I finally got to play with this plane in a gym where I could really wring it out. It has remarkably good performance, but the stock trim leaves something to be desired.
Specifically, it is tailheavy. VERY tailheavy. When under power, it will keep the nose up and climb, but let it get nose down, and it will tuck into an un-recoverable dive.
First, I added noseweight. This helped control the stall under power, and smoothed out the transition to level flight (25' ceiling was easily reached, and then careful cruise required to stay out of the girders). However, the incidence is still wrong so it would still tuck under if you let it pick up any speed.
Second mod. was to run some thread from the top of the v-tails to the wing support under very slight tension. This added some decalage, and prevented the tail from rotating negative when speed built up. Suddenly, we have a very nice flyer.
Finally the brainstorm. The wing is an elliptical planform with the tips at about 1/3 back. No airfoil, no twist. SOOOOO, I installed the wing backwards and removed the noseweight. The wing center of lift was thus moved about 1/2" back, which is as good as moving the cg 1/2" forward. BINGO! Great stability, controllable climb AND glide, and really surprising performance. Anybody got a blimp hangar handy?
