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2 Answers

Which airspeed changes with weight?

Asked by: 1145 views
Aerodynamics, Flight Instructor, Student Pilot

Can someone please tell me which airspeed changes with weight and does it go up or down... 

VNE 134kts      Airspeed which may never be exceeded
VNO 107kts Airspeed which shall not be exceed in gusty weather
VA              94kts Maximun airspeed for all permissible maneuvers
VFE 70kts Airspeed which may never be exceed in flap down configuration
VSO 38kts Minimum permissible airspeed in flaps down configuration
VS 44kts Stall speed / min steady flight speed for which that aircraft is controllable
VR 43kts Rotation Speed(cnmfort take-off)
VX 48kts Airspeed for the greatest altitude gain in short horiz 
VY 65kts Airspeed for the grestest altitude gain in short time

please help..

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2 Answers

  1. Jordan - CFI on Sep 17, 2016

    Va changes with weight. At a higher weight, Va is higher, because the aircraft needs a higher angle of attack to support the weight of the aircraft at a given airspeed. Therefore, the aircraft is closer to its critical angle of attack. Conversely, if the aircraft is at a lower weight, Va is lower, because the aircraft doesn’t need as high of an angle of attack to support the weight of the aircraft. Therefore, the aircraft is farther away from its critical angle of attack.

    Keep in mind that although stall speed changes with weight (among other factors) Vs and Vso are published airspeeds and it would be incorrect that the V speed itself changes. The published airspeed remains the same, the actual stall speed of the aircraft does. Remember, an airplane can stall at any speed. Stalls are a result of exceeding the critical angle of attack. Youtube: accelerated stall

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  2. Mark Kolber on Sep 18, 2016

    The short clue that might lead you to explore a longer answer is that performance airspeeds related to aerodynamic load factors change with weight. The airspeed goes up and down with weight by a formula that is related do to lift,

    So, from your list, all except Vne, Vno and Vfe change with weight.

    That includes Vs and Vso, so I think I disagree with Jordan on that part. Yes, you can stall at any airspeed, but published Vs and Vso are for specific flight attitudes – level flight at various bank angles. If there is only one speed for each published, that’s the stall speed at max gross. Lower weight in those configurations and assiciayed speeds lower as well.

    For fun, search google for a Diamond Star POH. That’s one of the light aircraft POHs that actually list most of these speeds at various weights, from Va to a single to Vx and even some not so critical ones as the recommended en route climb speed.

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