A .90 equivalent brushless motor on 4S or 5S lipo should fly a 1/4 scale Cub model in a scale like manner with some power to spare. There must be someone on this forum who can tell you what motor, battery and prop combination has worked well, E-Flite has some brushless motor/IC equivalency info on their website. Lucien Miller of Innov8tive Designs is can recommend a good power setup using one of his Cobra motors and speed controls. Heads Up RC is also helpful. I am flying a Sig 1/6 scale Cub, 71 inch wingspan, about 5 lbs.with battery and using a Cobra 3515/14 low KV motor on two 3S 2200mahLipos in parallel for 4400mah.This gives me enough power for Cub aerobatics and 9 minutes safe duration. Recommend you make a functional side door and window for battery access and place battery pack forward in cabin with front of pack in line with instrument panel. This arrangement works in my Cub without extra nose ballast.Set CG per model instructions. Should hang slightly nose down for maiden flight. I fly with coupled aileron and rudder most of the time and switch it off for cross-controlled maneuvers. Cubs require coordinated aileron and rudder and use of right rudder for takeoffs. Start takeoff run with up elevator to keep tail wheel on the ground then release elevator to let tail rise and steer straight with rudder. Let model lift off with little or no up-elevator at about 3/4 throttle, keep climbs gradual to avoid stalls. Trim for level flight at 1/2 throttle. Wheels should be aimed straight ahead or slightly pigeon toed. Practice takeoff runs to control ground looping.There are a lot of You tube videos about flying tail-draggers. Cubs require a lot of rudder coordinated with ailerons to bring tail around for graceful turns.
Recommend wing strut to fuselage attachment with large metal clevises and silicone tubing keepers, less fiddly than nuts and bolts. Attach struts to wings with large pinned hinges. Jury struts are for looks. I used a Carl Goldberg scale-like tailwheel assembly, looks good and is durable. Land on main wheels until you know your Cub's stalling characteristics. Don't fly too slow down wind when setting up to land to avoid stalling. Practice stalls with some altitude. Don't fly in strong cross-winds until you watch how-to videos, My Cub lands best with a little headwind, tends to overshoot end of our short club runway.
Last edited by E-Challenged; 06-11-2016 at 07:43 PM.