Sopwith Triplane (oz12403)

About this Plan

Sopwith Triplane. Control line scale model.

Quote: "Sopwith Triplane, by Walt Musciano.

WHEN your enemy openly praises a weapon of yours you can be sure it is good. Upon witnessing the performance of the Sopwith Triplane, the German Air Force Chief-of-Staff claimed it was the finest ship at the front and much work had to be done to develop an adequate opponent.

The Sopwith Tripe made its appearance in 1916 and immediately ran up an impressive string of victories. Superb maneuverability was the reason for its success. Powered by a Clerget Rotary Engine of 110 hp, the Sopwith had a speed of 115 mph. Standard models were equipped with a single Vickers machine gun, although some versions mounted twin guns.

All during his modeling days the author has been intrigued by flying scale triplanes but, try as he did, all attempts at successful tripes were in vain. However, with the advent of control line flying this dream became possible.

As a model, the Sopwith Triplane makes an excellent stunt plane because of its concentrated wing area. The high aspect ratio wings and large gap reduce interplane interference to a minimum. The 'I' type cabane and interplane struts add to the already simple construction; as will be seen later, these struts simplify the annoying problem of rigging a model of this type. The full scale craft is so well proportioned that the model required no alteration in its outline shape.

A Forster .29 was used in the prototype with excellent results. Less power may be used successfully but a more powerful engine should not be installed unless the builder has had many hours of control line flying. The plans have been drawn half size with airfoils and struts shown full size. When the plans are enlarged by stepping off with dividers or by means of photostating, they should be studied carefully until every construction step is clearly understood.

Construction should begin with the fuselage which is made of hard balsa. The side frames are 3/16 s. with gus-sets of 3/16 sheet. It will be noted that the 1/8 plywood cabane struts are constructed integral with the side frames. The cowl is made from a soft balsa block hollowed as indicated on the plans. Remember to cement the plywood wing joiners in the fuselage slots. The 1/16 landing gear struts are attached to the forward joiner and bulkhead A. A 1/16 sheet plywood bellcrank support is fastened to bulkhead B and the fuselage structure, using plenty of cement.

The tail surfaces can now be cemented to the fuselage and the bellcrank and pushrod installed. Quite often when a model makes a rough landing the engine tears loose and with it come the mounts which rip out a good portion of the fuselage. A method well tried in free flight models is used on the triplane. It consists of an engine bearer 1/2 by 3/16 cemented well to the fuselage; to this is cemented, rather lightly, the engine mount also of 3/4 by 1/2 in stock. In event of a crash landing the mount will detach from the bearer, thus saving engine and fuselage and cutting repair time to a minimum.

Wiring of the ignition system is next. Be sure to solder all connections. The switch and batteries should be located in the cockpit for accessibility. After all the above mentioned items have been completed, the 3/32 sheet formers and 1/8 by 1/4 stringers may be added. The fuselage, from cowl to fuselage station C, is filled in with dead soft 1/8 sheet balsa. When the fuselage has been well sanded it is covered with Silkspan and given three coats of clear dope. The model in the photographs has an olive drab fuselage with light blue cowl and white stripe just forward of the empennage. The entire tail is colored buff with red, white and blue rudder stripes.

Sparless type wings were selected using heavy leading and trailing edges which have a high strength-weight ratio. Note that the leading and trailing edges are notched to meet the ribs. This simplifies assembly of the wing and strenghthens the structure. The upper and lower panels are identical, and the intermediate panel would have been the same except that the designers had to cut away a portion to..."

Direct submission to Outerzone.

Cleaned, scaled, alinged. This plan is derived from the raw scans posted by 50+AirYears, see datafile.

Supplementary file notes

Article.

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