+ float torque = thrust/gamma;
+ if(lambda > 1) {
+ // This is the negative thrust / windmilling regime. Throw
+ // out the efficiency graph approach and instead simply
+ // extrapolate the existing linear thrust coefficient and a
+ // torque coefficient that crosses the axis at a preset
+ // windmilling speed. The tau0 value is an analytically
+ // calculated (i.e. don't mess with it) value for a torque
+ // coefficient at lamda==1.
+ float tau0 = (0.25f * _j0) / (_etaC * _beta * (1 - _lambdaPeak));
+ float lambdaWM = 1.2f; // lambda of zero torque (windmilling)
+ torque = tau0 - tau0 * (lambda - 1) / (lambdaWM - 1);
+ torque *= 0.5f * density * V2 * _f0;