I've never seen so much discussion over what should be a relatively straight-forward matter
The application of the various simplifications (e.g. 1% of TAS) is good in practice. Perhaps the original poster needed something more accurate, as may be required when working out OEI Escape Routes etc.
The two formulae given below apply 2 different constants, one for entry speed in Knots, the other for entry speed in Km/Hr.
If Entry speed is in Knots :-
R = TAS^2 X .02698711 / Tan AoB
If Entry speed is in Km/Hr :-
R = TAS^2 X .00786818 / Tan AoB
Example : TAS = 200 Kt (370.4 Km/Hr) at Bank angle 25 degrees.
R = 200^2 X .02698711 / Tan 25 = 2314.96 M....... OR
R = 370.4^2 X .00786818 / Tan 25 = 2314.96 M
If you want the answer in Km, divide by 1000
