I'm getting 12 minute flights so far, but I've calculated that 15 minutes with 20 percent reserve should be no problem.. Using a 10.5 wood prop (APC would probably work better, but you just need a wood prop for a cub!).. As far as the motor mount goes, I had to make one from light ply. I ordered the Great Planes Medium mount and it was too big for the cowling no matter what I did with it.. I'll take some happy snaps this evening and post for you.. Overall very pleased with this setup plenty of torque that's for sure.. I put a little more moto than it needed but that's because I want to put floats on it at some point.. Also I think that your wt. is a bit high.. I'll weigh mine this evening also with battery.. I don't think that it's more than 3 pounds ready to fly..