Flare (countermeasure)

Flares (English, like: jet flames ) are decoys against missiles with infrared homing head. The heat generated during use of flares heat radiation distracts simple seeker sensor from the actual target. The goal is to steer the missile from the thermal radiation of the aircraft on the heat radiation of the flares. The newer sensor takes into account specific turbine engines and emission spectra and only by specific, selectively bright flares ( eg NC flares) distractible.

IR decoys included as an energy storage either pyrotechnic, pyrophoric solids or liquids and flammable solids. If the flares lit, so a highly exothermic reaction is triggered, with a more or less strong visible flame and smoke development goes hand in hand depending on the chemical composition of the energy storage.

Caliber

There are a number of calibers and dies for decoys. Due to lack of space on board aircraft cuboid decoys are used in many platforms of American origin and of NATO member countries. Cylindrical decoys are also available on board American aircraft, as the MJU 23 / B aboard the Rockwell B -1 or the MJU -8A / B to the F-18, but preferably aboard French aircraft and those of Russian design such as the PPI -26 IW aboard the Mig - 29th

Cubic caliber types and typical decoys in this caliber

Cylindrical caliber types:

• 2.5 inches eg MJU -23 / B ( MTV -based)
• 1.5 inches eg MJU 8 A / B ( MTV - based)
• 1 inch eg PPI 26 IW

A typical MJU-7A/B-Täuschkörper is shown opposite. It consists of an outer aluminum sheath (1), an electrically ignitable impulse cartridge (2) which causes the ejection of the active charge and, where appropriate, their ignition and formed into a tube securing the sabot (3 ) having an ignition of the active mass ( 4) with the accentuation (5) and the envelope usually self-adhesive aluminum foil (6) to allow only outside of the cartridge case. The cartridge is closed at the front by a cover plate (7).

Active charges

Pyrotechnic active charges

Active charges with black body characteristics

Certain pyrotechnic compositions such as magnesium / Teflon / Viton ( MTV ) provide whilst burning a temperature-dependent signature and can be described as gray bodies of high emissivity. These decoys are called blackbody active charges (English: black body payload ). Other compositions, such as iron / potassium tablets deliver only a small flame development and also show a temperature-dependent signature. However, in these reactions due to the considerably lower temperature less energy in the short wave infrared range emitted as comparatively at a Magnesium / Teflon / Viton formulation. Other blackbody active charges include, for example ammonium perchlorate / anthracene / magnesium and a polybutadiene based binder.

Active charges with selective radiation pattern

Other active charges eventually produce during burn large amounts of hot carbon dioxide and thus provide a largely temperature-independent, selective radiation in the wavelength range between 4-5 microns. Typical active charges of this type are similar, for example, pyrotechnic Pfeifsätzen and usually contain potassium and hydrogen- poor organic fuels. Other active charges of this type are similar to double base propellant powders and contain nitrocellulose and other nitrate ester compounds or organic nitro compounds as oxidizing agents such as hexanitroethane and nitro compounds and nitramines as fuels. Advantage of the active materials is the low visual visibility. This is based on the absence of condensed reaction products and also on the absence of thermally readily excitable alkali metals such as sodium or potassium which are, however, included in the above-mentioned whistle -like formulations.

Pyrophoric active charges

In contrast to the pyrotechnic active charge pyrophoric substances found in the oxygen necessary for the combustion air. Therefore, the performance pyrophoric decoys is basically the use of height, ie the oxygen partial pressure dependent. A typical liquid pyrophoric medium for decoys, for example, triethylaluminum ( TEA). During combustion, this provides a selective infrared spectrum is dominated substantially by carbon dioxide and water. The combustion products of aluminum are not IR - active in this area.

Solid pyrophoric active charges are based on iron sheets which are provided with a very porous aluminum layer. Due to the very high specific surface area of the aluminum foil, this oxidized spontaneously in contact with air and provide in contrast to the temperature-dependent radiation pyrophoric TEA.

Highly inflammable active charges

This group of active charges eventually usually contains red phosphorus as energy fuel. The red phosphorus to be processed into paste with organic binders and coated onto a thin plastic film. The combustion of the sliver provides - due to the absence of IR-active mode for the combustion products of the phosphor in the 0.8 to 5 micron range - a substantially temperature-dependent intensity distribution, which inert by adding additives, such as finely divided silica modified further can be.

Tactics

For slow- flying aircraft, such as military transport aircraft or helicopters, they are an important part of the self-protection system, as they are threatened by their speed or altitude particularly hard by IR-guided surface to air missile. So come, for example, German Transall transport aircraft in their landing in Kabul flares out as soon as the missile warning device ( Missile Approach Warner ) indicates a threat to possible attacks with portable anti-aircraft missiles (English MANPADS Man Portable Air Defense System ) as the FIM -92 Stinger or Strela -2 to make it more difficult. It usually several flares are ejected salve -like, thereby producing a large heat curtain side and rear of the machine. Gases are produced by a small propellant charge, which takes them to a speed of 150 km / hr. The exact output rates and patterns are controlled by an associated computer system that varies according to the use of the threat of the protected target and the parameters of the flares.

Combat aircraft, in addition to ground -to-air missiles also threatened by infrared- homing air - to-air missiles of other aircraft, such as the AIM-9 Sidewinder or the various Russian models.