Re: gurney flaps

Date:         27 Dec 96 04:41:02 
From:         David Lednicer <>
Organization: Analytical Methods, Inc.
References:   1 2 3
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John Roncallo wrote:
> A similare concept is used on the Sikorsky S-76 helicopter
> stabilizer. Except I belive instead of a lip it is a T as to act in both
> directions. I will have to take a better look at one.

	The Gurney flaps on the trailing edge of the S-76 horizontal
tail first appeared on the S-76B.  How do I know?  I helped design the

	The tail on the S-76A is an inverted NACA 2412.  When they first
flight tested the B with this tail, they didn't have enough maximum lift
coefficient in the upwards direction.  After trying several new upper
surfaces, we settled on mirroring the lower surface, to make the tail
symmetrical.  This gained a lot of lift, but then flight test wanted
more.  We tried vortex generators, but the Gurney flap worked far better.

David Lednicer             | "Applied Computational Fluid Dynamics"
Analytical Methods, Inc.   |   email:
2133 152nd Ave NE          |   tel:     (206) 643-9090
Redmond, WA  98052  USA    |   fax:     (206) 746-1299