How to use this calculator
- Enter reference Va. Use the published Va tied to the reference weight.
- Enter reference weight. Usually this is maximum gross weight, if that is how Va is published.
- Enter actual weight. Use the loaded aircraft weight for the highlighted marker.
- Set table range. Choose the minimum percent of reference weight for the chart.
How it works
The chart applies Va_actual = Va_ref x sqrt(W_actual / W_ref) from the minimum table weight up to the reference weight.
Use it with Va weight adjustment, weight and balance and stall speed by weight.
Worked example
Verified against the live calculator
A 105 kt Va at 2,300 lb becomes 97.9 kt at 2,000 lb because 105 x sqrt(2000 / 2300) = 97.9.
Frequently asked questions
How is Va adjusted by weight?
Use Va_actual = Va_ref x sqrt(W_actual / W_ref) when the aircraft data permits that relation.
Why make a table?
A table makes the square-root drop in Va visible across common operating weights.
Can actual weight exceed reference weight?
The calculator will show it, but that is usually a warning sign to check the aircraft limits and entered data.
Does this replace a POH Va table?
No. Published aircraft data controls whenever it gives specific values.
Method & assumptions
- Assumes the manufacturer allows square-root Va adjustment by weight.
- Does not account for separate published speeds, turbulence procedures, configuration or CG effects.