|
Re: Tail Plane Design
It is not just a matter of Vmc but more basic stability. The twin fins sit in the propwash, which is considerably faster than the free air thus benefitting rudder power and control, especially on take-off. It can be a different matter for directional stability. When an aircraft yaws - the nose pointing away from the direction of flight - the fin in free air sees this alteration and produced a force to correct it. With twin fins, they will still see the air from the engines, which is necessarily parallel to the fuselage and so the yaw is not noticed. That's why you'll see very tall fins on low-set tailplanes, and high-set tailplanes to get the top of the fin into the free air. Perhaps the He219, with its dihedral tailplane to get the fins high, is the most extreme example of this: you can also see the growth in height of the fins on the Manchester/Lancaster and the Ar240 for this reason.
|