REFLECTOR: Cruise Speed "Speed Brake"

[Chuck Harbert]

Guys, I think we're comparing apples and oranges. The Velocity speed brake 
works on an entirely different principle than that of the Mooney speed 
brake. The Velocity SB just adds drag, where the Mooney SB reduces the lift 
of the wing (the opposite of vortex generators). The Mooney unit is about 3" 
x 8" plate flush with the top of the (mid) wing, and extends a "fence" up 
about 3" above the wing surface. It separates the air from the wing, so it 
cannot make lift. Until you flown with these, you really can't see how 
dramatic they can affect lift for a small simple device.

I don't know why Alan would say these would produce a deep stall unless he 
misunderstood the question. These are used at high speed to allow a rapid 
descent that is not anywhere near stall conditions. You wouldn't normally 
deploy them at low speeds (unless you were high on final approach, and then 
only for a brief period). I'd forgotten how nice these were until I 
remembered how great it made high speed descents and saved several high fast 
approaches. I'll get some pictures and info this week.

Chuck H


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Jim S. wrote:
Spoilers outboard on the wing would seriously screw up the aerodynamics,
require a lot of structure and hideously complicate construction IMO.
Beefing up the structure on the current belly board would be an order of
magnitude easier and simpler.  Stronger foam, a couple of hard points
and some carbon fiber should do the trick.  If I wanted to get really
REALLY cute, I might consider split flaps on a foot or two of the
inboard wing TE.  It's not a significant lifting surface and the air
there is already pretty much separated so the hinges and what not
wouldn't cost much in cruise.  It would still complicate construction a LOT.

I'd have to stay with a more robust belly board ...