MFW June 2013 - Page 12

The original intention was to create a series of combat “Bump’n go” series of Warbirds with a centrally mounted motor and propeller to reduce damage to the enemy, but the first attempt turned out to be a rather tubby cartoon character. I had great difficulty getting the CofG anywhere near the correct position, in fact it was so rearward that the plane was almost an un-flyable disaster. Moving on, the concept was for a low cost and quick Profile combat easily built model of scale profile and good flying characteristics that would capture the interest of members and could be produced “en masse” as a club group build project. Bump n go The design is worked around a 2200MAh Lipo battery, a brushless outrunner motor producing between 300 and 380 watts on 11 volts and a 30 to 50 Amp ESC, all of which many members have or can purchase cheaply. Profile warbirds Profile Motor Mount / ESC recess The wings are hot wired from white foam (scrounged from builder’s demolition) and the cores are cut down the spar line and a channel is cut into the rear half to allow access for the aileron servo wires. For reference, I have used the Richard Ferriere Free Plan 3 views, available on the web at... and then scaled and adjusted the lines and proportions to suit the project. Construction is of brown paper and foam, with the fuselage having a tapered foam core, some 30mm wide at the front, thinning down to 6 / 8mms at the rear, and sheeted each side with 3.00 mm balsa (the most expensive part) glued on with Gorilla polyurethane glue. Profile Mustang Cores Profile Fuz Construction Before sheeting, appropriate channels are cut in the foam to accommodate the servo wires back to the centrally placed receiver box. After sheeting, recess boxes for the ESC and Receiver are cut into the fuselage (Port side) and the battery box Starboard side front, and lined with 3.00mm balsa, all contributing to a very rigid structure. The motor mount plate is a 64mm round disc of 6.5mm liteply epoxied into the slotted fuselage front and faired each side with a piece of shaped triangle stock balsa. Pre-fit the motor and glue in the t/nuts before epoxying into fuselage. Profile wing servo access channel The carbon capped 3.00mm hard balsa sheet spar is epoxied in. It is better to measure the sliced cores and cut the spar balsa to fit, allowing for the thickness of the carbon caps. I prefer to make my own carbon laminate, laying up Carbon uni and cloth on a glass sheet under vacuum.