"Mark James Boyd" wrote in message
news:401eb7ea$1@darkstar...
A spin means both wings have too high AOA and
one wing has more AOA than the other.

If you can change the AOA of both wings so they are unstalled,
using elevator only, and the stress from the now entered spiral
doesn't make the aircraft wings twist and shatter during recovery dive,
then fine, do that.

If you can't, then it would be great to have both
wings at the same AOA, then reduce the AOA. Rudder is
a possible way to do this (make both wings have the
same AOA by making them both the same airspeed, by
countering the yawing motion). In the ensuing dive
recovery, the wings are level. In some aircraft
these stresses are different than turn/spiral stresses
and the wing structure handles them better.

I suspect this is the reasoning behind
the PARE mnemonic, where rudder is used before elevator.

Power off (for them motorglider thingies)
Aileron Neutral
Rudder Opposite
Elevator forward enough to break stall

Of course, even this mnemonic doesn't work all the
time (sometimes extra power to make the tail surfaces
more effective is better, etc.).

So results for any generalization may vary...

I did this calculation for my Nimbus 2 and found a 14 Kt. speed difference
across the 20 meter span in a normal thermalling situation with the ship
dry. (45 Kts/45 degree bank.)

Pushing the envelope a bit by slowing up and tightening the turn, I found
the typical big wing roll-off toward the low wing, but it didn't seem like a
spin departure. What I think is happening is that the inside wing is on the
back side of the polar and outside of the drag bucket, but still not
stalled. This produces a pronounced roll and yaw into the turn which
develops into a spiral dive if allowed to continue. The recovery is the
same as an incipient spin, reduce the back pressure, let the speed increase
a bit, reduce the bank and stay coordinated.

Bill Daniels