How to use this calculator
- Enter published Va. Use the speed tied to the reference weight.
- Enter reference weight. Use the weight from the aircraft manual for that published Va.
- Enter actual weight. Use the loaded operating weight for the planned condition.
- Read adjusted Va. Treat the result as a screening number unless the manual authorizes it.
How it works
The weight relation is Va_actual = Va_ref x sqrt(W_actual / W_ref). A lower operating weight lowers the maneuvering-speed estimate.
Use it with aircraft weight and balance, maneuvering speed and stall speed.
Worked example
Verified against the live calculator
A published 105 kt Va at 2,300 lb adjusted to 2,000 lb is 105 x sqrt(2000 / 2300) = 97.9 kt.
Frequently asked questions
How does Va change with aircraft weight?
For this screening relation, Va changes with the square root of operating weight divided by reference weight.
Why does Va go down at lower weight?
At lower weight, the aircraft can reach the critical angle of attack at a lower speed for the same load factor.
What should I use for reference weight?
Use the weight tied to the published Va in the aircraft manual, often maximum gross weight.
Is this valid for every airplane?
No. Use this only when the POH or AFM allows this relation or publishes equivalent weight-adjusted speeds.
Method & assumptions
- Assumes the square-root weight relation is appropriate for the aircraft and manual context.
- Does not validate maximum weight, CG envelope, category selection or published limitations.