Piper Comanche (oz14646)

About this Plan

Piper Comanche. Radio control sport scale model.

Quote: "Keep your free cover-mounted plan safe. You'll need it to build Simon Delaney's 56 in sport-scale interpretation of one of the world's most widely used light aircraft.

The idea for this model started after seeing several semi-scale light aircraft at my local flying field. Although tempted by kits such as the Graupner Monson and other similar aircraft, I thought it might be fun to design my own light aircraft. It would certainly work out cheaper that way.

There are several advantages with this type of model. The tricycle under-carriage provides effective ground handling on most club sites, the scalish appearance is a bit different from the average sport model and the construction can be kept simple and quick to build. Colour schemes are bright, which makes for good orientation and a bit of embellishment in the cockpit only takes a short time and makes the whole model come to life.

The prototype model used foam wings, although the rib stations are shown on the wing plan if you wish to make a built-up version. The total construction took about three weeks. The Comanche is fully aerobatic on the 0S45 used in the original model but would be quite happy with a 30 size engine. If you would like to fly a model which is slightly different from the run of the mill 40 size aerobatic planes, then the fun starts here.

If you are going to use the foam winged version, the first thing to do is ring up Nexus and order them from the plans department. If you prefer to bash the balsa, then the ribs can be produced by using the sandwich method which involves placing the required number of blanks in between the root and the tip templates shown on the plan. It is up to you whether you wish to sheet the entire wing or just the area in front of the main spars. In either case the spars should be webbed with 1/16 balsa with the grain vertical. Although the above instructions are brief, the builder who has decided to opt for the built-up version will know what he is doing anyway.

The foam panels have balsa leading and trailing edges and a block tip. Once glued in place these can be sanded to section and the aileron torque rods and tubes added to the trailing edge. I used 12 gauge wire and some scrap plastic tubing with control horns that were adjustable by sliding a captive collet up and down the wire. This is a quick, simple and inexpensive way round a sometimes fiddly job. You can, if you wish, use strip ailerons, but I felt that inset ailerons looked more scale-like and were worth the extra effort. If the latter are used, the inboard trailing edge can be cut away to accept the aileron tube before gluing in place. Next cut the aileron servo box and line with balsa and cut out the undersurfaces of the wing as shown on the plan to accept the 1/4 in ply undercarriage plates. These are a lot easier to fit than hardwood blocks as the area can be sanded away with a 60 grade sanding block. I used PVA to glue these in and they never came out, although the prototype model had many stiff landings. Did I mention joining the wings? Use bandage and resin for the foam winged version. The built-up wing will need two ply braces but I didn't need to tell you that, did I!

Fuselage: Nothing tricky here. Make up two fuselage sides from 1/8th balsa and 1mm ply. Note that the ply doubler finishes 6mm short of the front to allow Fl to align correctly. Glue F2 and F3 to one side, checking that they are at right angles, and when dry, add the other side. Once this is thoroughly dry, pull in the front sides and fix F1 in place. Chamfer some 3/8" triangular balsa strip to shape and glue in place to reinforce the joint. Pull in the tail end and add the rest of the formers. I used snakes for control runs but balsa pushrods can be used if you prefer. Sheet in the rear of the fuselage underneath, making sure that the grain runs crossways.

Place the wings on the fuselage and drill through F2 and the leading edge of the wing. Fit a 1/4 in hardwood dowel to locate the wing and then fit the rear wing mounting fittings by drilling through the wing from inside the fuselage. I used plastic L shaped brackets glued to the sides and supported by hardwood blocks. In the event of a bad landing or - dare I say it - crash, the wing mounting pulls away from the fuselage with the minimum of damage and can be easily repaired. Once satisfied with the wing mounting, remove the wing and add the 1/16th ply plate to the cockpit floor. This gives the fuselage some strength as the large glazed area needs some beefing up.

Glue the tailplane in place, checking for squareness, and then add the rear upper fuselage sides and the top sheet which should be cut oversize and then sanded back to the line of the fuselage sides. I built a floor for the fuel tank from 3/16" balsa sheet and siliconed the tank to it after routing the fuel pipes through F1. Sheet the top front decking with 1/8 balsa sheet..."

Piper Comanche from RCM&E, October 1995.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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