Aerodynamic Performance of the Smart Wing Control Effectors

Abstract

This paper presents and discusses the wind tunnel results obtained during Phase 1 and Phase 2 of the Smart Wing program. A series of four tests was conducted, two in each phase. The purpose of the tests was to evaluate the performance of smart material based control effectors in representative aerodynamic environments. In Phase 1, wing twist using a Shape Memory Alloy (SMA) torque tube and smoothly contoured trailing edge surfaces enabled by SMA wires were evaluated on a semi-span, 16% scale model of a typical fighter wing. The focus of Phase 2 was to address the design and demonstration of a high-frequency, large-deflection, and smoothly contoured trailing edge control surface capable of a spanwise variation in deflection. The actuation system for this control surface was based on piezoelectric (PZT) ultrasonic motors. A smoothly contoured leading edge control surface was also built and tested using SMA wires. These designs were evaluated on a 30%, full-span model of a representative Unmanned Combat Air Vehicle (UCAV). In each wind tunnel entry comparisons were made to the performance of conventional control surfaces. Successful results included: improved aileron effectiveness at high dynamic pressures; demonstrated improvements in lateral and longitudinal control effectiveness with smoothly contoured control surfaces over conventional hinged control surfaces; continuous spanwise shape control; and, large deflections at rates over 80°/s, which is well within the desired deflection aileron rates for control of fighter aircraft.

Experimental testing of spanwise morphing trailing edge concept

“…Airfoils with conformal control surfaces that vary smoothly over the chord of the airfoil have been shown to have an aerodynamic advantage over airfoils with conventional, articulated ailerons [4]. For airfoil profiles Reynold's numbers in the 10 5 to 10 6 range, typical of the range for a small RC aircraft to larger UAVs, smoothly-varying the surface of the airfoil can positively influence several boundary layer features.…”

Morphing Trailing Edge Control Using Flexible Matrix Composite Actuators

“…In general, morphing aircraft is developed to increase vehicle performance by changing their external shapes during flight. 1 Morphing on a larger scale that involves significant changes in the camber, 2-4 wing span, [5][6][7] twist, 8,9 or sweep 10,11 has been profoundly investigated since the early 90's with NASA's Morphing Project. 12 A recent review on morphing aircraft, focusing on structural active morphing concepts, can be found in Barbarino.…”

Bistable Composite Flap for an Airfoil

“…These design solutions can be successfully used to control aircraft but they can have significant deficiencies with regard to aerodynamic performance, mass penalties, and complexity. There have been a number of shape-adaptive airfoil demonstrators in recent years that have attempted to address these problems [1][2][3][4][5][6][7]. The Intelligent Responsive Composite Structures (IRCS) program at the University of Bristol was initiated to investigate the design of adaptive structures using bistable composites as a means of providing aerodynamic control [8][9][10].…”