Sopwith Dove (oz7558)

About this Plan

Sopwith Dove. Radio control scale model biplane. A 1/8 scale RC model for .15 to .20 cu ins and 3-4 function radio equipment.

Quote: "WHEN I DESIGNED and kitted my 1/8th scale Sopwith Pup, it was based on the Shuttleworth collection aeroplane and this, by coincidence, was modified from an original Sopwith 'Dove' brought by Richard Shuttleworth. Some time after the kit was introduced (it is now kitted by Micro-Mold) I noticed, at one of the Old Warden Scale Days, a modeller with a very nice example of a 'Dove' of about the same size as the kit 'Pup' model. Talking to the owner I was assured that it had been converted from the kit and, ever since seeing it fly delightfully around the Old Warden skies, I have had a yearning to build one. Here it is and I hope that it gives you as much pleasure in building and flying as the prototype, constructed by my nephew Matthew, has done.

Sopwith's introduction of the 'Dove' (converted from the 'Pup') was made at the end of the 1914-18 war as an attempt to produce a light, two seat biplane at a reasonable cost and to be suitable for club and sports pilots. Ten aircraft were built, most of them sold abroad, and G-EBKY was re-converted to the 'Pup'.

Construction of the model: As the prototype Dove was converted from the Pup, so the model can use the Micro Mold 'Pup' kit as a basis for this design. It will save you a lot of rib and former cutting and the kit is complete with cowl, wheels, pilot and pre-bent U/C parts, the remainder of the modifications are quite straightforward. Anyone who has built an open structure scale biplane - particularly a DB design - should find the construction of the `Dove' quite straightforward.

Do plan the R/C installation before you commence construction and keep the R/C equipment as far forward as possible to eliminate the need for adding ballast to the nose to attain the correct balance point (the swept back wings help in this respect). Closed loop control linkages can be used for the rudder but it is easier to use a pushrod linkage for the elevator.

Construct the fuselage side frames from 3/16 strip and the 3/16 sheet fuselage lower frame, the 1/8 lower fuselage doublers are glued to the inside of the frames. The engine mounts must be spaced to suit the engine to be used, and the plywood/beech units are screwed and epoxied to the front of former F1. Fix an anchor nut (for the wing fixing bolt) to the 1/4 x 5/8 beech cross piece and glue this to F3. Pre-drill the 5 mm plywood front cabane and U/C supports to receive the saddle screws. Join the front of the fuselage frames with F1, F16, F3 and cross pieces and, when this assembly has set, bring the rear of the fuselage together with F4 and the cross pieces in position - check for 'squareness!'

The 3/16 sq longerons must be slotted where the rear cabane struts are fixed to the fuselage, clean all wire parts thoroughly and roughen the wire where it is to be bound and glued to F2. Bind the rear struts to F2, clamp the front strut with the saddles and temporarily bind the wing support in position. When you are satisfied that the complete cabane assembly is correctly aligned (use a straight, flat board to check) solder the wires and epoxy to the former and cross piece, glue the 3/16 sheet forward of the rear cabane strut. Do not add the bracing wires at this stage. Add formers F9-F15, the cockpit decking is from three pieces of .4 mm plywood, it will be easier to glue it to the fuselage longerons if pieces of 1/8 sq are fitted between the formers and chamfered to contours. Cut openings after fitting the ply-wood decking - keep the outer surface clean and free from glue as this is varnished at a later stage. Complete the fuselage by adding side formers, stringers and sheeting etc.

Wing construction is completely conventional and the wing panels can be built directly over the plan. Due to the wing sweep back it is necessary to pack out the wing spars in the outer panels at the position of the dihedral braces, cut the slots for the braces after the wing panels have been constructed. Note that the wing spars extend out to wing tips and that the 3/32in. tips are curved, by packing out the spars, to give an undercambered effect. Taper the spars and packing pieces to the outline of the tips.

Fix the interplane strut split pins in position, bend over the pin legs and epoxy them to the spars and 1/bin. hard sheet. Bend and glue the 14g. brass tubing to the underside of the upper wing centre section (for the cabane strut rear fixing) checking that the spacing is ( H fed for the wing supports. Lower wing/fuselage fixings are achieved by 3/16 dia dowels at the front and a single bolt (4ba or 4mm) attachment at the rear. The dowels are housed into the front dihedral brace and should be reinforced with scrap balsa over the dowels; line the wing bolt hole with a suitable sized piece of tubing. Sheet the underside of the lower wing centre section with .8mm plywood after the wing panels have been joined - prop up the tip ribs to give the correct dihedral angle.

Tail surfaces are constructed flat from 3/16 sheet and strip, the tailplane has 1/8 sq strips glued to the top and bottom of the crosspieces and sanded to an aerofoil section. Hinge the control surfaces with nylon strip or miniature pinned hinges after covering.

Covering and finishing: The prototype model was covered in nylon and doped in the normal way. The unpainted covered areas on the original aircraft were represented by a light spray of Humbrol 'linen' matt enamel paint followed by a 'mist' spray of brown; the effect is very realistic as the covering remains semi-transparent. Plywood decking and interplane struts are stained and varnished and the cabane and under-carriage struts painted to match the remainder of the woodwork. It is worth-while binding the undercarriage struts and fairings with nylon to strengthen the assembly. Fuel proof the whole model with a matt polyurethane clear varnish.

Rigging and bracing arrangements are essenl ially the same as for the 'Pup', on the model the cabane and undercarriage bracing should be from stranded steel wire i.e. Lightweight Laystrat(-.! C/L wire, the remainder is non functional and shirring elastic may be used. Interplane struts are permanently hinged to the lower wing fittings, the split pin for the strut is slipped through the split pin on the wing and then epoxied or cyano'd into the pre-drill strut. The top of the struts are retained with a length of 20g pianowire slipped through the corresponding split pins.

Flying: Your Dove should weigh in the region of 3 lb (1-1/4 kilo) and, with luck, it should not require any additional ballast to obtain the correct balance point. If the balance is slightly rearwards (tail down attitude when supported under the top wings) do add weight to the cowl, don't worry if it is slightly nose heavy.

Use a large diameter, low pitch, propeller (Top Flight 10 x 3-1/2 for instance) even if you are using a '1.5' engine, with a 19 or 20 modern engine there will be more than sufficient power available and a 11 x 4 prop could be fitted. A mustard tin fuel tank fits neatly between the engine mount, you could fit a tank in the fuselage but this takes up valuable radio space and moves the C of G further rearwards.

With the side thrust incorporated it should not be necessary to include any right rudder trim for power flight, a left turn is less likely to develop into a spiral dive than one to the right. Keep the elevator movements to about 3/4 in each way and rudder to 1 in each direction for initial flights.

The 'Dove' can be ROG'd if you have a suitable surface, or hand launched. Try not to over control initially, let the model fly itself with gentle corrections via the transmitter. Once you have become familiar with the handling characteristics you will enjoy the agility of this little model - as with the original, it flies like a thoroughbred."

Direct submission to Outerzone.

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