Stall Speed vs Weight and Bank Calculator

Stall speed rises when the airplane is heavier and when you bank. In a level, coordinated turn the load factor is n = 1 / cos φ, and stall speed is Vs_ref × √(W / W_ref) × √n. Enter a book stall speed (Vs1 or Vs0 — match the configuration), the weight it belongs to, the weight you will fly, and a bank or a load factor. A table of 0°, 15°, 30°, 45°, and 60° is included.

Weight and bank

Lift has to equal n times weight. The stall angle of attack is (to a first approximation) a property of the wing and the configuration, so stall speed scales as

V_s(W, φ) = V_s,ref × √(W / W_ref) × √n, with n = 1 / cos φ

in a level, coordinated turn. At 0° bank, n = 1. At 45°, n = √2 ≈ 1.41 and stall speed is about 19% higher. At 60°, n = 2 and stall speed rises by a factor of √2 ≈ 1.41. A worked example: 48 kt at 2,550 lb, flown at 2,200 lb in a 45° bank, is about 53 kt.

Related tools

The turn radius calculator uses the same load-factor and stall-in-bank identities, and adds rate of turn and turn radius. The maneuvering speed calculator scales Va with weight and relates it to Vs × √n_lim. Use the POH figures first in every case.

Sources

FAA Pilot’s Handbook of Aeronautical Knowledge, Chapter 5 (load factor, stall speed in a turn); FAA Airplane Flying Handbook; NASA Glenn Beginner’s Guide (lift, load factor).

Frequently asked questions

Does flap setting change the formula?

The identity is the same; the reference stall speed changes. Enter the Vs that belongs to the configuration (Vs0 with landing flaps, Vs1 clean, or a POH figure for takeoff flaps).

What if I am not in a level turn?

Then n is not 1/cos φ. A pulling-up pull-up or a descending turn has a different load factor. Enter n directly if you know it.

Is this indicated or true airspeed?

POH stall speeds are indicated (or calibrated) airspeeds. Scale them in that same unit. Do not convert to TAS first.