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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Dwayne on May 02, 2013, 04:12:23 PM
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Hey all, I tried a little something different today and it did not work. Set up is, E-Flite 15, FM-2sr timer, ice lite 45, 2650 4s. I set it up with a 11X5 EP at 9500 rpm it worked well but used to much batt. so I changed to a 11X7 at 8800 rpm and the motor sagged and slowed down at around 3 min, I could barely keep it in the air. What's up with that?
Thanks for the help
Dwayne
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Higher pitch should drive current up, lower speed should drive it down. Did you check the current on the ground? Did you look at how charge got stuffed in when you recharged the battery?
Maybe you were just pulling a lot more current than before, and than you thought?
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What plane?, What the weight of the plane? How old is the battery, Are you sure it was fully charged? Was the battery or motor real hot when you landed? Is your battery puffed? Do you keep your batteries in storage mode when not in use? Sorry for all the questions but a little more info may make it easier to figure out what went wrong?
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From the replies I'm going to assume this setup should work at 8800 rpm, so I guess I should check the battery. It happened on the first flight, I didn't want to take a chance and hurt something so I didn't try again, tomorrow I use a different battery and try again.
plane is scratch built with a 490 sq inch wing and weighs 40 oz ready to fly.
Thanks
Dwayne
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should work wine with those # if everything is good.
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ESC will run throttled down it can cause ESC overheating, it could also a reason.
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Thank you for the replies. Ok so now I'm nervous again, Igor thinks if the rpm is to low esc will over heat, this for sure would cause damage wouldn't it?
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it COULD overheat :- )))
It will go certainly warmer as the throttle goes down, but it does not mean that ESC MUST over heat. It could be one of reasons why it slows down. I do not have such experience with CC, but my Jeti Spin will do just that ... when it sees the temperature goes over preset value, it will simply slowly stop motor to prevent itself from burning.
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I would expect an E-Flite 15 with an 11x7 turning 8800 RPM to run at most for a couple minutes before the motor burned up and slowed to a stop.
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I would expect an E-Flite 15 with an 11x7 turning 8800 RPM to run at most for a couple minutes before the motor burned up and slowed to a stop.
Thanks Dennis. Sorry but I don't understand, the E-flite 15 is rated for up to a 13X6.5, could you please add a little more detail.
Thank you
Dwayne
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I don't recall an ICE Lite at 45 Amps. Maybe you have a 50 or a regular Phoenix 45. In any case, if you have hit your cutoff voltage (what is it set for) and the Castle Creations ESC will slow the rpm (because it thinks you are flying a helicopter) to allow a safe landing. It could be that your battery has a bad cell that discharged more rapidly than the others and pulled the voltage down to the cutoff level. Also you may have the cutoff level set too high (it should be set to 3.2-3.3 volts).
If you do infact have an ICE ESC what do the data show (you did download it didn't you?)??
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Thanks so much for all the replies. It was the battery, put another one in today and it worked perfect.
Thanks again
Dwayne
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Thanks Dennis. Sorry but I don't understand, the E-flite 15 is rated for up to a 13X6.5, could you please add a little more detail.
It's also rated for 7.4 - 14.8V. The big prop is for the low voltage. Put a 13x6.5 on it at full throttle on 4S, and it'll probably overheat.
I'm not sure how it'd do with your 11x7 prop, because you're turning it at 8800 RPM which won't demand nearly as much current as if you were running it at full throttle.
If the motor isn't hot right after you land, you're probably OK.
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I'm not sure what people are assuming, but a higher-pitch prop won't necessarily take less power. A greater fraction of power is lost by the propeller than by any other component in an electric stunt plane, so picking an efficient one is pretty important. Efficiency is kinda complicated, although you can calculate it, at least for a steady flight condition.
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I'm not sure what people are assuming, but a higher-pitch prop won't necessarily take less power. A greater fraction of power is lost by the propeller than by any other component in an electric stunt plane, so picking an efficient one is pretty important. Efficiency is kinda complicated, although you can calculate it, at least for a steady flight condition.
I kind of passed over that myself. A 6-pitch prop should be OK at 9500 RPM in this setup, and should regulate the speed better.
Dwayne, what led you to believe that the 6-pitch prop used "too much power"? Could you have been misled by the same battery problem?