Tomahawk (oz8250)

About this Plan

Tomahawk. Free flight glider model. Class E canard towline design.

Quote: "WAY back in the early thirties there appeared on the model-building scene several highly successful tractors, which were quite similar to our present tractor designs. Until this time, nearly oil models had been of a canard configuration. Because of the success of the tractor designs and the pleasing lines compared to canards of that era, it was only a short while before they began to dominate the model-building scene. Of course, there were many old-timers aware of the merits of a canard configuration, but as they kept dropping out of the picture, so did canards.

Today if a model builder so much as suggests building a canard, he is suspected of having a few loose screws. This is primarily due to the fact that the majority of present-day model builders have taken up the hobby after the canard recession. Therefore, not being aware of its merits or not having the time to evolve successful designs through experimentation, the average builder is drawn towards more conventional designs.

To infer that canards are superior to the conventional tractors would be erroneous. It would he more exact to say there are times when the advantages of a canard configuration weigh heavily in its favor, overshadowing its disadvantages and also the advantages of conventional designs.

The canard configuration in the present case was chosen mainly to accommodate an unusual airfoil. As you will note from the drawing, the airfoil appears radically different from the types generally used on model aircraft. The airfoil is the LDC-2, a Laminar-flow section developed by the Low Speed Aerodynamics Research Association (LSARA), in England several years ago. The results obtained with the airfoil were considered astounding when compared with such popular airfoils. as the Clark Y and the RAF 32. However there are several drawbacks, which make it necessary to take certain precautions in order to obtain peak results.

Many of us are aware that the wake from an ordinary turbulent flow wing section is wide and diffuse, and although the tailplane on it conventional design is almost always within it, the resultant loss in tailplane efficiency is usually not more than 20%. However, in the case of the laminar flow LDC-2, the wake is very thin and concentrated. For this reason, it is imperative that the tail surface be mounted high enough to clear the upper camber of the wing surface. If not, the resultant tailplane efficiency may be as low as 50%. While this may more often than not constitute a major problem in a conventional design, the canard configuration presented herein lends itself quite readily to such an arrangement.

In view of the fact that the WC-2 is not as stable as many of the popular airfoils, it is of prime importance to use that type of configuration from which longitudinal stability can most easily be obtained. The type which is best suited is the canard.

Many hours were spent working on the design to achieve a balance between ruggedness and streamlining. Both of the objectives were reached to a high degree. Although enough balsa was used to stock a hobby shop, the model weighed in at less than 8 oz. For flying in competition, this constitutes a minor problem since little or no ballast will be required to balance the model. In fact, the original model used no ballast whatsoever. Trim adjustments were made with a tab on the right panel of the rear wing, and with the rudder tab shown on the plans

Right now many of you are probably wondering how the model reacts on a towline. Since good towing is dependent on models stability, towing the Tomahawk is no more trouble than if you were towing a conventional model. If you are looking for something new that is a sure fire threat in competition, you can't go wrong with the Tomahawk. So, why not scale up the plans and take a crack at it. All bulkheads, ribs and formers are shown full size, thus eliminating the greatest portion of the preliminary work..."

Note this is not a fullsize plan, this is a scan of the drawing as printed in the magazine. Formers are shown at 100%, the general layout is shown at 25%.

Supplementary file notes

Article pages.

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