Pyroorganic flares - state of the art and progress

IR decoy flares proved as effective measure to protect various military platforms as well as civilian airplanes. Recent missiles equipped with modern seeker technology are able to distinguish between target and decoy flares evaluating spectroscopic emission. So advanced decoy flares have to be adapted to the thermal and spectral emissivity of the platform to be protected. Conventional MTV decoy flares emit a continuous IR spectrum, whereas the exhaust plume of a jet gives distinct band signatures of carbon dioxide and water. In [1] an approach called ""pyro-organic flares"" was introduced including the idea to combine hydrocarbon combustion to settle spectral requirements and pyrotechnic mixtures to increase the radiation intensity. In recent developments HTPB bonded samples including AP as oxidizer and different pyrotechnical mixtures were prepared and tested with regard to potential use as a spectral flare. Two thermite mixtures and a titanium/graphite mixture were used. Lab-scale combustion experiments were performed once in free atmosphere at normal pressure, and in a vessel at reduced air pressure of 10 to 100 kPa that covers the complete profile of potential application. All investigated samples satisfied in combustion properties as well as spectral properties at these pressure levels. Measured emission temperatures determined on the distinct CO2 and water bands were several hundred Kelvin higher compared of MTV. The studies indicate post-combustion with ambient air of the binder residues and the pyrotechnic reaction product TiC resulting in a favorable v/a-ratio. Most promising compositions were selected for real scale investigations at the ICT aerodynamic test stand in flow fields corresponding to helicopter, transporter and jet plane conditions. All specimens ignite prompt and burn stable under all tested aerodynamic conditions forming large flare volumes with thermal and spectral properties close to those achieved during the lab-scale tests.