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3 Answers

Why does Va Increase with weight of the aircraft?

Asked by: 3315 views Aerodynamics, Flight Instructor, General Aviation, Private Pilot, Student Pilot

Why does Va decreases with weight of the aircraft?

 

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3 Answers

  1. Best Answer


    John D Collins on Apr 20, 2016

    Va is related to the clean stall speed. It is the stall speed times the square root of the maximum load factor. It is related to the stall speed because when the aircraft stalls, one can’t impose any more load on the structure. The stall increases with the square root of the load factor. So if you are pulling 4 G, the stall speed doubles. Since the stall speed varies with weight and is higher for a higher weight, the Va goes up with higher weight by the square root of the ratio of the weights times the Va at a lighter weight. Another way of looking at it is that the greater mass of a heavier aircraft is not moved as much by a gust than an aircraft with a lighter weight or mass, and therefore a gust induces less of a load on the structure at any speed. A 747 is barely moved at all by turbulence that might be considered as heavy turbulence by a cessna and the pilot as well as the aircraft feel the additional difference in the load by a gust in the smaller and lighter aircraft.

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  2. Steve on Apr 20, 2016

    Sir, do you know which source you did refer from?

    Steve.

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  3. John D Collins on Apr 21, 2016

    Any book on aerodynamics will discuss this. All of this is derived from the basic lift equation. See FAA-H-8083-25A Handbook of Aeronautical Knowledge or Aerodynamics for Naval Aviators. The first can be downloaded from the FAA site and I believe the other is available as a download from this site.

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