Shrunken Treasure (oz14416)

About this Plan

Shrunken Treasure. Control line stunt model.

Quote: "Another good-looking entry in the 'compact' class of half-size aerobatic craft - this design has already proven itself in Mid-Western stunt circles.

Shrunken Treasure is a high performance contest stunter designed to fly on .15 power. It will interest the beginning stunt man because of its simplicity, low building and operating costs. It will interest the experienced stunt man because it is somewhat different from the conventional .35 powered 'lumber wagon'. Its small size and racy Goodyear lines make it a standout among other aircraft.

The craft has a good contest record; she's won two firsts in well attended AAA meets around the St. Louis area plus several smaller AA contests.

There are two main differences between ST and other stunt models. One is the .15 up front, and the other is the absence of wing flaps. There is sound reasoning behind both points.

First the engine. About six years ago .15 powerplants made their appearance on the American market apparently designed for use in the free flight events where light weight and high power were the order of the day. This makes them quite suitable for stunt flying. They are very economical to own and operate; you can fly all day on a pint of fuel.

Wing flaps are used to increase lift and thereby increase the maneuverability of an airplane. If, and only if, the plane is heavy will the use of flaps make it fly better. ST weighs only eighteen to twenty ounces finished and ready to fly. It has 325 square inches of wing area - this gives a wing loading of approximately .06 ounces per square inch. This is well below the wing loading of most flap jobs.

How does one build such a light model? Through careful selection of light, clear, soft balsa, coupled with a good finish procedure; it's easy. But more about that later.

In designing the craft, I tried to eliminate one bad characteristic found on many stunt jobs. A number of planes yaw or throw their nose back and forth when they turn a tight corner. This has been eliminated on my design by sweeping back the wing's leading edge, and by using a lot of side area in the aft half of the fuselage.

The engine is mounted upside down for its protection. If we make a miscalculation while inverted, there is less chance of ripping the engine out of the airplane. The landing gear helps to protect the powerplant if we bobble while flying in the upright position. Also, an inverted mounting makes the aircraft look more realistic.

Begin construction by cutting out all wood parts, and by bending the landing gear and pushrod. Starting with the wing, mark the rib locations on the spars. Use small marks for this, because long and deep ones tend to weaken the structure.

The inboard wing panel is longer than the outboard panel. Pin the ribs in their proper locations on the spars. Add the trailing edge planking and leading edge stick, and glue everything in place. Glue in the bellcrank mount, and, when this is dry, add the bellcrank with pushrod and lead-outs attached. Leave the other ends of the lead-outs unbent.

Next comes the leading edge planking. Do the bottom first. Cement the planking down to the spar and allow this to dry. Then dampen the wood with warm water. Pin the planking down at the center section first, and work out to each tip, gluing as you go. Masking tape will prove to be useful in holding the planking to rib contour. Repeat the process for the topside planking.

Plank the center section, and add the tips and the tip ribs. Cement the aluminum tube line guides in place. Install them so that the rear line runs straight out of the wing and the front line is swept back..."

Shrunken Treasure, American Modeler, August 1959.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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