Wills Electric Aeroplane Page

The following should be considered as building hints and tips and not building instructions.

Volks Cobra has been designed for 4 minute pylon racing. As such it is not considered as a beginners model. Micro servos and receiver are required. Choose a high visibility colour scheme it’s a fast model. Try to use wood that is not too heavy. Cover with iron on film.

Although two wings are shown on the plan (A&B) the prototypes only flew with wing ‘B’. Wing ‘A’ differs from ‘B’ in only in area, which may well make it more suitable for sport flying. The model would be marginally slower with ‘A’ but stall characteristics will improve. Accuracy of construction is essential. A building board should be used.

It is recommended that the two fin ribs and fin spar be glued to one of the fin sides first. Then a simple jig should be made /used to hold the two ribs in alignment while the other fin side is gluing. The jig can be made from Balsa.

The fuselage formers are not big enough to allow the sides to be bent around them in the usual way. So blocks of 9mm balsa are placed at the Former positions after the formers have been glued in. The motor bulkhead can then be installed and the rear fuselage joined. The blocks can then be removed. The plan shows the use of 34g/sq.m glass cloth/epoxy from the nose to a point aft of the wing. This is primarily to reinforce the fuselage corners and make the fuselage more durable.

The receiver aerial should exit through a hole drilled under the rear fuselage just ahead of the fin leading edge. A piece of soft wire can be passed through this hole and wrapped around the end of the aerial. Then pulled back through taking the aerial with it, the wire can then be removed.

If a brushless motor is being used then the air intake and outlet should be relocated to cool the controller.

I would strongly suggest getting someone to launch for you. This allows you to be ready on the controls. The model requires a fast, firm, flat launch. Launch the model from above your head. It should be like a javelin throw but flatter. We used a plywood mock-up to practise with, ballasted to the correct weight. It should be a high energy launch. This should prevent the model tip stalling. As this is a racer it is not intended that it be flown very slowly. Despite this it can be slowed to a sensible landing speed. Landings are best made from a flat approach.

The Graupner 5.5" x 5.5" Cam propeller has been found to give the best performance. Unfortunately the small size of this and similar props give the model a relatively slow acceleration. Do not make large control inputs during this stage. If the model is allowed to accelerate unhindered it will achieve a very high speed.