Wills Electric Aeroplane Page

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

Try to use wood that is not too heavy. Cover with iron on film.

Accuracy of construction is essential. A building board should be used.

Construction is of an open structure consisting of three 3x3mm (1/8"sq) hard Balsa spars, 1.5mm(1/16") ribs with 6mm (1/4") leading edge with 30mmx1.5mm trailing edge pieces.

The centre section and tips are built as separate sub assemblies before being joined. Make sure all the end ribs of these assemblies are set to the correct angle so that the correct Dihedral is achieved. The leading edges should be sanded and the leading edge sheeting added before the sub-assemblies are joined. Use light 1.5mm (1/16") Balsa for the leading edge sheeting. 12mm (1/2") soft Balsa is used for the tips that are sanded to shape once they are glued on. Note: the panels are webbed between the ribs. The Balsa used for the webs should have its grain vertical.

The sub-assemblies are glued together and reinforced by 1.5mm (1/16") ply Dihedral keepers. These should be pre-bent (but not broken) to allow them to align with the swept back tip spars. Alternatively they could be laminated from 0.8mm (1/32") ply. The wing should be carefully jigged to maintain the correct Dihedral angle at the tips while the glue dries. Clothes pegs/clips are useful to hold the panels together at this stage.

This is a simple box structure constructed from 1.5mm (1/16") sheet Balsa with 10mm (3/8") triangular Balsa and 3mm (1/8") sq. strip. The 0.4mm ply doublers should be attached to the fuselage sides before the triangular stock. My way of attaching the doublers is to apply a thin film of PVA (white wood glue) to the inner surfaces between the doubler and its respective fuselage side. Allow the glue to dry on both items but do not join them yet. Then take a hot domestic clothes Iron, accurately position the doubler (glue side down) on the fuselage side (glue side up) and iron it in place. A chemical action occurs which bonds the two together.

This is built as a separate item with ribs and frames. The elevator control ‘snake’ outer is secured within the fin structure prior to covering with 0.8mm (1/32") sheet Balsa.

The tailplane is secured to the top of the fin with two small screws or alternatively glued on (But remove the covering on the tailplane and the top of the fin if you glue). Screws allow for fine adjustment and ease of transportation. Use screws that are about 12mm (1/2") long and 1.5 – 2mm (1/16") in diameter.

The control ‘snakes’ shown are a lightweight version consisting of plastic tubes with 24SWG piano wire inner pushrods. It is important that the piano wire is a good fit within the plastic tube. Any slop will result in slop in the elevator and bad centring. However these ‘snakes’ may be hard to obtain. 2mm nylon snakes could be used with the clevises at the servo ends. The rudder could also have a small clevise (‘Mini Quick link’) fitted at the rudder end of the snake.

The elevator should have a small length of brass tube with a wire ‘L’ piece bound (with lightweight fuse wire or a strand of wire obtained from some electrical cable) and soldered (see fig.1). This unit must be a tight fit on the nylon rod. This is then carefully crimped (use some blunt wire cutters or pliers) and Cyanoed in place.

I would strongly suggest getting someone to launch for you. This allows you to be ready on the controls. The model requires a firm, flat launch. Launch the model from above your head.

The prototype used the Graupner 6" x 3" folding propeller but with Graupner 7"x3" prop blades fitted instead. These required filing to allow them to fit and to allow them to fold correctly. This was used on a direct drive 7.2Volt speed 400 running on 7x500AR Sanyo Ni-Cad cells. A speed control with a brake is required…the brake is needed to ensure that the prop folds correctly. BEC (Battery eliminator circuit) was used on the prototype but a small receiver pack could be used.