Fast Cat 2 (oz11451)

About this Plan

Fast Cat 2. Rubber sport model. Experimental speed plane.

Quote: "Rubber-powered Free Flight speed planes are making a comeback. This twin profile is for fun and racing. It's simple - and stable because of right- and left-hand props. Fast Cat 2, by John Walker.

Speed has always been a fascination to man - How fast will it go? Every modeler hears this no matter what type of plane he's flying.

Rubber-powered speed models have enjoyed a comeback in recent years. And why not? They offer an inexpensive challenge to the technically minded modeler. There is no need for him to invest a pile of 'green stuff' in a hot engine, nor will he burn up a gross of glow plugs in a day of flying. Also he doesn't have to know a 'mad scientist' to brew up a batch of special fuel.

Rubber-powered speed does have its problems though. The model must travel in a reasonably straight line to have its top speed timed accurately. And the initial burst of power and torque do cause the model to have a tendency to auger (spiral) through the air causing drag and resulting in lower timed speeds than the model is capable of achieving. Spiraling can be overcome in a number of ways:

(1) Slightly increase the area of one wing.
(2) Make a 'pusher-puller' model with two engines a la Dornier Do-335.
(3) Go back to the old twin pusher.
(4) Use contra-rotating props.
(5) Build a model with the configuration of the Fast Cat2, with right-hand and left-hand rotating propellers.

Fast Cat2 is offered only as a starting point. You take it from here. Increase the model size. Try more power. Try different pitched props (you'll have to become acquainted with the old art of carving your own propellers). These are just a few ideas. What ideas can you incorporate in the model to increase its speed?

If you aren't turned on by rubber-powered speed, increase wood thicknesses (and select a bit harder grade) and add a pair of 02's and U-Control gear and do your own thing. Just watch your fingers when starting the engines.

Increase the model's size and wing span, and you have a unique Free Flight model with the same engines.

Construction is straightforward and no problems should be encountered if both props have the same pitch, rubber motors are identical, both motors have the same number of winds and the model tracks straight while it is on the ground.

The original model was constructed from Sig contest grade balsa. Make sure the wood used is straight grained. Rather than ruin the plans, place a sheet of tracing paper over the plans and carefully draw the fuselage outlines onto it. Remember, one fuselage is longer than the other. Use carbon paper under the drawings to transfer the outlines to the wood. Cut to shape and round edges with fine abrasive paper. Cheek outlines and location of slot for the elevator by placing the parts over the plans. Correct as necessary.

The angular shapes of the wing and tail surfaces can be transferred to balsa quickly by measurement. Cut them to shape, and sand. There are two easy ways to build dihedral into the wing. The first involves making the wing in three sections. Place them on a section of transparent wrapping film and block in the re-quired dihedral. When satisfied, glue them in position. We used Ambroid.

In the second technique, a straight-edge and hard lead pencil are needed. Make the wing in one piece and locate the dihedral breaks..."

Direct submission to Outerzone.

Supplementary file notes

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