Global Stability and Control Analysis of Aircraft at High Angles-of-Attack.
Annual technical rept. no. 1, 1 Jun 76-31 May 77,
SCIENTIFIC SYSTEMS INC CAMBRIDGE MA
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Aircraft dynamic behavior at high angles-of-attack is highly non-linear and, in the past, there has been a lack of suitable techniques for analyzing the global behavior of nonlinear systems. This report describes a new approach based on Bifurcation Analysis and Catastrophe Theory Methodology BACTM. The approach has been applied to specific jump, hysteresis and limit cycle phenomena such as roll-coupling, pitch-up, wing rock, buffeting, departure and divergence. Three different aircraft have been considered for comparison purposes, and it has been shown how different types of instabilities and families of limit cycles arise as the control variables are varied. A complete representation of the aircraft equilibrium and bifurcation surfaces is given in an eight dimensional space consisting of roll rate, pitch rate, yaw rate, angle-of-attack, sideslip angle, elevator, aileron and rudder deflections. Two dimensional projections of the equilibrium and bifurcation surfaces provide pictorial representations of the aircraft global stability and control behavior at high angles-of-attack. The use of BACTM for spin entry, spin prevention, stability augmentation at high angles-of-attack and nonlinear system identification are also considered. Author
- Theoretical Mathematics