Wing Derringer (oz6803)

About this Plan

Wing Derringer. Radio control scale twin model. January 1980, RCM Plan #786. Scanned from full-size plan and cleaned up by shinck. Scale is 1/4.

Quote: "RCM is proud to present what we feel to be one of the most outstanding one quarter scale twins. Powered by two standard sixties, the Derringer's performance and flying stability will amaze you.

The Derringer's size is ideal for a 1/4 scale model. At this scale, the model is small enough for a single piece wing that is easily transportable. It is adequately powered by two standard .60 engines, yet it is large enough to provide the visual impact and the flight stability associated with larger 1/4 scale aircraft.

The model design was based on 3-view drawings found in the January 1964 Air Progress and the manufacturer's sales brochure.

Two intentional deviations from scale were made. The first is the retraction sequence of main gear. The model's main gears retract simplistically inboard toward the fuselage, and are not covered by any doors. The full sized Derringer uses a rather complex arrangement which allows the gear to fold completely within each nacelle. The retraction is similar to the F8F Bearcat sequence where the upper portion of the leg slides tipward while the gear is coming up. The Derringer's main gear retraction is depicted clearly in the previously mentioned issues of Air Progress. Sport Flying and the manufacturer's brochure.

The second deviation from scale is the use of a non-laminar flow airfoil. The full sized Derringer employs a NACA 652415. I felt safer using a thick 23000 series airfoil to provide high lift and gentle stall characteristics.

One attribute which came closer to scale than I intended is the model's weight. I projected that the model would gross at 15 pounds, however, it finally flew at 25 pounds. This caused all sorts of concern about a wing loading in excess of 50 oz/sq ft, and the ability of the Rhom retracts to withstand the landing shock. Nevertheless, the model flies, and it is surprisingly docile. Furthermore, the landing gear has withstood numerous sod field landings with no apparent damage. Of course, the model would be infinitely more enjoyable at a lower flying weight, and I suspect that an 18 pound gross is achievable.

The plans reflect several structural changes from my model in an effort to lower the weight. I will discuss these modifications in the building notes..."

Direct submission to Outerzone.

Supplementary file notes

Article pages, text and pics, thanks to hlsat.

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