Flight Behavior of an Asymmetric Body through Spark Range Experiments Using Roll- Yaw Resonance for Yaw Enhancement

Report No. ARL-TR-7334
Authors: Frank Fresconi; Bernard Guidos; Ilmars Celmins; Wayne Hathaway
Date/Pages: July 2015; 64 pages
Abstract: The maneuvers required for guided flight are often obtained through inducing aerodynamic asymmetries. The goal of this study is to understand the flight behavior of asymmetric flight bodies. The configuration considered was a fin-stabilized projectile featuring a pair of canards representative of a class of rolling airframes with a single plane of actuating control surfaces that have recently undergone successful guided flight demonstrations. In addition to this aerodynamic asymmetry, an asymmetric mass was placed within the body. This internal asymmetry creates a trim moment and angle of attack that is amplified during free-flight as the roll rate of the body increases from zero at launch and passes through the natural yawing frequency of the projectile. Increasing the angle of attack amplitude in this manner enables analysis of a rich set of flight behaviors. Free-flight experiments were conducted on this flight body in the spark range at the Transonic Experimental Facility at the US Army Research Laboratory. Aerodynamic parameter estimation was performed on the spark range measurements using a maximum likelihood method with a body-fixed 6-degrees-of-freedom flight model. Nonlinear aerodynamic models including asymmetries in the pitching moment, normal force, and dynamic derivatives were accommodated in these techniques. Aerodynamics were compared to results obtained using computational fluid dynamics and onboard sensor techniques. Experiments also permitted analysis of the amplification factor due to roll-yaw resonance and provide a means of more easily collecting high-quality experimental data on guided projectile configurations in the future.
Distribution: Approved for public release
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Last Update / Reviewed: July 1, 2015