Sharp Leading Edge at Hypersonic Flight: Modeling and Flight Measurement

The octahedral sharp leading edge of the sharp edge flight experiment SHEFEX II is made from carbon fiber reinforced ceramic with a tip radius of <1 mm. It is instrumented by thermocouples and pressure ports and the measurement values are compared with a theoretical model. A duplicate was ground tested in the arc-heated wind tunnel L3K. During ground testing, the thermocouples measured up to 1219 degrees C, with the very tip of the leading edge reaching 1635 degrees C, and the leading edge was in good order after testing. Transient thermal response of the material to the aerothermodynamic load was simulated by the heat balance method Heat Exchange Analysis for Transpiration Systems and compared with the measurement data. The data correspond well to both thermocouple data and data from an external infrared camera. During the ballistic return flight between Mach 10.2 and 9.3, the maximum temperature transmitted to the ground station was measured at 30 km altitude with 867 degrees C just before the vehicle dove behind the horizon. The heat balance predicts the measurement with an accuracy on the order of 10%.