Questions About Ballast

[Nev]

Nice work, and mirrors what others have experienced.

It's great having the utility of a very large CG envelope, but it does become somewhat self limiting.
If the empty CG is too far forward then the elevators tend to lose authority at low speed and forward CG.
If the empty CG is too far aft then the aft CG limit tends to be reached before MTOW is reached, and the tail wheel/ aft fuselage is subject to additional stress.
Moving the engine or prop further forward tends to decrease yaw stability due to the large cowl surface area forward of the CG.
Incidentally, I think having a light tail or a "tippy" aircraft is perhaps more a function of the main wheel position. Bearhawks generally tend to be heavier in the tail. It's a compromise either way, but probably the better of two evils. Damage at the aft end is usually less expensive to fix than damage at the forward end.

Speaking of my own aircraft (a 4-place), it handles very nicely when the CG is around mid-point (15-17"). However for backcountry flying I prefer to keep it fairly light, which generally dictates a more forward CG, and with that I need to keep power on at low approach speeds to maintain elevator authority.

[kestrel]

Very good analysis and useful regardless of final choices. One point though...

Also notice that at very light conditions, the CG gets only about 2.5" from the main wheels (mains are at -1.5"). This makes the a/c likely to tip on its nose due to a small upward load on the tail.

This is only true when in a level flight attitude. Because the wheels are well below the height of the CG, in a three point attitude the mass is well behind the main wheels. I take advantage of this when trying to stop short. Once I have bled off some of my touchdown speed (it only takes a moment) I reduce my braking to lower the tail and can then use the brakes more aggressively without concern about nosing over. If the tail is kept up, you have to be more careful and limited on the brakes.

Bearhawk tails are generally difficult to lift by hand, but this movement of the CG can be easily seen on a J-3. It is reasonable, but still an effort to lift the tail off the ground. But, the higher you lift it, the lighter it gets.