Article

Pyrotechnic Countermeasures: II. Advanced Aerial Infrared Countermeasures

Authors:
  • Lutradyn Energetic Materials Sciene & Technology Consulting
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Abstract

This paper discusses the technology of advanced aerial infrared countermeasures and related work disclosed in the unclassified literature. Missile-seeker head counter-countermeasures include spectral discrimination, kinematical discrimination, rise-time discrimination, UV/VIS discrimination and area temperature matching. Advanced flare payloads designed to counter dual color seekers contain selectively emitting compositions based primarily on high carbon fuels and perchlorates. Other advanced payloads consist of low temperature emitters like pyrophoric metal foils and gasless pyrotechnic compositions like Fe/KClO4. The optimization of black body flares, still considered essential to a successful countermeasure solution, make use of new fuels based on e.g. meta-stable alloys and nanometer-sized powders as well as high energetic oxidizers. Kinematic flares today use combined propellant and infrared grains. 116 references from the public domain are given. For part I see Ref. [1].

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... Pyrotechnic infrared countermeasures (IRCM) are by far the most mature, reliable, robust, and cost-effective approach to defeat IR guided missiles [9]. Altering the IR signature of the target platform and low-, middle-and highenergy lasers distracting and destroying missile seekers are emerging new technologies, but so far play only an insignificant role compared to pyrotechnic countermeasures [10]. ...
... Pyrotechnic IRCM are expendable bodies yielding an electromagnetic signature intended to interfere with the IRmissile seeker. The signature of which depends on the duration and intensity of the exothermal reaction of the payload and on the chemical nature of the combustion products [10] [11] [12]. Typical payloads effective against first and second generation seekers [10] comprise pyrotechnic compositions based on magnesium (Mg) and fluorocarbons [13]. ...
... The signature of which depends on the duration and intensity of the exothermal reaction of the payload and on the chemical nature of the combustion products [10] [11] [12]. Typical payloads effective against first and second generation seekers [10] comprise pyrotechnic compositions based on magnesium (Mg) and fluorocarbons [13]. Upon combustion these payloads yield an intense grey body-type radiation. ...
Article
In the presented work two experimental pyrolants for use in blackbody infrared decoy flares showing higher performance than baseline magnesium/polytetrafluoroethylene/Viton® (MTV) were investigated. These pyrolants are based on fuels hitherto unknown to pyrotechnics: magnesium diboride, MgB2, and dimagnesium silicide, Mg2Si. Both fuels were formulated with polytetrafluoroethylene, PTFE and a fluorocarbon binder Viton® (designated MbTV and MsTV). MsTV yields higher radiance, L λ (W cm−2 sr−1) in the mid infrared range (2–5 μm) than MTV at same stoichiometry. The volumetric spectral efficiency E λ (J cm−3 sr−1) of MbTV is also superior to MTV. MbTV thus allows for size reduction of black body countermeasure flares and thereby has potential to enhance the survivability of aircraft in hostile environments. Due to its very high burning rate MsTV qualifies for first fire and igniter applications.
... During the last decades, several attempts were directed to enhance performance of traditional Magnesium/Teflon/Viton (MTV) decoy flare, in an attempt to keep up with recent developed IR-missiles. Enhanced decoy flare formulation should secure thermal signature with higher intensity over α band (2-3µm) and β band (3-5µm) [2]. Consequently, IR missile could favor the decoy flare over the aircraft. ...
... It has been reported that recommended Ɵ value should be in the range from 0.5 to 0.8 according to the aircraft signature. Tailored spectral performance of the traditional MTV composition can be achieved via introducing novel materials for instance silicon [3][4][5][6][7], phosphorous [8][9][10][11][12], boron [2,6], ytterbium [13], deuterium [14], ferric oxide [1,7,[15][16][17][18], and graphite [2,[19][20]. Graphite is an attractive material as it can act as black body emitter [2,15,19]. ...
... It has been reported that recommended Ɵ value should be in the range from 0.5 to 0.8 according to the aircraft signature. Tailored spectral performance of the traditional MTV composition can be achieved via introducing novel materials for instance silicon [3][4][5][6][7], phosphorous [8][9][10][11][12], boron [2,6], ytterbium [13], deuterium [14], ferric oxide [1,7,[15][16][17][18], and graphite [2,[19][20]. Graphite is an attractive material as it can act as black body emitter [2,15,19]. ...
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Article
Graphite particles can offer high interfacial surface area as well as high emissivity as black body; therefore it can find wide applications in advanced decoy flares. In the current study, graphite particles of 100 µm size, were employed with different reactive metal fuels including Mg, Al, and Mg-Al alloy. Different formulations based on graphite ratio up to 8 wt % were developed via granulation with subsequent pressing. Thermal signature was measured using IR spectrometer (1-6 µm) Arc-Optics. Composite flare based on Mg-Al fuel, and graphite demonstrated superior spectral intensity; this formulation offered an increase in average intensity by 83 % to reference MTV flare. In the mean time, composite flare based on Al and graphite offered the highest relative intensity value θ of 0.6. Graphite, as an allotrope of carbon, can act as an excellent source of carbonaceous materials; that can strengthen incandescence emission. Furthermore Mg-Al reactive metal alloy can offer novel synergism as Mg could vaporize at 1000 °C offering efficient combustion process. It can be concluded that tailored flare with customized thermal signature can be developed
... Infrared (IR) guided missiles cause 90% of aircraft damage. Furthermore, the rapid development of IR guided missiles requires extensive development of decoy flares as an effective countermeasure against IR missiles (Koch 2006(Koch , 2012a(Koch , 2006. Decoy flare must be able to secure thermal signature similar to aircraft to distract IR missiles away from aircraft (Koch 2006). ...
... Infrared (IR) guided missiles cause 90% of aircraft damage. Furthermore, the rapid development of IR guided missiles requires extensive development of decoy flares as an effective countermeasure against IR missiles (Koch 2006(Koch , 2012a(Koch , 2006. Decoy flare must be able to secure thermal signature similar to aircraft to distract IR missiles away from aircraft (Koch 2006). ...
... Furthermore, the rapid development of IR guided missiles requires extensive development of decoy flares as an effective countermeasure against IR missiles (Koch 2006(Koch , 2012a(Koch , 2006. Decoy flare must be able to secure thermal signature similar to aircraft to distract IR missiles away from aircraft (Koch 2006). Moreover, a key radiometric parameter known as average intensity ratio (Ɵ), the average intensity of α band/average intensity of β band (Ɵ = I α / I β ), should be similar to aircraft value. ...
Article
Hydroxyapatite (HA) is one of the most common biocompatible material with high phosphorous content (18.5 wt %). HA is thermally stable compound that requires high temperature to decompose; upon decomposition active phosphorus can offer enhanced thermal signature for effective countermeasure of infrared missiles. High reaction temperature can be accomplished via high energy density materials such as nanothermites. This study reports on the facile synthesis of Fe2O3 nanoparticles (5 nm average particle size) and HA nanoplates (530 nm length, 140 nm width) using hydrothermal synthesis. Whereas ferric oxide was employed for nanothermite reactions, HA was employed as phosphorous source material. The effect of developed nanomaterials on thermal signature of traditional Magnesium/Teflon/Viton (MTV) decoy flare was evaluated using Arc-Optics IR spectrometer (1–6 µm). Whereas Fe2O3 (8 wt %) offered enhanced average intensity value by 67%; synergism between HA and Fe2O3 particles offered enhanced spectral performance by 97%. Key radiometric performance parameter is the relative intensity ratio Ɵ(Ɵ = Iα/ Iβ); synergism between HA and Fe2O3 offered superior radiometric performance with Ɵ value of 0.59; this value is similar to aircraft value. This novel spectral performance shaded the light on HA as novel phosphorus material for advanced infrared countermeasure flares.
... Many attempts were devoted to improve the spectral performance of traditional magnesium, teflon, viton (MTV) decoy flare. Decoy flare should offer high-intensity thermal signature over α band (2-3 µm) and β band (3-5 µm) (Koch 2006). Another momentous factor for IR countermeasure is the average intensity ratio of α band/β band (Ɵ = I α /I β ). ...
... Accepted Ɵ value should be in the range from 0.5 to 0.8. Performance of traditional MTV flares could be enhanced through novel materials such as boron (Koch 2006;Koch et al. 2012a), ytterbium (Koch and Hahma 2012), silicon (Andreotti and Hirschman 1994;Erwin 2003;Klapotke and Rienacker 2001;Koch et al. 2012a;Weiser et al. 2007), deuterium (Koch 2009c), ferric oxide (Elbasuney et al. 2018a(Elbasuney et al. , 2018bKoch 2012bKoch , 2009aKoch , 2009bWeiser et al. 2007), phosphorous (Comet et al. 2010;Klusáček and Navratil 1997;Koch and Cudziło 2016;Koch and Dochnahl 2003;Wardecki et al. 2006), and graphite (Koch 2006(Koch , 2008Nadler 2004). Black body radiation is the main source of decoy flare emissivity. ...
... Accepted Ɵ value should be in the range from 0.5 to 0.8. Performance of traditional MTV flares could be enhanced through novel materials such as boron (Koch 2006;Koch et al. 2012a), ytterbium (Koch and Hahma 2012), silicon (Andreotti and Hirschman 1994;Erwin 2003;Klapotke and Rienacker 2001;Koch et al. 2012a;Weiser et al. 2007), deuterium (Koch 2009c), ferric oxide (Elbasuney et al. 2018a(Elbasuney et al. , 2018bKoch 2012bKoch , 2009aKoch , 2009bWeiser et al. 2007), phosphorous (Comet et al. 2010;Klusáček and Navratil 1997;Koch and Cudziło 2016;Koch and Dochnahl 2003;Wardecki et al. 2006), and graphite (Koch 2006(Koch , 2008Nadler 2004). Black body radiation is the main source of decoy flare emissivity. ...
Article
Reduced graphene oxide (RGO) possesses unique thermal and optical properties. It could act as black body emitter with high-infrared emissivity. RGO could meet wide applications in advanced infrared decoy flares. In this study, RGO nano-sheets were synthesized through the reduction of GO after applying Hummers’ method using graphite powder as a precursor. The synthesized RGO owns 10 µm dimensions and 10 nm thicknesses. TEM analysis revealed the amorphous structure of the prepared nano-sheets. XRD diffractogram demonstrated the amorphous RGO structure. Moreover, Raman spectroscopy confirmed the complete reduction of GO into RGO. In addition, decoy flare formulations based on RGO, reactive metal fuels, and fluorocarbon polymer were developed. Additionally, thermal signature was evaluated using Arc-Optics IR spectrometer (1–6 µm) to reference formulation. Our results revealed that nanocomposite flare based on 6 wt % RGO demonstrated superior spectral intensity with an increase in average intensity by 147%. Moreover, advanced radiometric performance with superior relative intensity value (Ɵ) of 0.7 was recorded. To sum up, RGO can act as an excellent source of carbonaceous materials that can strengthen incandescence emission. Surplus magnesium could vaporize and combust with substantial heat output that could promote black body emission.
... The neutralization of aircraft threats created by infrared (IR) guided missiles is a major requirement. IR decoy flares were introduced as an effective countermeasure against IR missiles [1,2]. Decoy flares should be capable to secure thermal signature analogous to aircraft; accordingly, they could be ready to distract IR missiles [1]. ...
... IR decoy flares were introduced as an effective countermeasure against IR missiles [1,2]. Decoy flares should be capable to secure thermal signature analogous to aircraft; accordingly, they could be ready to distract IR missiles [1]. ...
... Carbon black could act ideal a black body; pyrotechnic systems offering large heat output and carbon black could be candidates for decoy flare applications. Tailored spectral performance can be achieved by integrating novel particles such as graphite [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Graphite is an attractive material as it is an outstanding source of carbon particles that can act as black body emitter (Fig. 1); the resulted black carbon can further extend the advanced thermal signature [1,15,17]. ...
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Article
Graphite has attracted scientific interest due to its exceptional physical and chemical properties. On combustion, graphite particles offer high emissivity as a black body; therefore, it can find wide application in advanced decoy flares. Thermite particles (metal oxides/metal) can offer a high reaction temperature that is required to stimulate emitting species. In this study, graphite particles were employed with super-thermite Fe2O3 NPs. Novel Mg–Al bimetal alloy was employed as a reactive metal fuel; Viton A (fluorocarbon polymer) was employed as an energetic binder. Multi-component nanocomposite flares were developed via granulation with subsequent pressing. The thermal signature was measured using the IR spectrometer. Nanocomposite flares based on 6 wt% graphite and 2% Fe2O3 NPs demonstrated superior spectral intensity. This flare formulation offered an increase in average intensity by 248% to reference formulation. It offered the highest relative intensity value θ of 0.54. Graphite, as an allotrope of carbon, acts as an excellent source of carbonaceous materials that can strengthen incandescence emission.
... This was the beginning of a classic " cat and mouse " activity between the measures and the countermeasure, which continues to this day. Goddard [24] and Koch [40] present the state of the art in present day countermeasures, the extent of their information being of course limited to what is available from unclassified sources. Goddard points out that initially flares were almost 100% effective against the first generation of missiles. ...
... Because their motion is the same as that of the aircraft, kinematical discrimination will not help identify them. Koch [40] and Titterton [69] mention IR missile defeat mechanisms other than flares that are already used and some that could eventually be developed. This sophistication of flares makes it clear that it has also become more and more challenging to produce seekers that can effectively discriminate between the aircrafts and the flares they deploy, that is to devise IR counter-countermeasures (IRCCM). ...
... Many missiles exist today with that technology, such as the AIM-9X that is the successor of the Sidewinder missile [ 2] and that presently arms the F-16 and F-18 fighters. Sagem Défense Sécurité, Safran Group [51] sells the MICA infrared seeker for air-to-air missile that, they claim, offers a high protection against infra-red countermeasures through the use of dual band infrared imaging, highly sophisticated image and signal algorithms.Table 1, taken from Koch [40], gives an overview of the evolution of IR seeker technology. process that isolates the blobs that correspond to the objects present in the scene. ...
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Article
The last generation of infrared imaging aircraft seekers and trackers uses pattern recognition algorithms to find and keep a lock on an aircraft in the presence of decoy flares. These algorithms identify targets, based on the features of the various objects in the missile's field of view. Because modern both aircrafts and missiles fly faster than sound, speed of operation of the target identifier is critical. In this article, we propose a target recognition system that respects this time constraint. It is based on an artificial neural network implemented in hardware, as a set of parallel processors on a commercially available silicon chip called a ZISC, for Zero Instruction Set Computer. This chip would be integrated in the infrared missile seeker and tracker. We describe the characteristics of the images that the image processing module of this seeker and tracker extracts from the infrared video frames and show how to construct from these translation and rotation invariant features that can be used as input to the neural network. We determine the individual discriminating power of these features by constructing their histograms, which allows us to eliminate some as not being useful for our purpose. Finally, by testing our system on real data, we show that it has a 90 % success rate in aircraft-flare identification, and a processing time that during this time, the aircrafts and missiles will have traveled only a few millimetres. Most of the images on which the neural network makes its mistakes are seen to be hard to recognize even by a human expert.
... In a separate field, the needs of various methods including countermeasures to secure civilian airliners from the threat of terrorism have also been emphasized since late 2001 [14] [15]. Thus, many types of countermeasures have been researched and developed [15] [16]. Among these technologies, Koch [16] mentioned spectrally adapted payloads and UV/Vis discrimination as notable examples. ...
... Thus, many types of countermeasures have been researched and developed [15] [16]. Among these technologies, Koch [16] mentioned spectrally adapted payloads and UV/Vis discrimination as notable examples. In that report, the spectral adaptation was supported by the appropriateness of changing emission spectral ranges. ...
Article
An optical emission spectrometer (OES) was designed and constructed to detect the absolute spectral radiant exitance of UV signatures for a wavelength range of 240 nm to 440 nm. Using a directly heated graphite black body furnace operating at a temperature of 3000 K, the spectral response of the OES in the UV range was calibrated. To evaluate the performance of the OES system, the emission spectra of molecules were measured in a butane flame and the absolute emissions of the UV signatures were calculated. The uncertainty of the absolute measurement of the UV signature was analyzed by considering various uncertainty budgets, and the total uncertainty of the OES was found to be 1.66 %.
... Recently, two reviews on progress in the field of aerial infrared decoy flares have been prepared by the author [1, 2]. The fast development in the field already delayed the preparation of the second report by nearly a year. ...
... The new MJU 61 B comprises new safety mechanism and payload design to meet present operational and safety standards [63]. Rheinmetall reports about " CIRRUS Flare " [64] 1 Â 1 Â 8 inch variant of introduced DM 69 A2 flare based on RP sheet-technology described earlier in Ref [2]. Rheinmetall has announced the low-cost softkill system IRRADON [65] based on their disclosure [66] to go into trials shortly. ...
Article
The most recent progress in the field of advanced aerial infrared decoy flare technology is documented. 71 references from the public domain are given. For the last review please see Ref. [2].
... For commercial Si powder, Mason et al.[22]have reported screening experiments for several oxidizers, and have shown that polytetrafluoroethylene (PTFE) has the highest predicted adiabatic combustion temperature of any fuel-oxidizer system investigated, suggesting that this composition may be of interest. Metal/ PTFE compositions have had considerable use as pyrotechnics[23][24][25][26][27][28][29][30], particularly as illuminants[23][24][25][26], due to the high radiant intensity of their combustion products. Recent studies on Si/PTFE combustion[3,29,31]have focused on external characteristics (i.e., oxidizer, equivalence ratio, pressure, etc.), but have not addressed the role that SSA, active content, morphology, and particle size has on the combustion performance. ...
... For commercial Si powder, Mason et al.[22]have reported screening experiments for several oxidizers, and have shown that polytetrafluoroethylene (PTFE) has the highest predicted adiabatic combustion temperature of any fuel-oxidizer system investigated, suggesting that this composition may be of interest. Metal/ PTFE compositions have had considerable use as pyrotechnics[23][24][25][26][27][28][29][30], particularly as illuminants[23][24][25][26], due to the high radiant intensity of their combustion products. Recent studies on Si/PTFE combustion[3,29,31]have focused on external characteristics (i.e., oxidizer, equivalence ratio, pressure, etc.), but have not addressed the role that SSA, active content, morphology, and particle size has on the combustion performance. ...
Article
Due to its thin passivation layer, potentially good aging characteristics, and ease of surface functionalization nanoscale silicon (Si) may offer some advantages over nanoaluminum as a reactive fuel in nanoenergetic compositions, particularly with fluorine-based oxidizers. Currently, Si nanopowder can be quite expensive and the quality of commercial powders has been found to vary drastically. As a result limited efforts have focused on the role of specific surface area, active content, morphology, and dominant particle size of the powder have on the combustion performance. In this work we report the effect of such characteristics on the combustion of silicon (Si)/polytetrafluoroethylene (Teflon)/FC-2175 (Viton) (SiTV) nanoenergetics. A cost effective combustion synthesis route, salt assisted combustion synthesis, was used to produce several Si powders and these were directly compared to commercial nanoscale Si powders. Reactive mixtures of SiTV were burned at atmospheric conditions and burning rates, combustion temperatures, spectral intensities, and effective plume emissivities were measured. Measured combustion temperatures ranged from 1664 to 2380 K and were limited by Si powder active content. This was found to drive plume emissivity and maximum spectral intensity, which had values ranging from 0.10 to 0.55 for effective plume emissivity and 17.6 to 48.1 kW m−2 sr−1 μm−1 for maximum spectral intensity. Burning rates ranged from 0.7 to 3.4 mm s−1 and were found to be dependent on the dominant particle size of the powder. Powders synthesized with salt assisted combustion resulted in comparable burning rate, plume emissivity and maximum spectral intensity to porous Si powder (Vesta Ceramics).
... Among the SAMs especially the man-portable shoulder-fired systems (MANPADS) with two-colour counter-countermeasure capability such as e.g. the Russian SA-18 (GROUSE) pose the major threat to low flying crafts. Recently the author has discussed the available technology to counter infrared guided missiles234 with advanced pyrotechnic decoy flares. Spectral flare compositions either contain a carbon or boron based fuel in order to give the highly selective emitters CO 2 and/or X-B = O [3]. ...
... Recently the author has discussed the available technology to counter infrared guided missiles234 with advanced pyrotechnic decoy flares. Spectral flare compositions either contain a carbon or boron based fuel in order to give the highly selective emitters CO 2 and/or X-B = O [3]. Carbon based payloads now may comprise virtually any type of carbon source [5] and oxidisers that will readily give off oxygen such as e.g. ...
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Article
The radiometric performance and burn rate of four spectral flare compositions (R-X) based on 1,4-dicyanobenzene (1), 3,5-dinitrobenzonitrile (2), E-stilbene (3) and 9,10-dihydroanthracene (4), potassium perchlorate and polyacrylate binder are described. The burn rates, spectral efficiencies, Eλ, in both α- and β-band have been determined. The composition R-4 displays the highest efficiency in both α- and β-band as well as lowest color ratio, θB/A. R-1 yields the highest color ratio and second highest spectral efficiency in β-band. For part IV see Ref. (1).
... The aircraft fuselage emits radiation at a wavelength of 8-10 μm, hot exhausts emit radiation at 3-5 μm, and hot jet engines (main IR radiation source) emit radiation at 2-2.5 μm [3]. Heat-seeking missiles normally search for radiation emitted from the aircraft over α = 2-3 μm and β = 4-5 μm bands [4]. Countermeasures that can be used to protect the aircraft against a thermal detector include multiple decoys that are emitting IR radiation of the type and energy output that mimic what the detector is specifically looking for [5]. ...
... sherif basuney2000@yahoo.com. metals with burning temperatures equal to or hotter than the aircraft engine [1,4,11]. Decoy flare compositions should burn with similar radiation as the aircraft, but with higher intensity [3]. ...
Article
Infrared (IR) guided missile is known to cause 90% of aircraft damage. Magnesium/Teflon/Viton (MTV) decoy flares are customized materials, which are capable of yielding thermal signature to interfere with IR guided missile seekers. In this study, the IR-signature of an MTV flare is measured in a jet engine nozzle. The jet engine IR-signature is characterized with two characteristic peaks over the α-band (2–3 µm) and β-band (3–5 µm); this is correlated to black body emission at 690° C. The MTV decoy flare with 65% Mg offers an increase in the average intensity of the α- and β-bands by 21 and 4 times, respectively, to that of the jet engine. Quantification of emitting species in the combustion flame is conducted by using the ICT thermodynamic code. The developed MTV formulation offers the relative intensity ratio of the α- and β-bands equal to 0.96, which is comparable to that of an aircraft (0.7).
... Heat-seeking missiles normally search for radiation over α (2-3 µm) and β (4-5 µm) band [4]. Countermeasures that can be used to protect against thermal detector include [5]: ...
... Nanoparticles were harvested from their synthesis medium by distorting the electric double layer associated with each particle. Fe 2 O 3 nanoparticles were re-dispersed into acetone for the development of MTV pyrolants with Fe 2 O 3 content ranging from (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Nanocomposite pyrolants were developed by granulation and subsequent pressing. ...
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Article
Infrared (IR) guided missiles are real threat; they caused 90% of aircraft damage. Fluorocarbon polymer nanocomposite based on super-thermites can offer superior thermal signature to countermeasure IR guided missile seekers. This study reports on the sustainable fabrication of mono-dispersed colloidal Fe2O3 nanoparticles with 3 nm average particle size. Fe2O3 nanoparticles were dispersed in acetone for subsequent integration in fluorocarbon polymer. The impact of Fe2O3 content on thermal signature was evaluated using (FT-MIR 2–6 μm) spectrophotometer. Nanocomposite polymer with 8 wt% Fe2O3 offered an increase in the average intensity of α (2–3 μm) and β (4–5 μm) bands by 50 and 85% respectively to that of reference formulation. Quantification of stimulated emitting species in the combustion flame was conducted using ICT thermodynamic code. The developed nanothermite particles extended the primary reaction zone by 183%. Full discussions about combustion zones with associated exothermic chemical reactions have been represented.
... Thus in the early 1950ies IR decoy flares were therefore considered to imitate the hot tail pipe radiation [62]. The technology of IRCM flares /seeker interaction has been discussed by the author [63][64][65]. Depending on the duration and magnitude of the exothermic reaction of their payload IR decoy flares yield a distinct electromagnetic signature that is influenced by the chemical constituents of its combustion products. ...
Chapter
Energetic materials are characterized in that they are capable of undergoing a spontaneous highly exothermic reaction. They can be classified into high explosives (HE), propellants, and pyrolants. High explosives upon initiation yield a detonation – that is a supersonic shock wave sustained by a chemical reaction. Propellants and pyrolants in contrary undergo a thermally propagated reaction and yield either large amount of gaseous species or as in the case of pyrolants yield mainly condensed products. In contrary to most high explosives which are homogeneous organic compounds comprising nitro- and nitramine - groups pyrolants and most propellants are heterogeneous fuel / oxidizer mixtures. The term pyrolant describes hot burning compositions that are constituted from micrometric or nanometric metal powders and crystalline and/or polymeric oxidizers. Typical pyrolants are used as illuminant (Mg/NaNO3), thermite (Al/Bi2O3) and igniter (Zr/BaCrO4) compositions, in addition coruscative combinations such as e.g. Zn/S or Mg/P find use as both amateur propellants (sic) and incendiaries. An important group of pyrolants are combinations of metal powders with halocarbon compounds. The large energy content of metal halocarbon pyrolants stems from the high enthalpy of formation of the corresponding metal-halogen bond M-X. Thus especially fluorocarbon and chlorocarbon compounds are used as oxidizers. The following table lists the gravimetric and volumetric enthalpy of combustion, adiabatic flame temperature and ignition temperature for selected energetic materials taken from the groups of high explosives, propellants and pyrolants.
... In fact, the maximum of the thermal spectral radiation is located in the MIR regime, as seen in Fig. 1.4. Therefore, this spectral range is an ideal candidate for thermal-based purposes, showing a compelling interest for many critical applications, such as security surveillance or warfare counter-measurements [14][15][16]. Blackbody radiation at different temperatures as a function of the wavelength. In background: normalized atmospheric transmission [6]. ...
Thesis
The mid-infrared (MIR) spectral range, commonly defined from 2 to 20 µm wavelengths, has attracted a great interest over the past two decades due to its unique characteristics for detection and security purposes. In particular, the fingerprint region (from 3 to 13 µm wavelength) allows high sensitivity detection of most of molecules due to fundamental molecular vibrational modes that lead to specific absorption lines in this spectral range. The work I present here leverages on previous passive devices demonstrations based on Ge-rich graded-index SiGe platforms to go a step further towards the implementation of a complete on-chip MIR photonics system. To that end, I address the design, modeling, cleanroom fabrication and characterization of three missing functionalities based on thermal-tuning, nonlinear and electro-optic effects, showing a broadband operation in the MIR range. First, I demonstrated propagation losses lower than 4.6 dB/cm from 5 to 11 µm wavelength, which are compatible with most integrated MIR applications. I also confirmed the broadband performance of graded-index SiGe platforms by the characterization of two MZI devices. Then, I discussed an integrated spectrometer approach based on a spatial heterodyne configuration, in which I thermally tuned the path delay imbalance of a MZI array to overcome the classical trade-off between resolution, operational bandwidth, and number of interferometric structures required. These results facilitate the development of compact and robust spectrometers operating in the MIR fingerprint region. Next, I demonstrated a supercontinuum generation that spans from 3 to 13 µm wavelength in a 5.5 mm long graded SiGe waveguide. This demonstration provides a broadband and coherent MIR light by mean of a single device, opening exciting perspectives for the simultaneous detection of multiple molecules. Finally, I experimentally evaluated the effect of free-carrier plasma dispersion in a wide MIR range, to later demonstrate an integrated electro-optical modulator operating from 6.4 to 10.7 µm wavelength and showing up to 1.3 dB extinction ratio in current injection regime and 225 MHz modulation bandwidth in carrier depletion. This device is essential to implement synchronous detection and thus significantly improve the sensitivity of integrated detection systems. In conclusion, this thesis has successfully addressed the development of integrated waveguides and three associated functionalities missing in the literature operating in a wide MIR spectral band. Therefore, this work opens exciting prospects in a plethora of high-impact applications, paving the way towards the long-term development of compact multi-molecular sensor systems.
... These countermeasures also have high energy rises upon ignition. 4 Seeker missiles developed rapidly in complexity, utilizing complex rosette reticle patterns, reflecting mirrors, and more robust signal analysis methods to prevent a lock-on break with the a Electronic mail: slorenzo6314@gmail.com target. ...
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Article
We introduce an optimized aperiodic multilayer structure capable of broad angle and high temperature thermal emission over the 3 μm to 5 μm atmospheric transmission band. This aperiodic multilayer structure composed of alternating layers of silicon carbide and graphite on top of a tungsten substrate exhibits near maximal emittance in a 2 μm wavelength range centered in the mid-wavelength infrared band traditionally utilized for atmospheric transmission. We optimize the layer thicknesses using a hybrid optimization algorithm coupled to a transfer matrix code to maximize the power emitted in this mid-infrared range normal to the structure’s surface. We investigate possible applications for these structures in mimicking 800–1000 K aircraft engine thermal emission signatures and in improving countermeasure effectiveness against hyperspectral imagers. We find these structures capable of matching the Planck blackbody curve in the selected infrared range with relatively sharp cutoffs on either side, leading to increased overall efficiency of the structures. Appropriately optimized multilayer structures with this design could lead to matching a variety of mid-infrared thermal emissions. For aircraft countermeasure applications, this method could yield a flare design capable of mimicking engine spectra and breaking the lock of hyperspectral imaging systems.
... Nevertheless a large series of silicon halide hydride compounds display appropriate vibrations close to 4 mm [30]. ...
Article
The application of silicon as fuel in common pyrotechnic and explosive compositions is reviewed. For part V see Ref. [56].
... Flares are made of magnesium or other chemicals which become very hot or bright when combusted. This causes heat-guided projectiles to follow the decoy and not the aircraft[42]. A C-17 deploying flares is illustrated infigure 8. ...
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Technical Report
A survey of specifications and the performance of currently used UGCV's is conducted and used to develop a design concept with proposed component and design improvements. The structural and movement characteristics of the vehicle are analysed under the initial deisgn and costs for the procurement of the vehicle are estimated.
... At present, the infrared guidance method has been developed from point source to imaging guidance, and its anti-interference technology has been greatly improved. The significant difference between infrared decoy and target radiation performance can be distinguished by the infrared imaging guidance of the bait and target [1,2]. Therefore, the Mg-PTFE is made into particles, in an attempt to increase the radiation area of the agent, and to appropriately reduce the radiation intensity. ...
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Article
In order to improve the radiation radiation area of Mg-PTFE infrared bait agent and reduce the radiation intensity, the Mg/PTFE/NC particle type agent was prepared by solvent evaporation method to study the infrared radiation performance of the particle agent. The results showed that the radiation area of the granular agent increased by 60% on average and the radiation intensity decreased by 84% compared with the equal-quality powdery agent. For granules, the radiation performance increases with the increase of particle size. When the particle size increases from 690.6μm to 1048.3μm,the average radiation area increases from 139.51cm ² to 172.83cm ² ,and the average radiation intensity is 2.89 W• Sr ⁻¹ increased to 4.56 W•Sr ⁻¹ ; while the mass fraction of Mg-PTFE in the granules also increased with the increase of mass fraction, and the effect on the radiation area was small; mass fraction When increasing from 30% to 70%,the radiation intensity increases from 2.64 W•Sr ⁻¹ to 5.62 W•Sr ⁻¹ .
... Infrared (IR) guided missiles are imminent threat to aircrafts; this hazard implies the development of effective decoy flares [1][2][3]. Decoy flare should yield thermal intense signature similar to aircraft; to attract IR missile away from the target [3]. However, advanced flares can further distinguish target via relative intensity ratio (average intensity over α band / average intensity over β band). ...
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Article
Infrared-guided missiles caused 90% aircraft damage. Infrared decoy flares are effective counter measure against infrared missiles. Decoy flare thermal signature depends mainly on black body emission of carbonaceous combustion products. Thermite particles can offer substantial heat output to promote black body emission. Reduced graphene oxide (RGO) is a promising material for advanced infrared decoy flares. RGO could act as ideal black-body emitter with superior thermal properties and high interfacial surface area. This study is dedicated to investigate novel synergism between Fe2O3 and RGO; Fe2O3 NPs of 3.56 nm were fabricated using hydrothermal synthesis technique. RGO nano-sheets of 10 µm dimensions and 10 nm thickness were developed via the reduction of graphene oxide, developed by Hummer̓ method. Complete reduction of GO to RGO was confirmed by Raman spectroscopy. Amorphous nano-sheets structure was observed using TEM; XRD diffractogram demonstrated tiny characteristic broad peak for amorphous RGO. Decoy flare formulation based on Fe2O3, RGO, reactive metal fuel (Mg), and fluorocarbon polymer (teflon) were developed. Thermal signature was evaluated using Arc-Optics IR spectrometer (1–6 µm). Multi-component MTV nanocomposite flare based on 6 wt % RGO and 2 wt % Fe2O3 demonstrated superior spectral and radiometric performance. It offered an increase in average intensity by 130% to reference MTV formulation; additionally it offered superior relative intensity Ɵ value of 0.76. While RGO could act as novel black body emitter; thermite reaction between Fe2O3 NPs and surplus magnesium fuel could provide substantial heat output; that could promote RGO black body emission.
... Pyrotechnic aerial infrared decoy flares have been reviewed by the author recently [62, 63]. It has been reported that pure RP yields relatively cool flames of T < 1000 8C. ...
Article
This paper reviews the military applications of phosphorus in obscurants, incendiaries, float and smoke signals, friction igniters and decoys. Whereas white phosphorus (WP) is still in use as both incendiary and obscurant ammunition it has been mainly replaced today by red phosphorus (RP). For part VI see Ref. [1].
... Thermal signature of an aircraft is generated by several IR emitting components, for instance: metal skin emits between 8 and 10 µm, jet engine nozzle emits between 2 and 2.5 µm, and plume emits between 3 and 5 µm [3]. Heat-seeking missiles normally search for thermal signature over α (2-3 µm) and β (4-5 µm) band [4]. Pyrotechnic pyrolant is one of the most common countermeasures that can be employed to protect against IR seekers [5]. ...
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Article
Super-thermites can offer large amount of energy up to 16736 J/g. Flares based on super-thermites can offer superior thermal signature to countermeasure infrared (IR) guided missile seekers. This study reports on the sustainable fabrication of mono-dispersed Fe2O3 nanoparticles of 3 nm average particle size. Colloidal Fe2O3 nanoparticles were harvested from their synthesis medium and re-dispersed in acetone. Fluorocarbon polymers (teflon and viton) as well as aluminum metal fuel were integrated into Fe2O3/acetone colloid. The colloid mixture was granulated and mold pressed to develop the desired grain. The impact of Fe2O3 nanoparticles on thermal signature was assessed using (FT-MIR 1–6 µm) spectrometer. Flame propagation was investigated by video imaging of combustion wave. Combustion zones were quantified using image analysis. Quantification of flame temperature and main IR emitting species was performed using ICT thermodynamic code (virgin 2008). Nanocomposite flare with 12 wt% Fe2O3 offered an increase in the intensity of β band by 230% to that of reference formulation. The primary reaction zone was extended by 164%. Super-thermite particles not only offered superior spectral performance but also altered the combustion mechanism.
Article
Radiometric performance of a sulphur-based flare composition has been investigated. Composition comprising sulphur, potassium perchlorate and antimony sulphide has acceptable band ratio but an order of magnitude weaker spectral efficiency than typical carbon-based compositions. The use of other sulphur compounds with potential for increased performance is discussed. For part III see Ref. [1].
Article
Deceiving with TNT: Melt-cast pyrotechnic mixtures based on 2,4,6-trinitrotoluene (TNT)/KClO(4) (see picture for flame) spectrally matched infrared decoy flares and show superior performance and greatly reduced sensitivity in comparison to common pyrotechnic or double-base material currently in use for IR countermeasure flares.
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5H-Perfluoroalkyltetrazoles (alkyl = CF3, C2F5, C3F7) react with aqueous Ca(OH)2 to give the corresponding calcium salts 1, 2 and 3. Compounds 1 – 3, which form hydrates, were characterized by elemental analyses, differential heat flow calorimetry, multinuclear NMR, FTIR and Raman spectroscopy. A crystal structure determination was carried out on the solvate 2 ·2H2O·4CH3OH. Compounds 1 – 3 were tested as oxidizers in ternary pyrolant mixtures with magnesium and VitonTM. The burn rates, u (g s−1), of the pyrolants based on 1 show a distinct influence of the exothermicity of the primary reaction, whereas the burn rates of 2- and 3-based pyrolants do not show such behavior but display a steady increase of burn rate with increasing Mg content. At stoichiometries below 40 wt.-% Mg, the specific intensity Eλ (J g−1 sr−1) of the pyrolants based on 2 and 3 is superior to that of the standard mixture magnesium/polytetrafluoroethylene/VitonTM (MTV). This is assumed to be due to the expansion of the flame envelope by nitrogen.
Book
This exciting book details all aspects of a major class of pyrolants and elucidates the progress that has been made in the field, covering both the chemistry and applications of these coompounds. Written by a pre-eminent authority on the subject from the NATO Munitions Safety Information Analysis Center (MSIAC), it begins with a historical overview of the development of these materials, followed by a thorough discussion of their ignition, combustion and radiative properties. The next section explores the multiple facets of their military and civilian applications, as well as industrial synthetic techniques. The critical importance of the associated hazards, namely sensitivity, stability and aging, are discussed in detail, and the book is rounded off by an examination of the future of this vital and expanding field. The result is a complete guide to the chemistry, manufacture, applications and required safety precautions of pyrolants for both the military and chemical industries.
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A mid-IR (MWIR) optical emission spectrometer (OES) was designed and constructed to detect the absolute spectral radiant exitance of IR signatures. A 256-array PbSe detector was adopted to analyze the MWIR emission spectrum. Various IR signatures from two flame sources were examined in order to evaluate the performance of the OES and verify its usefulness for low observable technology. The absolute emissions of their IR signatures were calculated and the amount of each emission was compared. The spectral response of the OES in the MWIR range was calibrated using a directly heated graphite blackbody; in addition, the total uncertainty of the OES was determined to be 5.24%.
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Deploying flare decoys against heat seeking threats involves various parameters like flare timing, flare ejection velocity, direction of ejection and the number of flares used. In this study, an attempt has been made to identify the key parameters among these that impact the performance of flares the most. For this, engagement studies involving 6-DOF models for an air-to-air heat seeking missile and a fighter aircraft were carried out using the CADAC++ simulation environment. The effect of flare parameters was studied using their impact on missile envelopes. Studies show that the effectiveness of the flare decoys is a strong function of the flare timing and the number of flares used.
Article
The use of the intensity change and line-of-sight (LOS) change concepts have previously been documented in the open-literature as techniques used by non-imaging infrared (IR) seekers to reject expendable IR countermeasures (IRCM). The purpose of this project was to implement IR counter-countermeasure (IRCCM) algorithms based on target intensity and kinematic behavior for a generic imaging IR (IIR) seeker model with the underlying goal of obtaining a better understanding of how expendable IRCM can be used to defeat the latest generation of seekers. The report describes the Intensity Ratio Change (IRC) and LOS Rate Change (LRC) discrimination techniques. The algorithms and the seeker model are implemented in a physics-based simulation product called Tactical Engagement Simulation Software (TESS™). TESS is developed in the MATLAB®/Simulink® environment and is a suite of RF/IR missile software simulators used to evaluate and analyze the effectiveness of countermeasures against various classes of guided threats. The investigation evaluates the algorithm and tests their robustness by presenting the results of batch simulation runs of surface-to-air (SAM) and air-to-air (AAM) IIR missiles engaging a non-maneuvering target platform equipped with expendable IRCM as self-protection. The report discusses how varying critical parameters such track memory time, ratio thresholds and hold time can influence the outcome of an engagement.
Article
The spectral performance, sensitiveness to ignition stimuli and burning rate of bi-spectral flare formulations based on tetrazole containing fuels, 5-phenyl-1H-tetrazole, 5,5′-(1,4-phenylene)bis(1H-tetrazole) and 5-(4-nitro-phenyl)-1H-tetrazole, utilizing potassium perchlorate as the oxidizer, are reported. The formulation based on 5-(4-nitro-phenyl)-1H-tetrazole yielded the highest spectral efficiency in the β-band (44.1 J g−1 sr−1). The formulation based on 5-phenyl-1H-tetrazole gave the highest color ratio (θβ/α=6.8) and was the least sensitive.
Article
Kaum eine andere Anwendung aus dem Bereich der Chemie weckt in der Allgemeinbevölkerung so positive Assoziationen wie die Feuerwerkerei. Dabei wird das Umweltverschmutzungspotenzial von Feuerwerken sowie zivilen und militärischen pyrotechnischen Anwendungen häufig außer Acht gelassen. Moderne Entwicklungen in der Pyrotechnik konzentrieren sich verstärkt auf die Implementierung stickstoffreicher, energetischer Verbindungen wie Tetrazol- und Tetrazinderivate, um der längst fälligen Ökologisierung Rechnung zu tragen. Der vorliegende Aufsatz widmet sich den Umweltaspekten der Pyrotechnik und den aktuellen Bestrebungen, ihr ein neues, umweltverträglicheres Gesicht zu verleihen.
Article
To solve the problem caused by jamming, an acousto-optic tunable filter (AOTF)-based imaging spectrometer and a corresponding spatial–spectral discrimination method are proposed for aerial targets. The system has the capability of staring imaging and is electronically tunable, which provides the spatial location and a distinguishable spectral feature in a few images. Since AOTF operates in a frame mode, the spectral brightness of the targets can be predicted by Kalman filtering, like with the motion model. The final target state is updated by using synthetic spatial–spectral information to realize fast decision-making. The results show that the proposed method is more targeted to solve the problem caused by jamming, compared with the traditional energy discrimination method.
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Aluminum because of its high enthalpy of combustion has been added to energetic materials. Several research efforts have been directed to understand the mechanism and model the oxidation of aluminum particles. In this work, a two dimensions and time dependent thermal model is developed and assessed to describe the interrelated processes of Aluminum particle oxidation. The thermal model consists of thermal radiation, forced convection and thermal conduction and oxygen diffusion and surface reactions. It is assumed the aluminum particle is coated with Aluminum oxide layer.
Chapter
Decoy FlaresNonexpendable FlaresMetal–Fluorocarbon Flare Combustion Flames as Sources of RadiationInfrared CompositionsOperational EffectsOutlookReferences
Article
Green-light emitting illuminant and green pearls that are currently being used for pyrotechnics are mainly composed of barium carbonate and polyvinyl chloride (PVC), which lead inevitably to the substantial generation of abundant harmful products for environmental pollution. There is thus considerable scope for the development of a novel emitting illuminant with an improved “green” composition instead of compositions incorporating barium based oxidants and polyvinyl chloride for environmental protection. For this purpose, a new composition composed of boron carbide, potassium perchlorate, and guanidine nitrate with a suitable burning rate of 5∼15 mm/s required for fireworks, the high luminous intensity of 34665 Cd and spectral purity of 67.1 % at a primary wavelength of 562 nm was developed. Notably, PM10 data demonstrated that the new composition generated less than half the amount of the smoke relative to the original one. More importantly, all of the safety parameters of this new formulation meet well with the standards’ requirements, i. e., a remarkable low sensitivity to friction (0 %) and impact (8 %), relative stability to electric discharge (374.4 mJ), flame (14.0 cm) and heating (unburned, unexploded at 75 °C for 48 h), as well as a high ignition temperature of 504.0 °C and a low moisture absorption rate (0.66 %). Taken together, the new emitting illuminant developed herein showed great potential to be used for fireworks and signal flare in both military and civilian applications.
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The limited effort in this paper is focused on studying the infrared radiation performance of Ammonium Perchlorate/ hydroxy-terminated polybutadiene(AP/HTPB) and Magnesium/ Teflon(MTV) agents, in order to compare the differences in the spectral distribution of the two agents at different doses and tube shell sizes. A FTIR remote-sensing spectrometer was used to characterize combustion flame radiation products and a Spectraline SC7000 imaging spectrometer was used to test the radiation performance of each band. The test results show that the radiation energy of AP/HTPB agents is 5-8 times smaller than that of MTV agents under the same conditions. In addition, as the mass is small (5g), the spectral distribution of AP/HTPB agent θα / β / λ . is 0.6:1:0.15, which is better than MTV agent whose θα / β / λ . is 2.3:1:0.15. But as the mass increased to 40g and the diameter of the tube shell increased to 40mm, the mass burning rate of the MTV agent increased from 0.287g/s to 4.167g/s, and the mass burning rate of AP/HTPB agent increased from 0.258g/s to 2.920g/s. At this time, the MTV spectral distribution did not change much, but the radiation energy of AP/HTPB agents is changed more concentrated in the near-infrared band, and the spectral distribution θα / β / λ . becomes 1.4:1:0.3.
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A computing model of foil-surface-type IR decoy radiation which considers the changes of combustion time, relative air velocity and height of the decoy is established in this paper. The diffusion concentration of oxygen in the pyrophoric multi-hole activated metal is studied firstly. By solving the heat balance equation of foil, the combustion model of foil is established. Based on this, the infrared radiation of a single foil is calculated and verified by comparison with the experimental results. Finally, the infrared radiation characteristics and the infrared image of the whole foil-surface-type IR decoy are obtained. The calculated results are in good agreement with the experimental measurements, so the computing model provides an effective method for predicting the combustion temperature of foil-surface-type IR decoy under high-altitude and high-speed launching conditions…
Article
As infrared seeking technology evolves, threats are better able to distinguish defensive infrared (IR) flares from true targets. Spectrally matched flares, which generally employ carbon‐based fuels, are better able to decoy some advanced missiles by more closely mimicking the IR emission of the target. Cubane is a high‐energy carbon‐based scaffold which may be suitable for use as a fuel in spectrally matched flares. The enthalpy of formation and strain energy of a series of cubanes was predicted in silico, and their thermal and impact stability examined. All were found to undergo highly exothermic decomposition in sealed cell differential scanning calorimetry, and two cubanes subsequently underwent quantitative sensitiveness testing. Despite their F of I values being in the secondary explosive range, cubane‐1,4‐dicarboxylic acid (F of I=70) and 4‐carbamoylcubane‐1‐carboxylic acid (F of I=90) were identified as potentially useful fuels for pyrotechnic infrared countermeasure flare formulations.
Chapter
Nanomaterials are a relatively untapped resource for energetic materials research and development. This is partly due to the new-fangled nature of nanotechnology, but more so due to a lack of mature processing science for their incorporation into conventional materials. The high surface area of nanomaterials provides the opportunity to realize enhanced reactivity, superior burn rates, and enhanced detonation properties. In addition, particle size effects may also offer an ability to achieve tunable energetic materials. Nanoscale metallic powders are known to be highly pyrophoric, with noble metals being the exception. In addition, we will discuss how mechanically milled metal powders can be made pyrophoric with a minimal amount of processing time. Nanoporous thin films and coatings exhibiting pyrophoricity are also presented. Work is currently ongoing in exploiting the high surface area of three-dimensional foam materials. All of these materials require special handling and storage considerations, which will be discussed briefly.
Article
The influence of chlorinated paraffin/titanium (C24H29Cl21/Ti) additives on burning and radiance performances of Magnesium/Teflon/VitonTM (MTV) foil-type was investigated via a high-speed camera, high-temperature differential thermobalance, far-infrared thermal imager and Fourier Transform Infrared (FTIR) remote-sensing spectrometer. We found that the burning temperature, radiance brightness, radiance area and radiance intensity after addition of C24H29Cl21/Ti are improved by 124-196 °C (8-13%), 300-475 W·m⁻²·sr⁻¹ (12-19%), 943-1422 mm² (67-101%) and 3.17-4.99 W·sr⁻¹ (88-138%), respectively, and are maximized at the addition ratio of 10%. The substances formed by adding C24H29Cl21/Ti could improve the middle and far infrared radiation.
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Conference Paper
It is the aim of this presentation to discuss the sensitivity of certain pyrotechnic compositions applied in countermeasure stores based on data from the literature. It is recommended to investigate the IM properties of in-service pyrotechnic ammunition. Introduction Today pyrotechnic ammunition is of paramount importance when it comes to the protection of the warfighter against sophisticated threats. IRCM-flares protect airplanes, helicopters and naval vessels [1-2]. Obscurants mainly based on red phosphorus protect both marine and land targets [3]. Finally signaling and illumination ammunition is necessary for illumination of the battlefield and perimeter protection. Due to the catastrophic accidents in the 1960s involving explosives on the aircraft carriers USS Oriskany and USS Forrestal the US Navy started the development of explosives that would be less vulnerable to unplanned stimuli such as fuel fires and bullet impact than conventional explosives in use at that time. The result is now a large array of insensitive and also extremely insensitive detonating substances (EIDS) which in recent times are applied in a constantly increasing number of articles. Based on the US Navy standard MIL-STD-2105A the STANAG 4439 Ed. 2 and AOP 39 Ed 2 have been developed which describe in detail the test methods to evaluate insensitive munitions [4]. The public perception of insensitive munitions focuses on high explosives and propellants nearly exclusively. However the importance of pyrotechnic countermeasure ammunition as part of the soft-kill concept in protecting the troops requires consideration of the vulnerability of pyrotechnic ammunition. Contrary to high explosives and propellants which have been developed to detonate, to deflagrate and to burn fiercely pyrotechnic compositions most often are designed to burn in slow fashion. It is perhaps hence that catastrophic reactions of pyrotechnic ammunition are not expected in general upon subjection of pyrotechnic ammunition to unplanned stimuli such as fast heating or bullet impact. Within the context of this presentation catastrophic reactions are considered Type I – IV reactions according to STANAG 4439 Ed. 2, that are detonation, partial detonation, explosion and deflagration.
Article
在红外干扰弹自身特性研究领域中,与其相对静态的辐射特性研究相比,其复杂多变的动态气动特性研究对于实战应用显得尤为重要。为此,本文针对红外干扰弹多元气动特性影响,利用空气动力学原理及大气模型,系统分析了红外干扰弹的飞行速度与马赫数之间的紧密关系,进而高效模拟了红外干扰弹气动模型在三维立体空间中的作用效果。通过VC++.net及OpenGL开发工具对干扰弹的实际弹道模型进行综合模拟仿真设计实验,将红外干扰弹的气动特性进行自适应调节,基本达到了预期的改进目标,进而为红外干扰弹改进实战效能提供了有力支撑。 In the research field of the elastic characteristics of infrared decoy, the dynamic aerodynamic characteristics research is particularly important for the practical application of it compared with the relatively static radiation characteristics research. Therefore, considering the influence of the multi dynamic characteristics of infrared decoy and using the principle of aerodynamics and at-mospheric model, we systematically analyzed the close relationships among the variation law of gravity attenuation, flight speed and Mach number of the infrared decoy, which effectively simu-lated the trajectory effect of the pneumatic model of the infrared interference missile in three- dimensional space. Using development tools like VC++. Net and OpenGL to do integrated simulation and design experiment on the actual trajectory model of the decoy and adaptively adjust the multiple dynamic characteristics of the decoy basically reaches the expected improvement goal, and further provides a strong support for the improvement of the tactical infrared decoy combat effect.
Chapter
In the last 10 years there have been a significant number of investigations of the application of aerogels and sol–gel-derived materials and methods to the field of energetic materials (e.g., explosives, propellants, and pyrotechnics) specifically through the synthesis and characterization of nanostructured energetic composites. Aerogels have unique density, composition, porosity, and particle sizes as well as low temperature and benign chemical synthetic methods all of which make them attractive for energetic nanomaterials candidates. The application of these materials and methods to this technology area has resulted in three general types of sol–gel energetic materials (1) sol–gel inorganic oxidizer/metal fuel pyrotechnics (thermite-like composites); (2) sol–gel-derived porous pyrophoric metal powders and films; and (3) sol–gel organic fuel/inorganic oxidizer nanocomposites (propellant and explosive-like composites). This chapter details results from synthesis and characterization research in all three areas. General trends are detailed, analyzed, and discussed. In general, all sol–gel nanostructured energetic material behaviors are highly dependent on several factors including surface area, degree of mixing between phases, the type of mixing (sol–gel or physical mixing), solids loading, and the presence of impurities. Sol–gel methods are attractive to the area of nanostructured energetics because they offer a great deal of many processing options such as monoliths, powders, and films and have broad compositional versatility. These attributes coupled with strong synthetic control of the microstructural properties of the sol–gel matrix enable the preparation of energetic nanocomposites with tunable performance characteristics. Various aspects of the present literature work are reviewed and future challenges for this technological area are presented and discussed.
Article
A single crystal of iron (II) carbohydrazide perchlorate [FeII(CHZ)3] (ClO4)2 (FeCP), a novel, lead-free, energetic coordination compound, was synthesized and its structure determined by X-ray single crystal diffraction for the first time. The crystal belongs to the monoclinic system P2(1)/n space group, with a = 1.0066(2) nm, b = 0.8458(2) nm, c = 2.1194(4) nm, β = 100.693(3)° and Z = 4. The central Fe(II) ion is coordinated to three bidentate carbohydrazide units through the carbonyl oxygen atom and an amino nitrogen atom, forming a six-coordinated, non-centrosymmetric complex cation. The thermal analyses by differential scanning calorimetry and thermogravimetry show that the onset temperature of thermal decomposition (152.7 °C) and the critical temperature of thermal explosion of FeCP (161.2 °C) are both much lower than those of other transition metal carbohydrazide perchlorate compounds, and also those of some other primary explosives in service. FeCP has a high enthalpy of combustion, as measured by oxygen bomb calorimetry. The impact, friction and flame sensitivity tests indicate that FeCP is extremely sensitive and hazardous. Unexpected explosions occurred even during the operational processes. In order to explore the intrinsic cause of these explosions, theoretical calculations of the orbital energies were performed based on DTF. These results reveal that the impact sensitivity is positively correlated with the energy gap between HOMO and LUMO: the smaller energy gap results in the higher impact sensitivity.
Chapter
Mainly spurred by the United States Department of Defense, as a result of increasing federal and state regulations and the need to improve human health and to minimize collateral damage, the area of “green” pyrotechnics is a continuously evolving field. Described are some success stories and ongoing efforts in the environmentally friendly development of pyrotechnic illuminants, flash-bang formulations, a host of training simulators, incendiary munitions, igniters, electric matches, delays, and smoke formulations for signaling and obscuration purposes. Specific areas addressed to “green” the aforementioned pyrotechnic areas of interest include the removal of perchlorates and the elimination of heavy metal-based barium, lead, and hexavalent chromium compounds from a host of pyrotechnic formulations. The removal of sulfur from some pyrotechnic formulations, and the replacement of a host of potentially hazardous organic materials with environmentally acceptable technologies, are discussed in detail. Of the many challenges that remain unsolved in the area of “green” pyrotechnics, several suggestions are provided that should be helpful in addressing and solving some of these remaining concerns.
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Conference Paper
In the present work two experimental pyrolants for use in blackbody infrared decoy flares showing higher performance than baseline magnesium/polytetrafluoroethylene/Viton® (MTV) have been investigated. These pyrolants are based on fuels hitherto unknown to pyrotechnics: magnesium boride, MgB 2 and magnesium silicide, Mg 2 Si. Both fuels were formulated with polytetrafluoroethylene, PTFE and a fluorocarbon binder Viton TM (designated MbTV and MsTV). MsTV yields higher radiance, L  (W cm-2 sr-1) in the mid infrared range (2-5 µm) than MTV at same stoichiometry. The volumetric spectral efficiency E  (J cm-3 sr-1) of MbTV is also superior to MTV. MbTV thus allows for size reduction of black body countermeasure flares and thereby has potential to enhance the survivability of aircraft in hostile environments. Due to its very high burn rate MsTV qualifies for first fire and igniter applications.
Article
The following investigation evaluated the effectiveness of expendable infrared countermeasures (flares) in the protection of a fast jet against imaging infrared seekers. The report presents an effectiveness evaluation process and analyzes the results of Monte Carlo simulation runs. The goal of the investigation was to determine if expendable countermeasures (specifically spatially distributed flares) could be effective against imaging IR-guided threats.
Full-text available
Conference Paper
This paper describes investigations carried out with new materials to influence the spectral ratio B/A of infrared decoy flare compositions. Formulations based on traditional oxidizer, potassium perchlorate, KClO 4 , were considered with tetracyanoethylene, C 2 (CN) 4 and s-tricyanotriazine, C 3 N 3 (CN) 3 . For comparison phthalodinitrile C 6 H 4 (CN) 2 was considered also. Due to high com-bustion temperatures (~ 2900 K) and virtually no water content higher specific energies E λ are available in B band (3.5 – 4.8 µm) compared to state-of the art compositions based on aromatic carboxy anhydrides and KClO 4 . In addition experimental compositions based on ammonium perchlorate-d 4 and anthracene-d 10 were investigated. Substitution of H by D leads to bathochromic shift of corresponding hydrogen species (HCl and H 2 O) and thus to an improvement of both B/A ratio and specific energy E λ emitted in the B band. Radiometric data as well as thermochemical calculations and equilibrium composition of the compositions studied are presented.
Article
The application of smoke and various types of smoke bombs/devices developed are narrated. The light output of 51 mm, 81 mm, 120 mm and 120 mm LRM illuminating bombs developed is 2.6, 9.0, 10.8 and 15 lakhs candela, respectively. The IR flares developed for first and second generation anti-tank missile are in regular production. An IR decoy flare is developed for CMDS. Feasibility study on multi-spectral smoke and IR flare compositions is completed. 1W-1A No fire capability EED is developed. Gas generators 1200 cc, 2400 cc, 6000 cc are developed. Accuracy of pyro delay is improved. Laser initiated pyrocartridge is developed. Nanoscale Fe2O3 is synthesised and studied. A few toxic ingredients are replaced to march towards green pyrotechnics. Objectives for improved pyrotechnics are included.
Full-text available
Conference Paper
The performance I = E x m' [J s -1 cm -2 ] of various fluorocarbons to act as oxidizers in metal based pyrolant systems is considered on a theoretical basis. Hybridisation, molar C/F ratio, strain of the parent carbon skeleton of the fluorocarbon determine the performance.
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Article
The Planck mean absorption coefficient, a(p), has been calculated for HBr, HCl, and HF over a temperature range from 300 K-2300 K using data from the 1996 edition of the HITRAN molecular database. Plots of a(p) Versus temperature showed monotonically decreasing behavior over this temperature range, with peak values at 300 K of 45.9 (atm-m)(-1), 5.3 (atm-m)(-1), and 1.95 (atm-m)(-1) for HF, HCl, and HBr, respectively. The magnitude of these values suggests that HBr, HCl, and HF can significantly impact calculations of radiative transfer inflames containing these species. Two sets of additional calculations were performed for CO to validate the methodology used for calculation of ap for HBr, HF, and HCl. In the first approach, which employed the narrow band model RADCAL, the calculation procedure was similar to that of the present calculations. The second approach utilized tabulated values of the integrated intensity for each CO band and an average value of the Planck Junction within each band. Results from the three methods showed general agreement. Polynomial expressions are provided as fits to ap as a function of temperature for HBr, HCl, HF, and CO.
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Article
The steady-state mass burning flux and the radiative flux profiles to the surroundings were measured for a series of burning silicone fluids and organic fuels in 0.1-m, 0.3-m, 0.6-m and 1-m pool burners. Short-chain silicone oligomers and aliphatic/aromatic hydrocarbons exhibited a strong dependence of the mass flux and the radiative fraction on pool size. The longer chain length silicone fluids and alcohols exhibited both markedly lower mass fluxes and radiative components of heat release and these parameters were virtually independent of pool size. Silica, a gas-phase combustion product of the silicone fluids, was observed to deposit into the vaporizing liquid pool, the yield increasing with silicone chain length. This necessitated correcting the measured apparent mass flux for the liquid volume displaced by the silica. The measured radiative power emitted from flames burning silicone oligomers and hydrocarbons was substantially larger than the power radiated by flames burning long-chain silicone fluids or alcohols. The mass gasification flux and the radiative fraction of the silicones fluids and the organic fuels were well correlated by the ratio of the heat of combustion to the heat of gasification of the fluids.
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Article
New infrared (IR) decoys are being developed that will be forward launched from a moving aircraft. Autophagous (self-consuming) materials and components that quickly combust after deployment into harmless debris are considered in this study. The possibility of engine ingestion of an intact IR Decoy strongly suggests the use of relatively 'soft' materials that will minimize damage. Based on this and other findings determined in this study, a laminate shell design comprised principally of polymeric and organic (e.g., paper) layers joined or embedded with pyrotechnic substances is recommended for further research and development. Such a shell will probably require one or more layers of aluminum foil for oxygen and moisture barrier purposes and an inertia or electric activated primer system for ignition after launch. Properly designed, such an autophagous shell should be capable of providing: (a) protective and safe packaging for the IR Decoy during handling and launch; (b) sustained IR reactivity through protection from the atmosphere; and (c) disintegration via combustion of fragmented pieces prior to possible interaction with the launching aircraft.
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Article
The combustion of silicon based pyrotechnic compositions is observed with time resolved infrared spectrometry. This revealed the build up of strong emission at 9.1 ± 0.1 μm, which is associated with condensed silicon dioxide particulates. Time averaged spectra for compositions containing different oxidants or binders illustrate the dependence of SiO2 emission intensity on composition.
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Conference Paper
A detailed study was conducted on factors which could possibly influence the burn rate of Fe/KClO<sub>4</sub> heat pellets. The primary variables studied included the composition, density, temperature, and thickness of the pellets. Heat powders from two commercial suppliers were characterized and the effect of Fe particle size was examined in limited tests. Substrate effects were also investigated. The burning process was monitored with a high-speed video analysis system. The substrate and pellet thickness had little effect upon the burn rate of heat pellets. The pellet density, composition, and Fe particle size, however, affected the burn rates significantly. By proper adjustment of these parameters, the burn rate of heat pellets can be affected. This, in turn, can be used to influence the rise times of thermal batteries that use this type of pyrotechnic heat source
Article
A review is given on aerial infrared decoy flares and compositions disclosed in the open literature.
Article
The paper introduced the applications of the jamming technology for infrared decoy and chaff. It was found by the test that: (1) different additives can increase the radiation intensity of Mg-Teflon composite in the wavelength regions of 3 approx. 5 μm and 8 approx. 14 μm, in which Fe3O4 is best for 3 approx. 5 μm and Mg-Al is best for 8 approx. 14 μm; (2) the 4 mm × 1 mm rectangular aluminum chaff can widen the frequency bandwidth, V-type chaff of the aluminum has higher radar reflection cross section (RCS) for centimeter and millimeter waves. The jamming technology of the centimeter wave chaff is also efficient in the millimeter waves.
Article
A model for the combustion of pyrophoric metal foils has been developed. The diffusive mass transport, heat transport, and chemical reactions of porous iron foils have been described. The temperature and radiated energy of these materials has been predicted as a function of the physical characteristics of the material (porosity, pore size, specific surface area) for different atmospheric conditions (temperatures and oxygen concentrations varied with altitude and wind velocity).
Article
Consolidated stoichiometric mixtures of graphite fluoride (1) and magnesium (2) upon ignition under argon atmosphere (0,1 MPa) yield very high flame temperature of ∼ 5600 K as determined by infrared emission spectroscopy. The combustion product was analysed by X-ray powder diffraction and revealed the presence of magnesium fluoride and graphite as well as structurally low ordered carbon. A possible reaction mechanism is discussed.
Article
The infrared spectra of gaseous lithium, sodium, and cesium metaborate have been examined between 2500 and 225 cm-1. Bands were observed at 1935 and 600 cm-1 for LiBO2, Li6B02, NaBO2, and CsBO2, and at 2000 and 610 cm-1 for LiB10O2, NaB10O2 and CsB 10O2. The two frequencies have been assigned to a stretching and bending vibration, respectively, of the metaborate BO2 group. Their similarity to the corresponding frequencies of the ion B0 2- suggests a bond structure of the form M +(0--B+-O-) for the alkali metaborates. The variation of the bonding of the BO2 group in a series of related compounds and the absence of alkali-anion stretching frequencies from the spectra of both alkali metaborates and cyanides are also discussed.
Article
Consolidated stoichiometric mixtures of graphite fluoride (1) and magnesium (2) upon igni­ tion under argon atmosphere (0,1 MPa) yield very high flame temperature of ~ 5600 K as determined by infrared emission spectroscopy. The combustion product was analysed by X-ray powder diffraction and revealed the presence of magnesium fluoride and graphite as well as structurally low ordered carbon. A possible reaction mechanism is discussed.
Conference Paper
The term of "detonics" is generally applied to all the physical phenomena that occur in connection with the detonation of conventional high explosives. The reaction and/or detonation velocities are of the order of 1000 m/s to 9000 m/s, at pressures of several hundreds of kbar. In order to obtain records or pictures of the detonative event with little motion blur and high time resolution, exposure times of less than 10 ns and frame rates higher than 106/s are desirable. About one or two decades ago, new discoveries and improved knowledge in the field of detonics were heavily dependent upon developments in high speed photography. Nowadays, however, special cameras are available for diagnosing detonation phenomena, and to events caused by high pressure and shock waves, and their commercial development has produced reliable and easy-to-use instruments. Thus, the scientist working on detonics problems can now concentrate on developing measuring techniques instead of developing measuring instrumentation. A short overview will be given of the different most used and important optical equipments and cameras in the field of detonics diagnostics. Further some sophisticated, and even "tricky", configurations for optical high-speed measurements in the field of detonics will be shown in various examples which have recently been in refinded detonation diagnostics.
Article
Measurement of infrared emission spectra for boron-based pyrotechnic combustion has enabled the elucidation of a number of boron oxidation products. The raw spectra were corrected for instrument responsivity and atmospheric attenuation for the region 1500 to 3000 cm-1. The alkali metal metaborates and boron oxide (B2O3) were among the principal combustion products depending on which of three different oxidants were used. In addition, thermochemical modeling studies were undertaken on each composition to predict the combustion products. The thermochemical modeling data were qualitatively in agreement with the identified combustion products.
Article
The burning velocity of lean premixed disilane-oxygennitrogen flames has been measured at disilane and oxygen concentrations ranging from 0.55% to 1.05% and from 2% to 21%, respectively. The general trend of burning velocities has been found to be very similar to those for silane flames. However, a few different points have also been noted; above stoichiometric concentrations part of the oxygen remains unconsumed through the reaction zone, though disilane is consumed almost completely. Even in oxygen-rich flames, oxygen consumption is always less than is required for complete combustion of disilane. Further, the general trend in hydrogen production is remarkably different from that of silane flames. A large number of compounds containing SiH and SiH2 bonds are found in the solid products. The difference between disilane and silane combustion seems to be caused by the difference in the flame temperature.
Article
Premixed flames of trimethylaluminium vapours and oxygen have been stabilized at reduced pressures (3 to 25 mm of mercury) and a number of their characteristics (stability region, burning velocity, emission spectrum) have been investigated. The flame is characterized by a double reaction zone, the first caused by aluminium reactions, and the second by hydrocarbon reactions. The experimental results lead to the conclusion that the overall burning velocity is kinetically controlled by hydrocarbon reactions with the aluminium supplying only additional heat. The usefulness of investigating metalalkyl flames for the understanding of metal combustion in general is discussed.
Article
Air-to-Air Homing Missile has widely adopted infrared seeker, which makes use of thermal energy emitted from the target to detect it exactly. The target is equipped with countermeasure (CM) such as flare to protect itself from homing missile. The purpose of this paper is to develop counter-countermeasure (CCM) to cope with the CM operated by the target. Not only the radiant features of the target but also that of the flare at ultraviolet band have been compared and analyzed to select the band that can effectively remove the effects of the flare. We use a reference level for removal of the noise effects and the background. The simulation results show that our CCM algorithm can detect precisely the target location in spite of the presence of the flare.
Article
Silane combustion was studied by use of an opposed jet diffusion flame technique. When a flow of nitrogen containing silane was collided with a flow of air, a spontaneous ignition occurred. The necessary silane concentration for the ignition was above around 3% and that for maintaining the flame was above around 2% when the average flow rate of the individual opposed jet was kept 30 cm s-1, respectively. The color of the flame was pale whitish-blue when the silane concentration was low, but changed to bright orange above around 4%. The emission spectroscopy revealed the existence of SiO(ÃX∼), OH(ÃX∼), and SiH(ÃX∼) band emissions as well as continuum emissions. The emission corresponding to the orange color was ascribed to a black body radiation from SiO2 particles of around 1700 K. The analyses of gaseous and solid materials by appropriate methods suggested the following overall reactions, (S i H4 + O2 ⇀ S i O2 (s) + 2 H2, (1); S i H4 + 2 O2 ⇀ S i O2 (s) + 2 H2 O (2)). The contribution of the first reaction increased with the decrease of the silane concentration. The temperature was measured along the burner axis by use of a scanning thermocouple and was compared with calculated adiabatic flame temperatures. It was suggested that there might be some difference in temperature between the gas phase and the particle surface. The elementary reactions of silane combustion were also discussed.
Article
The optical properties of particulate emitted from fires burning two distinct polydimethylsiloxane fluids (D-4 and M-2 or MM, where D=(CH3)(2)SiO and M=(CH3)(2)SiO2)were obtained using a transmission cell-reciprocal nephelometer in conjunction with gravimetric sampling. The specific absorption coefficient of particulate ash from fires burning D-4 and MM is significantly lower than that of particulate soot from an acetylene (hydrocarbon) flame. Scattering is the dominant part of extinction in fires burning the silicone fluids. This is very different from extinction by soot particles in hydrocarbon fires, where absorption is approximately five times greater than scattering. Temperatures and particulate volume fractions along the axis of a silicone fire (D-4) were measured using multiwavelength absorption/emission spectroscopy. The structure of the D-4 flames is markedly different from hydrocarbon flames. The temperatures and particulate volume fractions very close to the burner surface are much higher than in comparably sized hydrocarbon flames.
Article
In large-scale fires and flames, radiative transport can be an important factor determining the rate of fuel volatilization and flame spread in condensed fuels, and in general can affect the amount of soot that is produced by the flame. The radiant flux can be significantly attenuated by core hydrocarbon gases that have absorption features in the infrared. The spectral absorptance of the Ïâ (centered at approximately 3020 cm⁻¹) and Ïâ (centered at approximately 1306 cm⁻¹) fundamental bands of methane were measured at elevated temperatures. The measurements were made using a FTIR spectrometer coupled to a gas cell that was maintained at a constant temperature in a furnace. The partial pressure of the methane was varied between 5 and 95 percent, yielding pressure path lengths between 1.14 and 21.74 atm-cm. The total pressure was maintained at 1 atm. Measurements were made at temperatures between 296 and 900 K. The effect of spectral resolution on the measurements and derived parameters was examined. Spectral resolutions between 4 and 32 cm⁻¹ were used. The spectral mean parameters of line strength and line shape were determined for the Elsasser narrow band radiation model using the data taken at a resolution of 4 cm⁻¹. The band model parameters were incorporated into RADCAL, a narrow band model used to predict spectral intensity and transmittance. 13 refs., 10 figs., 1 tab.
Article
Spontaneous emission spectra in the wavelength range from 200 to 420nm from a SiH4/H2/O2/Ar diffusion flame (used for the synthesis of nanosized particles) were obtained. Si, SiH and SiO intermediates were identified from the spectral emission signature. Emission from the SiO A1Π–X1Σ+ transition was analyzed in detail. Comparison of the experimental data with an emission model for SiO indicated significant vibrational non-equilibrium. The level of vibrational excitation was quantified in terms of a vibrational temperature independent of a translational temperature. The best-fit model results obtained by comparison with the experimental data, yielded a translational temperature of Ttrans=3250±500K and a vibrational temperature of Tvib=15000±5000K for high oxygen concentration systems. The vibrational temperature corresponds to an energy equivalent of ∼29kcal/mol and changes in fractional population of over an order of magnitude from equilibrium distributions for some vibrational levels. For low oxygen concentration systems, the vibrational temperature was significantly higher Tvib=40000±15000K, which indicates a different SiO formation mechanism is active for these conditions.
Article
The role of pyrotechnic and pyrophoric decoys in decoying incoming IR homing missiles was discussed. The pyrotechnic decoy flares are the most commonly used passive countermaster to lure away incoming heat seeking missiles. The application of decoy flares was proposed through two patents having payloads constituted from multiple sub-pellets thus enhancing surface to volume ratio. Flares with constant weight to drag ratio and aerodynamic and propelled flares were used to overcome the problem of countermeasure. Better projection to aircrafts was achieved by improved kinematic behavior, spectra matching and area target like signature.
Article
Explosive light sources consisting of 20-g and 200-g explosive charges fired in containers filled with argon were observed by a grating spectrograph and a phototube radiometer. The infrared spectra showed a continuum with superimposed strong emission lines characteristic of argon. The visible and ultraviolet spectrum showed a continuum with the intensity increasing steadily from the visible into the ultraviolet. Radiometer measurements showed that the ratio of ultraviolet to visible radiation was that of a blackbody at about 20,000°K.
Article
A counter-countermeasures (CCM) algorithm in a target tracking system is required for efficient target tracking under countermeasures (CM) such as infrared flares. Most of the CCM algorithms employ some forms of spectral band discrimination to distinguish between a target and CM. We adopt two detection bands based on the spectral distribution characteristics (SDC) of a target and flares and define the energy ratio between the two band signals (MNR) to represent their SDC and to distinguish them. The proposed algorithm computes the MNR of the incident band signals and its histogram, detects the MNR of flare signal from the histogram, and extracts target signal only from the target and flare mixed signal. To estimate the performance of the proposed algorithm, we simulate it under various conditions. The simulation results show that the proposed algorithm can eliminate the effect of CM well.
Article
The specific intensity in mid infrared band (2 µm–5 µm) and mass burn rate of MTV compositions is investigated with respect to stoichiometry.IR-Emissionsverhalten von Magnesium/Teflon/Viton (MTV) SätzenDie spezifischen Intensitäten im mittleren Infrarot sowie der Massendurchsatz von MTV-Sätzen wird in Abhängigkeit von der Stöchiometrie untersucht.Comportement de l'émission IR de compositions Magnésium/Téflon/Viton (MTV)Les intensités spécifiques dans le moyen infrarouge ainsi que le débit massique de compositions MTV sont étudiés en fonction de la stœhiométrie.
Article
This paper presents a dynamic simulation loop that gives tracking results for a two-color concentric annular ring (CAR) reticle seeker. Our simulation tool includes a target flare model and a proportional navigation guidance loop. The CAR reticle system's performance and the flare effects are analyzed in various scenarios. When a flare is present in the field of view, the simulation results show that the reticle seeker cannot maintain precise target tracking. We propose a two-color countercountermeasure using the least- mean-square method to cope with a presence of infrared (IR) flares. The proposed method makes use of simultaneous processing of the modulation output in two IR wavelength bands. One is the midwave IR (a primary input signal), and the other is the shortwave IR (a reference input signal). Simulation results have shown that our adaptive algorithm can achieve effective cancellation of flare signals with high intensity.
Article
The infrared emission characteristics of six pyrophoric mixtures have been investigated at simulated altitudes up to 60,000 feet and the data compared to kerosene burned under the same conditions. The experiments were performed in large vacuum chambers with the mass flow rate being varied from 1 to 5 grams per second. Pyrophoric mixtures were atomized in a mixing nozzle by nitrogen and released as unchoked exhaust plumes. One series of tests demonstrated that the mixtures: (1) spontaneously ignited at all simulated altitudes, (2) emitted solely in the CO2 (4.2 to 4.4 microns) and the H2O (2.5 to 3.3 microns) bands, (3) resulted in radiation figures of merit above 200 watts/steradian/gram/second and (4) had an ignition time between 5 and 20 milliseconds. A second series of tests were performed with a co-flowing airstream created by releasing air into the vacuum chamber through a choke. These tests demonstrated the significant effect of airflow on the radiant intensity of unchoked exhaust plumes. A chemical equilibrium computer program was used to gain insight into other parameters affecting infrared radiation. Plume temperatures and the distribution of significant exhaust species were computed as a function of mixture ratio.
Article
Manned aircraft that are intended for surveillance or to complete a bombing mission will very likely be engaged by surface to-air-missiles having guidance systems based on infrared (IR) technology. The objective of this study was to characterize via simulation the amount of "cover" that can be obtained by dropping from a pre-launched, unmanned tactical air launched decoy (TALD) a sequence of pyrophoric materials to create an IR cloud, analogous to the interference created by microwave chaff, that would protect the manned aircraft from the missile. The performance analysis is based on a simple reticle based model in which the two-dimensional (2D) image is reduced to either a composite signal, created by the aircraft, or a composite noise, created by the pyrophoric expandable. The analysis leads to a computer simulation model producing time and space dependent signal-to-noise ratios. It is demonstrated that the simulation model can answer questions such as how long the materials need to burn, how much intensity is needed, what wavelength range is most effective, which pyrophoric packets should be dropped, and how many. A visual model of the time dependent IR pyrophoric cloud has also been created.
Article
The treatment of radiant emission and absorption by combustion gases are discussed. Typical applications include: (1) rocket combustion chambers and exhausts, (2) turbojet engines and exhausts, and (3) industrial furnaces. Some mention is made of radiant heat transfer problems in planetary atmospheres, in stellar atmospheres, and in reentry plasmas. Particular consideration is given to the temperature range from 500K to 3000K and the pressure range from 0.001 atmosphere to 30 atmospheres. Strong emphasis is given to the combustion products of hydrocarbon fuels with oxygen, specifically to carbon dioxide, water vapor, and carbon monoxide. In addition, species such as HF, HC1, CN, OH, and NO are treated.
Article
The performance of poly(carbon monofluoride) (PMF) (synonym: graphite fluoride) (CFx)n, (1) as oxidizer in a fuel rich Mg based pyrolant (ξ(Mg)=0.45) is investigated. The radiance [W sr−1] under both static and dynamic conditions, the spectral radiant exitance [W cm−2 μm−1], the linear burn rate [mm s−1] and the mass consumption rate [g s−1 cm−2] have been determined. Calculations for enthalpy of anaerobic and aerobic combustion [kJ g−1] and for the equilibrium composition of the combustion products as well as combustion temperature are given. A mechanism for the reaction is discussed. The combustion product from Mg/(CFx)n surprisingly reveals the formation of single walled carbon nanotubes (SWCNT) and “carbon nano carpet rolls” (CNCR). For part V see Ref. [1].
Article
The potential of strained fluorocarbons, which can act as oxidizers in metal-based pyrolant systems, is investigated. The oxidizing performance of fluorocarbons is evaluated by the enthalpy of combustion ΔcH(298K) and the fractional electron transfer ΔN. ΔcH(298K) can be related to hybridisation, molar C/F ratio and strain of the parent carbon skeleton of the fluorocarbon. Considered fluorocarbons are tetrafluorotetrahedrane (CF)4 (3), tetrakis(trifluoromethyl)tetrahedrane C4(CF3)4 (4), hexafluoro[3]prismane (CF)6 (5), hexakis(trifluoromethyl)[3]prismane C6(CF3)6 (6), octafluorocubane (CF)8 (7), octakis(trifluoromethyl)cubane C8(CF3)8 (8), eicosafluorododecahedrane (CF)20 (9), eicosakis(trifluoromethyl)dodecahedrane C20(CF3)20 (10), C60F48 (11) and perfluorofullerane (CF)60 (12). Powerful oxidisers in terms of exothermicity are those possessing both tertiary CF-units and strained carbon skeletons. Nevertheless the reactivity, which is estimated on basis of ΔN, the fraction of electrons transferred according to Pearson, has been found to be high with the corresponding perfluoromethyl derivatives and maximum with the fluorofulleranes. For part IV see Ref. 17.
Article
The thermochemical and combustion behaviour of pyrotechnic payloads based on magnesium, Teflon® and Viton®, so-called MTV is discussed. Thermochemical and FTIR-spectroscopic analysis of magnesium/Teflon® combustion residues indicates the intermediate formation of a Grignard-type CMgF compound in the condensed phase as part of a preignition reaction (PIR). The PIR is mainly responsible for the observed burning rate which rises exponentially with rising magnesium weight fractions from ξ(Mg)∼0.2 to ξ(Mg)∼0.70 and declines at ξ(Mg)>∼0.70. A tentative mechanism for the combustion process is presented.
Article
Metals such as Al and Mg have high combustion enthalpies and they are widely used as additives in energetic materials for propellants, explosives, and pyrotechnics. However, long ignition delays and slow combustion kinetics limit their current applications. An approach suggested in this work is to design new metal-based materials in which pre-determined phase changes will occur and trigger ignition at a desired temperature and also accelerate the rate of heat release during combustion. As a first step, metastable solid solutions of Mg in Al (10–50% of Mg) have been produced by mechanical alloying. The ignition temperatures of the produced alloys in air were determined using digital imaging and three-color pyrometry of the electrically heated filaments coated with different alloy powders. Combustion of mechanical alloys in air was studied using a laminar, premixed flame aerosol burner. The ignition temperatures were around 1,000 K, much lower than the pure aluminum ignition temperature of about 2,300 K. The steady flames of mechanical alloy powders were produced at lower equivalence ratios and had higher propagation velocities than similar pure aluminum powder flames. Phase compositions of the combustion products were determined using X-ray diffraction. In addition to Al2O3 and MgO, significant amounts of Al2MgO4 were found in experiments.
Article
Shock-tube measurements are described for the quantitative spectral measurement of the i.r. signatures and band strengths of molecular boron species. The boron species were effectively isolated under conditions of optimum concentration and calculated thermodynamic conditions using the shock tube technique. Spectral measurements were performed using a scanning i.r. spectrometer which was specially designed for these experiments. System calibration experiments were performed using shock heated CO and CO2 mixtures in diluent argon, and the measured band strengths were in excellent agreement with the accepted values for these molecules. Quantitative spectral measurements were performed on the HBO2 fundamentals at 2.7 and 5.0 μm and OBF at 5.0 μm. The corresponding band strength values measured for these band systems were 650, 1375, and 1760 cm-2 amagat-1, respectively.
Article
A model for the combustion of pyrophoric metal foils has been developed. The diffusive mass transport, heat transport, and chemical reactions of porous iron foils have been described. The temperature and radiated energy of these materials has been predicted as a function of the physical characteristics of the material (porosity, pore size, specific surface area) for different atmospheric conditions (temperatures and oxygen concentrations varied with altitude and wind velocity).
Article
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Article
This users manual is the second part of a two-part report describing the NASA Lewis CEA (Chemical Equilibrium with Applications) program. The program obtains chemical equilibrium compositions of complex mixtures with applications to several types of problems. The topics presented in this manual are: (1) details for preparing input data sets; (2) a description of output tables for various types of problems; (3) the overall modular organization of the program with information on how to make modifications; (4) a description of the function of each subroutine; (5) error messages and their significance; and (6) a number of examples that illustrate various types of problems handled by CEA and that cover many of the options available in both input and output. Seven appendixes give information on the thermodynamic and thermal transport data used in CEA; some information on common variables used in or generated by the equilibrium module; and output tables for 14 example problems. The CEA program was written in ANSI standard FORTRAN 77. CEA should work on any system with sufficient storage. There are about 6300 lines in the source code, which uses about 225 kilobytes of memory. The compiled program takes about 975 kilobytes.
Article
This report presents the latest in a number of versions of chemical equilibrium and applications programs developed at the NASA Lewis Research Center over more than 40 years. These programs have changed over the years to include additional features and improved calculation techniques and to take advantage of constantly improving computer capabilities. The minimization-of-free-energy approach to chemical equilibrium calculations has been used in all versions of the program since 1967. The two principal purposes of this report are presented in two parts. The first purpose, which is accomplished here in part 1, is to present in detail a number of topics of general interest in complex equilibrium calculations. These topics include mathematical analyses and techniques for obtaining chemical equilibrium; formulas for obtaining thermodynamic and transport mixture properties and thermodynamic derivatives; criteria for inclusion of condensed phases; calculations at a triple point; inclusion of ionized species; and various applications, such as constant-pressure or constant-volume combustion, rocket performance based on either a finite- or infinite-chamber-area model, shock wave calculations, and Chapman-Jouguet detonations. The second purpose of this report, to facilitate the use of the computer code, is accomplished in part 2, entitled 'Users Manual and Program Description'. Various aspects of the computer code are discussed, and a number of examples are given to illustrate its versatility.
The Infrared and Electro-Optical Systems Handbook, Vol 7 Countermeasure Systems
  • N Brune
  • Expendable
N. Brune, Expendable Decoys, in: J. S. Accetta, D. L. Shu-maker (Eds.), The Infrared and Electro-Optical Systems Handbook, Vol 7 Countermeasure Systems, SPIE Optical Engineering Press, Bellingham 1996, pp. 289–321.
Elimination of Perchlorate Containing Oxidizers from Red and Green Pyrotechnic Flare Compositions, 31st International Pyrotech-nics Seminar, Fort Collins
  • R G Shortridge
  • C K Wilharm
  • E Dreizin
R. G. Shortridge, C. K. Wilharm, E. Dreizin, Elimination of Perchlorate Containing Oxidizers from Red and Green Pyrotechnic Flare Compositions, 31st International Pyrotech-nics Seminar, Fort Collins, July 11 – 16, 2004, p. 851.
Pyrofora Alkylaluminium Föreningar i Motmedelsfacklor, FOA Rapport C 20562-E4
  • B Gelin
B. Gelin, Pyrofora Alkylaluminium Fçreningar i Motmedels-facklor, FOA Rapport C 20562-E4, November 1984.
Pyrotechnic Composition and Uses Thereof
  • P L Posson
  • A J Bagget
P. L. Posson, A. J. Bagget Jr., Pyrotechnic Composition and Uses Thereof, U. S. Patent 6 427 599, 2002, BAE Systems Integrated Defense Solutions Inc., USA.
Neue Lenkflugkçrper Luft-Luft Internationale Rüstungskooperation der Luftwaffe, Soldat und Technik
  • R Meller
R. Meller, Neue Lenkflugkçrper Luft-Luft Internationale Rüstungskooperation der Luftwaffe, Soldat und Technik 1996, 5, 302.
High-Speed Photography Tactical Missile Warheads
  • M Held
M. Held, High-Speed Photography, in J. Carleone (Ed.), Tactical Missile Warheads, Vol 155 Progress in Astronautics and Aeronautics, A. R. Seebass (Ed.), American Institute of Aeronautics and Astronautics, Washington 1993, p. 609.