Thread: Discussion Marutaka Pitts Special S-2
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Old Jan 28, 2007, 10:40 AM
BEA flyer is offline
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Concord, MA
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I think you could use a lower pitch prop and still have the High KV, although 760 or 800 doesn't seem to be "high." I think 12-4 is a size avilable here. I got a prop speed of 88 mph for the 11 7 on PCALC for 5 cells which seems about in the range. Someone said you wanted a propspeed 2 1/2 times the stall speed of the plane. I know the plane barely flies if the propspeed is too low, and the second you bank to turn it falls out of the air.

My recent experience has been that you do not want to push the Lipo's too hard if you are interested in lots of charge cycles from them. If they say 20c, run them at 15, if 15, try 12, if 12, run them at 10c, etc. They want to sell you batteries, so they want you to run them hard for fewer cycles and then replace them. That is what is so great about free market economics. I had read on the web to not overcharge or over-discharge lipos. Then there are the A123 batteries... They don't go to 4.25 a cell fully charged, but the maanufacturer says they can be discharged to a much lower voltage. So you need different charge and ESC settings. But they are more crash resistant.
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