Re: Langley_wind_tunnel_on_Q.pdf [1 Attachment]


quickieaircraft
 

Jay,

I am missing the details (I knew I was missing good material at spring fling!) and may not have the full picture. I enjoy your usual aerodynamic analysis.

What is causing the cg position change with alpha? Alpha is an aerodynamic term and we do not normally see changes in cg position due to aerodynamic terms.
I'm also curious about the separation bubble extending as far beyond the canard as you've labeled it. Most of us have props that are have a decent diameter (60in for me) and both blown wing effects and ground effect have created enough difference in feel that I do not expect they are negligible.

I fully appreciate your caution against over rotation and would agree with that. All sorts of bad things there.

Best,
IF

--------------------------------------------

On Tue, 5/22/18, 'Jay Scheevel SGT' jay@... [Q-LIST] <Q-LIST@...> wrote:

Subject: [Q-LIST] Langley_wind_tunnel_on_Q.pdf [1 Attachment]
To: Q-LIST@...
Date: Tuesday, May 22, 2018, 6:23 PM


 









Talked to a few people at
Kevin’s spring fling about this, but a few pictures are
better than a lot of talk. I superimposed some Langley Wind
tunnel pics on top of the Q canard so you can see where the
turbulent air mass caused by the stall ends up. Obviously
over-rotation is not a good thing. This could happen in an
accelerated maneuver or on the runway in a Tri-Q. If it
happens on the runway (only possible in a Tri-Q), the CG
rotates aftward very close to, or perhaps even behind, the
main gear axis and there is no recovery except to apply
brakes and get the nose back down. PDF attached for your
consideration.
 Cheers,Jay









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