Hi!
At that weight I would not expect too much of it!
I had a SIG CAP 231 EX a couple of years ago powered by a MVVS 25cc glow engine swinging a 18x6 Menz wooden prop, and that plane weighted 5kg (11lbs/ pounds) and I could hower it at 2/3 power and climb straight up indefinitely. I still thought it lacked in power though.

15 pounds is way way to much if you want to do any manouvering than just flying straight and do a loop now and then.