Mark Steitle wrote:

DEEP STALLS

 The July '91 issue of Sport Aviation (and also Nov.'91 Kitplanes) contains a very fascinating article on the investigation of the deep stall characteristics of the Velocity 4-place canard aircraft. In 1988 and 1989, there were 3 reported instances where 3 different Velocities 'locked in" a deep stall condition from which the pilots were unable to recover. The aircraft descended almost vertically, but in a flat attitude, at an unusual ly slow rate of descent, variously reported as 1200 fpm or 15 to 20 mph. Per Burt Rutan, this is several times slower than theory would predict. Two of the aircraft splashed down in water, and one on land. One pilot was uninjured, and the other two received "minor" injuries.

This is one thing I've never understood.  Maybe someone can explain it to me.
Why was the descent rate so much slower than predicted for the Velocities in
the deep stall?  Like the report said, 1200 fpm, "several" times slower than
theory would predict, according to Rutan.

Is there some mysterious unkown form of lift occurring? I think Rutan was
going to investigate but I never heard what his conclusions were.

I know Nat Puffer did a lot of tests in the Cozy also.

I think there were some Long-Ez accidents that were caused by deep stall
that were fatal, unlike the Velocity incidents.  Might have to research those
incidents to be sure.

Bill Freeman, do you have any answers on this?
--
Perry J. Mick
Mick Duckt N7XR
http://www.ductedfan.com

 
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