AJEP Wittman Tailwind (oz7831)

About this Plan

AJEP Wittman Tailwind. Radio control scale model. 39in wingspan sport scale model designed by Peter Holland for light 3 function R/C and 0.75cc diesel or .049 glow motors.

Quote: "Build this design for a light, three-function WC sports model. The Wittman Tailwind, by Peter Holland.

One look at the side view of the Wittman Tailwind two-seater was enough to inspire this builder. Electric was the first idea, then he looked at the diminutive wing area, and realised that even with today's light nicads, a little diesel would serve the purpose quietly inside the capacious cowling.

Yes, yes, yes! That smooth side view with the almost aerofoil shaped cabin top-cum-windscreen. The lean, lean back undercarriage. The flat looking cowling. It's all 'get up and go'. I got up and went for it. Just a minute: the front view looks wide. That's because the wingspan is on the short side. Well, it is a racer, albeit one with a side-by-side seating arrangement, and from a modellers' point of view, a doddle to model; thanks to the box-type rear fuselage.

I am old fashioned. I prefer a reasonably light wing loading on almost anything that flies. I cheated a wee bit. The fuselage is one-eighth scale and the flying surfaces at the slightly larger scale of seven and a quarter to one, with the resulting loading of about 10 or 11 ounces per square foot.

There is so much cabin glazing around that vital wing attachment area, that the one piece wing, chosen for ease of aileron linkage, cannot separate in the usual manner. The windscreen, and rigid 2 mm styrene side glazing pieces, are integral with the centre section, and the whole unit is retained by a self tap screw at the front and two dowels at the rear.

Any other method would have made those slim glazing bars far to bulky for scale, and prone to wear and damage. You can now see right through all that glazing. Then, with the screw removed, lift off the cabin, there is room for a dance in there; unobstructed access. That's another thing to its credit.

Sticks and paper. The fuselage frame is 3/16 square medium strip over the side view part of the plan (suitably rubbed with candle wax where the joins go). Put pins each side of the strip longerons to coax them to the bottom curve, and gusset well with 3/16 sheet at the tailplane step.

Add the diagonal 1/8 x 3/16 braces. Sheet where shown with firm 1/16 sheet. Remove when dry, and make a second side with the sheet on the opposite side. Pin the un-sheeted frame to the sheeted one while you do this, to avoid the bare second frame becoming distorted, once it is off the board.

Make up the formers F2 and F3 from strip overlapped, and cut Fl and the engine mount from 3 mm birch ply. Epoxy the latter pair together.

Assemble the sides, sheet outwards over F2 and F3. Use a set square to get it true. Pull the tail ends together and hold them with a spring clothes peg. add the four bottom cross pieces in the cabin area. Do not add any cross pieces aft of F3.

Now slice diagonally through the longerons at F3 and allow them to form a straight line to the tail. Wick cyano into these joins. Add the rest of the cross pieces top and bottom.

Assemble the cowling front from four pieces of 1/2 in square, when dry, pull the sheet sides forward of F2, into contact with 11 and the cowl front. Add triangular strip top and bottom, cover the bottom with two pieces of 3/16" sheet; shorter on the starboard side for cooling.

Shape the opening in the cowl front to clear the prop driver and fuel proof with PVA. Mount the engine, mine is a Mills .75 replica, quiet enough to be silenced by the cowling alone, Make a small tank from tinplate or 5 thou sheet brass and tube. Test by blocking these and putting in hot water. Bubbles show if there are leaks.

Add rubber or neoprene fuel tubes (if yours is a diesel too). Now fuel proof the tank bay and install the tank. sheet the cowl top with 3/32 medium, and add the blister shapes from 1/8 sheet chamfered all round before gluing. Cut along the cowl hatch lines for access to the engine and reinforce the piece you took out Make a wire clip to go over the cart or cylinder and fix it with cyano. Bend it about until the hatch holds firmly, then add bits of thin ply to form stops. Remember to fuel proof these new parts with more PVA. Now break off to sort out the undercarriage..."

Direct submission to Outerzone.

Update 28/03/2017: added article, thanks to RFJ.

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