Aircraft technical Basics: TM 1-409, Aircraft Armament and Pyrotechnics, 1941: III. - Pyrotechnics

Section III - PYROTECHNICS

17. General.-Prior to the entry of the United States in the World War there were few requirements for pyrotechnics in the Army, and the pyrotechnic devices necessary were procured from commercial concerns.

a. It was probably due to the fact that war on the European battle-fields developed into trench warfare in which the opposing forces held the same sectors for days at a time and in which the opposing infantry occupied trenches that at times were less than 100 yards apart, that pyrotechnics became of importance for signaling and illumination in military operations.

b. Night attacks were frequent and in guarding against night raiding parties, a method of illuminating no-man's land between the hostile forces was of vital necessity. Field or mobile radio equipment was more or less in the development stage and was not adapted to all phases of warfare. Field telephones were used to good advantage in the battle zones and telephone wire was strung under hazardous conditions. The lines, however, were subject to destruction by shell fire. Panels were used for signaling from the ground to the air in the daytime, but this method of signaling was of no value at night. Pyrotechnics were not subject to these limitations, and their usefulness was due to a great extent to the mobility of the pyrotechnic devices under battle conditions.

c. Pyrotechnic signals used in the World War were small and self-contained. Rockets were used in the trenches as well as the back areas, and both the signals for the grenade discharger and the Very pistol could be carried by the soldier when attacking. Position lights used for signaling from the trenches to friendly airplanes were used in great quantities. Both the position lights and projected signals were for day and night use. The messages were usually by pre-arranged code. Some signals called for immediate action, while others were used for identifying the position of troops.

d. In general, pyrotechnic signals were used

(1) Between troops on the ground.

(2) Between troops on the ground and aircraft.

(3) Between aircraft and troops on the ground.

(4) Between aircraft.

(5) Between aircraft and airdromes.

(6) For night illumination.

The use of aircraft for offensive and observation purposes provided the requirement of a flare to be released from aircraft, for use in illuminating hostile territory at night, for observation, and for the purpose of locating targets for bombing airplanes.

e. When the United States entered the World War in April 19I7, in addition to the urgent demands for various types of .munitions, the Ordnance Department was assigned the problem of developing and procuring from American manufacturers pyrotechnic devices comparable to those of our allies. The types necessarily had to meet the service requirements and, due to the urgent demand, had to be of such a nature that they could be manufactured by the fireworks industry of this country with existing facilities. Contracts had been made and a number of types of pyrotechnics were in process of manufacture when instructions were received to the effect that since the American forces would operate with the French and the pyrotechnics would be issued from the same depots, to avoid confusion both in interpretation of messages and use, the French system of pyrotechnics would be adopted. This order caused considerable delay in manufacture, as samples and drawings were necessary, and when the drawings were received, they had to be revised to conform to American standards. With minor modifications in design to suit American manufacturing facilities and methods, production was started on the French system of pyrotechnics. Until pyrotechnics of American production could be shipped to France, our forces were furnished pyrotechnics by the French.

FIGURE 1.-Aircraft parachute flare, M8.

18. Flare, aircraft parachute, M8.-a. Use.-The aircraft parachute flare, M8, is used primarily for emergency landings at night, either by airplanes in distress or for landings on fields on which there is insufficient ground illumination. Experiments are being conducted from time to time to use it for night reconnaissance and for illuminating targets, both bombing targets and machine-gun targets. Thus far it has not been accepted as standard for these last-mentioned uses. It should be noted that the latest types of military aircraft are not equipped to carry landing flares, the present thought being that they are not needed.

b. Description.-(1) The MS flare burns for approximately 3 minutes with a brilliance of approximately 300,000 candle power. It is 25.5 inches long and 4.25 inches in diameter. It can be released from either a vertical or a horizontal launching tube installed in the interior of the airplane, or from the internal or external bomb racks. The parachute case consists of a metal tube, closed at. the upper end by a cover which is attached to the case by means of the tear-strip assembly. The hangwire assembly is located immediately beneath this cover and is held in position by a shoulder formed in the case and sealed by wires passing through the edge of the container and case. The ends of these wires are twisted together and secured by soldering.

(2) The space in the parachute case immediately below the hang-wire container is filled with the top cord, parachute, shroud assembly, and suspension wire, in the order named. The remaining 2 inches of space below the second shoulder is occupied by the upper end of the illuminant assembly. This is inserted as far as the shoulder will permit. and fastened in place by four wood screws.

(3) The illuminant assembly consists of a cardboard cylinder 15 3/4 inches long entirely filled with illuminant with the exception of a recess in each end of the cylinder and a center tube of card-board in which the quickmatch is located. The large recess in the upper end of the cylinder contains the base block assembly. The recess in the lower end is empty and provides an air space around the lower end of the quickmatch. The lower end of the recess is closed by the body cover assembly.

c. Perpetration of flare for use.-All M8 flares when received from the Ordnance Department have a cover installed over the upper end of the flare. This cover is hermetically sealed in place by a metal strip, which is soldered in place with one end free. This piece of metal, used for sealing the flare, is termed a "sealing tear strip." This sealing tear strip, together with the flare cover, must be removed before the flare can be placed in use. After removing the cover, the flare must be securely latched on the carrying rack. The swivel loop of the hangwire will then be carefully secured in the arming mechanism of the shackle or on the retaining pin of the rack or adapter. If the flare is installed in a vertical launching tube it is supported by the clip, but if it is attached to the bomb rack the flare is supported by two suspension bands encircling the body of the flare over two black stripes painted at the correct location on the flare body for this purpose.

d. Operation.-The operation of the M8 flare is the same whether carried vertically or horizontally. When the mechanism carrying the flare is released, the operation of the flare is as follows:

(1) The flare falls to the full length of the hangwire, pulling the hangwire container out of the parachute case, following which the top cord, the parachute (closed), the shrouds, and the suspension wire are withdrawn.

(2) As the entire weight of the illuminant assembly comes on the tear strip to which the top cord is attached, the strip is broken, and the parachute falls free and opens.

(3) At approximately the same time, the weight of the illuminant assembly on the parachute and its suspension wire draws the pull wire, to which the friction wire loops are attached, out of the upper recess in the illuminant assembly. This withdrawal of the friction wire through the primer charges causes ignition of the quickmatch which projects into the space around the ignition block in the base of the base-block assembly. The quickmatch burns down through the long center cardboard tube in the illuminant assembly and ignites the first fire charge carried in the base of the illuminant case. This burns out the lower disk and the lower rim of the illuminant case, freeing the body cover assembly from the case. The main body of the illuminant. is ignited by the first fire charge and burns steadily upward as the flare descends. The interval of time required for full ignition of the flare after release is approximately five seconds.

(4) In a recent modification of the flare, the hangwire container automatically becomes detached from the hangwire after the flare is released. This modification was made necessary due to the tendency of the container to cut the fabric of the airplane as it was blown rearward by the slip stream.

19. Flare, aircraft parachute, M8A1.-a. Description.-The parachute flare, M8A1, has now replaced the M8 flare as standard. However, the M8 is "limited standard" and as such will be used until the supply on hand is exhausted. The improved M8A1 flare has the same external dimensions as the M8 aircraft parachute flare. The modifications made to the M8 flare are the use of

(1) Different illuminant composition to eliminate the shadows in the area illuminated by the candle.

(2) Aluminum base block instead of the wooden block used in M8 flares to eliminate the splitting of the boxboard illuminant case.

(3) Shock absorber consisting of a hard-drawn copper tube over the suspension cable to act as a shock absorber to eliminate failure of parachute and suspension wires when flare is released at speeds of approximately 200 miles an hour.

(4) Additional wax seal stamped with six impressions of the letters PA around the juncture of the hangwire container and the parachute case to prevent theft of the flare parachute.

b. Inspections.-The inspections of the M8 and M8A1 flares are identical with the exception mentioned below. This will be per-ormed as follows:

(1) Installation check.-At the time of installation of flares in the flare racks, the operation of the racks and release mechanism will be checked by installing the flares without securing the hangwire swivel loops and then operating the release mechanism. When this check is being made, someone will be stationed beneath the airplane to catch the flare before it strikes the ground. A check will also be made at this time to ascertain whether binding of the flare in the parachute occurs at any point. If binding occurs, other flares will be tried to secure one which will slide freely in and out of the parachute.

(2) Preflight inspection.-Prior to the first flight each day of airplanes with flares installed, the flares will be visually inspected for deterioration, proper anchorage of the hangwire swivel loop, and security of engagement of the carrying hook or bands with the carrying mechanism of the rack. If, for any reason flares are not installed on airplanes equipped for flare installations, or if at any time during the day the flares are removed, a notation that the flares are not installed will be entered in the space for remarks on the back of Form No. 1, for the information of pilots on subsequent flights.

(3) Twenty-hour inspection.-At each 20-hour inspection of the airplane, flares which are installed will be removed from the racks and inspected for dents, corrosion, wear of carrying hooks, damage to or deterioration of the cardboard body covering the illuminant, loosening of lower body cover assembly, broken hangwire container sealing wires, damaged hangwire, corrosion to the container which might prevent withdrawal of the hangwire container, or any other visible defects or damage. Any flares found to be damaged or defective will be turned over to the local ordnance officer for disposition.

c. Additional inspections.-In addition to the above, the following obtains: The top cover or hangwire container of the M8A1 flare is retained in position by means of a sealing compound. When these flares are installed on airplanes which are parked in the direct rays of the sun for more than 1 hour, with the temperature in the shade at 32° C. (90.° F.) or more, the sealing compound will soften and allow the top cover to become loose. This may allow the parachute, to emerge from the top of the flare with subsequent malfunction at the time of release. Pending an investigation of this condition and the issuance of appropriate instructions, the M8A1 flares will be inspected as follows:

(1) Prior to installation, examine each flare carefully to determine if the sealing compound on the parachute end of the flare has melted or softened sufficiently to permit the hangwire container to be pushed partly or entirely out of the parachute case. If either condition exists, the flare will not be installed, but will be reported to the Ordnance Department for disposition.

(2) Whenever ground temperatures of 32° C. (90° F.) or over prevail, or have occurred since last inspection, all M8A1 flares installed on airplanes will be inspected immediately prior to each flight that may involve possible use of the flares. The flares will be replaced if necessary.

d. Maintenance, storage, and issue.-The M8 and/or M8A1 flare is stored. and issued by the Ordnance Department. Requisitions for flares will be submitted to the local ordnance representative.

(1) Care will be exercised in handling flares that the carrying hooks are not bent and that the flare body is not dented or otherwise damaged. All those which are damaged or unserviceable will be turned over to the local ordnance officer for disposition.

(2) Flares carried on aircraft will always be carried "armed," that is, with the hangwire swivel loop properly anchored. This is to prevent the flare assembly being accidentally dropped without burning, which is extremely hazardous in populous areas. Although constructed so as to be practically waterproof under normal conditions of use, a flare should not be exposed unnecessarily to dampness. Unless the installation is such that the flares are properly protected, airplanes which are not stored in hangars will have the flares removed and properly stored during damp or rainy weather.

(3) Proper safeguarding against fire hazard in the care and handling of flares which have been issued for aircraft installations will be a responsibility of local commanders who will issue such instructions as will insure the maintenance of safe and reasonable practices under the conditions prevailing locally. Except as noted above, flares may be left continuously installed on airplanes which are being used for missions involving night flights unless some local condition exists which would make this procedure undesirable.

(4) The installation and inspection of flares on internal and external flare racks will be made only by experienced personnel, and with the utmost precaution exercised to insure full latching of the carrying and releasing mechanism and the engagement therewith of the flare carrying hooks or lugs of the suspension bands.

e. Restrictions on use.-The useful life of flares for flights where emergency night landings might be involved will be

(1) Six years from date of manufacture for flares which are packed in hermetically sealed containers when manufactured; or 1 year from the date the seal is broken-the combined period not to exceed 6 years.

(2) Three years from the date of manufacture for flares which are not packed in hermetically sealed containers when manufactured; or 1 year from the date they are first used on an airplane-the combined period not to exceed 3 years.

f. Training flares.-When the useful life has expired, flares which are otherwise serviceable will be assigned for training use only. This applies to all flares even though they have not been used on airplanes. Individual flares removed from airplanes because they have been installed for over 1 year will be inspected, and if serviceable will be used in training flights in which emergency night landing cannot be involved.

20. Projector, pyrotechnic, aircraft, M2.-a. Use.-The projector is used for firing parachute signals and flares from aircraft.

b. Description.-This projector is of the self-cocking type, having detachable barrels. It was developed to meet the requirement that the pilot be able to load, fire, and extract the empty signal or flare case with one hand. To accomplish this, the signal or flare is assembled in a light, expendable, detachable barrel, the barrel of the pistol serving only as a seat or socket into which the detachable barrel is inserted. The base of the detachable barrel is provided with an annular groove which accomodates the locking lug on the pistol. The signals are carried in racks in the airplane convenient to the pilot or observer, with the primer end up.

c. Operation. In operation, the barrel of the projector is placed over the base of the signal or flare which is automatically locked in. place. A. continuous pull on the trigger cocks and fires the pistol.

The detachable barrel is unlocked by depressing the thumb release on the left side of the breech of the projector, and is then free to fall from the pistol by gravity. In case of misfire or hangfire, the signal can be disposed of in the same way without endangering the aircraft by bringing the loaded discharger into the cockpit.

21. Flare, aircraft parachute, M9.-a. Use.-This flare was developed to satisfy the requirement for a small parachute flare for reconnaissance work.

b. Description.-The flare has an over-all length of 13.8 inches and a diameter of 2 inches. The illuminant. burns for 1 minute with 90,000 candlepower. It weighs 30 ounces. The flare consists of an extruded aluminum flare case, reduced in size at the base to fit in the detachable barrel. The propelling charge cup, containing a black powder charge is attached to the inner wall of the base. The fuze train (2 1/2 seconds delay) is housed in a metal flanged tube which is secured to the base of the flare, the outward end of which is exposed to the flame of the propelling charge, housed in the breech of the detachable barrel. The opposite end of the fuze is in contact with the expelling charge. The illuminant charge is contained in a candle case. The base of the candle case provides a means of attaching the parachute wire. The gas check protects the silk parachute from the flame of the expelling charge. The upper end of the flare case is provided with a closing cap.

22. Signal, white star parachute, M10.-a. Use.-The signal is for use with the Air Corps signal pistol, M2. It is used primarily for signaling between aircraft and from aircraft to ground. Secondarily, it may be used to signal from the ground to aircraft or between forces on the ground.

b. Description.-(1) The signal is 7.7 inches long, 1.56 inches in diameter, and weighs 9.8 ounces. The star burns for 30 seconds, with a brilliance of approximately 30,000 candlepower and produces a white light. In raised letters on the top (or muzzle) end is stamped "WP," and the entire top is painted white for identification. In addition there is stenciled in black on the side "M10 Signal, Aircraft, 'White Star Parachute," as well as the lot number.

(2) The case (or cartridge) fits into the M2 projector and forms the expendable barrel. This barrel contains the propelling charge and an inner barrel or container. In the inner container is the illuminant charge and igniter, the parachute, and an expelling charge.

c. Operation.-When the M2 projector is fired, the propelling charge expels the entire inner container with sufficient force that the height of projection from the ground is 210 feet. At the same time, the blast of the propelling charge ignites a powder train into the expelling charge. This train is so designed that the expelling charge is exploded by the powder train at about the instant the projectile will have reached its peak of ascent (if fired from the ground). The explosion of the expelling charge both expels the parachute and illuminant charge and ignites the black powder igniter of the illuminant charge.

23. Signal, red star parachute, M11.-Everything said about the M10 signal above is true of the M11 signal with the following exceptions:

a. The star burns for 30 seconds with a brilliance of 30,000 candle-power and produces a red light.

b. In raised letters on the top (or muzzle) end is stamped "RP" and the entire top is painted red for identification. In addition, there is stenciled in black on the side "M11 Signal, Aircraft, Red Star Parachute," as well as the lot number.

24. Safety rules for M9 flares and M10 and M11 signals.-a. Care should be exercised not to damage or break the waterproof seal in the end of the case.

b. Care should be taken to avoid denting or deforming the aluminum case.

c. Allow no object to rest on, strike, or press upon the primer.

d. Signal cases which have serious dents or which are so damaged that they will not fit properly into the projector will not be used.

e. Do not allow the signal case to come in contact with oil or grease.

f. All foreign substances, such as dirt, sand, mud, or grease, will be carefully removed before use.

25. Photo flashbomb, M12A1.-a. Description.-The M12A1 photo flashbomb is equipped with an adapter. This bomb has an over-all length of 34 1/2, inches. It is 7 1/2 inches in diameter and weights approximately 33 pounds and is supplied with suspension straps and fittings for holding the bomb in a horizontal position. This is the only position in which this type of bomb can be suspended. The parachute compartment is provided with a small square pilot parachute which is released after the. bomb leaves the airplane and causes the fuzes which are placed in the fuze head to function. The powder chamber is filled with 25 pounds of flashlight powder prepared in accordance with Air Corps specifications. Suitable quickmatch is interspersed through the flashlight powder and connected to the fuzes for igniting simultaneously the entire charge of powder. The case is made of laminated cardboard equipped with 3/4-inch plywood heads and bottoms suitably anchored to resist the expansion of the gases in the powder until the whole charge has become ignited. The entire case is suitably wrapped with mercerized cotton cloth to which has been applied acetate dope for making the case waterproof and sufficiently strong to withstand normal handling.

b. Installation.-M12A1 photo flashbombs are installed in the containers provided for same with suitable individual release cables running to the camera compartment for release by the camera operator. Instructions pertaining to the proper method for handling and installing are given on the label applied to the bombs and bomb packing case.

Caution: All personnel are enjoined to comply strictly with printed instructions.

c. Precautions.-When conducting peacetime night photographic practice missions, precautions will be taken so that M12A1 photo flashbombs will fall in water or in open areas where there is no probability of a "dud" being handled by unauthorized individuals. These bombs contain a sufficient powder charge to be extremely hazardous if handled by untrained personnel, and their use over populous areas is prohibited. All "duds" and unserviceable photo flashbombs will be destroyed under the supervision of qualified ordnance personnel only in accordance with instructions printed on the bomb casing.

d. The procedure outlined below will be followed when installing M12A1 photo flashbombs:

M12A1 photo flashbombs will be handled with care since they contain 25 pounds of flashlight powder which presents a fire and explosion hazard equal to a like quantity of black powder.

Caution: As M12A1 photo flashbomb is equipped with adapters, it must not be installed on standard bomb racks. The bombs can be used in the photo flashbomb installations which are provided on O-47A airplanes, in which case the upper bomb stop must be omitted. Bombs can be released manually through floor openings of F-2, B-18, and B-18A airplanes.