Sunday Flier (oz15544)

About this Plan

Sunday Flier. Radio control sport biplane model.

Quote: "Sports biplane with a vintage air. 46 inch wingspan for 20 size engines and three function radio. Sunday Flyer, by Mike Conrad.

I suppose the fact that I have been building nothing but Vintage models for the last 5 years has been the reason why Sunday Flyer came into being. I somehow felt that I had got to the point where my next model would have to be built without the constraints of someone else's ideas. And as all my non-vintage models had been my own design anyway. I decided to revert to type and get back to rolling my own.

Of course it had to be a biplane, it also had to be suitable for a newly acquired OS 20 four stroke, so it had to be light and not too large. Drawing on the experience of my previous biplanes, I went ahead and the 'Sunday Flyer' is the result.

My original came out at 3 lb 12 oz and the model flies quite happily and is reasonably aerobatic at this weight. I doubt if it can be built very much lighter, so if you feel the need for more performance, an HP25FS or PAW 29 Diesel might be the answer.

One other virtue this model had to have was ease of assembly. I know rubber bands are the traditional method of holding a vintage model together, but trying to cope with greasy rubber bands, on a freezing cold February morning, is not my idea of happiness.

So, how should it be held together? The top wing was no problem, using the fore and aft springiness of the cabane struts to engage in small plastic saddle clamps under the centre section has all been done before, and is dead reliable.

The method chosen to attach the bottom wing, however, may cause a certain amount of concern, but fear not, it works. The cupboard clips shown on the plan can be obtained at any B&Q store, and I am sure other DIY outlets stock these or similar types.

Is it safe? You may ask. Well I have rolled the model, flown it inverted in quite windy weather, and it's still in one piece. Quite honestly, anything more dramatic than this is not really in keeping with this type of model anyway. so if you must do bunts, fit wing bolts. As far as I am concerned, if one tries an unusual idea such as this, and it proves a success, it is a great source of satisfaction.

Now, I think I know the sort of modeller who may consider building this model, and I am sure he will not need me to give him detailed instructions. However, a few hints and tips will not go amiss.

Fuselage: The brass tube through which the tail wheel leg passes must be very firmly attached to the stempost, and the alloy plate underneath the fuz is very necessary, as it limits the vertical movement of the leg, which as you can see, goes through a right angle and controls the rudder. Tail draggers put quite a load on their tailwheels, and since rudder control is dependent on this component, it is very important that it should not be knocked loose on the occasional bumpy landing.

One other point concerning the fuz. Do eyeball the formers fore and aft before planking and fitting stringers. Perhaps it's the way I fit formers, but slight smoothing always seems necessary.

Wings: The wing construction is very straightforward. Yes, I know the top and bottom main spars are only 1/8 square spruce, but they are a long way apart on the very thick section, and in any case, the extra spars along the LE ensure adequate strength plus helping toward giving the model that vintage look. Struts are very easy to make fit top and bottom wings and run the 1/8 dowels through their holes in the triangular pieces on top and below the wings. Dowels should protrude into the wings about 1/2 in. Ensure gap between wings is equal on both sides and fit 1/16 hard sheet each side of the twin dowels. Be careful the glue does not get where it is not wanted during this operation.

Wing and tail tips are laminated strips of 1/8 x 1/32 ply. Easiest way, I found, was to put pins in all round the inner curve of the tip outline, bend round 4 strips of ply, leaving some extra length at each end, now push pins in round the outer curve, holding laminations together, then flood cyano right round the curve..."

Direct submission to Outerzone.

Quote: "Sunday Flyer Hi Steve, here are the plans for a vintage style sports RC biplane, complete with build article. Cheers, Dilwyn"

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