Counter-intuitive design – the conundrum of crooked

One of the most unconventional concepts in aviation is the oblique-wing aircraft. The concept was successfully tested on the AD-l (Ames-Dryden 1), a small, subsonic, single-seat research aircraft specifically designed and built for a NASA Dryden Flight Research Center test and evaluation programme that began in 1979 and continued until 1982. The most eye-catching feature was, of course, the wing, which pivoted about the fuselage in flight, remaining perpendicular to it during slow flight and swinging to angles of up to 60 degrees as aircraft speed increased.

The aim was to provide aerodynamic data for use in the development of fuel-efficient transonic aircraft  (i.e. flying at just above and below the speed of sound).

The concept was in large part the work of renowned NASA aerodynamicist Robert T. Jones – and many years later NASA still publishes a Thinking Obliquely book about the concept, the design and its legacy (how many radical technology ideas have that kind of longevity?!).

Although the oblique wing is still considered a viable concept for large transports, the less-than-pleasant flying characteristics of the AD-1 at extreme wing-sweep angles apparently discouraged aircraft designers from adopting this configuration.

Crookedly effective

One ióf the most mind-boggling things about the AD-l is that it’s not symmetrical – or anything anywhere near it. On just about every other aircraft any of us will ever see, (the oblique-wing-modified F-8 Crusader shown below never flew) the wings are the same (OK, mirror-imaged) on both sides – regardless of shape, sweep or other technology

configuration. When they’re not the same, we non-techies simply don’t have a framework for understanding what’s going on. If the aerodynamics and lifting/airflow forces are true on one side are true, how can they be equally true for an almost opposite configuration on the other side? Our whole cultural mindset is based on the value of constructs like symmetry, balance, and consistency, so this is literally mind-boggling …

Winged wonders

Strangely, there are numerous other weird and wonderful wing configurations that you’re never going to see at any commercial airport any time soon. From reverse-swept wings (RSW) to the flexible Adaptive Compliant Trailing Edge (ACTE) wing, from rotating wings to FlexFoils and more, this is a field where technical ingenuity has had a field day.

NASA photo of the Grumman X-29

These are niche successes that we never get to hear about, and that perhaps didn’t or don’t gel well with established industrial interests. But part of it is probably also that the narrative wasn’t strong enough, or it wasn’t promulgated with sufficient panache. I’ll be writing about some of these wacky wonderfulnesses in other posts.