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![]() "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 |
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