In my own designs, I try to get as much rudder and fin area below the thrust line as above the thrust line. This, I think, should greatly reduce the effect of the spiral prop wash tending to yaw the airplane to the left at high power and low airspeed, such as during the takeoff run. This seemed to produce a very straight takeoff run with virtually zero rudder input, except, of course, in a crosswind. Subfins and subrudders, I found, are also very helpful while flying at near stall airspeed, when the airstream over the upper part of the fin and rudder is badly messed up by turbulence induced by the wing and fuselage, while the subfin and subrudder fly in virtually clean air. The result is a model that is much more solid in yaw at low speed, and thus resists the tendency to snap roll into the ground.

Several of the flyers in this area added subfins, and where practical, subrudders as well, and gained greatly improved low speed handling.