Dick Ohm Special (oz8100)

About this Plan

Dick Ohm Special. Radio control scale model pylon racer. Prototype used K&B 35 series 64 engine. From RCM Annual 1968.

Quote: "Larry Roberts' Goodyear racer for competition under the NMPRA 450 class scale rules

The Dick Ohm Special was designed for competition under the scale section rules of the National Miniature Pylon Racing Association. This event as conceived by the East Bay Radio Controller's Club, and has been adopted by the AMA. The object of the NMPRA rules is to create a multi-plane pylon racing event patterned after the full size Goodyear midget racers. So far, the Goodyear pylon races that have been held here in the Northwest have created more excitement and interest than anything that has happened to R/C in many years.

My first Goodyear pylon racer was the Aeolus (oz9007) designed by Dick Riggs, an old friend and flying partner back when he hailed from this corner of the country. I think that the Aeolus was, and still is, one of the best designs available for pylon racing. However, as I began to accumulate experience competing in the Goodyear races I felt that the handicap start penalty imposed on the non-scale over the scale designs was simply too hard to overcome, and if one was to seriously compete, a scale design was in order.

Being able to evaluate most of the available designs at first hand under actual racing conditions enabled me to establish the parameters that I felt would lead toward a proficient competition ship. With most of the basic design requirements in mind I began a search for the scale Goodyear pylon racer that would best fit this bill. After much research, and many sessions with fellow modelers, the ship that seemed to qualify best was the NGH Stoppelbium and Ohm Special carrying racing number 15. This ship had a reasonably high aspect ratio wing, a generous nose and tail moment length combined with a fairly clean profile.

The original ship had a high rear turtledeck, rounded vertical fin, and a slightly longer wing span than the model version shown. For the races in 1947 the fuselage was modified by cutting down the rear turtledeck, squaring off the vertical tail, and refairing the front cowling to reduce drag. Other modifications included shortening the wing span and the installation of a bubble canopy. With the modification complete and the ship repainted in the original colors of red and black trim. the Dick Ohm Special had the classic lines and the basic potential of a winning racer.

It is this version that I decided would best fit the design parameters I had established as being essential for a consistent racing contender.

Construction of the Dick Ohm Special is similar to most multi-channel stunt ships with two exceptions, namely, the scale type fuselage and the unitized wing-body structure. I chose the built-in wing design because of the simplicity of construction and the inherent extra strength provided to the whole assembly.

I personally like the looks of fabric over stringer construction used on the full scale airplane, and wished to duplicate the effect in the model. This then dictated the classic built-up sides of 1/4 in square balsa longerons and stringers, which also has the advantage of being strong while still being lightweight. To start with, the fuselage sides are built directly over the plans using fairly hard 1/4 square balsa stock. When dry, add the 1/32" sheet plywood doublers on the inside face of each built-up side..."

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