Upshot (oz10159)

About this Plan

Upshot. Radio control 3 channel sports model. A later, tribute, half-size version of the Classic 1958 Chris Olsen Uproar RC design.

Quote: "When the plan of the Uproar (oz2220) was published, it represented an intermediate state of development. The original model, was a rudder, elevator and motor control version, but the published plan (and photograph) shows the Uproar with ailerons, which had been recently fitted to his aircraft. However, the drawings show the wing with the original dihedral angle, which must have been slightly counterproductive when performing rolls, but good for general stability.

When drawing the half-size version of the Uproar, as a tribute to Chris, I opted for the original non-aileron model, but you could fit ailerons with the 6g micro servos, or from a central mini-servo - and reduce the dihedral by 50%. The outlines follow the original exactly, as do the wing and elevator airfoils, only the construction has been changed in a few places, to simplify the structure.

You have a choice of fitting a small P/C engine, a Thunder Tiger 07 would be ideal, or a PAW .06 diesel, or a straight engine such as the Cox Black Widow. You will note from the photographs that the latter engine was used on the prototype 'Upshot' and that the HS81 mini servos were positioned at the rear of the fuselage equipment bay. This was a mistake, as with lightweight engines, the radio needs to go as far forward as possible to get near to the required balance point (on the main spar). A further 45g of lead ballast was needed on the nose, but even so, the total weight of the model only came to 14 1/2oz (425g), but I do hate having to stick lumps of lead on a model. With heavier engines, the situation will not be so critical.

There is room for a Sullivan 1oz. fuel tank in the bay behind the engine - you can just about squeeze a Radio Active 2oz. tank in, but it entails careful cutting away of F2 to fit it from the rear.

Before starting to cut out the parts, decide upon the engine to be used and adjust former Fl to suit. The nose doublers also have to be cut and glued to suit the engine bulkhead. Check also the size and positions of the radio equipment and controls - closed loop rudder operation was used on the prototype and a pushrod for the elevator. The fuselage sides are from 1/16 sheet, with doublers glued with contact adhesive. The straight rear underside of the fuselage it can be built over the drawing board as far as the undercarriage, and the U/C leg is bound and epoxied to F2 before it is installed in the fuselage. No longerons are used to the rear of the fuselage, it is only a small box and the 1/16" sheet all round (grain across for the top and lower sheeting) gives sufficient strength - but don't over round the edges.

Wing construction is not quite as simple as a flat bottom section - you must back up the spars and trailing edge to the correct height before adding the wing ribs, not forgetting to angle the root rib for dihedral. I formed the wing and tailplane ribs by the sandwich method, using 0.8mm (1/32) ply for the templates. Add the top sheeting while the wing is pinned down to the building board, dampening the outer surface of the 1/32 leading edge sheet forms a natural curvature. Centre section sheeting is on the top only, allowing you to join the wing panels with the dihedral brace fitted, clamping the centre ribs together with some of the powerful mini-clamps.

I opted for a soft 3/8" sheet elevator, but a built-up one should be fractionally lighter. An open structure fin would also be a touch lighter and worth considering when a Cox engine is fitted. 1/4 in triangular fillets help to secure the base of the fin.

Radio installation consisted of a Hitec feather receiver, two mini servos, a 300mAh Overlander battery and a standard switch (which tends to look out of scale with the other mini equipment). When the compartment behind the engine bulkhead is used for the battery and the Rx, as is the case of my Upshot, it is easier to line the area with foam during construction, rather than trying to fit foam-wrapped components through the access hole in former F2. For durability (and bearing in mind the gorse bushes in Devon), the model was covered in Solartex..."

Upshot, Model Flyer, January 2002.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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