<<The Mark II tail alone exacerbates flight problems at rearward
CGs since it adds such a large rearward moment. Thus the corollary
recommendation that the long engine mount be used to move the CG
forward.>>
Scott,
The longer engine mounts serves to move the CG forward. The
increased surface area of the MKII tail moves the neutral point
rearward. The difference between these two defines the static
margin. As the static margin goes to zero, the aircraft becomes
neutrally stable. This means the MKII tail can handle a more rearward CG
than the original for the same degree of stability or conversely, has greater
pitch stability for the the same CG location.
Two side notes: The long engine mount is actually somewhat
destabilizing in yaw and pitch due to the added surface area projected
out in front of the CG. The larger tail can also handle a more forward
CG since it has more pitch authority at low speeds.
The added area in the tail simply opens up the available CG range in
both directions. Either tail may be perfectly acceptable as long as
each is kept within its individual CG capability.
Chris
Chris Zavatson
N91CZ
360std