SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 7 - April 7, 2006

08 AIRCRAFT STABILITY AND CONTROL
Includes flight dynamics, aircraft handling qualities, piloting, flight controls, and autopilots.

For related information see also 05 Aircraft Design, Testing and Performance; and 06 Avionics and Aircraft Instrumentation.

20060009038 NASA Langley Research Center, Hampton, VA, USA

Non-linear controls influence functions in an aircraft dynamics simulator

Guerreiro, Nelson M.; Hubbard, James E., Jr.; Motter, Mark A.; [2006]; 14 pp.; In English; SPIE 13th Annual International Symposium Smart Structures and Materials, 26 Feb. - 2 Mar. 2006, San Diego, CA, USA; Original contains black and white illustrations Contract(s)/Grant(s): 23-090-20-ZC; Copyright; Avail.: CASI: A03, Hardcopy

In the development and testing of novel structural and controls concepts, such as morphing aircraft wings, appropriate models are needed for proper system characterization. In most instances, available system models do not provide the required additional degrees of freedom for morphing structures but may be modified to some extent to achieve a compatible system. The objective of this study is to apply wind tunnel data collected for an Unmanned Air Vehicle (UAV), that implements trailing edge morphing, to create a non-linear dynamics simulator, using well defined rigid body equations of motion, where the aircraft stability derivatives change with control deflection.

An analysis of this wind tunnel data, using data extraction algorithms, was performed to determine the reference aerodynamic force and moment coefficients for the aircraft. Further, non-linear influence functions were obtained for each of the aircraft s control surfaces, including the sixteen trailing edge flap segments. These non-linear controls influence functions are applied to the aircraft dynamics to produce deflection-dependent aircraft stability derivatives in a non-linear dynamics simulator. Time domain analysis of the aircraft motion, trajectory, and state histories can be performed using these nonlinear dynamics and may be visualized using a 3-dimensional aircraft model. Linear system models can be extracted to facilitate frequency domain analysis of the system and for control law development.

The results of this study are useful in similar projects where trailing edge morphing is employed and will be instrumental in the University of Maryland s continuing study of active wing load control. Author

Aerodynamic Forces; Aircraft Control; Simulators; Dynamic Tests; Wing Loading; Structural Design; Trailing Edge Flaps; Control Surfaces

Source: NASA