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Eagle Tree Systems Onboard data loggers, telemetry, and OSD support


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Old 07-19-2007, 02:18 AM   #1
twoturnspin
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Default RPM Data on Eagle Tree Micropower

I have a Eagle Tree MicroPower on my TRex 600 and it has been working great. I just added in a Brushless RPM Motor Sensor but can't seem to get it working right. It it telling me that my RPM is around 30,000 which is clearly wrong.
I'm running the standard 170 gear with a 10 tooth pinion and the standard 600 motor (6 pole) so I have put in 17:1 was the gear ratio and poles = 6 which I think is correct.
Does anyone know why my RPM would be showing 15 times higher than it actually is?
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Old 07-19-2007, 02:25 AM   #2
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Hmm looks like it is reading the RAW motor RPM I have an eagle tree but not with a RPM sensor so I have no experience. 30K is actually low if your running 100% throttle curve and 2200 head speed.

1620KV motor x 22.2V = 35.964 motor RPM at 100% thottle and 100% effeciency... Not sure it actually uses the gear ratio? Maybe it does just show real motor RPM?

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Old 07-19-2007, 02:34 AM   #3
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You've probably got it set up right. You just need to reconfigure your graph to plot "prop RPM" instead of RPM.
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Old 07-19-2007, 02:38 AM   #4
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Thanks Bob, I understand the maths but my understanding is that it should show the RPM of the blades not the motor based on the info on the Eagle Tree website.
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Old 07-19-2007, 02:52 AM   #5
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Ahhhh!!! Well that makes me pretty stupid!

Thanks for the heads up cbdane and Bob, all looks good now. Flight starts at 1800 and drops to 1700 by the end, I'm guessing an 11 pinion would take it 2000 max. I'm not sure if I should go to an 11 pinion or not, might have to try it to see how much more power it uses.

Thanks again, I thought I was going crazy for a while.
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Old 07-19-2007, 06:13 AM   #6
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I just got my RPM sensor yesterday. I'm pretty sure I'll use this information :wink:
Thanks guys!!!
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Old 07-19-2007, 07:49 AM   #7
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To get HS from a 17:1 gear down I just put 0.0588 in the calibration box and it seems to work fine
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Old 07-19-2007, 10:07 AM   #8
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twoturnspin - Are you using the L or XL motor?
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Old 07-19-2007, 11:26 AM   #9
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Quote:
Originally Posted by twoturnspin
Flight starts at 1800 and drops to 1700 by the end, I'm guessing an 11 pinion would take it 2000 max.
I had my curves set up on my XL and 10 tooth straight pinion to give me 2100rpm dropping to a little less than 2000 by the end of the flight. Still had decent flight times (~5.5min).

I now have the Neu 1515/2.5 running on 6S. Using the same headspeeds as above, I only use ~3700mAh after 6 minutes of fairly vigorous flight. Still with the 10T straight pinion.

Anyway, long winded response to say that you don't need 11T to run over 2000rpm and your motor will run cooler for it.
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Old 07-19-2007, 06:02 PM   #10
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Quote:
twoturnspin - Are you using the L or XL motor?
Using the L Motor, looking at cbdanes figures I'm guessing the xl motor would give me 300 more rpm at 2100. My curve for Idle 1 is 100-90-100 at present.

I don't particularly want to buy another motor (rather put it towards another battery) so the question for me is do I go with the 11t pinion to get me to 2000 or is 1800-1700 ok? My flights have rolls, loops, flips, tictocs, etc and my present goal is to try to clean them all up and make them neat before I move on (I'm a bit obsessed about this).
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Old 07-20-2007, 04:49 PM   #11
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what is your pitch set to? that can change the hs.
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