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3 Answers

Vmc decreased with altitude

Asked by: 6790 views Aerodynamics

WIth unsupercharged engines, Vmc decreases as altitude is increased,

: directional control can be maintained at a lower airspeed than at sea level

-> can you explain why?

 

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3 Answers



  1. Kris Kortokrax on Oct 17, 2014

    Easily. A turbocharged or supercharged engine can maintain sea level power to a higher altitude.

    If you are in the process of learning to fly, you should have a flight instructor. Have you asked him/her any of the questions you have posted here?

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  2. Gary on Oct 18, 2014

    Namugoni,

    Vmc is defined as the minimum airspeed at which a twin-engine airplane can be directionally controlled with the good engine operating normally.

    By definition the non-turbo engine in your example will have a more difficult, if not impossible,(depending on the altitude)task of maintaining altitude and directional control.

    Does this come anywhere close to answering your question?

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  3. Kris Kortokrax on Oct 18, 2014

    Actually Vmc is defined in Part 1 as follows:
    VMC means minimum control speed with the critical engine inoperative.

    The number marked on the A/S indicator is determined under a very specific set of conditions as outlined in 21.149.

    The non-turbocharged engine will not have a more difficult task of maintaining directional control. For the same horsepower, they would be equal at sea level. The turbocharged engine would have a more difficult task as altitude increases because it will maintain sea level horsepower up to a higher altitude. The normally aspirated engine will lose horsepower as altitude increases and will have less problems with directional control.

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