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Comment: Re:NASA did a test plane decades ago (Score 5, Interesting) 489

by Geoduck_87 (#15597920) Attached to: The Pentagon's Supersonic, Shape-Shifting Assassin
The control issues were also the subject of a well-regarded Ph.D. Thesis at Stanford in the early 1990's. The original NASA aircraft had the axis of wing rotation vertical in level, forward flight. The pivot joint was at the wingspan centerline.

The conclusions of the Ph.D. thesis was that one gets a much more controllable AD-1 if one modifies the wing / fuselage configuration as follows:

1. Tilt the pivot axis a few degrees away from the side of the aircraft that has the forward sweep of the wing.

2. The wing needs to be mounted a few percent off its centerline (that's right, an asymmetric configuration).

3. A couple other conclusions that I can not recall (anhedral / dihedral; spanwise changing airfoil; etc)?.

Note: This was an analysis of the AD-1. The fuselage / wing interactions drove quite a bit of the specific stability / control based modifications. If one has a different fuselage (for example, the illustration in the CNN article), the specifics will change.

A complex system that works is invariably found to have evolved from a simple system that works.