YF-40 (oz14455)

About this Plan

YF-40. Radio control sport / pylon racer model. Canard pusher layout.

Quote: "And now for something completely different. A 40-sized pusher canard with a reverse rotating engine. The YF-40 model 'B' is intended for sport pylon racing using front rotor-side exhaust engines, stock wood props and a 500 sq in, 15% thick wing.

This plane is enjoyable. Every time it is flown, either for fun or at a race, it seems someone is seeing a canard for the first time. You can spot 'em. Their jaws hang open and there is disbelief in their eyes. It has a wide speed envelope. Although not quite in the Formula I class at the top end, it will slow down to a crawl. It can be stalled in a scallop like waving motion, losing only five feet each time.

The 'M' model was clean and quite fast, but it had two faults. The fuel tank was too high for the inverted engine. With the tank mounted ahead of the engine, at an increased angle of attack the tank is raised further in relation to the en-gine. This is the situation that pre-vails in a pylon turn. It ran fairly well on a K&B 40, but with an. OS 40 FSR I never could get an even run. So the 'B' model has the engine on its side with the carburetor facing up.

The other fault was that it shouldn't have to weigh 3-3/4 lb with a light plastic covering. The distance from the prop to the CG location was 15 inches. Quite a bit of weight was required in the nose to put the CG where it belongs. I worried about the ability of the stab to lift its end through the turns - but it never stalled. Lord knows I tried. A slightly tail-heavy 'A' model made some impossibly tight turns one day on a test flight. I saw 'em but I still don't believe 'em. Good structural test of the wing. I found out what the problem was after a nervous landing. Balance yours with a full tank of fuel.

Now on to the 'B' model. By burying the engine in the wing, and sweeping the wing back, the prop to CG distance is down to 11 inches, with the weight at 3-1/4 lb. The lift loading (wing and stab area combined) is about 12 oz/sq ft. Float like a butterfly - Zing like a bee!

The big reason for using the canard configuration is to scare the pants off the competition. No, it isn't. It's to put the propwash behind the plane - lowering drag. One side benefit of this is that everything forward of the propeller arc stays nice and clean.

Only three channels are used - elevator, throttle and one aileron. The nose gear is non-steerable. It should be long enough to give the plane a positive angle of attack on the take-off run. The length of the main gear is dictated by ground clearance requirement for the prop. Set up this way, with its light wing loading, it will get off the grass in two or three yards. You wouldn't have time to steer anyway..."

Direct submission to Outerzone.

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