It's probably wise to use servos with at least 3 times the required torque. That not only prevents gear train failures like Paul's but also ensures the servo is not working at near it's stall current so the motor and driver circuitry isn't being overly strained and over heated by being asked to operate too close to it's limits.

Also did you do the calculations based on that 70 or 80 mph death dive?

Those calculators are great for getting a feel on what's needed but don't forget the limits under special circumstances.