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Old 12-27-2010, 01:17 AM   #21
pattern14
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Default nothing wrong with trial and error

Most of my planes are experimental, as that is where my interest lies. When I was a kid I built a ducted fan Mig 15 using a cox 049 glo motor with an integral tank. The impeller ( well, that was what it was supposed to look like) was made from a design out of a much loved aeromodelling book that I sadly no longer have. A piece of sheet metal cut out round and then cut towards the hub, which had a shaft diameter hole drilled in it. A number of cuts with a hacksaw to make the seperate blades, and these strips were then twisted to the same angle and bolted to the motor. The starter spring was modded slightly to engage the blades. Twisting the blades with pliers varied the pitch. Still awkward to start, but it flew successfully as a free flight plane, slowly and predictably. That little motor could not compare to the output of a modern brushless in terms rpm, and the "fan' vibrated horribly, but the very light weight ( stick and tissue) construction was the key to its success. Fast forward to 3 years back and I experimented with about 5 hairdryer and pc fans. One worked, the others just did not have the grunt, or had too much vibration, or spun off the shaft mount. Tried internal and external ducting and nacelles, homemade variable thrust nozzles, and all types of motor/esc/battery combo's. The pc fan from an ex games computer was successful, but primarily because it was married to an ultra light weight glider that was very efficient but just as fragile. Broke something on 3 successive flights, and was at the total mercy of the wind. Had an enormous amount of fun interspersed with many failures and dead end designs. So go ahead with this plane of yours, and the best of luck
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