Flare (countermeasure)
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A flare or decoy flare is an aerial infrared countermeasure used by an aircraft to counter an infrared homing ("heat-seeking") surface-to-air missile or air-to-air missile. Flares are commonly composed of a pyrotechnic composition based on magnesium or another hot-burning metal, with burning temperature equal to or hotter than engine exhaust. The aim is to make the infrared-guided missile seek out the heat signature from the flare rather than the aircraft's engines.
Tactics
In contrast to radar-guided missiles, IR-guided missiles are very difficult to find as they approach aircraft. They do not emit detectable radar, and they are generally fired from behind, directly toward the engines. In most cases, pilots have to rely on their wingmen to spot the missile's smoke trail and alert of a launch. Since IR-guided missiles have a shorter range than their radar-guided counterparts, good situational awareness of altitude and potential threats continues to be an effective defense. More advanced electro-optical systems can detect missile launches automatically from the distinct thermal emissions of a missile's rocket motor.
Once the presence of a "live" IR missile is indicated, flares are released by the aircraft in an attempt to decoy the missile. Some systems are automatic, while others require manual jettisoning of the flares. The aircraft would then pull away at a sharp angle from the flare (and the terminal trajectory of the missile) and reduce engine power in attempt to cool the thermal signature. Ideally the missile's seeker head is then confused by this change in temperature and flurry of new heat signatures, and starts to follow one of the flares rather than the aircraft.
More modern IR-guided missiles have sophisticated on-board electronics and secondary electro-optical sensors that help discriminate between flares and targets, reducing the effectiveness of flares as a reactionary countermeasure. A newer procedure involves preemptively deploying flares in anticipation of a missile launch, which distorts the expected image of the target should one be let loose. This "pre-flaring" increases the chances that the missile then follows the flares or the open sky in between, rather than a part of the actual defender.
Usage
Apart from military use, some civilian aircraft are also equipped with countermeasure flares, against
On 18 June 2017, after an AIM-9X did not successfully track a targeted
Decoying
Flares burn at thousands of degrees Celsius, which is much hotter than the exhaust of a jet engine. IR missiles seek out the hotter flame, believing it to be an aircraft in afterburner or the beginning of the engine's exhaust source.
As the more modern infrared seekers tend to have spectral sensitivity tailored to more closely match the emissions of airplanes and reject other sources (the so-called CCM, or counter-countermeasures), the modernized decoy flares have their emission spectrum optimized to also match the radiation of the airplane (mainly its engines and engine exhaust). In addition to spectral discrimination, the CCMs can include trajectory discrimination and detection of size of the radiation source.
The newest generation of the FIM-92 Stinger uses a dual IR and UV seeker head, which allows for a redundant tracking solution, effectively negating the effectiveness of modern decoy flares (according to the U.S. Department of Defense). While research and development in flare technology has produced an IR signature on the same wavelength as hot engine exhaust, modern flares still produce a notably (and immutably) different UV signature than an aircraft engine burning kerosene jet-fuel.
Materials used
For the infrared generating charge, two approaches are possible: pyrotechnic and
Upon ignition of the decoy flare, a strongly exothermal reaction is started, releasing infrared energy and visible smoke and flame, emission being dependent on the chemical nature of the payload used.
There is a wide variety of calibres and shapes available for aerial decoy flares. Due to volume storage restrictions onboard platforms, many aircraft of American origin use square decoy flare cartridges. Nevertheless, cylindrical cartridges are also available onboard American aircraft, such as MJU 23/B on the
Square calibres and typical decoy flares:
- 1x1x8 Inch e.g. M-206, MJU-61, (Magnesium/Teflon/Viton (MTV) based) M-211, M-212 (spectral flares)
- 2x1x8 Inch e.g. MJU-7A/B (MTV based), MJU-59/B (spectral flare)
- 2x2.5x8 Inch e.g. MJU-10/B (MTV based)
Cylindrical calibres and typical decoy flares:
- 2.5 Inch e.g. MJU-23/B (MTV based)
- 1.5 Inch e.e. MJU 8 A/B (MTV based)
- 1 Inch e.g. PPI 26 IW
Pyrotechnic flares
Pyrotechnic flares use a slow-burning fuel-oxidizer mixture that generates intense heat.
To adjust the emission characteristics to match closer the spectrum of jet engines, charges on the base of
Blackbody payloads
Certain pyrotechnic compositions, for example MTV, give a great flame emission upon combustion and yield a temperature-dependent signature and can be understood as
Spectrally balanced payloads
Other payloads provide large amounts of hot
Pyrophoric flares
Pyrophoric flares work on the principle of ejecting a special pyrophoric material out of an airtight cartridge, usually using a
The advantage of alkyl aluminium and similar compounds is the high content of carbon and hydrogen, resulting in bright emission lines similar to spectral signature of burning jet fuel. Controlled content of solid combustion products, generating continuous black-body radiation, allows further matching of emission characteristics to the net infrared emissions of fuel exhaust and hot engine components.
The flames of pyrophoric fuels can also reach the size of several metres, in comparison with about less than one metre flame of MTV flares. The trajectory can be also influenced by tailoring the aerodynamic properties of the ejected containers.[14]
Highly flammable payloads
These payloads contain red phosphorus as an energetic filler. The red phosphorus is mixed with organic binders to give brushable pastes that can be coated on thin
See also
- Anti-aircraft
- Anti-ballistic missile
- Countermeasure
- Electronic countermeasure
References
- ^ "Missile defense for El Al fleet". CNN. 24 May 2004. Retrieved 18 July 2006.
- ^ "El Al Fits Fleet with Anti-Missile System". Reuters. 16 February 2006. Retrieved 5 October 2010.
- Ynetnews, 26 February 2006. Accessed 18 July 2006.
- ^ Ziezulewicz, Geoff (10 September 2018). "The Inside Story of How a US Navy Pilot Shot Down a Syrian Jet". Navy Times. Retrieved 11 February 2023.
- ^ Mizokami, Kyle (27 June 2017). "How Did a 30-Year-Old Jet Dodge the Pentagon's Latest Missile?". Popular Mechanics. Retrieved 10 March 2023.
- ^ Majumdar, Dave (26 June 2017). "Why America's Mighty Military Doesn't Always Dominate the Battlefield". Task and Purpose. Retrieved 10 March 2023.
- .
- ^ J. Callaway, Expendable Infrared Radiating means, GB Patent 2 387 430, 2003, GB.
- ^ US 5834680, Nielson, Daniel B. & Lester, Dean M., "Blackbody Decoy Flare Compositions for Thrusted Applications and Methods of Use", published 1998-11-10
- ^ J. Callaway, T. D. Sutlief, Infrared Emitting Decoy Flare, US Patent Application 2004/0011235 A1, 2004, GB.
- ^ R. Gaisbauer; V. Kadavanich; M. Fegg; C. Wagner; H. Bannasch (2006). Explosive Body. Germany. WO2006/034746.
{{cite book}}
: CS1 maint: location missing publisher (link) - ^ Koch, E.C. (2006). Infrarotleuchtmasse (in German). DE 1020040043991.
- ^ Ebeoglu, Davut B.; Martin, C. W. (1 May 1974). "The Infrared Signature of Pyrophorics". Defense Technical Information Center. Archived from the original on 3 March 2007. Retrieved 5 October 2010.
- ^ CA 2027254, Halpin John L.; Verreault Maurice & Barton, Simon A., "Flame-Stabilized Pyrophoric IR Decoy Flare", published 1992-04-11
- ^ de, H. Bannasch; M. Wegscheider & M. Fegg et al., "Spektrale Scheinzielanpassung und dazu verwendbare Flarewirkmasse", published 1995
External links
- Media related to Decoy flares at Wikimedia Commons