Jimmie H. Butler
Information on Writing and the War in Southeast Asia

MK-24 PARACHUTE FLARES 

Bulletin #46 

12 Aug 66

MK-24 PARACHUTE FLARES

1. General:

a. The MK-24 parachute flare is being used extensively on a wide variety of missions in Southeast Asia . A-26's, C-47's, C-123's, and C-130's, as well as various fighter aircraft, are employed as dispensing aircraft and the missions range from "on call" defenses of besieged hamlets/forts, to armed route reconnaissance for vehicular traffic, to normal pre-planned strikes against static targets. Initially, flare reliability was very poor and there were a large number of duds. This was attributed primarily to the use of old flares, as well as the fact that, through necessity, personnel unfamiliar with safe munitions handling procedures were enlisted to prepare and dispense the flares ("flare-kickers") from cargo type aircraft. As personnel have become better trained and newer flares have come into use, this high dud rate has steadily decreased; however, there is still much room for improvement. The purpose of this bulletin is to provide users with a general summary of MK-24 flare handling, loading and dispensing procedures (applicable to all cargo aircraft) that may be used as a lesson guide for training purposes, as well as appropriate checklists (Atch 1). (A follow-on bulletin will be published in the near future covering more specific in-flight normal and emergency flare procedures for each type cargo aircraft.) This bulletin is oriented primarily toward the MK-24, Mod 3, flare since it is the model predominantly in use.

b. Specific storage, handling and inspection procedures for aircraft parachute flares are contained in T. 0. 11A10-1-177 and 11A10-19-7. These tech orders are currently being consolidated and revised by OOAMA. More specific data relevant to environmental effects of temperature, humidity, and shock have been requested to be included in the revised tech order.

c. All personnel engaged directly or indirectly in operations with MK-24 flares should be thoroughly trained in explosive safety and capable of recognizing hazards associated therewith. The safety requirements of AFM 127-100 must be complied with.

2. Description:

a. The MK-24 series aircraft parachute flares are incendiary illumination stores designed to be carried and dropped from any aircraft. The flare consists of a cylindrical aluminum case containing an ejection fuze assembly, an ignition fuze assembly, an illuminant charge (candle), and a parachute assembly. The ejection and ignition fuze assemblies contain time-delay mecha­nisms which may be adjusted for delay times of 5 to 30 seconds. (The five (5) second delay setting on the ignition fuze of MK-24 flares has been eliminated and should never be used. Production acceptance testing has indicated a high frequency of failures or duds when using this setting. The failures at this setting were the result of the firing pin not consistently impacting into the safety time fuze, causing failure to ignite. Reference OOAMA Message OOYIC 20656 Jul 66.) Dials for setting the time delay mechanisms are on the face of the flare (Atch 2)., A thumb screw on the face of the flare prevents inadvertent movement of the time-delay mechanisms. In addition to the thumb screw, the MK-24 Mod 3 flare has a safety pin inserted through the ignition set dial assembly to prevent lanyard movement if lanyard is accidentally pulled.

b. MK-24 characteristics:

                                             Mod 1                        Mod 2                  Mod 3

Weight (lbs)                           24                                 24                         27

Burning time (sec)                  150                            150                       180

Release Speed

(Knots) Max)                        *450                          *450                     *450

Release altitude

(Feet)                                  See Table 1.

Diameter (inches)                   4.874                         4.874                    4.874

Length (inches)                      36.003                       35.994                  35.994

Candle power (avg)               2,000,000                  2,000,000             2,000,000

Ignition delay

(Min-Max) (Sec)                   10 - 30                       10 - 30                 10 - 30

Ejection

(Min-Max) (Sec)                   5 - 30                         5 - 30                      5 - 30

*Maximum tested values. Launching speeds greater than 450 knots may be possible if ejection cartridge launching is not used.

c. The sequence of setting the ejection and ignition delay settings differ on the MK-24 Mod l, Mod 2, and the MK-24 Mod 3 flares. On the Mod 1 and Mod 2, the ignition set dial is set first and then the ejection set dial. When setting the flares back to "SAFE", the ignition set dial is set first on the MK-24 Mod 1 and 2 flares.

d. When released the flare falls, causing a twelve-pound pull on the lanyard, which activates the ejection fuze assembly. The lanyard separates from the flare when pulled with a 50-pound force. The flare, less lanyard, then free falls for the length of time set on the ejection fuze setting. The rate of fall is approximately 300 feet during the first five seconds, 700 feet during the next five seconds, and 1,000 feet for each five seconds thereafter. After elapse of the time set on the ejection fuze, the ejection time delay fuze ignites an ejection disc. The ejection disc initiates the ignition fuze and expels the ignition fuze, candle assembly and the para­chute assembly from the outer container. Upon clearing the outer tube the split container falls away, allowing the parachute to open and suspend the ignition fuze and candle assembly. The suspended ignition fuze and candle assembly then descend at a rate of 15 feet per second. After the preset time of the ignition fuze, the ignition time delay fuze activates a transfer disc which initiates an ignition disc that ignites the candle, causing the separation of the ignition fuze assembly from the candle assembly, The suspended candle assembly falls approximately 7.5 feet per second and pro­duces a minimum average of 1,650,000 candle power. Average burning times are 150 seconds for Mods 1, 2, and 2A, and 180 seconds for Mod 3 flares

e. Safe launching height and distances are dependent upon the burning time, fuze settings, rate of descent, and drift of the flare. Such factors must be considered in determining minimum height and distances of release, Determination of release height and fuze settings can be made by use of the^, following Table:

TABLE 1

MINIMUM LAUNCHING HEIGHT ABOVE GROUND LEVEL TO PROVIDE FLARE BURN OUT

EJECTION FUZE SETTINGS          5    10         15        20         25        330 LAUNCH ALTITUDE (Mods 1,2,2A) 1800'                        2500'    3500'     4500'    5500^'     6500'

LAUNCH ALTITUDE (Mod 3)   2050'     2750'     3750'    4750'     5750^’   6750’

NOTE: For each 5-second delay on ignition fuze setting, add 75 feet to above values.

3. Storage: The manner in which flares are stored, both on the ground and in the air, has a direct bearing on their reliability. The following requirements should be observed:

a. Keep weather cap in place during storage, handling and shipment. It, must not be removed until immediately before setting fuzes. This assures against accidental moving of the delay dials from the "safe" position or fouling the lanyard, which if pulled could cause the flare to become non-functional.

b. Keep ejection set dial on "SAFE" at all times during shipping, storage and handling

c. Protect flares from moisture. (Pyrotechnic material that has become e wet is hazardous to store.)

d. Protect flares from heat. Store at less then 100⁰ F. Keep magazine or flare aircraft well ventilated. (Flares stored at temperatures exceeding, 100 degrees may be unreliable.)

e. Flares should be stored in magazine or aircraft flare box, by lot number (malfunctioning flares from dispenser could thus be related to a specific lot.)