RCM 15-500 (oz6031)

About this Plan

RCM 15-500. Radio control club racer model. For .40 power.

Later also kitted by Bridi Hobby.

Quote: "Clean, honest, and fast, the RCM 15-500 is tailored to the emerging class of very simple sport or club racers using front rotor .40 engines, A one weekend project by Larry Maynard.

The 15-500 is an outgrowth of a series of similar designs dating from 1969 all of which have been easy to build and fun to fly. This latest version is tailored to the emerging class of very simple sport or club racers using front rotor .40 engines. With a wing just over 15 percent thickness and 500 square inches of area it meets all requirements under AMA sport racing rules while retaining the honest characteristics of a fine Sunday flier. With a smaller engine, ie a .19 to .35 it becomes as docile as all but tyhe very basic trainers.

The prototype was designed, engineered, and fully framed up over a weekend in which I also attended the B.I.R.D.S. annual Pattern contest. Insofar as practical the design has been tailored to standard material sizes and a materials list is provided to permit the builder to survey his supplies and scrap bin for necessary purchases. The structure has more than adequate strength so that any desired finishing technique may be used.

For basic construction I strongly recommend using regular model cement in other than high stress areas in order to keep the weight at a minimum. At the same time the builder is cautioned to spend the few extra minutes it takes to double-glue each joint. For attaching the wing sheeting it is a very simple matter to put the glue on the mating structure, lay the sheet on to transfer the glue, and then set it aside for a few minutes before re-gluing and pinning it in place. This method substantially increases joint strength and will save several ounces in airframe weight which can he the difference between winning and losing in a closely matched contest. A foam wing was also considered but fell by the wayside from weight considerations.

The construction notes have been laid out for minimum building time, so lets get with it.

Construction. Cut the fuselage sides from matched 3/16 x 4 x 36 in balsa to the outline shown, making sure to cut for the 2 degrees downthrust and the stabilizer inset. Draw lines on the inside of the fuselage sides to locale F3 and F4, and cement the 1/4 x 1/8 stiffeners in place. Epoxy the trailing; edge stock, firewall gussets, and wing nut blocks to the sides as indicated and set these assemblies aside to dry. Cut out F1, F2, F3, F4, and F5, and drill pilot holes in F1 for your motor mount, throttle controls and fuel lines..."

Direct submission to Outerzone.

Hi Steve - Here is Larry Maynard's RCM 15-500 from RCM magazine issue 10-73. Model # pl-539.

Update 6/10/2022: Rescaled this plan down very slightly to correct fullsize of wingspan 51 in, thanks to Balsaworkbench. This fix now allows the fuselage sides to be cut from a single 36 in sheet of balsa, as detailed in the build article.

Supplementary file notes

Article.
Previous scan version.

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