Pilatus Porter (oz15439)

About this Plan

Pilatus Porter. Radio control sport-scale model for .15 to .29 engines and 4 functions. Uses a foam core wing.

Quote: "Pilatus Porter. John Rutter offers scalish plans for the famous STOL load-carrier; 48 inch span for .15 to .30 engines, land or water operation.

The Porter is not a pretty aeroplane but it is extremely simple in outline and that makes it simple to model. The full-size plane is also remarkable in its STOL performance, seeming to float off the runway after almost no ground run. The high wing gives a number of modelling alternatives with regard to the use that the model is put to. Scale is an obvious choice, but with a larger amount of dihedral it could be a 3 channel trainer. With no dihedral and a more powerful motor it could be a 'Wot 4' with a scale outline (using 4 channel gear, of course).

I finished my model to the latter specification with an ST 29 on the front and it climbs away from take off vertically - definitely not scale, but impressive. With a little thought in the construction stage it can even be finished as a floatplane (and still be scale)! To add a little interest to an otherwise very simple model, I added a sprung u/c, floats and flaperons. The first two work very well, the flaperons are more problematical, but I'll say more about them in the flying notes.

Building: Wing construction is very straightforward and standard foam/veneer. The wing itself could hardly be simpler in outline; I cut mine in 2 x 2 ft lengths, and used 4ft veneers to give a one piece wing. If you can only get hold of 3 ft veneer or want to use some dihedral then you will have to reinforce the centre section joint with GRP. For scale, the wing should have about 1 in dihedral under each panel - for rudder steering 2 in or so would be better but even with a flat wing the model steers on rudder. For fully neutral aerobatic performance it could do with anhedral!

To build it, the LE, TE and tip pieces are all glued in place after veneering and sanded to section. The ailerons are then cut away (if needed) and the aileron servo mounts glued into the wing. If a wing-retaining dowel is to be used then this can be glassed onto the front of the wing while the retaining screw reinforcement plate is glued onto the trailing edge centre section. The entire wing can then be covered. I used film and top hinged the ailerons with film, too. The aileron torque arms are 14g piano wire and I used 16g brass sheet suitably drilled and soldered in place for the horns. The flaperon system shown in the photos was not entirely successful so I have not drawn it on the plan.

Tail end: The tail, like the wing, could hardly be easier, being simply cut out of 4 in wide sheet. I used fairly hard stock as the ST 29 is not very light. If a lighter motor is to be employed, then lighter tail sheet should be used. The tail was again covered and top hinged with film before the endplates were added and before the assembly was glued in place on the fuselage. The tailwheel was made to steer by epoxying and binding a sternpost to the fin; this meant glueing the fin in place before covering the fuselage but this didn't cause too many problems. The rudder was centre hinged with mylar strips.

Fuselage: The fuselage itself is a box with slightly rounded corners, hence all the 3/8in triangular strips. The formers are mostly ply or built up for strength and ease of pushrod installation. The nose is reinforced with 1/64in ply but don't use anything thicker than this or trouble will be experienced with the acute bend in front of F4. The motor mount and F3 may vary in size with the motor and tank used, so use those drawn as a guide only. I mounted my motor at 45° to help with the throttle snake location but you may want to do it differently. The tank I used was a 4oz SLEC but this may be a bit on the small side for some tastes. The tank access hatch is on the underside of the nose where it removes very little strength, the tank is held in place with silicone after fuel proofing the bay.

The u/c needs a bit of thought. The sprung version I used on the original model is quite easy to make and works well, but if you don't fancy the extra fiddling about it would be easy enough to fix a thicker plate in the bottom of the fuselage and attach a simpler piano wire u/c, or even a dural plate type. The source of the springs was KR Whistons of Stockport and they are a great source of other items at reasonable rates - send for their free catalogue. (No, they aren't sponsoring me!) If you want to be able to convert the model to a floatplane, then you will need to add a ply plate to the rear fuselage and waterproof the inside of the fuselage with dope. Wing fixing could be with elastic bands and dowels or with screws as on the plan - elastic bands are more forgiving in accidents.

Once all the decisions are made, putting the fuselage together is easy. Start by building the sides up to the necessary width and cutting it to shape, add the ply doublers with an impact glue and glue formers 4, 5 and 6 to one side flat on the plan. When dry, glue the other side over the first. Draw in the tail and cement the formers in place, followed by the nose and its formers. Be careful to maintain the thrustlines shown and use epoxy. Incidentally, if you intend to use the model over water, then waterproof glues will have to be used throughout - PVA won't do.

Add the 3/8 triangular strip, the tank bay top and the top sheeting for the nose. At this point I usually install the R/C gear, pushrods and control snake (throttle) so the motor/mount and tail have to be positioned temporarily. Add the fuselage top and bottom sheeting (grain down the length is strongest) and the wing mount doublers..."

Pilatus Porter from Radio Modeller, October 1986.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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