With the .91 4-stroke.. you'll want to use an APC 14 X 6. [img]i/expressions/face-icon-small-wink.gif[/img] I know because that's the engine I used in my 4*60. That prop will allow you to hover the plane when your skill gets to the needed level. Vertical unlimited at 3/4 throttle and it will take off at as low as 1/2 throttle.

Be CAREFUL advancing the throttle for take-off. LOTS of torque, so the tendency to do a 90 deg left turn will be uncontrollable if you just slap it to full throttle fom a dead stop.

See my review of the 4*60. I modified mine with retracts, and had a much wider wheelbase... the .91 FS's torque could still swing the tail around if I wasn't smooth with the throttle.