Piper Comanche (oz11251)

About this Plan

Piper Comanche. Radio control scale model, for Super Tigre 60 engine. Uses foam core wings.

Flaps, landing lights, and retracts.

Quote: "Designer Jackson was kept so busy by IBM working on the guidance computer for Saturn 5 rocket, he just had to employ every latest time-saving building procedure possible to quickly complete this: Radio Controlled Pulchritudinous Piper Comanche.

When I was considering which airplane to use as the prototype for an R/C scale copy, the principal characteristics required of the aircraft when built as a model were:

1. Attractive appearance.
2. Good flight characteristics.
3. Easy to build.
4. Able to utilize the full performance capabilities of a six channel proportional control system.

The Piper Comanche has more than met my requirements. The miniature was a pleasure to build and fly and its performance and appearance were sufficient to bring it second place in R/C scale competition at the 1965 National Championships in spite of some errors and omissions by the builder. The model plans were scaled from Piper Aircraft Corporation drawings. The only deliberate deviation from true scale was a ten percent increase in the size of the horizontal tail surface. The color trim and lettering were obtained from Piper sources.

Happily, the full size aircraft offers several interesting features which have been incorporated as functional elements of the model design. These include wing flaps, navigation lights, retractable landing gear and the single piece horizontal tail surface called a stabilator. The model has demonstrated that the extra control channels now available on proportional systems can be used to advantage in adding those touches of performance realism which makes R/C scale work so appealing.

Flight Characteristics: As the Comanche neared completion, it became apparent that weight was going to exceed my original estimate. This was confirmed when the finished model totaled 10 pounds, giving a wing loading of 31 ounces per square foot. Because of such a high wing loading I was somewhat dubious about flying performance. However, my pessimism disappeared completely during its first flight. After a short take off run along a grass field, the Comanche proceeded to perform beautifully with only slight trim correction required on the stabilator. On its initial landing approach speed seemed high so a second approach was made with flaps fully extended. The result was a successful first landing, certainly the most important part of a scale craft's first flight. Since then, many landings have been made with the flaps both up and down. Although the Comanche performs well without flaps, its slow speed ability with flaps makes their installation well worth while. At high throttle settings a slight pitch up tendency develops when the flaps are lowered. At low throttle the plane can be flown with good control at surprisingly low speed when the flaps are down.

What are the main factors that contribute to the excellent flight characteristics of this highly loaded model? The general arrangement of the full-scale Comanche with its long tail moment and adequate vertical tail surface makes for a stable configuration. And, of course, don't forget that the horizontal tail surface was increased to promote stability. The airfoil, previously used on another heavily loaded model, is a modified Ritz design, it has a three percent curvature of the mean chord line which produces a high maximum lift coefficient and results in the low stalling speed so welcome when making a slow speed landing. The ability to perform outside loops is probably impaired some, but this is generally not too important for scale planes.

Although no violent maneuvers have been attempted, the more graceful exhibition maneuvers such as Cuban Eights, Immelmanns, loops and rolls are easily and well done by the Comanche. A low pass with landing gear retracted always pleases the spectators - and the operator!

Construction. A major objective of this project was to minimize building time, a commodity which becomes increasingly scarce. All of the construction methods used were selected for their contribution along this line. For example, the principal time saver is the use of balsa covered Styrofoam for the wing and both tail surfaces. The foam wing technique offers a significant reduction in building time over conventional construction and is particularly..."

Direct submission to Outerzone.

Note the "Royal Flush" text and rib drawings included on this plan are from a different model, which also featured on the #566 plan set.

There is a low res scan of the (American Modeler, May 1966) Comanche article online at: http://www.rchalloffame.org/Exhibits/Exhibit19/index.html

Update 13/06/2019: Added article (at good, higher resolution), thanks to RFJ.

Supplementary file notes

Article.

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