Sportster 40 (oz7949)


Sportster 40 (oz7949) by Richard Simmons 1984 - plan thumbnail

About this Plan

Sportster 40. Radio control sport model for .40 - .45 power.

Quote: "A .40 powered high wing cabin design for the sport flier. It is easy to build and has an unusual fuselage shape. Sportster 40 by Richard J. Simmons.

The designer and builder is a born again modeler, returning to the Hobby in 1977 after an eighteen year absence. He was born in 1924 and started constructing so-called solid models at the age of nine, progressed over the years through free-flight and control-line up to an unsuccessful experience with a Sterling Wizard (oz5454) an R/C biplane (Cobb Micro-4 and too much vibration). He was self-employed in the construction field during this hiatus and his creative bent seemed to be satisfied by building an occasional house of his own design. He left that field of endeavor to go to work for the small town he lives in as Board of Health Inspector. (Getting too old and fat for manual labor.)

The model was designed about 1961. It was meant to be a single channel, rudder only, with the O.S. Pet in mind for power. Wing ribs and spars were cut out, then put away in a bureau drawer when interest waned. The winter of '76-'77 seemed to be a long one and out came the long forgotten ribs and spars. The end product was an O.S. 25 powered four channel version with strip ailerons. This proved to be a little too hot to learn to fly on, so the 40 size evolved. It's called the Sportster 40 because it was preceded by the Sportster 25 and, if the designer/ builder's wife doesn't find out prematurely, it will likely be followed by the Sportster 60.

The construction is fairly simple, though lengthy. A modeler who likes to build should enjoy it, although cutting out the parts is a little tedious. Only two adhesives were used, 15-minute epoxy for all plywood to plywood joints plus the spar joiners to spars, and ambroid for the rest.

Other builders may not find the control system to their liking and should feel free to improvise. The designer is addicted to wire control rods with snap links on both ends. (A lot of snap links, 29 to be exact, with a Carl Goldberg pushrod connector at the throttle to round it out.) Twin pushrods to the rudder and a homemade transfer linkage from the separate elevator horns are a little out of the ordinary but the throttle, flaps, and barndoor ailerons have standard hook-ups. Differential ailerons are obtained with the use of 60° Williams Bros bellcranks. (This ship is old in design but modern in someways. I was slightly insulted when I took the model to the flying field for the first time and overheard another model builder tell his model building son that all R/C planes looked like that years ago.)

One last comment. If you do not fully assemble the fuselage until the wing is finished, you will find the separate power module to be invaluable in aligning and keying the wing's location.

Construction. Please read entire article before cutting and assembling. Fuselage Sub-Assemblies. Power Module: The use of a small table saw will be helpful in cutting out the plywood parts since most of them have a width of 3-1/2 in. The motor mounts will have to be ripped to fit the engine of your choice. Mine was an O.S. 40 and about 1/16 was removed from the inside of each mount..."

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Sportster 40 (oz7949) by Richard Simmons 1984 - model pic


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