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MJU-10/B Infrared Countermeasure Flare

The MJU-10/B configuration is identical to the MJU-7A/B (containing the slider assembly), except the MJU-10/B is thicker (2.66 inches versus 1 inch), and it does not have a first fire mix. The first fire mix is also being eliminated in the MJU-7 to reduce cost and provide increased contractor safety by eliminating barium chromate. The MJU-10/B uses the BBU-36/B 'impulse cartridge. Approximately 2,000 of these flares are used by ACC units annually in the mid-1990s. There is also a simulator version, the MJU-10 (T-l), which uses the M-796 cartridge

The F-15E and F-15C employ MJU-7 A/B and MJU-10/B self-protection flares in approved airspace. The F-22A uses MJU-10/B self-protection flares. Self-protection flares are magnesium pellets that, when ignited, burn for 3.5 to 5 seconds at 2,000 degrees Fahrenheit. The burn temperature is hotter than the exhaust of an aircraft, and therefore attracts and decoys heat-seeking weapons targeted on the aircraft. Flares are used in pilot training to develop the near instinctive reactions to a threat that are critical to combat survival.

Self-protection flares are primarily mixtures of magnesium and Teflon (polytetrafluoroethylene) molded into rectangular shapes. Longitudinal grooves provide space for materials that aid in ignition such as:

  • First fire materials: potassium perchlorate, boron powder, magnesium powder, barium chromate, Viton A, or Fluorel binder.
  • Immediate fire materials: magnesium powder, Teflon, Viton A, or Fluorel
  • Dip coat: magnesium powder, Teflon, Viton A or Fluorel

Typically, flares are wrapped with an aluminum-coated mylar or filament-reinforced tape (wrapping) and inserted into an aluminum (0.03 inches thick) case that is closed with a felt spacer and a small plastic end cap. The top of the case has a pyrotechnic impulse cartridge that is activated electrically to produce hot gases that push a piston, the flare material, and the end cap out of the aircraft into the airstream.

The MJU-10/B and the MJU-7 A/B are semi-parasitic type flares that use a BBU-36/B impulse cartridge. In these flares, a slider assembly incorporates an initiation pellet (640 milligrams of magnesium, Teflon, and Viton A or Fluorel binder). This pellet is ignited by the impulse cartridge, and hot gases reach the flare as the slider exits the case, exposing a fire passage from the initiation pellet to the first fire mixture on top of the flare pellet.

Flares are tested to ensure they meet performance requirements in terms of ejection, ignition, and effective radiant intensity. If the number of failures exceeds the upper control quality assurance acceptance level, the flares are returned to the manufacturer. A statistical sample is taken to ensure that approximately 99 percent must be judged reliable for ejection, ignition, and intensity. Flare failure would occur if the flare failed to eject, did not burn properly, or failed to ignite upon ejection. For training use within the airspace, a dud flare would be one that successfully ejected but failed to ignite. That probability is projected to be 0.01 percent based upon dud flares located during military range cleanup.

These prior art infrared flare devices offered very poor stability subsequent to infrared flare launching, and consisted of generally inadequate areodynamically shaped component members. Poor trajectory of the infrared flare caused concern in decoying capability, as the decaying trajectory of a launched infrared flare generally proved to be of a short distance and of questionable azimuthal stability.

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