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{{Short description|Aeronautical phenomenon}}
'''Control reversal''' is an adverse effect on the controllability of [[aircraft]]. The [[Aircraft flight control system|flight controls]] reverse themselves in a way that is not intuitive, so pilots may not be aware of the situation
==Causes==
There are several causes for this problem
===Equipment malfunction===
Equipment failure may cause flight controls to behave unexpectedly, for example the possible rudder reversal experienced on board [[United Airlines Flight 585]].<ref name="AAR01-01 Final Report">{{cite book |url=https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR0101.pdf |title=Aircraft Accident Report: Uncontrolled Descent and Collision With Terrain, United Airlines Flight 585, Boeing 737-200, N999UA, 4 Miles South of Colorado Springs Municipal Airport, Colorado Springs, Colorado, March 3, 1991 |publisher=[[National Transportation Safety Board]] |id=NTSB/AAR-01/01 |date=March 27, 2001 |access-date=January 17, 2016 |archive-date=October 2, 2015 |archive-url=https://web.archive.org/web/20151002041524/http://www.ntsb.gov/investigations/AccidentReports/Reports/AAR0101.pdf }}</ref>{{rp|114}}
===Pilot error===
[[Pilot error]] is the most common cause of control reversal. In [[unusual attitude]]s it is not uncommon for the pilot to become [[
===Incorrectly connected controls===
Incorrectly connected controls are another common cause of this problem. It is a recurring problem after maintenance on aircraft, notably
===Wing twist===
{{main|Aeroelasticity}}
Another manifestation of the problem occurs when the amount of airflow over the [[wing]] becomes so great that the force generated by the [[aileron]]s is enough to twist the wing itself, due to insufficient [[Torsion (mechanics)|torsional]] stiffness of the wing structure. For instance when the aileron is deflected upwards
==Examples==
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===Supermarine Spitfire===
Due to the high speeds at which the [[Supermarine Spitfire]] could dive, this problem of [[aileron]] reversal became apparent when it was wished to increase the lateral maneuverability (rate of roll) by increasing the aileron area. The aircraft had a wing designed originally for an aileron reversal airspeed of 580 mph, and any attempt to increase the aileron area would have resulted in the wing twisting when the larger ailerons were applied at high speed, the aircraft then rolling in the opposite direction to that intended by the pilot. The problem of increasing the rate of roll was temporarily alleviated with the introduction of "clipped" wing tips (to reduce the aerodynamic load on the tip area, allowing larger ailerons to be used) until a new, stiffer wing could be incorporated.
This new wing was introduced in the [[Supermarine Spitfire (Griffon-powered variants)#Mk.C2.A021 .28type 356.29|Mk 21]] and had a theoretical aileron reversal speed of {{convert|825|mi/h|km/h|abbr=on}}.<ref>Jeffrey Quill OBE, AFC, FRAeS ''Spitfire - A Test
</ref>
===Boeing B-47===
The [[Boeing B-47]] was speed limited at low altitudes because the large, flexible wings would cancel out the effect of the control surfaces under some circumstances.<ref name="b-47">{{
===Gossamer Condor===
Control reversal also affected the [[Gossamer Condor]], the [[Kremer prizes|Kremer Prize]]-winning human-powered airplane. When a [[wing warping]] mechanism was tried as a solution to a long-running turning problem, the effect was to turn the airplane in the opposite direction to that expected by conventional airplane knowledge. When the Condor was rigged "conventionally", the inside wing slowed down so much that it settled to the ground. By employing "backwards" wired wing-warping, the inside wingtip [[angle of attack]] was increased so that the added drag slowed that wing while the added lift allowed the airfoil to stay aloft at a slower speed. The tilted canard could then complete the turn.
==References==
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