GUY NORRIS / LOS ANGELES
Joint programme will test feasibility of improving roll-control via aerodynamically induced wing twist
Tests of NASA's Boeing F/A-18A equipped with a flexible wing are due to start in July at Dryden Flight Research Center, California. The NASA, Boeing Phantom Works and US Air Force Research Laboratory programme aims to prove the Active Aeroelastic Wing (AAW) can boost roll-control and provide the basis for future low-weight designs.
The aircraft will be used to assess whether aerodynamically induced wing twist can improve roll-control on a full-scale aircraft at transonic and supersonic speeds. The data will be used to develop design information for blending flexible-wing structures with control techniques to assess the performance of current aircraft with lighter wings. This could hold the key to future aircraft design, says NASA AAW project manager Denis Bessette.
"The goal is to provide weight- competitive, higher aspect-ratio wings, which would allow you to lower take-off weight and resize the design," he says, adding the principle can be applied to "everything from a subsonic bomber to a future strike aircraft - or even the Quiet Supersonic Platform".
The AAW project began in 1996, and was to have begun flight tests last year (Flight International, 17-23 October 2000). But Bessette says "complex interactions" between the F/A-18 flight-control system and the Motorola 68040 processor installed in the AAW as the central flight control computer (FCC) have proved more of a problem than expected. The aircraft comprises the modified lightweight wings of the HARV high angle-of-attack research vehicle with the fuselage of an ex-US Navy F/A-18A. The wing is modified with a split leading-edge. The outer section and the ailerons will be used together to twist the wing, which will provide the roll force.
A two-phase flight test programme will gather data on internal loads and aerodynamic performance, which will be used to design new flight-control laws for installation in the FCC for full-up AAW test flights next year. USAF ARL programme manager Ed Pendleton says: "Aeroelasticity has caused problems and now we want to turn it to our benefit." Boeing Phantom Works programme manager Jim Guffey says data from the AAW will be evaluated for application on future projects ranging from unmanned air vehicles to the blended wing body.
Source: Flight International
