VMU test

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The VMU-test , VMU (Velocity, minimum, unstick V MU ; minimum Unstick Speed) is in aviation a prescribed for each aircraft test in which the least possible take-off at the maximum angle of attack (Engl. Angle of attack ) on the ground is determined.

In the case of aircraft with a nose wheel landing gear , shortly before the aircraft takes off, the stern hits the runway ( tail strike ). Without abrasion protection, the stern would be torn open and badly damaged. For this reason, wood or sheet metal reinforcements are usually installed temporarily to protect the lower fuselage shell. When the protective devices are dragged across the runway, sparks are generated, which can be seen regularly on recordings of such tests.

The VMU does not appear later in the flight manual , but it is important insofar as it is based on the V R (pronounced Vi-rotate; German speed at which it is rotated; not rotation speed ) at which the pilot drives The lifting process is initiated by pulling the control stick , is calculated. The V R must be selected so that the V LOF , the speed at which the main landing gear takes off, is at least 10% above the VMU during a normal take-off and in the event of an engine failure it is still at least 5% above the VMU.

literature

  • FAA, US Department of Transportation - Aircraft certification service flight safety program , 4040.26A, March 23, 2001
  • Press release at Intec 2006 - Airbus relies on Enidine , Bad Bellingen July 26, 2006
  • Anderson, John D., Jr. - Introduction to Flight, 3rd ed. , McGraw-Hill Book Company, New York, 1989.

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