Sopwith Triplane (oz15915)

About this Plan

Sopwith Triplane. Radio control scale model. Wingspan 46-1/4 in, for .25 - .29 engines.

Quote: "If two wings are better than one, then surely three are better than two. Build this sport scale version of the famous 'Tripe' and enjoy some relaxing and fascinating flying. Sopwith Triplane, by Norman Holme.

I always wanted to build a Sopwith Triplane, but was concerned that it might not behave very well without aileron control on rudder, elevator and throttle control only.

When out flying one day with my elderly 'Southern Cross' I decided to see how this model would fly without ailerons and using the rudder as the primary directional control. It seemed to perform even better in this configuration and I have continued to fly it this way ever since. Knowing that the Fokker would respond well to rudder gave me the confidence to proceed with the Triplane and this design has exceeded all my expectations.

Initially the model was fitted with an OS 25 engine, but the power for take-off was rather marginal, making it difficult to keep straight on the take-off run and gain sufficient speed for the lift-off. Once airborne she performed beautifully. A change to a 29 sized engine and a 10 x 6 propeller transformed the take-off, it now being crisp to control for a straight, clean run. Once safely airborne the power is reduced to prevent an excessively steep climb -although the prototype gained height quite rapidly.

If you do decide to fit a 25 engine make sure it is a powerful version. You will probably find that you need a few ounces of lead in the cowl so you may as well fit a larger capacity motor, a good size propeller and a dustbin silencer, that way you will get away with using a minimum of nose ballast.

Flying is very much in the sports/trainer class, the Tripe is well mannered, predictable and easy to handle. You will notice that the wings are banded on, if you wish to make the model to a higher scale standard you could change this method and the wing section. Remember, though, that she is intended as a regular weekend flyer and not for competition work - I leave those designs to others.

Fuselage: Cut the fuselage 1/16 sheet sides to the outlines shown on the drawings and pin one side to the plan. Cabane struts are from 1/8 (3-4mm) plywood, glue one of these to the fuselage side and then add 1/8 doublers and 1/8 x 3/16 longerons and spacers. Mark position of engine bearers on fuselage sides and then build the second side over the first (one left hand, one right hand - separate with polythene sheet or Clingfilm).

When the sides are set and separated, glue formers F1 to 3 in position on one side, check with set square to ensure they are upright. Add the opposite side to the formers and check again that they are square - and that the stern posts join accurately. Glue the 3/8 x 1/2 in beech engine bearers in position, followed by the 1/32 (.8mm) plywood former C4, over the bearer and up against F1. Cut and fit formers F5 and F7 and the 3/16 square spacers..."

Sopwith Triplane from R/C Scale Aircraft, Spring 1988.

Direct submission to Outerzone.

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