Flight Demonstration of Stealthy Closed-Loop Attitude Control

"Flight demonstration of modern stealthy aircraft with an active flow control system is an important, complex, and challenging opportunity. The probability of success is maximized by a progressive plan in which complexity is introduced gradually. Wepropose a plan that includes flight testing of a simple system in Phase I and progressing to a multi-axis demonstration in Phase II. The proposed program develops a closed-loop attitude control system for an air vehicle, implementing and integratingactive flow control actuators and sensors. Control system design will be based on robust, nonlinear sliding mode methods that account for air vehicle mechanics, large rotation kinematics and reduced-order modeling of the active flow actuators. Actuatortechnology focuses on stealthy approaches, such as synthetic jets, which eliminate the need for conventional hinged control surfaces. In Phase I, closed-loop roll control employing active flow actuators in the wing tip regions will be developed. Phase Iculminates in flight testing using a modified radio-controlled aerobatic model plane (approximately 9 ft. wingspan and 135 mph flight speed). In Phase II, the investigation will be extended to multi-axis control over a wider flight envelope, for ajet-powered radio-controlled model with a planform representative of modern stealthy aircraft. The successful completion of this program will provide a substantial advance in the capabilities of stealth aircraft."