I agree, it sounds like it is underpowered. On most of these trainers, the CG is about 2 to 3" from the leading edge of the wing. If your throws are set to 100 TO 125% nd it still doesn't get airborne, I would try a .51 to .61 sportng a 10/5 sport prop. If you have a tach, make sure you are getting about 12,000 rpm on the high end. you may want to go with a more agressive control arm on your elevator servo to gain more lift, assuming the servos can gain maximum travel. Be careful though. If it is this dificult to get off of the gound,
it will be squirly in the air, and I would think that a dead stilk landing would not be he easiest. Plane looks great though, but bet it would look better in the air!
Good luck!