Overview of Stability and Control Estimation Methods from NATO STO Task Group AVT-201

Kurzfassung

NATO STO Task Group AVT-201 on “Extended Assessment of Reliable Stability & Control Prediction Methods for NATO Air Vehicles” is studying various computational approaches to predict stability and control parameters for maneuvering aircraft. The ability to accurately predict both static and dynamic stability characteristics of air vehicles using computational fluid dynamics (CFD) methods could revolutionize the vehicle design process for NATO air vehicles. A validated CFD capability would significantly reduce the number of ground tests required to verify vehicle concepts and, in general, could eliminate costly vehicle ‘repair’ campaigns required to fix performance anomalies that were not adequately predicted prior to full-scale vehicle development. As a result, significant reductions in acquisition cost, schedule, and risk could be realized. The dramatic increase in computing power and the affordability of computer clusters now make it feasible for the majority of NATO nations to undertake time-accurate CFD simulations, and an assessment of the stateof- the-art has been carried out previously. The objective of the Task Group is to determine an overall strategy for creating stability and control databases for vehicle simulation at fullscale conditions, including the deflection of control surfaces, throughout the operational envelope of the vehicle. These assessments are being done on two vehicles: SACCON, a generic UCAV designed and tested for the predecessor to AVT-201 (AVT-161) and the X-31 highly maneuverable aircraft previously flight tested by the US and Germany. Extensive wind tunnel data has been (and is being) collected for these configurations, including static and dynamic cases, with and without control surfaces, and at low and high subsonic Mach numbers. The methods and approaches used in the Task Group will be overviewed, including an assessment of the state-of-the-art capability. The approaches for estimating static and dynamic stability parameters are discussed, including reduced-order model methods such as Volterra, Radial Basis, and Indicial functions. A status of these activities is provided and future work is overviewed, including future wind tunnel tests and simulation approaches.