I did a pull pull with the 120 oz servo mounted inside the vertical stab. Only the tips of the servo arms excend out of the stab. I used 120 oz due to the possibility of engine out, which has happened. Make sure your servo is large enough for the engine out possibility. On the real herk,, we could pull the flap control CB and move the flaps lever to greater than 20%, this would give 3000 psi rudder boost vs the 1250 normally used. So the rudder is a big deal if you lose an engine,, on the model and 1:1 size. Jim