Dave,
The short ones do fly stable, even with a very small tail. That was never the challenge. Your assumption that the take-off is the difficulty is correct. But over the course of multiple iterations, I managed to tame the take-off as well. There are two phenomena present that need to be dealt with.
The first is when you shorten the tail moment, the airplane sits on the ground with a higher angle of attack. If the landing gear is the same size and you move the tail skid forward 8 inches you can see what happens. On the first one I flew, I never knew which direction it would go in the air, as at the launch it would go ballistic to the left one time, and ballistic to the right the next.. After a handful of flights, the conclusion was that it was taking-off with one wing panel or the other stalled. The solution was the addition of a small extension to the tail skid to decrease the angle of attack on the launch. I should note that the tail was mounted 6 inches behind the wing on the first one. Currently I use 8 inches.
The other problem you will encounter is that with the short nose (which you can do now, mine are in the 2” range), is a tendency for the airplane to want to balloon on take-off. You can counter this with down elevator, but I consider that a Band-Aid. An aeronautical fix is to understand what is really going on, and correct that. As I posted before, local flow around the wing is an area that I am currently interested in. In front of the wing, (at least with the lifting section that I use) the air is actually rising from below the chord line to meet the wing. So when the engine, wing, and tail are mounted zero – zero – zero, the air that the prop is working in acts like the engine is mounted with up-thrust. So I counter the effective up-thrust with a touch of down thrust, about ½ degree. As they say, “Your mileage may differ”, so depending on your wing section, vertical location relative to the thrust line, and the fact that you live north of the 45th parallel, you may need to adjust that figure slightly.
You mentioned weight saving, and lower drag. My last fuselage glassed (natural wood finish) with the servo trays installed (plywood), and wing mounted weighed just 6 ¼ oz. before the tail was added. I cut both fuselage sides from a single sheet of balsa, measuring 4” x 36”, giving you an idea of the surface area. Total weight of the airplane with 5 servos and a brass Nelson required an additional 1 ¼ oz. of weight. And this was with the foam core wing skinned with 1/8” top sheeting and 3/32” bottom.
A side note – here is a truly remarkable homebuilt airplane. But to fly it you are betting your life on the engine, as the high stall speed virtually guarantees that any off airport landing is fatal. In fact it did kill the guy selling the kit and a guy that built OEM engines when one of his engines failed. But as it is clever in the methods of cutting drag, I thought I would toss it into the discussion.
Questair Venture
http://www.aircraftpaintschemes.com/...AircraftID=367