Originally Posted by
Speed of Sound
Does anyone know whether the friction on the threads of the jackscrew caused by high aerodynamic loading above Vmo is the same whether the motor is trying to trim NU or ND?
The friction per definition should be the same. However the force required will not be the same.
Think of this as pushing a car uphill against a slight inclination versus pushing it downhill the same inclination. The friction from the wheels running on the ground is the same in both cases, but in the first example you have the added force from the uphill inclination to overcome versus in the downhill example the force from the downhill inclination helps you pushing the car.