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Old 11-21-2005 | 08:20 AM
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Red B.
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From: Jonkoping, SWEDEN
Default RE: Wing affect on horizontal stab

Higher is not always better, especially if high alpha flight is on the menu.
The Britsh had severe problems with the BAC 111 due to deep stall conditions associated with a T-tail configuration.
Tests indicated that at high angles of attack near and above those associated with wing stall, the low-energy wakes of the stalled wing and fuselage-mounted engine nacelles impinged on the horizontal tail and significantly reduced its stabilizing effect. Also, the low-energy wakes severely reduced the effectiveness of the horizontal tail as a longitudinal control. These characteristics manifest themselves as an insidious poststall condition in which the angle of attack of the aircraft would increase to very large values (in excess of 40 degrees) in response to the loss of stability, and the pilot would be unable to recover from the condition because of the loss of horizontal tail control effectiveness. During this entire sequence, the attitude of the aircraft fuselage would vary over a relatively small angular range, and the uncontrollable aircraft would descend steeply in an almost horizontal, wings-level attitude with a high rate of descent to an unsurvivable crash.

/Red B.
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