|RESEARCH AIRCRAFT||Virtual Aircraft Museum / USA / Ames-Dryden|
Variable-geometry aircraft are now an accepted part of aeronautical engineering, but one of the latest experiments is in the field of the slew or skew-wing aircraft, also called the 'Yawed wing' by the Boeing company. A small test vehicle with twin jets, the AD-1, was delivered to NASA's Dryden Research Center in March 1979.
The basic form of the slew-winged aircraft consists of a one-piece wing positioned on the fuselage so that it can be pivoted with one wing moving forward, and the other back, thus offering less drag. Take-off and landing is effected with the wing situated straight across the fuselage.
As a commercial airliner such a design would fly only a little faster than the speed of sound at about Mach 1.1 or Mach 1.2, would give an improvement in the transonic lift: drag ratio over that of conventional aircraft and would also give a gain in speed of almost 50%.
Although the speed of a slew-winged airliner would not be so great as a current SST (supersonic transport) design, it would be easier to build and would produce a lower noise level. The sonic boom would be weakened due to the optimum pressure distribution and the sound would therefore be largely muffled before reaching the ground. An airliner of this sort would be less mechanically complex than say, a variable geometry one; and the trim/drag penalties would be less severe.
It is suggested that some control problems would be encountered, mainly because remotely piloted test vehicles, which fail to give the 'pilot' any visual reference points at high slew angles, have failed to show the type of handling characteristics that may be met. To answer these questions the low-cost, piloted demonstrator, AD-1, was ordered from Ames Industrial, the US distributor of Microturbo engines, two of which - 100kg thrust TRS18 versions - are fitted.
Trials were scheduled to begin in 1980 and the wing will be progressively traversed through 60° from the first neutral position.
The AD-1 is intended to act as a scaled-down model of a projected 200-seat airliner with twin decks and turbojet engines faired into the rear fuselage. It is anticipated that a second step in the development programme will be the modification of an F-8 Crusader with a slew-wing to determine the performance at higher speeds.
Bill Gunston "The Illustrated Encyclopedia of Commercial Aircraft", 1980