Thanks for all the replies! I noticed that ChiefAircraft.com lists the DL-55 as having 12.5kg of thrust at 1800 meters which is just about 27.5lbs of thrust at 5904ft. If AUW is kept to 16lbs which I'm sure it would be with the DL-55's light 2.9lbs of engine weight, that would give a 1.71:1 power/weight ratio. Is this enough to blast out of a TR? At sea level it would have 14.2kg or 31.24lbs of thrust, a 1.95:1 power/weight ratio. At 19lbs AUW that would be 1.64:1, probably the bleeding edge of acceptable. The motto around here is "Motor-up and Wing-up" meaning use more motor and increase wing area. I think the Big Bee is already winged-up, I'm just concerned about enough motor. Maybe a 70cc motor if there is one made? -Tom