Thermal Management of the Hexafly-Int Hypersonic Glider

This paper presents the sizing and choice of the technological solutions used for the thermal management of the critical hot parts, the main structure and the equipment of the Hexafly-Int hypersonic glider. Air conditioning into the fairing is used during pre-flight operations so as to maintain the temperature of the vehicle with its equipment below 20°C. During the flight, the thermal integrity of the nose is based on a heat sink approach by using massive blocks of metallic materials coated by zirconium whereas the wing leading edges and the flaps are made in C/C-SiC material. Among different assessed solutions, the temperature of the main titanium structure is maintained below 700°C thanks to an extra high emissivity painting applied on its external face. Equipment is protected from radiative heat transfer of the main structure thanks to a light flexible microporous insulator named Aeroguard® which exhibits extra high insulation performance at low pressure into the stratosphere. This internal thermal protection system is kept in place on the internal faces of the main structure thanks to thin flexible wires which allow fast depressurization of the insulator and mechanical strength to vibrations during the ascent phase of the flight. All equipment is also protected from conductive heat transfer coming from the hot main structure by using low thermal conductivity fixations based on Vespel® material. A special thermal management is dedicated to telemetry electronic boxes so as to absorb their dissipated power into a heat sink based on phase changing material.