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General control line discussion => Open Forum => Topic started by: Steve Riebe on May 18, 2013, 09:46:07 PM
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I usually start my planes by hand. I use APC props which have a really sharp trailing edge which I normally knock down with a knife. Does this affect performance to a substantial degree?
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Steve, I don't fly with razor blades. EVERY SINGLE prop I have gets what I call, a "prep" and balance. That is, ALL sharp edges removed, and a meticulous balance.
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I usually start my planes by hand. I use APC props which have a really sharp trailing edge which I normally knock down with a knife. Does this affect performance to a substantial degree?
Not as much as having blood on it. I take an exacto blade and the sandpaper to the TE of ever APC until I can run my finger over it without cutting it.
Brett
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Of course, the sharpness or dullness of a prop makes little difference once the prop is turning.
Some days ago, I came across an abandoned "multicopter" in a ... piece of unused land. Turns out the guy got his hand/wrist cut up while trying to fix a glitch by disconnecting and reconnecting power to the electronics. Those things have a lot more complex electronics and software than a fixed wing electric.
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All of my APC's get a good dose of Mr Sandpaper to both leading & trailing edges.
I then give them a bit of a balance, as I don't believe that fully balanced dose anything more than pride. Our engines are all pretty much out of balance to begin with and minor prop variations are not going to make too much difference.
I rarely start an engine without finger protection. I use rubber water pipe lagging wrapped in elastoplast bandage.
Greg
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I usually use a heavy leather glove. From time to time I will run an engine enough that I let my guard down and start with bare finger. If it is an APC prop. I put my finger against the front face, rather than around the trailing edge, to flip. Best to leave the glove on.
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Gloves or no. The best solution is a piece of rubber garden hose, or else an electric starter if you have a metal spinner.
F.C.
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My flying partner uses a piece of plastic air brake line from a bus. I usually use bare hands since I cut my teeth on a Super Tigre G21 35 combat engine.
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And you thought all my planes were painted red
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Does this affect performance to a substantial degree?
I don't believe that anyone has answered this point.
Yes blunting the trailing will effect performance but not to any substantial degree - for stunt use.
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Thanks for all the replies folks. I think I will continue to knock that sharp edge off. Someone at a hobby shop told me it affects performance, but apparently not enough to make a noticeable difference
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I believe that you would have to trim the rear of airfoil section ( as in squaring it off) rather than simply losing an edge for it be be noticed at sub sonic speeds.
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In my years of flying and running of engines, the sanding of the leading/trailing edge of a prop does not hurt performance. Sometimes I think it helps. I remember being told to get the trailing edge of fiber glass props as sharp as possible. After cutting a few cuts I decided it wasn't worth the trouble. But, it is not the flipping of the prop that cuts, it is the sliding of the finger along the edge that does the cutting. Take a piece of meat and a sharp knife. You have to push really hard to cut the meat. But, if you slide/pull the knife the meat cuts easily unless it is a piece of meat from an old bull we butchered one year. LL~ LL~
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Personally, I would rather sacrifice a performance than a finger.