Static Stability of the SCRAMSPACE I Mach 8 Hypersonic Flight Experiment

摘要

The free-flying SCRAMSPACE I Mach 8 hypersonic flight experiment will be launched using a two-stage sounding rocket motor system (RMS) from the Andoya Test Range in Norway in June 2013. The vehicle will reach an altitude of approximately 100km before detaching from the RMS, with the fuelled phase of the scramjet experiment occurring between 32km-27km during the down-leg of the ballistic RMS trajectory. Satisfying the static stability requirements specified by the launch service provider when SCRAMSPACE is attached to the RMS whilst also maintaining an acceptable static stability margin during the free-flying phase of the mission is shown to be an interdisciplinary and multi-constraint design problem. Inviscid computational fluid dynamics (CFD) tools have been used to perform a trade-off analysis between the competing requirements of the RMS and the desired SCRAMSPACE stability-margins from launch until termination of the experiment. The placement of both vehicles' (RMS and SCRAMSPACE) centre of gravity (CG) and centre of pressure (CoP) are a coupled problem, with the vehicle length, outer mould line, stability fin mass- and shape all having a profound effect on the stability margin evolution over the trajectory. The second (Improved Orion) stage is found to be the critical flight phase for the RMS stability during ascent. The addition of 50mm high strakes between the Improved Orion stability fins has been shown to ensure static stability throughout the ascent phase. The shape of the stability fins on the SCRAMSPACE vehicle has evolved to place the fin CoP as far aft as possible without interfering with the launch rail or RMS manacle band release mechanism. A nominal static margin of 5% for SCRAMSPACE has been achieved whilst reaching the required >1 calibre limit for the RMS.