Thread: Build Log 48" ufo
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Old Dec 06, 2011, 10:33 PM
Tsavah is offline
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Joined Oct 2010
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Lik'em Big!

If your battery was a little too warm, that would suggest the amp draw was a bit on the high side. Since the motor was hot I would think the propeller was a bit much for the motor. I would try the same length of propeller, but down one on the pitch. If it still runs hot, I would try the next size shorter with the lower pitch. At some point the motor should run warm (acceptable) and the battery pack just barely warm. That is a good indication of a good propeller, motor, and battery match. The ESC should be only slightly warm also, or it may be necessary to go up a few amps in rating and at least 5-10 C more on the battery pack rating. The question now is does the propeller combination provide enough thrust to equal at least 80% of the weight of the ready to fly model. If not, the flight characteristics might be limited and disappointing. It would also mean you could only fly on very calm days since the propeller combination wouldn't provide enough thrust to push into a head wind.

Having said all of that, I lik'em big and I tend to go for a slow flyer that can stay up for at least 10 minutes. So, what is your next scheme in the evolution of this 48" UFO design? If you are thinking it would be wise to stick with your propeller, motor, ESC, and battery pack for now, why not consider giving the 48" a trim to 44" to see if what you have will handle the slightly smaller size better? If you would rather build a new foamie and try some weight saving ideas, let me know. There are a lot of ways to trim the fat/weight of a foamie and make the round frame stiffer. One, real simple method involves thin, 1/2" wide balsa strips in strategic locations. We can talk more if you are interested. I am interested in this project because it mirrors one of mine I have on hold for the moment while I work on others. So naturally I am very interested in your UFO project. I lik'em round too.
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