The Flapper. Ornithopter. National record holder.
Quote: "Junior and Senior Record Holder Ornithopter. The Flapper, by Robert Horak.
AFTER designing and building several ornithopters following the general indoor trend of design, I reached the conclusion that indoor types were not adaptable for outdoor flying. I then set about trying to develop an ornithopter which would turn in successful outdoor flights. After trying various ideas and different aero-dynamic setups I finally arrived at the following conclusions:
1. It must have a large stationary sur-face with a high lift airfoil set at a high angle of incidence.
2. It must be extremely light but strong in the right places.
3. It must be streamlined in order to permit fast flights. Speed is essential since lift increases with the square of the velocity. In other words, a model producing 5 oz of lift at 5 mph will produce 25 oz of lift at only 10 mph.
4. It must have sufficient flap area to obtain the very necessary forward speed.
I designed the model presented here with these ideas in mind. The model presently holds both Junior and Senior National Records.
Read the article carefully, studying plans until all details of construction are clear. Lightness should be paramount throughout the entire model. Select materials indicated. Original model only weighed 1-1/2 oz.
Fuselage. Select four pieces of 3/32 sq medium hard balsa for the longerons. Pin longerons in position placing pins on either side of the wood and not through it as this weakens the structure. Next select a length of soft 3/32 sq stock. This is to be used for the crossbraces and uprights. Finish one side of the body and let it dry thoroughly; then place a piece of wax paper over it and build the second side directly over the first..."
Direct submission to Outerzone.
Update 28/02/2017: Added article pages, thanks to George.
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This model plan (like all plans on Outerzone) is supposedly scaled correctly and supposedly will print out nicely at the right size. But that doesn't always happen. If you are about to start building a model plane using this free plan, you are strongly advised to check the scaling very, very carefully before cutting any balsa wood.
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