    [Meteorological Balloons]
    [From the U.S. Government Publishing Office, www.gpo.gov]

    ﻿Document C 'T "T (J?) !~ fcA [““* n“™ JJ/J UUffIJO
    WAR DEPARTMENT TECHNICAL MANUAL
    non-circulating
    METEOROLOGICAL
    BALLOONS
    WAR DEPARTMENT •	24 APRIL 1944
    ^TSl! LIBO.HY
    _______ TM 11-2405 *c 1
    TECHNICAL MANUAL
    METEOROLOGICAL BALLOONS
    Changes'!	WAR DEPARTMENT
    No. 1 J	Washington 25, D. C., 13 April 1945
    TM 11-2405, 24 April 1944, is changed as follows:
    2.	Types
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    b. Pilot Balloons.
    *******
    (2)	The larger pilot * * * grams (3.53 ounces). The balloon neck is made of relatively thick rubber, is about 2% inches long, and is y2 inch or 1% inches in diameter. Pilot balloons are * * * and red (par. 4).
    *******
    3.	Definitions (Superseded)
    a.	Free Lift. Free lift is the actual upward force which causes the balloon to rise, and it is measured in ounces or grams. (A means of measuring free lift is provided by the selection of the proper cock or nozzle.)
    b.	Total Lift. Total lift is the gross upward force produced by the hydrogen in the balloon. It is equal to the sum of the free lift, the weight of the balloon, and the weight of the carried equipment, if any.
    5. Sources of Hydrogen Gas
    *******
    c.	(Superseded) Hydrogen Generator ML-303/TM. Hydrogen Generator ML-303/TM is a cylinder 5 inches in diameter and 15 inches long, with a threaded opening at the top for attaching an outlet tube and a threaded opening at the base for attaching a calcium hydride charge can. Two differen types of charge are used with Hydrogen Generator ML-303/TM. Calcium Hydride Charge ML-304/TM or ML-304A/TM is a metal can containing enough calcium hydride to generate G cubic feet of hydrogen gas for the inflation of a 30-gram balloon. Calcium Hydride Charge ML-305/TM or ML-305A/TM contains enough calcium hydride to generate 24 cubic feet of hydrogen gas for the inflation of a 100-gram balloon.
    Caution: Rescinded.
    d.	Hydrogen Generator Set AN/TMQ-3 (Added). Hydrogen Generator Set AN/TMQ-3 consists essentially of four Hydrogen Generators ML-303/TM () During high winds * * * in this example. If a ballast balloon of lesser weight than 400 grams is used, a free lift of either 400 or 500 grams should be computed, based upon the individual's own judgment.
    Z>. Insert -the vertical spout of Nozzle ML-196 into the neck of the sounding balloon, first making sure that the air is expelled from the balloon.
    * * *	*	*	* *
    14. Night Use of Pilot Balloons * * *	*	*	* *
    5. Lighting Units. * * *	*	*	♦ ♦
    (1) Battery light unit. * * *	*	*	* *
    («) Preparing parachute.	Locate the	cord	* * * when sus-
    pended (fig. 12). Parachutes are now being manufactured with
    the center cord already loose and the parachute ready for use. *******
    AGO 165C
    5
    15. Use of Balloons During Precipitation
    a. Pilot Balloons (Superseded). Rain, snow, or sleet decreases the rate of rise of the balloon and results in inaccurate observations. For this reason no pilot balloon flights are recommended during precipitation.
    *******
    16. Rate of Ascent
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    a. Ceiling Balloons.
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    (3) In some cases, an entirely different method, such as a pilot’s report, or double theodolite measurement, should be used. For example, if * * * balloon is required.
    c. One-Hundred-Gram Pilot Balloons. The 100-gram pilot balloon rises at a rate of approximately 320 to 330 yards per minute and consequently requires less time than the 30-gram balloon for high altitude flight. The 100-gram balloon travels faster during the first 14 minutes of flight. The corrections to be added, using 320 yards per minute as the average basic rate of rise, for the first 14 minutes are 22, 19, 19, 16. 16, 12, 12, 8, 8, 6, 3, 3, and 3 percent, respectively. Altitudes of 100-gram pilot balloons at the end of each minute of flight are contained in TM 11-2411.
    *******
    16.1.	Normal Bursting Altitudes (Added)
    The normal bursting altitudes given m this paragraph are the altitudes with neoprene balloons lit about 40° N. latitude in the spring of the year. It may be found that lower altitudes are obtained in arctic regions, higher altitudes in tropic regions; lower altitudes in winter, higher altitudes in summer. For this reason, the figures quoted should serve only as a guide. Also, since some lots of balloons contain a few “duds”, it is not expected that all balloons will reach the normal bursting altitudes.
    a.	Thirty-Gram Balloon. Balloons ML-50-A, ML-51-A. ML-64—A, ML-155-A, and ML-156-A will normally burst at 30,000 feet when rising at a rate of about 600 feet per minute and carrying no load.
    1)	. One-Hundred-Gram Balloon. (1) Pilot. Balloons ML-159-A, ML-160-A, and ML-161-A have a normal bursting altitude of 45,000 feet when rising at a rate of about 1,000 feet per minute and carrying no load.
    (2	) Radar target. A 100-gram balloon for carrying Radar Target ML-350/AP aloft is inflated so that, considering the wind prevailing at the time of release, the balloon will attain the highest possible altitude before passing out of the range of the radar set. For average prevailing wind in the temperate zones a free lift of 1,100 grams usually is satisfactory for this purpose.
    c. Three-Hundred and Fifty-Gram Balloon. (1) Radiosonde, Balloons ML-131-A, inflated to carry radiosonde aloft have average bursting altitudes which decrease as the rate of ascent increases. The
    6
    AGO 165C
    following average bursting altitudes for different rates of ascent have been found for properly treated balloons:
    Rate of ascent	Bur sting altitude
    feet per minute	feet
    600 ______________________________________ 63, 000
    1, 000______________________________________ 58, 000
    1, 200 _____________________________________ 53, 000
    (2)	Radar target. A 350-gram balloon for carrying Radar Target ML-307-A/AP or ML-307-B/AP aloft is inflated so that, considering the wind prevailing at the time of release, the balloon will attain the highest possible altitude before passing out of the range of the radar set. For average prevailing wind in the temperate zones a free lift of 1,700 grams usually is satisfactory, which will carry the balloon to an altitude of about 50,000 feet while it is still in the range of the radar set. In general, it has been observed that for a given amount of free lift, a 350-gram balloon for carrying a radar target aloft has a bursting altitude slightly less than the bursting altitude of a 350-gram balloon for carrying radiosonde aloft.
    17. Care of Cocks and Nozzles (Superseded)
    a.	General. Nozzles ML-186 and ML-196 require no special maintenance because of the large air passage through them. No lubrication is required on the nozzles, since there are no moving parts. However, Cocks ML-56 and ML-201-A do require special maintenance and lubrication when used with Hydrogen Generator ML-303/TM. Any accumulation of dirt or foreign matter in the opening of the cock causes a constriction of the passage and prevents a free flow of hydrogen through the cock. The low pressure of Hydrogen Generator ML-303/TM is not sufficient to blow the obstruction out of the cock or to inflate the balloon if the passage is badly constricted. The same condition prevails if the stopcock is not completely opened while inflating a balloon. To prevent this condition, give special attention to keeping the stopcock passages open and unobstructed.
    b.	Causes of Obstruction. (1) Talc. Talc, placed on the inside of meteorological balloons to prevent sticking of the rubber, tends to clog the cocks used for inflation.
    (2)	Grease. Dirt and dust adhere to grease used for lubrication of the stopcock. The combination of grease and dirt obstructs the opening.
    (3)	Lime. Sometimes an accumulation of hardened lime appears in the cock. The caked lime is a chemical byproduct of air and the solution resulting from the generation of gas.
    (4)	Dirt or dust. Careless handling or unusual weather conditions, such as floods or dust storms, may cause an accumulation of foreign matter in the opening of the cock.
    c.	Cleaning Cocks ML-56 and ML-201-A. (1) Inspection. Check the cocks frequently to see that the openings are unobstructed and that they permit a free flow of hydrogen. The cocks will operate properly, if it is possible to blow through them freely, when the stopcocks are completely open.
    (2)	Disassembly. To disassemble Cocks ML-56 and ML-201-A, remove the screw at the bottom of the stopcock and pull out the stopcock.
    Note.—When Hydrogen Generator ML-303/TM is used, the cocks should be examined daily or oftener if exi^erience shows it to be necessary.
    AGO 165C
    7
    (3)	Cleaning, (a) If there is an accumulation of hardened lime or other caked material in the cock opening, loosen it with a stiff wire. Knock the loosened foreign material out of the cock by hitting the cock opening down into the palm of the hand. Wash the cock in clear water.
    (ft) If an excess of grease is present, remove it with Solvent, Dry-Cleaning, Federal Spec. No. P-S-661a.
    (4)	Reassembly. Insert the stopcock into the cock in its former position and tighten the screw.
    d.	Lubrication. (1) The following table lists the lubricating material recommended for servicing Cocks ML-56 and ML-201-A:
    Approved symbol	Standard nomenclature	Specification No.
    GA		Graphite		U. S. Army 2-64A. U. S. Army 2-120. Federal P-S-661a.
    PS	 SD		Oil, Lubricating, Preservative, Special. Solvent, Dry Cleaning
    (2) Periodic lubrication of cocks is not required. Lubricate only after accumulated dirt and grease have been removed.
    (3) When lubrication is necessary, use powdered graphite (GA) in small amounts.
    (4) If powdered graphite (GA) is not available, apply a small amount of special preservative lubricating oil (PS). Too much oil, combined with dirt, is likely to form a greasy mass obstructing the free flow of hydrogen.
    18. Storage of Rubber Balloons
    a. Keep rubber balloons in their original, sealed containers, and store them in a cool, dry, dark place until needed for use. Rubber balloons deteriorate in high temperature. Provide special storage
    * * * * shape when inflated.
    *******
    20. (Superseded) Storage and Use of Neoprene Balloons
    a. General. Neoprene balloons require different conditions of storage and use than natural rubber balloons require.
    . (1) Neoprene balloons can be identified by the nomenclature which is the same as for a rubber balloon of the same weight and color, except that a suffix “A” is placed after the nomenclature. For example, Balloon ML-131-A is made of neoprene, while Balloon ML-131 is made of natural rubber.
    (2) Neoprene balloons have been found to burst prematurely if subjected to low or moderate temperatures in transit or in storage. Even 6 months’ storage at 70° F. will reduce the maximum obtainable bursting altitude. Neoprene balloons can be reconditioned. This is done by heating the balloon.
    b. Storage. Neoprene balloons should be stored in their original containers at a temperature of about 85° F. This storage temperature is not critical. Storage for several months at temperatures between 40 I. and 120° F. is permissible. Balloons stored at a temperature
    8
    AGO 165C
    near 40c F. will require reconditioning, but if they are stored at a temperature near 100° F., reconditioning may not be necessary.
    c.	Reconditioning Neoprene Balloons. The technique described in this paragraph has given the best results, and will be used in the field. The treatment consists of boiling in water for 5 minutes, as follows:
    (1)	Prepare the balloon for heat treatment by first removing any air that may be inside. Expel the air either by rolling up the balloon or by sucking the air out of the balloon neck. Double the balloon neck and tie it tightly with a shoelace or a cloth ribbon. In the case of thin-necked 30-gram balloons, stretch the neck over a tube or wooden cylinder, 1% inches in diameter, and tie the neck over the cylinder. The reason for tying the neck is twofold: first, it prevents air from entering the balloon, making it easier to keep the balloon submerged in the boiling water; and second, it prevents water entering the balloon.
    (2)	The container in which the balloon is boiled should be about the size of a 4-gallon pail. A 5-gallon oil can or a gasoline can will serve the purpose very well. Carefully eliminate all sharp edges, so that the balloon will not be punctured. Remember that a heated balloon becomes extremely soft and may be easily damaged, even by a fingernail.
    (3)	While the water is boiling, keep the balloon submerged in the water. A stick with a handkerchief wrapped around the end may be used to keep the balloon submerged. It is not necessary to keep the neck of the balloon under water. Take care that the balloon does not touch the portion of the container where the heat is applied, since this may cause the balloon to be damaged by overheating. Keep the balloon moving in the water to insure its being heated uniformly. After boiling for 5 minutes, remove the balloon from the water.
    (4)	If boiling the balloon is impossible, any heating will help, even if it will not totally recondition the balloon. The balloon may be placed over a radiator, near the field stove, or wrapped around an electric light bulb with insulation between the bulb and the balloon to prevent heating above 212° F. Another alternative is to lay the balloon on the cooler part of Generator ML-185-(&) when hydrogen is being generated and when the temperature is below 212° F. These alternatives shall be used only if boiling water is unobtainable.
    d.	Care and Inflation. Neoprene balloons become very fragile when warm or wet. Always handle them carefully to avoid abrasion, tearing, etc. When using Balloon ML-131-A, it is recommended that equipment, parachute, and Tine be prepared and ready to be tied to the balloon before the balloon is inflated. This sounding balloon may be allowed to dry, or may be inflated while still wet if it is not freezing outdoors. Pilot balloons must be dry before inflation in order to obtain correct lifts. Balloons may be dried in a warm room or near a field stove. Inflate and release balloons as soon as possible after reconditioning to prevent subsequent “refreezing.”
    e.	Summary. (1) Neoprene balloons perform poorly when subjected to cold (40° F.) for a short period or to moderate temperatures (70° F.) for a longer period.
    (2) Neoprene balloons may be reconditioned by heating, preferably for 5 minutes in boiling water.
    (3) Neoprene balloons are fragile and must be handled carefully.
    AGO 165C
    9
    22. List of Balloons and Associated Equipment
    *	*	* *				* ♦
    Signal Corps stock No.	Item	Function	Color	Weight		1 Dimensions and remarks
    				Grams	Ounces
    7A179		Balloon ML-	Pilot	White...	100 100	3.53 3.53	Spherical, 16-in. diameter; neck 2’/.>-3 in. long, in. or li/2 in. diameter. Spherical, 16-in. diameter; neck 2^-3 in. long, ’/2 in or P/2 in. diameter.
    7A180			159— <*) B alloon ML-	Pilot...
    	160—
    7A181	'	Balloon ML-	Pilot		ICO	3.53	Spherical, 16-in. di ameter; neck 2)4-3 in. long, U2 in. or I1/? in. diameter.
    	161—
    7A1207-100....	Parachute (min-	Used with light-	■	4	0.14 •	4 Paper, approximately 16-in. diameter. *
    ■	iature).	ing unit.	•	• 1
    23. Maintenance Parts for Inflation Shelter S-13/TM (Added)
    The following information was compiled on 3 March 1945 The an-Pf°P5iate section °f the ASF Signal Supply Catalog for Inflation Shelter S-13/TM is:
    t J0-900-* JnMon Shelter S-13/TM, Fixed Plant Maintenance List (when published).
    For the latest index of available catalog sections, see ASF Signal Supply Catalog SIG 2.
    [AG 300.7 (9 Dec 44)]
    By order of the Secretary of War :
    Official :
    J. A. ULIO
    Major General
    The Adjutant General
    G. C. MARSHALL
    Chief of Staff
    Distribution :
    AAF	AfeF ’ T of °Pn <5) ’’ DePt (5); Def
    9o°Amd <2).; !^Comd ’* AAF Comd (2) ; Arm & Sv Bd (2); S Div ASF (1); Tech Sv (2) ; SvC (5); Area A SvC (2) ; WDGS Lib (5) ; PC&S (2)'; PE (2) ; Dep 11 (2) ; Gen Oversea SOS Dep (Sig Sec) (2); GH (2) ; M Cone C (2); Air ’ GenzSv Sch <5) ; SP Sv Sch (10) ; USMA (10) ;
    ( aU	’ Slg AS (2) ’ ReP ShoP 11 (2) ; A (5) ;
    F (2) ’ AF ^4 Three (3) copies to each of the following: B J~627’ 3~267’ 4~45’ 4~155’ 4-260-1, 6-10-1, 6-75, 6-110-1 6-150-1, 6-160-1, 6-200-1, 11-107, 11-127 11-237 11-287, 11-587, 11-592, 11-597, 44-15, 44-115, 44-135. ’	’
    Refer to FM 21-6 for explanation of distribution formula.
    10
    AGO 165C
    U.S. GOVERNMENT PRINTING OFFICE: 1945
    W A R DEPAR T M E N T T E C II NI C A L MANUAL TM 11-2405
    METEOROLOGICAL
    BALLOONS
    WAR DEPARTMENT •	2 4 A P R I E 1944
    United States Government Printing Office Washington : 1944
    WAR DEPARTMENT.
    Washington 25, I). C., 24 April 1944.
    TM 11-2405, Meteorological Balloons, is published for the information and guidance of all concerned.
    [A. G. 300.7 (22 Mar 44). J
    By order of the Secretary of War :
    G. C. MARSHALL.
    Chief of Staff. Official :
    J. A. ULIO,
    Major General.
    The Adjutant General.
    Distribution :
    As prescribed in paragraph 9u, FM 21-6; IBn 1, 4. 6. 44 (5) : IC 3, 4,6 (8).
    1 Bn 1 : T/O and E 1-627, Weather Sq.
    I Bn 4 : T/O 4-95, CA Sep HD Bn, Type D ; 4-65, CA Bn HD ; 4-115, (’A Bn AA Gun (SM) ; 4-175 S. CA Bn AA (Sep) Gun (SM).
    I Bn 6: T/O 6-75, FA Obsn Bn.
    I Bn 44 : T/O 44-15, ('A Bn AA Gun (Mob) : 49-135. CA Bn AA SL (Mob) : 44-115, CA Bn AA Gun (SM) ; 44-135, CA Bn AA SL (SM) ; 44-315, CA Barrage Balloon Bn.
    I C 3 : T/O 3-2G7, Smoke Generating Co.
    I (’ 4 : T/O 4-66, Hq Hq Btry, CA Bn (HD) : 4-68. CA Btry SL (HD).
    I C 6: T/O 6-76, Hq Hq Btry, FA Obsn Bn: 6-110-1, Hq Hq Btry, Cav Div Arty.
    For explanation of symbols see FM 21-6.
    For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price 10 cents
    II
    CONTENTS
    SECTION 1	. Description.	Paragraph Page
    	General ..	1 ]
    	Types...	2	1
    	Definitions		3	3
    II. Installation and operation.
    Selection of color of balloon ______________.... _	4	4
    Sources of hydrogen gas ______________________________ ,5	4
    Shelter_____ __	__	_________ _	6	5
    Preparation for inflation _	   7	9
    Inflating ceiling balloons_____________________________ 8	9
    Inflating pilot balloons______ _______________________  9	JQ
    Inflating sounding balloons___________________________ 10	13
    Use and inflation of ballast balloons_________________ 11	15
    Use of parachutes___________________________________   12	16
    Releasing procedure___________________________________ 13	16
    Night use of pilot balloons____________________________14	17
    Use of balloons during precipitation______________ 15	20
    Rate of ascent______________________________________   16	22
    III. Maintenance.
    Care of hosecocks and nozzles_________________________ 17	25
    Storage of balloons_________________________________   18	25
    Patching balloons__________ ___________________ _	19	25
    Care of neoprene balloons_____ _____________________   20	25
    Moistureproofing and fungiproofing_____	_	_	21	26
    IV. Supplementary data.
    List of balloons and associated equipment_________	22	27
    119
    DESTRUCTION NOTICE
    WHY—To prevent the enemy from using or salvaging any of this equipment for his benefit.
    WHEN—When ordered by your commander.
    HOW—1. Smash—Use sledges, axes, handaxes, pickaxes, hammers, crowbars, heavy tools, etc.
    2.	Cut—Use axes, handaxes, machetes, etc.
    3.	Burn—Use gasoline, kerosene, oil. flame throwers, incendiary grenades, etc.
    4.	Explosives—Use firearms, grenades, TNT, etc.
    5.	Disposal—Bury in slit trenches, fox holes, other holes. Throw in streams. Scatter.
    USE ANYTHING IMMEDIATELY AVAILABLE FOR DESTRUCTION OF THIS EQUIPMENT
    WHAT—1. Smash—Generators, tanks, couplings, hosecocks, nozzles, lighting units, etc.
    2.	Cut—Balloons, tubing, parachutes, etc.
    3.	Burn—Technical Manuals, balloons, lanterns, parachutes, etc.
    4.	Bury or scatter—Any or all of the above pieces after breaking.
    DESTROY EVERYTHING
    SAFETY NOTICE
    Hydrogen mixed with air forms a very explosive mixture that needs only a small flame or spark to cause it to explode violently. Do not smoke or strike matches near hydrogen. Make sure that all electrical contacts are tight to avoid electric arcing. Place caution signs in conspicuous positions in the area.
    v
    SECTION I
    DESCRIPTION
    1. General
    Meteorological balloons are used to determine the direction and speed of winds aloft, to determine the height of clouds, and to carry aloft equipment which will take soundings of the temperature, humidity, and pressure of the upper air. The symbol (&), found in paragraph 55, refers to all models of procurements of the Generator ML-185 series.
    2. Types
    Three types of balloons are used in meteorological work; ceiling balloons, pilot balloons, and sounding balloons. When in use, all three types are inflated with hydrogen gas.
    a. Ceiling Balloons. Ceiling balloons are small balloons which ascend at an average rate of 360 feet per minute after the first minutes (par. 16«). They are used in the daytime to determine the cloud heights whenever the ceiling is approximately 2,500 feet or less. Ceiling balloons are supplied in two colors, in red and in a dark color (black, dark blue, or purple to contrast with the color of the sky at the time of observation (par. 4). Ceiling balloons, before inflation, are approximately 3}/2 inches in diameter and weigh about 10 grams (0.35 ounce). The balloon neck is about 2 inches long and approximately 1 inch in diameter.
    I). Pilot Balloons. Pilot balloons are used to determine the direction and speed of the wind in the upper air and to determine cloud heights at night if a ceiling light projector is not available. Pilot balloons are supplied in two sizes.
    (1) The smaller pilot balloons (fig. 1) are approximately 6 inches in diameter before inflation and weigh about 30 grams (1.06 ounces). The balloon neck is about 2% inches long and iy2 inches in diameter. The balloon is of one-piece seamless construction. Thirty-gram pilot balloons are inflated to ascend at a constant rate of about 200 yards per minute (par. 165) and are used for low-level observation (up to 30.000 feet). They are supplied in the following colors: white or uncolored, a dark color (black, dark blue, or purple), red, orange, and yellow to contrast with the condition of the sky at the time of observation (par. 4).
    (2) The larger pilot balloons are approximately 16 inches in diameter before inflation and weigh about 100 grams (3.53 ounces). The balloon neck is made of relatively thick rubber, is about 2% inches long, and is %6 inch to iy2 inches in diameter. Pilot balloons
    1
    are of one-piece seamless construction. Some 100-gram balloons have a mold mark near the center, but this does not weaken the balloon. The balloons are designed to ascend at a rate of approximately 330 yards per minute. Since they ascend faster than the smaller balloons, the 100-gram balloons are used when observations are of short duration or whenever an observation of the higher level is desired without increasing the time of observation. They are supplied in three colors; white, black, and red (par. 4).
    Figure 1. Thirty-gram pilot balloon, inflated and deflated.
    c. Sounding Balloons. Sounding balloons are larger than ceiling and pilot balloons because they are designed to carry aloft sounding equipment. The average sounding balloon is 2 to 3 feet in diameter before inflation, weighs approximately 350 grams (% pound), and has a neck about 4% inches long and 1 inch m diameter. Sounding balloons are always white since their visibility in the sky is not important. Usually, sounding balloons carrying meteorological instruments are inflated to ascend at a rate of about 450 to 600 feet per minute and will reach altitudes in excess of 50,000 feet before they burst (par. 16<7).
    2
    3.	Definitions
    a.	Balance. When a balloon is inflated just enough to float in the air at release, without rising or falling, it is balanced.
    5.	Free Lift. Free lift is the force required to raise the balloon and its equipment over and above the point of balance and is measured in pounds, ounces, or grams. When a balloon has reached the point of balance, any additional gas will cause it to rise at a definite rate. As gas is added, the rate of ascent will increase.
    c.	Total Lift. ' Total lift is free lift plus the weight of the balloon and any equipment it will carry in flight.
    581708' 44------2
    3
    SECTION II INSTALLATION AND OPERATION
    4.	Selection of Color of Balloon
    The appearance of the sky at the time of observation determines the color of the balloon which is to be used.
    a.	White or Uncolored Balloons. Use the white or uncolored balloon when the sky is clear. A white or uncolored balloon is observed satisfactorily even when there is light dust, light smoke, light fog, or haze in the lower layers of the atmosphere and when only a few clouds which are not increasing are present. In the upper regions, the balloon will appear as a pin point of reflected sunlight (d below).
    b.	Black Balloons. The black balloon stands out most clearly in an overcast sky with thick or thin clouds or a dense haze aloft. Regardless of other sky conditions, a black balloon will give the best results in the early morning at sunrise or in the late evening at sunset (when the sky is still sufficiently bright to make the use of a night light unnecessary).
    c.	Red Balloons. Use a red balloon when the sky is partly cloudy and provides either a blue or a cloudy background. Use the red balloon when conditions are indefinite or changeable.
    d.	Yellow and Orange Balloons. The yellow or orange balloon is best used when very thin cirrus clouds or a haze partially covers the sky. Some observers prefer a yellow balloon to a white one when the sky is clear, and some observers prefer an orange balloon to a red one in a partly cloudy situation.
    e.	Summary. Color sense varies with individuals; the observer should experiment to determine whether his color perception is different from that outlined above. Learn to use balloon colors to the best advantage. The general rule is the darker the sky, the darker the color of the balloon to be used.
    5.	Sources of Hydrogen Gas
    Meteorological balloons are inflated with hydrogen gas from one of the following sources:
    a.	Cylinder Filled with Hydrogen. The usual hydrogen cylinder contains about 190-cubic feet of hydrogen gas at sea-level pressure and at a temperature of 70° F. Excess heating from any source will produce increased pressure of the gas within the container and will result in a false lift measurement. Keep the container in the place where the balloon is to be inflated since the gas inside the balloon must be
    4
    at the same temperature as the air in which the balloon is weighed off. Keep hydrogen cylinders out of the sun.
    b.	Generator ML-18'5-(&). Generator ML-185-(&) generates from 90 to 100 cubic feet of hydrogen. Five pounds of caustic soda (sodium hydroxide), 4% pounds of ferro-silicon, and 16 quarts of water are thoroughly mixed in the generator by shaking. A full cylinder of hydrogen gas is generated two hours after the cylinder is charged.
    c.	Hydrogen Generator ML-303/TM(XO-1). Hydrogen Generator ML-303/TM(XO-1) is a cylinder 5 inches in diameter by 15 inches long with a threaded opening at the top for a hose nozzle attachment and a threaded opening at the base for attaching a calcium hydride charge can. Two different charges are used with Hydrogen Generator ML-303/TM(XO-1). Calcium Hydride Charge ML-304/TM (XO-1) is a metal can containing enough calcium hydride briquettes to generate 6-cubic feet of hydrogen gas for the inflation of a 30-gram balloon. Calcium Hydride Charge ML-305/TM(XO-1) contains enough calcium hydride briquettes to generate 24-cubic feet of hydrogen gas for the inflation of a 100-gram balloon.
    Caution: HYDROGEN MIXED WITH AIR FORMS AN EXPLOSIVE MIXTURE. Expel all air from a balloon before filling it with hydrogen. Electrically ground the hydrogen cylinder and all the metal parts from the cylinder to the hosecock or valve so that any static electricity can be dissipated without danger of an electric spark which might ignite the gas. Do not wear nailed shoes on a concrete floor during inflation because they might cause a spark.
    6.	Shelter
    a.	Permanent Shelter. Inflate balloons under a shelter since even the slightest wind will hinder determination of the correct inflation. Overhead ventilation should be provided for the removal of any hydrogen which might collect in the ceiling. For sounding balloons, the shelter should be at least 10 feet square with 8-foot doors on opposite sides. If only one door is possible, locate it on the side opposite the prevailing winds.
    Note.—If a permanent shelter is not available, use the portable shelter described below.
    b.	Portable Balloon Inflation Shelter. A portable balloon inflation shelter is made of 8-ounce canvas duck which is mildewproofed and waterproofed. The shelter is 7 feet square and 10 feet high. It is supported by four two-section poles and is guyed by four ropes from the tops of these corner poles. The roof is given a slight pitch by a l^-inch iron bar placed diagonally from the rear top left corner to the front top right corner. The door is a two-sectioned flap which slides on a cable to form an opening 7 by 9 feet (fig. 2).
    c.	Unpacking and Assembling Portable Balloon Inflation Shelter. (1) Carry the balloon inflation shelter in its folded form to the desired location (fig. 3).
    (2) Unbuckle the four canvas straps on the folded shelter case, and unfold the large side flaps.
    (3) Unbuckle the two canvas straps now accessible, and unfold the end flaps of the case.
    5
    ZW&A XSk. X
    'x'y V ^Illiiir
    VIEW A Xj’ >^'-’]^ /	.1	;
    /	!	/ /	^	!!	-f— RIGHT SIDE
    /	।	A /	■	.	!'	।
    /	l/	>	/	/	I	n	1 'Ml
    / ai//Jl£ >>'
    Ji/ .»C Jffi ? w
    •®Ww;‘JI*	d	'■‘i
    H MF
    /
    H / /	TL90259
    “’i ?
    V
    Figure 2. Portable balloon inflation shelter.
    (4)	Lift, out the tent and the four guy ropes wrapped around it.
    (5)	Take out the four bearing plates packed loosely in the case.
    (6)	Unfold the small canvas flaps at one end of each group of shelter pole sections packed in the large side flaps of the case, and slide the eight pole sections from the canvas pockets and loops that hold them.
    (7)	Unfold the small flaps at the ends of the two curved roof support rods; unbuckle the strap holding the rods and remove them.
    (8)	Unfold the flaps from one end of the four wooden stakes packed in the center of the case, and slide the stakes from the pockets and loops that hold them.
    (9)	Unfold the flap from the end of each of the two groups of Stakes GP-2 packed in the end flaps of the case, and take out the nine stakes.
    6
    7
    balloon inflation shelter—JI
    \ ---------------------------------------------------- — ■ (
    •/ ■
    WOODEN STAKES	}
    STAKES	*---^SHELTER POLE SECTIONS
    “MM ' ' V> I//
    I^s^sk Vs	HiiiniiLa"Lj:LL---riir	| ■n^-v •■
    ?*%x
    s.	\	/	;>-\...—— _—-------------~,	'*a^v^**^	✓
    /‘^pSSiS^
    \	R00F SUPPORT SECTIONS
    \	r	--CANVAS CASE
    TI *** ^ O 2 ^5 ?
    z^.-, , <«»w6a «M»B®SS»&«vS n. < x« v\x v x— , . , ^, .-■, , x •. > ^> - ,%x lx^% , , vX n H ^ ' '•• > &&» •> zKW: '	"M
    Figube 3. Portable balloon inflation shelter, unfolded.
    d.	Erecting Portable Shelter. (1) Take the four large wooden stakes, and drive one each into the ground at the corners of a 20-foot square.
    (2)	Assemble the two roof support rods (view A, fig. 2) by inserting the plain end of one rod into the hollow-sleeved end of the other. Match the holes in each of the joined ends, and insert the pin that is chained to the sleeved end of the rod.
    (3)	Unwind the four guy ropes from around the tent, and lay them aside.
    (4)	Unfold the tent. Place the roof support curve-up under the roof so that the support extends from the rear left corner to the front right corner (fig. 2). Fasten the support to the roof by the canvas straps.
    (5)	Assemble the eight pole sections to form the four shelter poles. Four of these sections have a hollow sleeve at one end and a pin extending from the other. These are the bottom sections of the shelter poles. The other four sections each have a longer pin extending from one end while the other end is plain. These are the top sections of the shelter poles. Take one top section and insert its plain end into the sleeve of a bottom section. Repeat to assemble each of the other three poles.
    (6)	Insert the long pin of one shelter pole into the hole in one end of the roof support and up through the grommet in that corner of the roof, so that the pin extends above the roof. Likewise insert another pole in the corner diagonally opposite.
    (7)	Slip the looped end of a guy rope over each of the pole pins extending through the tent roof, and raise the two poles and tent upright. Fasten each guy rope to a stake.
    (8)	Insert the long pin of a shelter pole through each of the grommets in the other two corners of the roof. Slip a guy rope over each protruding pin, raise the poles upright, and fasten each guy rope to a stake.
    (9)	Put a bearing plate on the ground under each shelter pole, and insert the pin through the hole in the plate and into the ground.
    (10)	Fasten the tent to the front poles by buckling the web straps provided in those corners.
    (11)	Drive a modified Stake GP-2 into the ground inside the tent beside each grommet provided along the bottom of the sides and along the back of the tent. Fasten each grommet on the adjacent stake hook, and drive the stakes further into the ground to tighten the sides and the back of the tent.
    (12)	Finally, make the tent as secure and as windtight as possible by piling earth on top of the flaps provided at the outside bottom of the sides and back.
    e.	Using Portable Shelter. Close the sliding front sections, and lap them over. Tie the web straps at the end of the outside laps to the straps on the outside of the tent. Tie the straps at the end of the inside laps to the straps on the inside of the tent.
    Note.—Whenever a balloon bursts during inflation, immediately ventilate the shelter.
    8
    7. Preparation for Inflation
    a. Balloon Temperatures. Warm a cold balloon before inflation by gently kneading it between the hands, by holding it under the garments, or by keeping it in a warm place for a short period of time before use. (See par. 20 for method of warming neoprene balloons.)
    &. Required Equipment. Couplings, hosecocks, nozzles, hose, tubing (fig. 4), and a source of hydrogen are used to inflate meteorological balloons. The specific size of equipment required is determined by the type of balloon being inflated.
    c. Preparation of Sources of Hydrogen. (1) Preparation of hydrogen cylinder. (a) Tightly attach Hose ML-81 (fig. 4©) to Coupling ML-49 (fig. 4@) or to Hydrogen Regulator ML-193 (fig. 7) if the regulator is used instead of the coupling. If the joint is loose, fasten a hose clamp, cord, or wire around it.
    (&) Quickly open and close the valve of the hydrogen cylinder to expel any dirt that may have accumulated in the valve opening.
    () Attach the free end of Hose ML—81 to the small end of Cock ML-56, and open the stopcock of Cock ML-56 to start inflation of the balloon.
    () Operator 2 connects the two black leads at the side of the radiosonde, and then tunes the ground station to the radiosonde signal.
    (c) Ground-station operator 2 takes the radiosonde, holding it upright by the bottom of the case.
    {d) Operator 1 releases the balloon, maintaining a sliding grip on the line between the balloon and parachute and transferring this grip to the line leading to the radiosonde as the parachute rises into the air.
    1 Instruction in the use of the theodolite may be found in the following Technical Manuals : TM 1-235, TM 4-240, and TM 11-423.
    16
    (e) The operator holding the radiosonde approaches the position of the release of the balloon and follows the balloon as the line shortens, running if necessary, until the radiosonde is lifted gently from his hands by the ascending balloon (fig. 8).
    (3)	Release in very high wind. In a very high wind, the line from the parachute to the radiosonde should be shortened to about 20 feet. Heavy rubber bands are tied in this line (called “spanning a bight,” as shown in fig. 9) to absorb the shock when the balloon lifts the radiosonde.
    (4)	Release in doivndraft. Occasionally a balloon may not rise in a downdraft. Do not release the radiosonde if the balloon has not risen sufficiently; in this way all danger that the radiosonde will strike
    —-	---—■	\i
    -----— WIND DIRECTION -------=~—	\ V
    BALLOON WILL SWING UP AND OVER	/fl
    HEAD OF MAN HOLDING RADIOSONDE	/JI
    fl	\	/- BALLOON ML-I3I	//
    /-PARACHUTE ML-132	RADIOSONDE	J#
    J ix	o nt
    MAN WITH RADIOSONDE FOLLOWS BALLOON,	TL7500
    RELEASING IT AS BALLOON GAINS SUFFICIENT ALTITUDE
    Figure 8. Method of releasing sounding balloons.
    the ground will be eliminated. The radiosonde must be saved, even if the balloon itself breaks away and is lost.
    14.	Night Use of Pilot Balloons
    a.	General. Thirty-gram pilot balloons, fitted with a lighting unit, are used for night observation of wind direction and velocity. If no ceiling light projector is available, lighted pilot balloons may also be used for the determination of ceiling height at night, since they have a known rate of rise and can be timed by the same method used for daylight observation of ceiling balloons (par. 16a).
    b.	Lighting ITnits. Two types of lighting units, battery light and candle lantern, are available for 30-gram pilot balloons.
    17
    (1) Battery light unit. The battery light unit consists of a battery a bulb, and a parachute (figs. 10, 11, and 12).	' ’
    («) Preparing parachute. Locate the cord which extends from
    “Im CT}nteii °fthe Parachute to a knot which joins the side cords (tig 10). Break this cord just above the knot, and turn the parachute inside out, thereby furnishing a cord extending from the top outside of the parachute. Take a short cord, and loop it around the battery
    TL 7502
    Figube 9. Spanning a bight.
    (fig. 11). Tie the ends of this cord to the knotted lines which extend 10m the sides of the parachute so that the bulb will hang down when suspended (fig. 12).
    (6) Inflating balloon. Inflate the balloon as described in paragraph Qa. Because of the additional load of the battery unit, the battery and an extra 40-gram weight must be tied to Cock ML-56 The balloon will be inflated to the free lift of 172 grams required to maintain a rate of rise of 200 yards per minute.
    18
    (c) Final steps. Tie the top cord of the parachute to the inflated balloon (fig. 12), and screw the light bulb so that it lights.
    (2) Candle lantern set. The candle lantern set consists of a paper lantern and a small candle packed separately. The lantern is packed flat (fig. 13).
    («) Preparing lantern. Open the top flap of the lantern, and push the lantern walls aside. Attach the candle either by sticking a straight pin up through the center of the bottom of the lantern and into the candle or by temporarily lighting the candle and letting a few drops of the molten wax fall on the inside bottom of the lantern, and then setting the candle in the soft wax which will harden and hold the candle. Tie a 4-foot cord to the lantern handle.
    \l^0REAK CENTER W/ CORD AT THIS
    » POINT
    TL7503
    Figure 10. Parachute for battery lighting unit.
    Caution: Do not light the candle where there is hydrogen or when very close to the inflated balloon.
    (&) Inflating balloon. Inflate the balloon as described in paragraph 9a. Because of the additional load of the candle lantern, weigh the balloon with the cord and lantern hanging from Cock ML-56. (This maintains a free lift of 132 grams. The rate of rise is decreased only 4 percent; this does not materially affect the accuracy of an observation.)
    (c) Final steps. Light the candle, and unfold the lantern (fig. 13) by twisting and separating the cardboard ends. Take care that the lantern walls do not catch fire. If there is a high wind, it may be
    19
    necessary to place the lantern in a wastebasket or bucket to provide shelter for lighting the candle. Tie the cord from the lantern handle to the neck of the inflated balloon. Push the top flap of the lantern through to the inside of the lantern to permit air to reach the candle flame.
    Note.—The burning life of the candle is only 40 minutes; release the balloon as soon as possible after lighting the candle.
    c. Night Release of Balloons. (1) Hold the neck of the balloon in one hand and the lighting unit in the other. Be sure that the cord between them is fairly taut and untangled. If a lantern is being used, hold the balloon down wind from the lantern.
    ( J T L 7504
    Figure 11. Battery lighting unit.
    (2) Swing the hands toward the wind, and release the balloon and the lighting unit at the same time. A wind stronger than moderate may cause some difficulty in releasing a balloon with lantern attached. Link three or four rubber bands together, and insert them in the cord at a point halfway between the balloon and lantern (fig. 9). This arrangement will absorb the initial shock to the lantern. Hold the balloon and lantern so that there is slight tension on the rubber bands, and release both at the same time. Successful launchings in winds 25 miles per hour or over can be accomplished by this method.
    15. Use of Balloons during Precipitation
    a. Pilot Balloons. Rain, snow, or sleet might decrease the rate of rise of the balloon and might result in inaccurate observations. Pilot
    20
    'balloon flights can be made during a light rain or snow with very little difference in the ascension rate.
    b. Ceiling Balloons. In very light rain or drizzle, ceiling balloon flights can still provide an estimate of cloud heights.
    c. Sounding Balloons. The ascent of sounding balloons with attached radiosonde equipment can be made regardless of weather conditions because no definite rate of rise is necessary in such observations.
    Figure 12. Battery light and parachute attached to balloon.
    21
    TL 7505
    16. Rate of Ascent
    The following tables and formulas are based on average rates of rise of meteorological balloons:
    a. Ceiling Balloons. The average rate of rise of a ceiling balloon inflated to a free lift of 40 grams is 360 feet per minute after the first
    Figure 13. Candle lantern light unit.
    1^ minutes. Use the following table to determine ceiling height after timing a ceiling balloon flight:
    Time (minutes)	Altitude (feet)	Time (minutes)	Altitude (feet)	Time (minutes)	Altitude (feet)	Time (minutes)	Altitude (feet)
    %		130	2%		940	4%		1, 660	6%		2, 380
    72		250	'2/i		1, 030	4%		1, 750	6/2		2, 470
    %		370	- 2%		1, 120	4%		1, 840	6%		2, 560
    1		480	3			1, 210	5		1, 930	7		2, 650
    1%		580	3%		1, 300	5%		2, 020	7%		2, 740
    1J4		670	6/2		1, 390	5%		2, 110	7H-'-		2, 830
    1%	___	760	3%		1, 480	5%		2, 200	7%		2, 920
    2		850	4		1, 570	6		2, 290	8		3, 010
    (1) Use a stop watch (or a watch with a second hand) to time a ceiling balloon flight. Release the balloon exactly on an even minute, 22
    TL-7512
    and note the exact time the balloon enters the cloud. Calculate exactly the number of seconds or minutes this occurs after release, and use the preceding table to determine the ceiling. Some clouds have smooth bases into which the balloon may disappear at once; others have ragged bases. If the balloon enters one of the lower portions, it indicates the ceiling more accurately than if it enters a hollow in the cloud (fig. 14). If clouds are broken, the balloon may drift into openings between the clouds and disappear. Such disappearances do not indicate true cloud height. Whenever a measurement is doubtful, immediately release another balloon, and take another measurement. Repeat as many times as necessary, taking the lowest of the several readings as the ceiling.
    MORE ACCURATELY IF TAKEN WHEN BALLOON ENTERS BASE OF LOWER PORTION OF CUDUD
    Figure 14. Cloud heights.
    (2) Whenever very accurate determination of cloud height is required, employ two or more theodolites separated by some distance. The height can be computed from the theodolite readings.
    (3) In some cases, an entirely different method, such as a pilot’s report, should be used. For example, if the ceiling must be known to within 200 feet at an altitude of 2,000 feet, a more accurate method than timing the ascent of the ceiling balloon is required.
    b. Thirty-Gram Pilot Balloons. (1) The rate of ascent of 30-gram pilot balloons is determined by the following formula:
    / F \5/8 '
    V= 158(^ ^12/3^
    F=rate of ascent in yards per minute.
    •^’=the free lift or actual lifting force of the inflated balloon expressed in ounces.
    7’=(he total lift (free lift, F. plus the weight of the balloon) expressed in ounces.
    23
    CLOUD HEIGHT NOT SO	[
    ACCURATE IF TAKEN WHEN	I
    BALLOON ENTERS-HOLLOW
    IN CLOUD.	/ 1
    CLOUD HEIGHT IS INDICATED
    U=72
    The same formula in metric units is: yay/s
    V=the rate of ascent in meters per minute. F=free lift in grams.
    7’= total lift in grams.
    Cock ML-56 weighs 132 grams (4.66 ounces) which is the lift necessary for a balloon weighing 30 grams (1.06 ounces) to rise at a rate of 200 yards per minute. Therefore, the total lift for a balloon of this size without any attached accessories is 5.72 ounces.
    (2) A pilot balloon near the ground will ascend faster than the calculated rate of rise of 200 yards per minute. This increase in rate averages 20 percent during the first minute after release, 10 percent during the second and third minutes, and 5 percent during the fourth and fifth minutes. Thus, a 30-gram pilot balloon with a free lift of 132 grams (4.66 ounces) will ascend at the following rates:
    First minute, 240 yards.
    Second minute, 220 yards.
    Third minute, 220 yards.
    Fourth minute, 210 yards.
    Fifth minute, 210 yards.
    Each subsequent minute, 200 yards.
    c. One-Hundred-Gram Ptlot Balloons. The 100-gram pilot balloon rises at a rate of approximately 330 yards per minute and consequently requires less time than the 30-gram balloon for a high altitude flight. I he 100-gram pilot balloon travels faster during the first 14 minutes of flight. The corrections to be added to the rate of rise for the first 14 minutes are 22, 19, 19, 16,16, 12, 12, 12, 8, 8, 6, 3, 3, and 3 percent, respectively.
    d. Sounding Balloons. The rate of rise of a sounding balloon, fully equipped with radiosonde and inflated to an approximate free life of 500 grams, is about 450 to 600 feet per minute. Uniformity of rate of rise is of minor importance for sounding balloon flights because altitude is accurately computed from the radiosonde record.
    REMEMBER THESE POINTS
    1.	Differently colored balloons are furnished so that the balloon which will contrast best with the appearance of the sky at the moment can be chosen. Take time to consider the choice !
    2.	Hydrogen is highly inflammable. Be extremely careful when using it. Do not smoke near it!
    3.	Do not become careless in weighing off the balloon. Be certain that it is inflated just enough to get the desired free lift. Do not underinflate or overinflate. Get it right!
    4.	When tying off a balloon after inflation, be sure that it is tied tightly enough to keep the gas in the balloon. Even a very slow leak affects the rate of rise and may make the observations inaccurate !
    5.	Keep in mind the fact that hydrogen gradually seeps through rubber. Do not inflate the balloon until shortly before the time to release it.
    24
    SECTION III
    MAINTENANCE
    17.	Care of Hosecocks and Nozzles
    a. C leaning. Large amounts of talc, placed on the inner surfaces of meteorological balloons to prevent sticking of the rubber, tend to clog the hosecocks and nozzles used for inflation. Keep hosecocks and nozzles clean of talc by shaking regularly. In extreme cases, clean by inserting a thin flexible wire into the hosecock or nozzle to loosen the talc; then shake out the talc.
    5. Lubricating. Use graphite or a paraffin-base oil to lubricate hosecocks and nozzles. NEVER USE OIL FOR LUBRICATING ANY PART OF A HOSECOCK OR NOZZLE UNLESS IT IS A PARAFFIN-BASE OIL. HYDROGEN REACTS CHEMICALLY WHEN PASSED THROUGH MANY OILS.
    18.	Storage of Balloons
    a.	Keep balloons in their original, sealed containers, and store them in a cool, dry, dark place until needed for use. Balloons deteriorate rapidly in high temperature. Provide special storage in summer. In winter, do not store them in an overheated room. If a balloon has been stored in a cold place, it must be warmed before using so that the balloon will retain its spherical shape when inflated.
    b.	Use balloons while they are fresh. Never allow an oversupply to accumulate. Use the old stock before starting on a new supply.
    19.	Patching Balloons
    Occasionally balloons, when received from the manufacturer, will have small pinholes. In some cases, such holes may develop during inflation due to small air bubbles or other defects. These defective balloons can be patched and used on days when clouds are low or a short observation is anticipated for any reason. Use pieces of burst balloons for patches, and hold in place with ordinary rubber cement. Place patches on the inside of the balloon for best results.
    20.	Care of Neoprene Balloons
    a.	Storage. Neoprene balloons should be stored in place at a WARM temperature from 80° F. to 85° F. Always keep a neoprene balloon warm until the instant it is released in flight.
    b.	Inflation. Inflate neoprene balloons in a warm room. Connect all associated equipment, and check the radiosonde before taking
    25
    neoprene balloon out for use. All haste should be made to release a neoprene balloon in flight as soon after inflation as possible.
    c.	Warming Neoprene Balloons. If a neoprene balloon is subjected to cold or becomes cold in transit, it must be conditioned, that is, it must be warmed before it is used. Remove the neoprene balloon from its container, and heat the balloon near a stove to a temperature of about 80° F. Make sure that the heat is distributed evenly over the entire surface of the balloon. Inflate in the usual manner in an inflation shelter.
    21.	Moistureproofing and Fungiproofing
    Moistureproofing and fungiproofing will not be required for this equipment.
    26
    SECTION IV
    SUPPLEMENTARY DATA
    22.	List of Balloons and Associated Equipment
    The symbol (*) is used in this table to refer to the original model of a series (as ML-157) and the mode] designated by suffix letter A.
    Signal Corps stock No.	Item	Function	Color	Weight		Dimensions and remarks
    				I Grams j	Ounces j
    7A177	Balloon ML-157-(*).	Ceiling	Black, dark blue, or purple.	10	0. 35	Spherical, 3)4-in. diameter; neck 2 in. long, 1-in. diameter.
    7A178	Balloon ML-158-0.	Ceiling 		Red		10	.35	Spherical, 3)4-in. diameter; neck 2 in. long, 1-in. diameter.
    7A150		Balloon ML-50-(*).	Pilot		White or uncolored.	30	1. 06	Spherical, 6-in. diameter; neck 2)4 in. long, l)4-in. diameter.
    7A151		Balloon ML-5'l-(*).	Pilot		Black, dark blue, or purple.	30	1. 06	Spherical, 6-in. diameter; neck 2)4 in. long, l)4-in.diameter.
    7A164..	Balloon ML-64-(*).	Pilot 		Red...	30	1.06	Spherical, 6-in. diameter; neck 2)4 in. long, 134-in. diameter.
    7A175.. 		Balloon ML-155-(*).	Pilot	Orange		30	1.06	Spherical, 6-in. diameter; neck 2)4 in. long, ,l)4-in. diameter.
    7A176	Balloon ML-156-(*).	Pilot		Y ellow	30	1.06	Spherical, 6-in. diameter; neck 2)4 in. long, l)4-in. diameter.
    7A179		Balloon ML-159-(*).	Pilot				White		100	3.53	Spherical, 16-in. diameter; neck 2)4-3 in. long, i/ie-in. to 134-in. diameter.
    7 A180		Balloon ML-160-(*).	Pilot 		Black		100	3.53	Spherical, 16-in. diameter; neck 2)4-3 in. long, Jis-134-in. diameter.
    7A181		Balloon ML-161-f).	Pilot		Red		100	3.53	Spherical, 16-in. diameter; neck 2)4-3 in. long, Ho-l^-in. diameter.
    27
    Signal Corps stock No.	Item	Function	Color	Weight		Dimensions and remarks
    				Grams 1 1	Ounces
    7A171 7A849 . 7A850-187 _	Balloon ML-131-0. Coupling ML-49. Coupling ML-187.	Sounding	 Connects Hose ML-81 to hydrogen gas'cylinder. Connects Tubing ML-188 to Hose ML-81.	White	350	12. 34	Spherical, 3-ft. diam eter; neck 4J^ in. long, (or 3 in. long if alternate provision for attachment of load is made 1-in. diameter).
    7A981	Hose ML-81	Used as connection in inflation of all balloons.				5 feet long, rubber.
    7A981-10.	Hose ML-81	Used as connection in inflation of sounding balloons.				10 feet long, rubber.
    7A656-.	Cock ML-.56	Used in inflation of 30-gram balloons.		132	4. 66	Gas hosecock with enlarged end for fastening balloon and attachment for rubber hose.
    7A 700-201A	Cock ML-201-A.	Used in inflation of 100-gram balloons.		575	20. 28	Gas hosecock with end for fastening balloon and attachment for rubber hose.
    7A1199A-186.	Nozzle ML-186.	Used in inflation of 10-gram ceiling balloons.		39	1. 38	Consists of wooden nozzle with end for fastening balloon and attachment for rubber tubing.
    7A1199A-196	Nozzle ML-196.	Used in inflation of sounding balloons.		1, 500 (basic)	52. 91	Consists of metal nozzle with end for fastening balloon.
    7A401	Candle ML-90.	Used in Lantern ML-91.		7	0. 25	Stearic acid and paraffin; melting point about 128° F.
    7 Al 105	Lantern ML- 91.	Used in making night flights with pilot balloon.		6	0. 21	Paper.
    7A1119 _	Lighting Unit ML-179.	Used in making night flights with pilot balloon.		35	1. 23	Consists of battery and bulb.
    7A1207-100	Parachute (miniature).	Used with lighting unit		4	0. 11	Paper, approximately 16-in. diameter.
    7A1207-132	Parachute ML-132.	Used with radiosonde			5	Paper or cloth, approximately 44-in. diameter.
    	Pins		Used to hold candle in lantern.		—		Straight.
    7 A1334-193	Hydrogen Regulator ML-193.	Used on hydrogen cylinder to indicate pressure and to provide a means of controllingrate of flow of gas. (Cannot be used with hydrogen generator.)				Consists of two gauges with a diaphram type reducing valve.
    28
    Signal Corps stock No.	Item	Function
    6M18	Rubber bands No. 16 or 18.	Used for tying off ceiling and 30-gram pilot balloons after inflation and as an aid in releasing lantern unit and radiosonde.
    7A1928 . ...	Tubing ML-188.	Used with Nozzle ML-186 for inflation of ceiling balloon.
    6Z8820.1	Twine >.	Used with lighting unit and lantern, and for tying off sounding balloons and 100-gram pilot balloons.
    6Z8822 .	Twine 1. Wrench. .	Used for suspending radiosonde from sounding balloon. Used to attach Coupling ML-49 to hydrogen cylinder.
    	Weight
    Color	Grams	Ounces	Dimensions and remarks
    —
    	—
    	—		8-ply cotton.
    			16-ply cotton.
    			Jaw opening at least 1J4 in.
    Any cord of the same weight and about 50 pounds test strength can be used.
    U. S. GOVERNMENT PRINTING OFFICE: 1944
    29
    „ 4 P
    cs 17,6
    UNT LIBRARIES DENTON TX 78203
    HIIIIIIIIIIII
    1001896185
    BTSfl LIBRARY.^