I had a similar problem on mine powered by an OS65AX, roll to left on take off fortunately into a corn field with no damage. Post incident assessment was insuffcient speed on rotation even though i was fairly sure the speed was sufficient . Second attempt more speed and flat climb out with no problem. The model flies well with no tendancy to tip stall and landings with full flap are smooth & stable . The nose gear is unfortunately complete rubbish as you will no doubt find out after a few landings, i spend more time modifying the gear than flying the model and in reality it needs changing for a Robart or something similar. Good luck with the re-build