will be furnished with each apparatus
and must be stored in the case provided. Since certain tools
are specially designed for the hydrogen generating plant
and are not in the normal line of supply, extreme care must
be taken to prevent loss or damage to them.
64
BARRAGE BALLOON
72-74
b. Spare parts. — Each battalion should maintain in the
field an assortment of spare parts, including high-pressure
valves, bolted flange unions, bolts, nuts, and any parts which
operation experience proves to be necessary.
c. Clothing. — (1) Each man will be provided with non-
woolen coveralls, or some like garment on which there are
a minimum number of flaps which might snag on the
equipment.
(2) Each man will wear rubber footgear, preferably rubber
overshoes or boots.
(3) Each man mixing the caustic solution will be provided
with rubber gloves, the length of which will be sufficient to
protect his wrists and lower forearms.
(4) Each generator operator will be provided with extra -
heavy canvas gloves.
(5) All remaining personnel will be provided with canvas
gloves.
(6) All personnel will wear close-fitting hats or caps to
eliminate scalp irritation from caustic fumes.
(7) All personnel will be provided with goggles, which must
be worn whenever the plant is in operation. This rule must
be stressed, because all operators have a tendency to remove
goggles whenever possible, contrary to instructions.
Section IV
GAS PURITY
■ 73. General. — Gas must be tested for purity in order to
determine its lifting power. The purity of hydrogen gas in
a balloon must ordinarily be checked daily in order to insure
that an explosive mixture is not present. Each crew or shift
operating the hydrogen generating plant must check the
purity of gas produced at least once during the shift. Several
methods for testing gas purity have been devised. The prin-
ciples of these methods are discussed below.
■ 74. Methods of Determining Gas Purity. — a. Army effu-
sion method . — The Army effusion apparatus is an apparatus
for determining the difference in time- required for equal vol-
umes of air and the gas tested to pass through an orifice
under the same pressure. The ratio between the air time and
65
74
COAST ARTILLERY FIELD MANUAL
gas time is determined, and from that the purity (for hydro-
gen) may be found in the chart in TM 1-315. A detailed
description of the method of operating this apparatus may be
found in TM 1-315.
b. Absorption method , using alkaline pyrogallol . — Alkaline
pyrogallol will absorb the oxygen from a mixture of hydrogen
and air. To make this test a certain volume of hydrogen
is exposed to alkaline pyrogallol. When the oxygen is com-
pletely absorbed, the volume remaining is measured. The de-
crease in volume is equal to the volume of oxygen originally
present. A detailed description of the apparatus required
for this test and the method of operation may be found in
TM 1-315.
c. Absorption method , using ammonia-copper solution . —
The principle for this method is the same as described above,
except for the absorption medium. A detailed description
of the method may be found in TM 1-315.
d. Other methods. — Other methods of testing gas purity,
which make use of other physical or chemical properties of
the gas involved, are now being considered and may be
adopted as experience shows their capabilities.
BARRAGE BALLOON
75
CHAPTER 2
SAFETY PRECAUTIONS IN MANUFACTURING AND
HANDLING HYDROGEN
Paragraphs
Section I. General 75-76
II. Manufacture ‘ 77
III. Handling, storing, and transporting cylinders 78-80
IV. Inflation 81
V. Deflation 82-83
VI. Typical accidents 84
Section I
GENERAL
■ 75. Characteristics of Hydrogen. — a. Hydrogen gas is
colorless, odorless, and tasteless and cannot be distinguished
from air except when containing impurities which may give
it a slight odor or color. An element of danger is always
present with hydrogen gas because of its inflammable and
explosive nature when mixed with oxygen or air. Hydrogen
is very inflammable under all conditions encountered in prac-
tice, and is easily ignited. Ignition may be caused by an
open flame, static sparks, sparks from the use of ferrous
metal tools, heated exhaust pipes or manifolds of gasoline
engines, etc. The hydrogen flame is intensely hot and when
burning at moderately low pressure is pale blue or colorless
arid rather difficult to see, especially in the sunlight. When
the gas is burning at relatively high pressure, the flame be-
comes yellow because of the heating of particles of sodium
always present in the air, and not because of the intrinsic
properties of the flame. Under certain conditions, mixtures
of hydrogen and oxygen or hydrogen and air, when ignited,
are very explosive. The explosion is caused by the rapid
propagation of the flame through the mixture, no additional
oxygen being necessary to support the combustion of the
hydrogen in the mixture.
b. Air alone contains sufficient oxygen, to produce an ex-
plosive mixture in a hydrogen-filled balloon when the purity
is lowered to 74 percent. Diffusion of oxygen through balloon
fabric is more rapid than that of nitrogen. Therefore, if a
67
75-76
COAST ARTILLERY FIELD MANUAL
balloon has been inflated for some time and the only source
of impurities is diffusion through the fabric, the percentage
of oxygen in the balloon is likely to be high. To allow for
this oxygen enrichment, it is recommended that hydrogen-
filled balloons be deflated when the purity is lowered to 85
percent.
c. The bases for most precautions when using hydrogen
are —
(1) To keep sources of ignition a safe distance away from
any volume of hydrogen regardless of its purity.
(2) To keep the purity of any volume of hydrogen used
above explosive limits.
d. While an absence of accidents is likely to give a false
sense of confidence, it is impossible to be too careful and the
necessary precautions must always be observed.
■ 76. Ignition.— a. Prevention . — A certain amount of im-
purities is present in the balloon at all times, and therefore
the danger of fire or explosion may be present. The following
general fire-preventive measures should be observed at the
balloon bed, hydrogen generating plant, hydrogen cylinders,
and nurse bags:
(1) No fire or other source of ignition must be permitted
within a distance of 150 feet. The winch should not be
operated within 150 feet of a hydrogen-filled balloon.
(2) A specific smoking area should be designated at a
distance of at least 150 leet away.
(3) The sentry on duty should at all times enforce fire
prevention regulations!
(4) Signs should be erected to denote the limits of the
danger and smoking areas.
(5) All animals should be kept away from installations as
a precaution against static electricity.
(6) Wool outer clothing should not be worn by members
of a balloon crew, gas generating detail, or cylinder handling
detail, since the wool may create static sparks capable of
igniting the hydrogen. If wool clothing is worn, cotton
coveralls should be worn as an outer garment. Cotton caps
or some other head coverings should be worn.
68
BARRAGE BALLOON
76-77
(7) Extreme care must be exercised during inflation,
topping-up, and deflation of the balloon, as during these
maneuvers the danger of igniting the hydrogen is increased.
b. Action in case of fire . — In case of fire at a balloon site
or other installations listed above, the following action should
be taken:
(1) The person who first observes the fire will call: FIRE.
Other persons in the vicinity will repeat the call until it is
certain that all are aware of the fire.
(2) All gas cylinder valves will be closed immediately.
(3) If, in the judgment of the balloon chief or other man
in charge, it is possible to extinguish the fire, he will order
all available men to combat the blaze.
(4) If at any time, in the judgment of the balloon chief
or other man in charge, personnel will be seriously en-
dangered by remaining at the site, he will order all personnel
out of the danger zone by the command: ABANDON SITE.
Other personnel will repeat the command until it is certain
that all are aware of the order.
(5) When the site is ordered abandoned, everyone should
clamp his hand over his nose and mouth if there is a pos-
sibility of breathing in flames, close or cover his eyes if this
does not interfere with getting away, run at least 100 feet,
fall forward, and crawl on his stomach until out of the
danger zone.
(6) If burning fabric falls upon him, an individual should
roll over and over in order to remove the fabric or put out
the fire. If he attempts to remove the burning fabric with
his hands he is likely to damage his hands and fail to remove
the burning fabric.
Section n
MANUFACTURE
■ 77. Precautions. — The following precautions should be ob-
served in operating the high-pressure hydrogen generating
plant, and in handling materials and equipment used in
hydrogen generation:
a. Air should be flushed from the generator and lines at
the start of operation and before any gas is used, by opening
69
77
COAST ARTILLERY FIELD MANUAL
the drain valves beneath the sludge separator, moisture sep-
arator, and drying* bottle.
b. Care must be exercised to keep all joints and connections
gastight.
c. A careful periodic check must be made for leaks in all
lines by applying a soapy water solution with a brush. A
match should never be used to test for leaks.
d. Men working at the generating plant should be protected
by goggles, rubber gloves, and preferably by rubber clothing.
They should wear rubber-soled shoes. It is advisable for
the men to rub a light coating of boric acid ointment on
their hands and faces.
e. White lead, red lead, or any materials containing linseed
oil should not be used in making repairs to the generator.
Glycerin and litharge mixed to the consistency of a thin
paste should be used.
, /. Ferrosilicon should be shipped in airtight drums and
stored in dry, well-ventilated compartments.
g. Ferrosilicon and sodium hydroxide should not be stored
together in such a way that a mixture may result from
damaged or broken containers,
h. Tests for the purity of the hydrogen produced should
be made at least once by each shift working at a generating
plant.
| i. If generation is carried on indoors the building should be
well ventilated. The engine should be provided with a flame
arrestor on the exhaust system and rubber caps on the
spark plugs and ignition system to avoid the possibility of
Igniting any hydrogen- air mixture which may exist within
the building. To avoid producing sparks, all personnel using
tools on metal equipment should be warned not to strike
metal to metal. Brass, or other nonsparking tools should
be used.
1 ' j. A first-aid kit containing plenty of absorbent cotton,
boric acid ointment, and a saturated solution of boric acid
should be kept at the generator. Vinegar or acetic acid may
also be supplied. This kit should be inspected at least once
each week and contents replenished if necessary. A bucket
of clear water should also be kept on hand.
70
BARRAGE BALLOON
77-79
k . Caustic that gets on the skin or clothing of individuals
operating the hydrogen generating plant should be removed
immediately with clear water, either by submerging the
affected area in water or dousing it with water. The skin
and eyes should then be treated with boric acid solution.
Vinegar or acetic acid may be used on the skin, but should
not be used in the eyes. The affected area should not be
rubbed. Persons with eye burns should be taken to the
hospital immediately for treatment to prevent adhesions.
l. A carbon dioxide type fire extinguisher and a supply of
sand should be available for use in case of fire.
m. Before an attempt is made to repair a high-pressure
line, the pressure should be removed from the line.
Section III
HANDLING, STORING, AND TRANSPORTING
CYLINDERS
■ 78. Identification of Cylinders. — a. Army hydrogen cyl-
inders are painted with a standard olive drab paint, or are
galvanized, with the neckbands and caps painted olive drab.
The word HYDROGEN is painted on the cylinder body.
b. All Navy hydrogen cylinders are painted black with a
white band around the middle.
c. Commerical hydrogen cylinders are usually painted black.
Sometimes, though very rarely, they are painted red.
■ 79. Precautions. — In handling gas cylinders the following
precautions will be observed:
a. Because of high pressure, cylinders must always be
handled with care. They should never be dropped or sub-
jected to heavy jars. This also applies to empty cylinders.
Dangerous, or even fatal accidents easily result when high-
pressure cylinders receive heavy or sudden jars or blows.
b. Cylinders will never be exposed to fire or heat. They
should- be protected from the direct rays of the sun if the
temperature is above 90° P. by means of suitable covering,
such as a tarpaulin or foliage.
c. The valve protecting cap will be kept in place at all times
except when inflation is in progress or when the cylinders are
being filled.
71
79 COAST artillery' field manual
d. Standard size gas cylinders should always be handled by
two men. One man should handle each end of the cylinder,
and they should avoid striking the cylinder caps and possibly
causing a leakage of gas or an explosion.
e. Cylinders will be stacked in groups of not more than
60 cylinders, and not more than 6 tiers high. Groups should
be not less than 10 feet apart.
/. The cylinders will be stacked upon dunnage. , Each cyl-
inder of the bottom row should be securely chocked with wood
blocks so that no rolling or sidewise movement is possible.
p. Each stack of cylinders will be grounded at all times.
This is done by grounding s an uninsulated copper wire which
is placed between the first and second tier of cylinders while
the cylinders are being stacked.
h. As the cylinders are stacked, the valve outlets will be
pointed downward with all the valves on the same side of the
stack.
i. In order properly to connect the inflation manifold hose
to the valves of the bottom tier of cylinders, a trench 6 inches
wide and 6 inches deep will be dug directly underneath the
line of valves; or the bottom row may be stacked with the
valves pointed to one side.
j. When preparing to discharge a cylinder, all connections
and joints will be cleaned of dirt, grit, and foreign materials
with a brush before making the connections. Care should be
exercised to see that all joints are gastight.
k. Cylinder valves will be opened slowly and progressively
to prevent them from being clogged (frozen) because of accu-
mulated frozen moisture, and to guard against flash firing
of small particles of foreign matter which may have accumu-
lated in the valve opening.
l. When the gas is exhausted from a cylinder, it will be
labeled at once by means of the letters MT marked with
crayon or chalk.
m. The cylinder valve of an empty cylinder will be kept
closed to prevent air from entering the cylinder.
n. The valve of a gas-filled cylinder will not be opened
unless it is attached to a manifold hose or a pressure gage,
or unless it is necessary to discharge a damaged cylinder.
72
BARRAGE BALLOON
79-80
o. Any cylinder which fails to discharge, is exposed to fire,
dented by rough handling, or suspected of being defective
will be marked DEFECTIVE and returned, together with a
full explanation.
p. Repairs to valves will not be made in the field. Tighten-
ing of the gland nut to prevent leakage is permissible. Any
valve which cannot be opened by hand will be marked DE-
FECTIVE and the cylinder returned. A wrench will never
be used on a valve.
q. Cylinders will be tested for leaks immediately after
charging, and on every occasion when the valve is opened
and closed without completely discharging the cylinder. The
method of testing for leaks is to apply soapy water plenti-
fully with a small paint brush to the gland of the valve
stem, the gas outlet, the valve body and safety plug, and
where the valve screws into the cylinder.
r. If leakage is found at the gas outlet the cylinder will
be connected to a manifold and the valve opened and closed
rapidly. A quick partial turn is all that is required. If
the above action does not stop the leak, the cylinder should
be discharged into a balloon as soon as possible.
s. If leakage is found where the valve body screws into
the cylinder, the leaky cylinder will be discharged into a
balloon as soon as practicable. No attempt should be made
to tighten the valve body.
f. If, as a result of an accident, the condition of a cylinder
is considered dangerous, and a gas service officer is not imme-
diately available to inspect it, the cylinder will be grounded
and discharged into the open air by partially opening the
valve.
u. In case of fire, carbon dioxide extinguishers will be used.
Ordinary fire extinguishers will not extinguish hydrogen
issuing under high pressure.
■ 80. Storing and Transporting Cylinders. — Cylinders will
be stored in a shed that has free ventilation. This prevents
the accumulation of hydrogen in the event of a leaky valve.
When cylinders are shipped by railway car, motor truck, or
boat they should be securely chocked to prevent undue mo-
tion, and should be placed in well- ventilated compartments.
Hydrogen will not be shipped in closed boxcars.
73
81-82 COAST ARTILLERY FIELD MANUAL
Section IV
INFLATION
■ 81. Precautions. — The following precautions should be ob-
served when inflating a balloon with hydrogen gas:
a. The ground cloth and inflation tube should be thoroughly
wetted.
b. All air must be completely exhausted from the balloon.
c. All connections in the inflation system from the gas
cylinders to the balloon must be inspected for leaks before
the inflation starts.
d. The inflation tube should be rolled up to force out all
air, attached to the manifold, rolled out flat, and attached
to the balloon appendix. The appendix should not be twisted
when the thimble and inflation tube are attached.
e. When inflation starts, each gas cylinder valve should be
opened very slowly until there is a good flow of gas. Before
removing a manifold hose, the valve should be opened fully
to make certain that all gas is exhausted from the cylinder.
/. The inflation tube must not be allowed to become kinked
or twisted while a balloon is being inflated. If there is a
wind, the tube should be secured to stakes.
g. The electric bonding must be grounded during inflation.
h. When inflation is completed, the appendix must be tied
off before the inflation tube and thimble are removed.
i. If inflation takes place inside a building, ample ventila-
tion must be provided.
j . All precautions to prevent igniting the hydrogen gas
must be observed.
Section V
DEFLATION
H 82. General. — When the purity of hydrogen within a bal-
loon falls below 85 percent, the balloon must be deflated.
Except when rain is falling or the ground is wet from rain,
dew, or surface water, deflation should take place between
sunset and sunrise. Balloons that do not have a valve at
the tail are normally deflated by pulling the rip cord. Bal-
loons having a valve at the tail are deflated by removing
the valve and allowing the gas to escape through the valve
74
BARRAGE BALLOON
82-83
orifice. During this operation, the nose of the balloon should
be held down so that the orifice is always at the highest
point on the balloon. Balloons having a valve in the side
of the envelope near the tail may also be deflated by this
method. The orifice is kept at the highest point by rolling the
balloon on its side as deflation progresses.
■ 83. Precautions. — The following precautions should be ob-
served when deflating a hydrogen -filled balloon:
a. Ground cloths and the surface of the balloon around
the rip panel, or around the valve, must be wet down before
the deflation starts.
b. Electric bonding should be grounded before deflating.
c. More than one opening at a time should not be permit-
ted in a balloon that is being deflated, as more than one
opening will permit a surge of air through the balloon, and
a dangerously explosive mixture of hydrogen and air will
result.
d. When deflating a balloon through the valve orifice, a
wet blanket or other large cloth should be held over the valve
while it is being removed. A wet cloth is then inserted into
the orifice so as to hang approximately half in and half out
of the balloon, and left there until the balloon is completely
deflated.
e. Caution should be used when rolling -up a deflated bal-
loon because of the danger of gas pockets in folds of the
fabric. All gas must be removed from the folds of the fabric.
/. No attempt should be made to hasten deflation by walk-
ing on the fabric.
g. All equipment and all personnel not required for the de-
flation will be not less than 200 feet up wind from the balloon
bed.
h. All engines within 200 feet of the balloon should be
stopped, and all precautions to prevent igniting the hydrogen
gas should be observed.
i. Under no conditions should the blower be attached to
the appendix to deflate a hydrogen -filled balloon.
75
84
COAST ARTILLERY FIELD MANUAL
Section VI
TYPICAL ACCIDENTS
■ 84. General. — a. An observation balloon was deflated in
a tent hangar. While some of the crew were rolling the
balloon, other men walked on the balloon in woolen socks,
pushing little, pockets of gas toward the valve opening with
their feet. Result — an explosion. Three men were killed, 30
men were hospitalized for severe burns, and the balloon and
hangar were destroyed.
b. To hasten the deflation of a free balloon, the appendix
and valve were both opened at the same time. A little pop
was heard, and then a flame rapidly consumed the balloon.
c. During inflation a man crawled under a balloon to
straighten the appendix. As he touched the metal thimble
a spark jumped from his hand to the thimble, causing a fire.
d. One man dropped a full hydrogen cylinder while moving
it. The valve was snapped off. The cylinder thrashed
around crazily, finally plunging through a wood wall.
e. A machinist removed the cap from the check valve of
the caustic pump on a hydrogen generator while pressure
was on the line. The check valve in the main line gave way,
causing caustic to be blown into the face of the machinist.
/. A workman tapped a high-pressure gas cylinder with a
hammer in passing. The cylinder exploded, killing the
workman.
76
BARRAGE BALLOON
85 - 8 ?
CHAPTER 3
HELIUM PURIFICATION PLANT
■ 85. General. — Since the supply of helium is limited, it will
not ordinarily be used to inflate balloons in a barrage.' How-
ever, it is used to inflate balloons used for training purposes.
Diffusion of air through the balloon fabric reduces the purity
of helium in a balloon, thereby decreasing the lift. When it
becomes necessary to deflate a helium-filled balloon, due to
low gas purity and insufficient lift or other reasons, the helium,
is purified and reclaimed through the use of a helium purifica-
tion plant. Hydrogen-filled balloons of low gas purity are
deflated by allowing the gas to escape into the atmosphere,
and no attempt is made to reclaim the hydrogen.
■ 86. Principles of Helium Purification. — The principal im-
purities likely to be found in helium gas are oxygen and nitro-
gen. Oxygen, nitrogen, and helium will liquefy at —182°,
— 196°, and' ^268° C., respectively, at the pressures developed
in the helium purification plant. Therefore, the oxygen and
nitrogen may be liquefied and drained off, leaving the purified
helium. The helium purification plant contains an air cycle
and a helium cycle. The purpose of the air cycle is to produce
liquid air, which in turn produces a sufficiently low tempera-
ture to liquefy the oxygen and nitrogen impurities. The pur-
pose of the helium cycle is to provide means for separating
the impure helium into liquid impurities and gaseous purified
helium, and for removing the impurities.
■ 87. Helium Purification Plants. — Two types of helium
purification plants are now in use. One type is mounted
on a railway car, and is referred to as helium purification
plant, car No. ( ). Car No. 1, now in use, is capable of;
purifying 5,000 cubic feet of helium per hour. The other typer
is mounted on a trailer, and is referred to as mobile helium
purification laboratory, type B-l (originally type A-3). This,
laboratory is capable of purifying 1,500 cubic feet of helium
per hour. An explanation of the principles of operation of
these plants and instructions for operation may be found in
A. C. Technical Order No. 16-1-5, December 1, 1941.
77
88
COAST ARTILLERY FIELD MANUAL
■ 88. Personnel. — a. Helium purification plant , car No. 1 . —
The recommended size of crew for operating this plant is six
enlisted men, including the technical sergeant who is in charge
of the operation. The other five men are employed as follows :
one man to operate the air compressor, one to operate the
helium compressor, one to operate the control panel, and two
men to attach the source of impure helium to the helium
compressor and to attach the manifold to cylinders for' col-
lecting the purified helium. Due to the heat in the air com-
pressor room, the air compressor operator may alternate with
the helium compressor operator, or may be relieved by the
sergeant in charge.
b. Mobile helium purification laboratory , type B-l. — The
recommended size of crew for operating this laboratory is
seven enlisted men, including a technical sergeant who is in
charge of the operation. The other six men are employed as
follows: one man in the compressor room to operate the air
and helium compressors, one man to operate the control panel,
two men to attach the source of impure helium to the helium
compressor and to attach the manifold to cylinders for col-
lecting the purified helium, and two men to handle the helium
cylinders. Due to the heat in the compressor room, the
compressor operator may alternate with the control panel
operator, and may also be relieved by the sergeant in charge.
78
BARRAGE BALLOON
89-90
CHAPTER 4
AIR INFLATION, INSPECTION, AND DEFLATION
■ 89. General. — Before a balloon Is delivered to a balloon,
site for use, it must be air inflated and inspected. Air infla-
tion and inspection is ordinarily accomplished by the service
platoon of the barrage balloon group or separate battalion.
Initial gas inflation of a balloon is ordinarily accomplished at
the balloon site, and should not be attempted unless the bal-
loon has been previously inflated, inspected, and repaired if
necessary. Instructions covering gas inflation and deflation
at the balloon site may be found in PM 4-108.
■ 90. Air Inflation. — a. Facilities and equipment needed . —
If possible, the balloon should be air inflated and inspected
inside a building of suitable size and accessibility. If a suit-
able building cannot be obtained, the air inflation may be ac-
complished in the open on a balloon bed in a central and
easily accessible location. Equipment needed for air inflation
includes an inspection lamp, blower, inflation tube, and thim-
ble and elastic tie-off cord. An auxiliary lighting unit is also
needed if no other source of electricity is available.
b. Procedure. — (1) In the discussion that follows, it will be
assumed that the inflation is conducted in the open. The
balloon box is placed on the down-wind side of the bed at the
edge of the ground cloth. The ground cloth must be care-
fully swept. The top of the box is removed, the canvas liner
is laid back, and the waterproof container opened. The box
is then turned over on the side, so that the top of the box
faces the bed. Crew members from opposite sides then care-
fully grasp the fabric at intervals of a few feet and carry the
balloon onto the bed. The lobes, fins, and folded fabric are
spread so that the balloon lies flat on the bed. All parceling
is removed from the ropes and fittings and saved for
rewrapping.
(2) After the balloon is unfolded and parceling removed,
the crew members extend the mooring and handling lines to
the sides and attach sandbags to them. The air blower is pro-
cured, inspected, and given a test run. The gas and air valves
79
90-91
COAST ARTILLERY FIELD MANUAL
are procured and installed. The inflation tube is attached to
the appendix and to the blower by means of thimble and
elastic tie-off cords. Riggers inspect the external rigging, as
described in paragraph 91. Crew members place a row of
sandbags across the envelope one-third of the balloon length
away from the appendix in order that the balloon being in-
flated may be more easily controlled. If sandbags are not
available, a number of crew members with shoes removed
may be directed to stand on the balloon, or a rolled-up ground
cloth may be used. Crew members who will walk on the bal-
loon fabric must remove their shoes or wear special shoe cov-
erings prescribed by standing operating procedure to prevent
damage to the fabric.
(3) After preparations for air inflation are completed, the
air blower is started. Care should be used to insure that fumes
from the engine exhaust are not sucked into the fan and blown
into the balloon. As the inflation proceeds and air fills the
envelope, crew members move the sandbags placed across the
balloon away from the appendix. Sandbags are attached to
the first bridles or to the catenary curtain grommets as in-
flation proceeds. The crew members adjust the handling and
mooring lines on their respective sides of the balloon, and
when inflation has proceeded to a point where sandbags at-
tached to the lines are being dragged along the ground, crew
members will be directed to tie the handling and mooring
lines through the screw picket eyes. When a balloon is air
inflated inside a building, it is not necessary to hang sandbags
on the bridles or catenary curtains, or to tie down the
handling and mooring lines.
(4) Inflation will proceed until the entire balloon and gas-
inflated fins are well filled. The inflation tube is disconnected
from the appendix and the appendix is closed. In the case
of a ballonet balloon, the air chamber must be filled with suf-
ficient air to allow an inspector to move about under the
diaphragm. The air chamber is not inflated until after the
gas chamber has been air inflated and inspected.
■ 91. Inspection. — a. Initial external inspection. — While the
balloon is being air inflated, the riggers will inspect all seams
and finger patches on the outside of the balloon for signs of
defective cementing. All of the rigging is also inspected to
80
BARRAGE BALLOON
91
see that the balloon is properly rigged according to the manu-
facturers’ specifications, or according to marks locating the
^positions of the knots on the rigging. All splices and serv-
ings are inspected for imperfections. Fabric will be inspected
for signs of chafing by the rope rigging, which may have
occurred while the balloon was packed.
b. Initial internal inspection . — This inspection is conducted
by the riggers for the purpose of locating any holes or tears*
in the balloon envelope and fins. One or more riggers enter
the balloon through the appendix with an inspection light.
When the light is turned off the inspector will be able to locate
all holes in the fabric upon a thorough inspection of the
interior. If the balloon is inspected inside a building it will
be necessary to use a bright light on the outside of the
envelope and each panel must be inspected carefully. The
inspector will mark each hole by circling it with a red pencil
or chalk. The entire envelope is inspected in this manner.
The balloon may be turned over on its side for inspection of
the bottom. The fins are inspected from the inside through
an opening between the envelope and fins. Care must be
exercised by the men in the balloon, so that the fabric will
not be damaged. They must enter the balloon with their
shoes removed, or wear special shoe coverings, prescribed by
standard operating procedure. All of the patches made as
a result of the original inspection are made on the inside
of the envelope.
c. Inspection of ballonet diaphragm. — One rigger will enter
the gas chamber with an inspection light and another rigger
will enter the air chamber. By prearranged plan, the in-
spectors will progress from one end of the diaphragm to the
other. When a hole or tear is found, the inspector under
the diaphragm will hold his finger against the diaphragm at
that point, while the other rigger will circle the spot with
red pencil or chalk.
d . Inspection for storage . — The balloon will be air inflated
and inspected as described above. The fabric will be cleaned
of all foreign matter and oil. Benzol will be used to remove
oil from neoprene-treated fabric. An excessive amount
should not be used, as benzol may damage the seams. Fab-
ric must be thoroughly dried, and it is advisable to sprinkle
81
91-93 COAST ARTILLERY FIELD MANUAL
talcum powder on the envelope if it is believed that the storage
will be of long duration. All rope rigging will be carefully
inspected, and any worn or damaged ropes will be replaced.
All dirt or foreign matter will be removed from the ropes,
and they must be thoroughly dried.
■ 92. Air Deflation. — I f the balloon is to be deflated by man-
power, the valves are first removed. The appendix is then
held open and the crew members roll the entire envelope up
tightly toward the appendix, while the lines are released
from pickets as deflation proceeds. If an exhauster is used,
a metal tube is attached between the appendix and the
exhauster. The balloon is deflated and lies spread upon
the bed.
■ 93. Packing. — After the balloon has been deflated the parts
of the rigging that may damage the fabric are wrapped in
parceling cloth. All handling and mooring lines are properly
coiled and tied. Starting from the tail, the balloon is folded
and is placed in the packing case. When placing the balloon
in the case, the balloon should be lifted and not dragged over
the edge of the case, so the fabric will not be damaged.
The metal parts are replaced in their original packings and
securely fastened. The canvas and waterproof packing are
folded over the balloon and the waterproof packing is
cemented shut. The top of the case is screwed on tightly.
82
BARRAGE BALLOON
94-95
CHAPTER 5
TRANSFERRING HYDROGEN FROM ONE BALLOON TO
ANOTHER
■ 94. General. — The following instructions for transferring
hydrogen from one balloon to another are to be complied with
whenever it is necessary to deflate one balloon and inflate
another at the same site. This operation should not be under-
taken in high winds and should be done only when the purity
of hydrogen is 90 percent or more. In the following instruc-
tions, the balloon to be deflated is referred to as A and the
one to be inflated as B.
■ 95. Procedure. — In dry weather this operation should be
done between sunset and sunrise. The ground cloths ' and
the junctions of the inflation tubing are liberally wet down.
The purity of the gas in A is taken. If the purity is 90
percent or more, the procedure is as follows:
a. A is transferred to a temporary screw picket bed just
ahead of and to the windward of the permanent bed so that
A lies with the nose into the wind and affords some protec-
tion to B during the first stages of inflation. If possible, A
should be placed on lower ground than B to assist inflation.
On very inclosed sites, A may be placed on either side of
and parellel to B. The air-inflated stabilizers of A are furled.
A is trimmed so that the end of the balloon containing the
inflation appendix is as high as possible on the bed.
b . B is laid out on the permanent bed with the nose into
the wind and prepared for inflation in the usual way.
c. The inflation appendixes of A and B are connected by
inflation tubing, usually two lengths. All junctions should
be securely tied to prevent leakage. The junction of the two
inflation tubes should be grounded by a grounding rod at-
tached to the metal thimble. For this purpose one end of a
copper wire may be inserted between the thimble and the
tube, and the other end of the wire attached to a rod or pipe
driven into the ground.
d . If A is of the ballonet type the air should be exhausted
from the ballonet.
83
95
COAST ARTILLERY FIELD MANUAL
e. Sandbags are to be hung from the catenary curtain of
A, starting from the end of the balloon opposite the inflation
appendix.
/. When A has been deflated to a point where the pressure
within the balloon is no longer sufficient to force gas into B,
crew members commence rolling up A, starting at the end
opposite the inflation appendix. They should roll the balloon
as tightly as possible, and take care not to allow gas to blow
back into the rolled portion. As the balloon is rolled up,
handling and mooring lines are released as reached.
g. When B starts to inflate, the gas entering the balloon is
controlled by placing a row of sandbags or a rolled-up ground
cloth across the envelope. The sandbags or ground cloth are
gradually moved away from the inflation appendix as inflation
progresses.
h. Throughout the process of rolling up A } the inflation
appendix should be kept as high as possible above the ground
to prevent the appendix or inflation tube from being kinked
or twisted.
i . When A is sufficiently deflated, 12 to 14 men are distrib-
uted around the balloon and the remaining gas is expelled
by folding inward from all sides toward the inflation appendix.
j. When all gas has been transferred, the inflation appendix
of B is tied off and a purity reading is taken. If B is a
pressure-type ballonet balloon, the ballonet is filled with air.
B is topped-up if necessary.
84
BARRAGE BALLOON
96-98
CHAPTER 6
MAINTENANCE AND REPAIR
■ 96. General. — Minor repairs to barrage balloon materiel
may be made at the balloon site by the balloon squad under
supervision of the platoon rigger. Major repairs to cable,
rigging, fabric, winches, hydrogen-generating plants, and
automotive equipment are made by the service platoon of
the barrage balloon group or separate battalion.
■ 97. Cable. — Steel cables must be inspected frequently for
signs of rust, corrosion, broken wires, or chafed surfaces.
Rust must be removed. When a cable shows signs of corrosion
or chafing at the cable terminal assembly, a sufficient length
must be cut from the end of the cable to allow an unworn
portion of the cable to be inserted in the assembly. Cables
will ordinarily be protected by a light coating of oil, or by
other cable preservatives which may be tested and approved
from time to time. Cables which are likely to be exposed to
salt water should be impregnated with a mixture of linseed
oil and lampblack, or with any other tested and approved
mixture which will serve to prevent corrosion. The ad-
miralty splice is used in splicing balloon cable. The proper
method of making this splice is described in Army Air Forces
Specifications No. 98-25515.
■ 98. Cordage. — a. Maintenance. — Ropes will be inspected
frequently for signs of wear, and will be replaced if necessary.
Exposure to rain and frost causes ropes to deteriorate. When-
ever possible, wet ropes should be laid out in such a manner
as to insure rapid drying. Frozen ropes break easily, and
should not be used until they have been thawed out. Rope
which has been exposed to water or to the elements should
be thoroughly dried before it is stored. Ropes should be kept
free from sand and grit, and should not be permitted to come
in contact with acids. Broken or deteriorated ropes are
replaced with new ropes when available.
b. Repair . — Broken ropes are repaired by splicing if neces-
sary. Either a short or long splice may be used, but a short
85
98-100 COAST ARTILLERY FIELD MANUAL
splice will result in an enlargement of the rope at the point
of the splice.
■ 99. Fabric Maintenance. — Great care must be taken to
prevent damage to balloon fabric. It should not be allowed
to come into contact with sharp or uneven surfaces, and
should not be allowed to rest on the ground or any other
surface unless a clean ground cloth has previously been laid.
No one should be allowed to walk on the fabric unless he
removes his shoes or wears special shoe coverings prescribed
by standard operating procedure. The neoprene-treated
balloon fabric is more resistant to the deteriorating action of
oils and greases than rubberized fabric; nevertheless, care
should be taken to prevent the fabric from being exposed to
oils and greases. The life of balloon fabric may frequently
be extended by coating it with a type of dope manufactured
and authorized for that purpose. Doping, either internal or
external, may overcome deterioration of the fabric and de-
crease permeability. It is preferable to apply the dope on the
inside of the balloon.
■ 100. Fabric Repair. — a. General . — Holes up to 12 inches in
diameter may be patched. If holes are larger than 12 inches,
it is generally advisable to replace the entire panel. Patches
are applied by stitching and cementing. Small patches re-
quire no stitching. Stitches used are the baseball stitch, back
stitch, and saddler’s stitch. Stitching by hand requires a cor-
rectness of execution which may be attained only through
constant practice and infinite care and patience. The cement
used is neoprene cement. The cement should not be applied
in direct sunlight or in a dusty or humid atmosphere.
Neoprene cement is highly inflammable, and should be kept
away from sources of ignition. The fumes from the cement
are dangerous to breathe for any length of time, and are also
explosive. Therefore, the cement should not be used in an
enclosed space without proper ventilation. Fabric selected
for patches should be of the same diagonal as the fabric
of the panel to be repaired, and should be of the same color
if possible.
b. Deflated balloon. — (1) Large holes are repaired by apply-
ing a filler patch. The edges of the hole are trimmed evenly
86
BARRAGE BALLOON
100
so that a piece of fabric may be cut to fit the hole exactly.
The patch is started by cementing a piece of fabric over the
hole on the inside of the envelope and stitching it with the
saddler’s stitch. This piece of fabric should overlap the hole
at least 3 inches on all sides. The hole is then “filled” with
a piece of fabric that has been cut the same size and shape
as the hole. This piece of fabric is cemented to the inside
patch. The hole is then covered from the outside by a piece
of fabric cemented to the envelope and filler. The outside
patch should overlap the hole at least 2 inches on all sides.
(2) Small holes may be repaired by simply cementing a
piece of fabric over the hole, allowing the patch to overlay
the hole sufficiently on all sides. If possible, the patch should
be applied from the inside of the balloon.
(3) Tears are replaced by first bringing the edges of the
tear together by means of a baseball stitch. The tear is
then covered with a piece of fabric cemented to the inside
of the envelope. If the patch is rectangular in shape, the
corners should be rounded.
(4) Holes larger than 12 inches in diameter are usually
repaired by replacing the entire panel. The old panel must
first be removed. This is done by soaking the cement loose
with benzol (applied with an oilcan) and gradually working
the edges of the panel away from the adjoining panels. The
cement remaining on the envelope is removed by erasing it
with a piece of raw rubber. The surfaces of the envelope
where cement is to be applied are washed lightly with ben-
zol. The required number of coats of cement (according
to manufacturer’s directions) are applied to one of the long
edges of the hole and to the corresponding edge of the new
panel. The cement must be worked thoroughly into the
fabric. Cement is applied to only one edge at a time, and
the panel is cemented to this edge before additional cement
is applied. After the cement is applied, a line is marked *4
inch from the edge of the panel to be used as a guide line.
Two men are required to cement the edge of the panel to the
envelope. One man starts from each end and works toward
the center for about 18 inches. The men then thoroughly
roll the surfaces cemented together before proceeding further.
During these operations, the remainder of the cemented
87
100
COAST ARTILLERY FIELD MANUAL
surfaces are prevented from becoming stuck together inad-
vertently by a piece of cheesecloth placed between them. The
cheesecloth is removed as the cemented edges are pressed to-
gether. After the 18 inches at each end are rolled, the fabric
is stretched by pulling from the ends. Weights are placed on
the portions already cemented together. This process is re-
peated until the center of the panel is reached. The remain-
ing three edges of the panel are cemented in place in the
same manner. The panel must then be allowed to dry for 12
hours before tape is applied. The cemented edges of the
panel and the uncured neoprene side of the tape must be
washed lightly with benzol. The required number of coats of
cement are then applied to the seams. Cement is not applied
to the tape. Guide lines 1 y$ inches apart are marked on the
envelope. The tape is applied 18 inches at a time and is rolled
thoroughly. Both the outside and inside of the seams must
be taped. To permit the repairmen to enter the balloon to
tape the inside seams, the balloon is inflated with air. After
the operation is completed, the cemented area is powdered
with soapstone. In cementing, it is extremely important that
the surfaces be rolled thoroughly to force out air bubbles and
distribute the cement evenly. In the application of benzol,
an excessive amount should not be used, since it will wash
the neoprene out of the fabric.
(5) A rip section that has been pulled out is ordinarily
repaired by replacing the entire panel in the manner de-
scribed in (4) above. The new panel may be obtained from
the manufacturer with the rip section in place. If the
new panel is not available, it is possible for an experienced
repairman to use his own judgment and replace the rip
section in the old panel.
c. Inflated balloon . — Small holes are repaired by cement-
ing a patch over the hole on the outside of a balloon. Stitch-
ing of tears is practically impossible. The edges of tears
should be joined quickly to prevent the escape of gas. This
may be done by cementing a patch of fabric over the tear
or by cementing bands of fabric across the tear. Either
of the above should then be covered by a larger patch. The
edges of this patch should be covered with a band of fabric
to help prevent further tearing.
88
BARRAGE BALLOON
101
■ 101. Winch Maintenance. — a. Inspections. — In addition
to the daily inspections performed by the winch operator at
the balloon site, the following inspections by the battery
engineer officer are necessary to insure proper maintenance.
(The instructions contained in this paragraph refer to the
type A-9 winch, but may be applied, with modifications, to
other types of winches which may be adopted.)
(1) After each 50 hours of operation —
(a) Thoroughly clean engine.
( h ) Inspect clutch for 1 inch free travel of pedal.
(c) Inspect winch gear case for leaks.
(d) Inspect transmission for leaks and check bellhousing
bolts for tightness.
<e) Check water pump for leaks.
(/) Inspect and tighten engine mounting support bolts.
( g ) Adjust fan belt tension and replace belt if worn.
(2) After each 100 hours of operation —
(a) Clean magneto cap and inspect timing contacts.
(b) Clean carburetor inlet screen.
(c) Check ignition timing.
(d) Clean and adjust spark plugs.
(e) Tighten all wiring connections and check for chafing.
(/) Remove and clean gasoline strainer screen.
(3) After each 150 hours of operation —
(a) Inspect winch mounting bolts for tightness.
(b) Check cylinder compression.
(c) Clean cooling system thoroughly and remove all rust
and sediment.
( d ) Clean gasoline strainer screen, remove and clean sedi-
ment trap, and blow out fuel line.
(e) Check spooling device chain drive for tightness and
make necessary adjustments.
(4) After each 200 hours of operation —
(a) Check and adjust valve clearances.
(b) Inspect radiator hose and replace if deteriorated.
(c) Check and tighten bolts attaching unit to base.
b. Lubrication . — The more important points of lubrication
and the methods are given below. More detailed instruc-
tions will be found in the lubrication chart furnished by
the manufacturer.
89
101
COAST ARTILLERY FIELD MANUAL
(1) Engine crankcase . — Check and fill to proper level as
required. Drain and refill every 100 hours of operation.
(2) Water pump . — Give grease cup three turns every 75
hours of operation. Refill if needed.
(3) Fan. — Remove plug and fill hub with engine oil every
75 hours of operation.
(4) Air cleaner. — Wash in gasoline and dip in light engine
oil every 100 hours of operation or more frequently if air is
abnormally dusty.
(5) Transmission. — Fill to level plug opening every 100
hours of operation. Drain, flush with light oil, and refill
every 250 hours of operation. Use high-grade mineral gear
oil. In winter use SAE 90, and in summer use SAE 140.
(6) Winch gear case. — Fill to level plug opening every 100
hours of operation. Drain and refill every 250 hours of
operation. Use high-grade mineral gear oil. In winter use
SAE 90, and in summer use SAE 140.
(7) Clutch release bearing. — Grease with pressure gun
every 75 hours of operation. Use No. 5 cup grease.
(8) Clutch release shaft. — Grease with pressure gun every
75 hours of operation. Use chassis lubricant.
(9) Clutch release transfer lever. — Grease with pressure
gun every 75 hours of operation. Use chassis lubricant.
(10) Clutch pedal. — Grease with pressure gun every 75
hours of operation. Use chassis lubricant.
(11) Spooling device . — Grease with pressure gun every 75
hours of operation. Use chassis lubricant.
(12) Storage drum. — Grease left-hand bearing with pres-
sure gun, using chassis lubricant, and place a few drops of
engine oil on right-hand bearing every 75 hours of operation.
(13) Spooling device idler. — Grease with pressure gun every
75 hours of operation. Use chassis lubricant.
(14) Lead-off gear. — Grease with pressure gun every 75
hours of operation (three fittings). Use chassis lubricant.
(15) Lower right cable sheave. — Grease with pressure gun
every 75 hours of operation. Use chassis lubricant.
(16) Spooling device upper guide rod. — Place a few drops
of oil along rod every 75 hours of operation.
(17) Magneto. — Place a drop of engine oil on contact lever
pivot and grease cam follower with high-pressure grease every
100 hours of operation.
90
BARRAGE BALLOON
101-103
(18) Service brake pedal shaft . — Grease inner end with
pressure gun, using chassis lubricant, and place a few drops
of engine oil on outer end every 100 hours of operation.
(19) Clutch linkage . — Place a few drops of engine oil on
clevis pins and other moving parts every 75 hours of
operation.
(20) Governor control linkage. — Place a few drops of
engine oil on clevis pins and other moving parts every 75
hours of operation.
(21) Clutch pilot bearing . — Grease with pressure gun every
250 hours of operation. Use No. 5 cup grease.
■ 102. Lubrication of Vehicles. — a. Vehicles should be lub-
ricated according to instructions issued by the manufacturers
in the handbooks pertaining to the vehicles. Methods of
lubrication and types of lubricants are given in FM 25-10.
b. The proper grease and oil as recommended in the hand-
books for the vehicles should be used for each fitting. The
mixing of different brands of oils and greases should be
avoided.
c. In cases where no lubrication chart or instructions are
available, the instructions for a vehicle of similar type should
be used.
■ 103. Compressors. — a. All types of compressors must be
kept clean at all times. Care must be taken to see that no
dust, dirt, grit, or foreign matter of any kind is allowed to
enter the compressor. Dirt of any kind will collect with the
oil to form a gummy mass which will eventually impair the
proper functioning of the machine. All parts should be pro-
tected from rust, particularly when the compressor is not in
use. Parts which are not painted should be coated with
grease or vaseline.
b. When the compressor is not in use, the water should be
drained from the cooling system. The intercoolers and water
jackets should be washed out thoroughly at least once a
month to prevent formation of a deposit, which will retard
the flow of water through them.
c. All valves should be examined at least every 2 weeks while
the compressor is in use, and before it is placed in service
after a period of idleness. If a valve is leaking and the valve
91
103-104 COAST ARTILLERY FIELD MANUAL
seat requires the removal of only a small amount of metal to
prevent leakage, it is advisable to lap the valve on the seat.
If a valve or valve seat is pitted or otherwise distorted to any
extent, the seat should be replaced and the seating face of
the valve should be refaced. In each case the valve should
be properly lapped on the seat. When regrinding is neces-
sary, fine emery and glycerin should be used. The valve and
valve seat should be wiped clean after lapping.
d. A heavy grade, high flash point oil is used for lubrica-
tion of compressor cylinders. Care must be taken to see that
the proper amount of oil circulates through the compressor.
Intercooler passages should be blown out occasionally to
avoid accumulation of oil carried through from the cylinders
with the flow of gas. An excessive amount of oil should not
be used for the lubrication of journals, crank pins, and
guides. If oil is allowed to collect on these parts, dust may
be drawn in with the oil and cause unnecessary wear.
■ 104. Hydrogen Generating Plant. — The pipe used on the
high-pressure hydrogen generating plant is extra heavy with
extra heavy fittings. Outside diameter of the pipe is the
same as for standard pipe, but the wall thickness is much
greater, making the inside diameter much smaller. Prom
the outside, high-pressure pipe can be distinguished from
other pipe by the larger, more bulky fittings, and the maxi-
mum pressure it will carry is usually marked on the pipe.
When high-pressure pipe is replaced, care must be taken to
insure that no standard pipe is used, since it will not with-
stand the pressures encountered in the high-pressure system.
High-pressure pipe must always be cut with a hacksaw, and
not with a pipe cutter. Any remaining bur must be removed
from the inside of the pipe so that it will not decrease the
pipe opening. Threads must be carefully made so as to insure
maximum strength and to prevent possible leaks at the
joints. Longer threads must be made on high-pressure pipe
and the pipe must be screwed farther into the fittings than
in standard pipe work. When a high-pressure globe valve
is used, the valve should be placed so that the pressure is on
the under side of the valve away from the valve stem pack-
ing; otherwise, the pressure would be against the packing at
92
BARRAGE BALLOON
104
all times. The pressure should always be removed from a
line before it is repaired or adjusted. Care should be taken
at all times to insure that fittings and pipe are not subjected
to excessive strain from the wrenches. If the threads will
not come loose at a joint without excessive strain, some form
of heat may be applied if the generating plant has been
purged of all hydrogen. In making up new connections, a
mixture of glycerin and litharge may be used. A compound
containing white lead, red lead, or linseed oil should not be
used. If glycerin and litharge are not available, the con-
nection may be made without them, and any small leaks
which may occur may be peened out with a small punch and
light hammer.
104
COAST ARTILLERY FIELD MANUAL
Appendix
LIST OP REFERENCES
PM 4-107, Organization, Tactics, and Technique, Barrage
Balloon.
FM 4-108, Service of the Balloon and Balloon Equipment,
Barrage Balloon.
FM 4-115, Operation of Materiel and Employment of Per-
sonnel, Antiaircraft Searchlight Units.
FM 4-120, Formations, Inspections, Service, and Care of
Materiel.
FM 5-30, Engineer Antimechanized Measures.
FM 21-5, Military Training.
FM 22-5, Infantry Drill Regulations.
FM 24-5, Signal Communication.
FM 25-10, Motor Transport.
FM 100-5, Operations.
TM 1-230, Weather Manual for Pilots.
TM 1-315, Hydrogen.
TM 1-325, Aerostatics.
TM 3-240, Meteorology.
AR 265-10, Tactical and Training Inspections.
Air Corps Technical Order No. 16-1-5, December 1941.
Air Corps Specifications No. 98-25515.
94
INDEX
Paragraph Page
Absorption method of testing gas purity 74 65
Alkaline pyrogallol 74 65
Ammonia-copper solution 74 65
Aerodynamics 28 30
Air deflation 92 82
Air inflation:
By whom accomplished 89 79
Facilities and equipment needed 90 79
Procedure 90 79
Purpose 89 79
Altitudes, maximum obtainable 17* 21
Angle of trim 28 30
Assistant balloon chiefs:
Qualifications 47 43
Training 51 46
Attainable height, calculating 15 20
Ballonet balloon:
Inspection of diaphragm 91 80
Internal pressure 6 3
Minimum volume 8 5
Principles of operation 6 3
Balloon chiefs :
Qualifications 47 43
Training 50 45
Balloon types 6,7 3,4
Cable, maintenance 97 85
Calculations :
Attainable height 15 20
Form 14 14
Inflation and weigh-off, approximate methods. 13 13
Limited operating ceiling 17 21
Maximum altitudes attainable--. 17 21
Operating ceiling 17 21
Pressure height 14 14
Superheat corrections 20 24
Volume of gas needed for inflation 14 14
Weigh-off 14 14
Chauffeurs, training 58 49
Classes of weather risks to balloons 45 40
Clouds, effect on balloon operation 32 33
Cold, effect on gas and air valves. 34 33
Communication workers, qualifications 47 43
Compressors, maintenance 103 91
Concealment of balloons, use of clouds and fog 32, 33 33
Cordage:
Maintenance 98 85
Repair 98 85
Cylinders :
Identification 78 71
Precautions in handling, storing, and trans-
porting 79 71
95
INDEX
XJCJUtlLlUAi.
Air. ( See Air deflation.) Paragraph
Safety precautions 83
When to deflate 27, 82
Determining volume 10
Diaphragm :
Page
75
29, 74
10
Inspection 91 80
Operation 1 6 3
Dilatable balloon :
Minimum volume 8 5
Principles of operation 7 4
Duties of weather section 40, 42 37, 39
Effusion method of testing gas purity 74 65
Elastic cords, purpose 7 4
Fabric maintenance 99 86
Fabric repair :
Deflated balloon 100 86
General 100 86
Inflated balloon 100 86
Fire:
Action in case of 76 68
Prevention 76 68
Fog, effect on balloon operation 33 33
Forecasts, weather 37, 41, 45 36, 38, 40
Formation for inspections 64 52
Form, computation 14 14
Fullness, percent 1 9 6
Gas, determining volume in balloon 10 10
Gas, expansion and contraction 5 3
Gas purity:
Absorption method of testing —
Using alkaline pyrogallol 74 65
Using ammonia-copper solution 74 65
Army effusion method of testing 74 65
Reasons for testing 73 65
Gas valve 6, 7 3, 4
Gas workers:
Qualifications 47 43
Training 53, 54 47
General problems, barrage balloons 3 1
Generating plant, hydrogen. (See Hydrogen gen-
erating plant.)
Groove depth method of determining volume 10 10
Helium purification:
Personnel required 88 78
Principles 86 77
Reasons for 85 77
Types of purification plants 87 77
High-pressure piping 104 92
Humidity, effect on lift 24 28
Hydrogen :
Action in case of fire 76 68
. Characteristics 75 67
Identification of cylinders 78 71
Prevention of ignition 76 68
96
INDEX
78
77
Hydrogen- — Continued . Paragraph
Safety precautions:
During deflation 82,83
During inflation 81
In handling, storing, and transporting
cylinders
In manufacture
Transferring from one balloon to another:
General
Precautions
Procedure
Typical accidents with hydrogen
Hydrogen generating plant :
Component parts
Conditions affecting rate of reaction. .
Description
Equipment for personnel
Field location
Maintenance
Method of operation
Necessity for
Reaction and general process
Reaction materials
Safety precautions
Selection of operating personnel
Size of operating crew
Ice, effect on balloons
Individual training
Indoctrination of personnel
Inflation:
Air, (See Air inflation.)
Calculations.
Safety precautions
Inspection, air-inflated, balloon:
For storage
Ballonet diaphragm
Initial external
Initial internal
Inspections:
Formations
Sites
Tactical
Technical
Training
Kiting:
Definition
Limitations to use
Lift:
Effect of —
Humidity
Loss of gas, how avoided.
Superheat
Superpressure
Static. (See Static lift.)
Page
74, 75
74
71
69
91
80
95
83
95
83
84
76
66
55
68
59
66
55
72
64
69
63
104
92
68
59
65
55
... . 68
59
67
58
77
69
70
64
71
64
34
33
48
45
49
45
... 13,14
13, 14
81
74
91
80
91
80
91
80
91
80
64
52
... 63-64
51
63
51
63
51
63
51
28
30
28
30
24
28
22
28
... 19, 20
23,24
23
28
12,14
12, 14
13,14
13, 14
.... 12, 14
12, 14
97
INDEX
Limited operating ceiling: Paragraph Page
Calculations 17, 20 21, 24
Definition 16,20 21,24
Lubrication :
Vehicles 102 91
Winch 101 89
Maintenance and repair:
Cable 97 85
Compressors 103 91
Cordage 98 85
Fabric 99, 100 86
General 96 85
Hydrogen generating plant 104 92
Materiel, special for balloon barrage 4 1
Maximum altitudes for day and night flying 16, 17 21
Minimum percent of fullness.. 8 5
Minimum volume:
Changes due to stretch 8 5
' Definition 8 5
How to determine 8 5
Increase in 8 5
Mission of barrage balloon, how accomplished 3 1
Net lift, how determined 12 12
Operating ceiling:
Atmospheric density as an effect on 18 23
Calculations 17 21
Definition 16 21
Limited operating ceiling 16, 17 21
Pressure height as limiting factor 17 21
Organization of weather section 38 36
Packing, balloon 93 82
Panel replacement 100 86
Percent of fullness:
Definition 9 6
How determined 9 6
Minimum 8 5
Personnel :
Hydrogen generating plant, selection 70 64
Weather section:
Composition 38 36
Selection 47 43
Training 57 49
Pressure height:
Ballonet balloon ; 6 3
Calculating pressure height 14 14
Definition 9 6
Dilatable balloon 7 4
Effect of raising balloon above 9 6
Factors affecting 9 6
Purification of helium. (See Helium purification.)
Purity, gas. (See Gas purity.)
Qualifications of personnel:
Balloon chiefs 47 43
Communication workers. „ 47 43
Gas workers 47 43
Hydrogen generating plant operators 70 64
98
INDEX
Qualifications of personnel — Continued. Paragraph Page
Riggers 47 43
Weather station personnel 47 43
Winch operators 47 43
Rain, effect on balloons 34 33
Reaction materials, hydrogen generation 67 58
References 2 1
Repair. (See Maintenance and repair.)
Riggers :
Qualifications 47 43
Training 55 48
Safety precautions in handling hydrogen:
Action in case of fire 76 68
Deflation 82, 83 74, 75
Handling, storing, and transporting cylinders. 78-80 71
Inflation 81 74
Manufacture 77 69
Preventing ignition 76 68
Typical accidents 84 76
Safety valve, gas 6, 7 3, 4
Sample calculation, inflation and weigh-off 14 14
Scope 1 1
Security and protection 62 50
Shape of balloon, how maintained 6, 7 3,4
Shock cords, purpose 7 4
Sites, inspection 63, 64 51, 52
Snow, effect on balloons 34 33
Static lift:
Amount needed, how determined 1 11 11
Checking by measuring volume 12 12
Checking by weigh-off 12 12
Storage, inspection 91 80
Stretch, changes due to 8 5
Sunshine, effect on balloons 35 35
Superheat :
Calculating corrections 20 24
Definition 20 24
Effects 19, 20 23, 24
Limitations to use 21 27
Superpressure 23 28
Supplies, special for barrage balloons 4 1
Teamwork 60 49
Telephone operators, training 56 48
Topping-up :
Reasons 25 28
Time 25 28
Gas 26 29
Training, individual:
Assistant balloon chiefs 51 46
Balloon chiefs 50 45
Chauffeurs 58 49
Chief gas workers 53 47
Gas workers 54 47
Indoctrination of personnel 49 45
Other crew 1 members 59 49
Riggers 55 48
Telephone operators 56 48
99
INDEX
Training, individual — Continued. Paragraph Page
Weather section 57 49
Winch operators 52 46
Training inspections 63 51
Training, unit:
Method 61 49
Security and protection 62 50
Teamwork 60 49
Transferring hydrogen from one balloon to another.
(See Hydrogen — Transferring from one balloon
to another.)
Types of barrage balloons 6, 7 3, 4
Unit training (see also Training, unit) 48 45
Valves, effect of cold 34 33
Valve, gas safety 6,7 3,4
Vehicles, lubrication 102 91
Volume :
Methods of. determining :
Diaphragm-height 10 10
Groove depth 10 10
Needs for inflation, calculating 13, 14 13, 14
Weigh -off 10 10
Volume, minimum:
Definition ' 8 5
How to determine 8 5
Increase due to stretch 8 5
Weather, classes of risks to balloons 45 40
Weather elements, effect:
Balloons 29 32
Clouds 32 33
Fog 33 33
Ice and snow 34 33
Lightning 30 32
Rainfall 34 33
Sunshine 35 35
Wind 31 32
Weather station:
Examples of weather messages 45 40
Information supplied to barrage 37, 41-45 36, 38
Observations made 40, 42 37, 39
Personnel 38, 47 36, 43
Station equipment 39 37
Station operation 40, 42 37, 39
Training of personnel 57 49
Weather message 37,41,45 36,38,40
Weigh-off 12, 14 12, 14
Method of determining volume 10 10
Record, example 27 29
Winch :
Inspections 100 86
Lubrication 100 86
Maintenance 100 86
Winch operators:
Qualifications 47 43
Training ” 52 46
Wind, effect on balloons 31 32
100