Originally Posted by
Rotaryphile
I have tried all-moving horizontal stabs on two models, and couldn't see much difference in performance. A further experiment with an all-moving combination fin/rudder was a total failure - about half as powerful as a conventional fin/rudder of the same total area, despite extreme deflection angles. The stab/elevator or fin/rudder combination acts, when its control surface is deflected, like a cambered airfoil, which can develop far higher lift than any thin symmetrical airfoil that is simply inclined to the airflow.
For model airplanes, the benefit is slightly less drag for the required lift. The models that gain the most are gliders. Since humans really can't judge airspeed at all (since they can't see wind), gains in cruise efficiency aren't going to be visible. We aren't going to see the difference in performance that is improved. We also have a problem creating a valid test comparison between the two designs.