> Doug Davis wrote: > > Now that we've beat the take-off / landing thing almost to death, and > remembering one comment made about bad behavior with 13degree > uptravel, my mind ( as feeble as it is) has been wondering, and here's > one for the group: Is the coupe with more uptravel more likely to be > able to spin, and if so, how would one recover. Now my guess is this > is going to be interesting!! Personally, I think the stall would be > more pronounced, but still no tendency to spin. What do you think, and > has anyone ever done any physical research (test flying) on the > subject? > Doug > P.S. We're talking about two control coupes now, ok?
According to Fred Weick, the unacceptable behavior was at 1400 lbs, 85
hp engine, and 13 degrees of up travel. With the slip stream pushing
the tail down you could get into an angle of attack range that was too
high when loaded to 1400 lbs.
With power off or medium power, he didn't think there was a problem with
13 degrees.
Keep in mind, you are not allowed to be flying a 415-C Coupe with more
than 1260 lbs.
Related to the stall-spin factor:
It takes distinct back pressure on the controls to force the tail
down
enough to approach stalling the wing. The disrupted (stalled) airflow
starts at the wing root and propagates outward in a fan shape leaving
the outer parts of the wing flying cleanly. Before the outboard parts
of the wing can stall, the disrupted airflow ruins the downward "lift"
of the tail preventing you from pushing it down too far. When you
release the back pressure the weight of the front end of the plane will
immediately drop the nose until you get the wings out of stall.
When you are over gross or out of center of gravity aft, all bets
are
off.
> P.S. We're talking about two control coupes now, ok?
Mine is a three control 415-D. With my plane at 1300 gross I
tried
successive CROSS-CONTROLLED approaches to stalls. Life got exciting as
I tried higher and higher power settings. I chickened out about 200 rpm
below max. Bouncing and directional control degraded as I approached
the higher power settings to the point where I decided the next
increment wasn't worth exploring. Toward the end, with full left
rudder, I couldn't hold the left wing up to maintain directional control
-- it turned sharply left. In all cases, neutralizing the controls
brought INSTANT return to smooth, well controlled flight.
Mind you this did not include hammer head stall entries, flat
spins,
out of CG, or any such.
As "Stick and Rudder" says, a spin is a stalled condition where
one
wing is more stalled than the other and the aircraft rotates around the
more stalled wing. You might be able to induce a short spin via
hammerhead stall, aerobatics or some such. I think that you cannot HOLD
a within-CG Coupe in a spin even with mis-applied controls. It'll
return to controllable flight on its own.
Kids, don't try this at home. Adults, approach such experimentation
cautiously a little increment at a time, if at all.
--
Ed Burkhead
Peoria, Ill.
N3802H
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