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Old Jan 01, 2012, 04:40 PM
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Brushless eficiency. DJI, Herkules esc, Droidworx CX4 and Axi 2217/2

Hi friends.
I made today several flying test with ghe following equipment. DJI wokong, droidworx CX4, herkules II esc, 4s 3300 bat, 4 axi 2217/20 engines and three different airscrews that reported the following numbers:
Graupner 10x5 : 18.5 A/h 9 min. Flying time. 45°c temperature inside the engines.
Graupner 11x5: 17.5 A/h 9.5 min Flying time. 38°c temperature inside the engines.
APC 12x3.8: 15 A/h 11 min Flying time. 60°c temperature inside the engines.

Al flights where done at outdors temp of about 10°c and hovering all the time. The setting in the esc includes a 24 degree timming as recomended by AXI for this engines.

The question are:
1) Why a lower total amp. consumption whith the APC generates higher engine temperature?
2) A friends exactly equal equipment and settings with the graupner 10x5 but a different brand of flying board instead of DJI gets the same numbers but absolutely zero increase of engine temperature over the outdoors temperature. Is the DJI specially agressive with the engines may be due to a faster comunication of variations to the engines? Have heard something so related to MK with the last firm but refered to the esc temperatures. Any idea?
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Old Jan 01, 2012, 05:40 PM
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Norge, Vestfold, Tønsberg
Joined Apr 2010
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I'm using these motors a lot, and they run relatively cool on my MK/4S setup with 11x4.7 SF.

I think your low amp/high temp observation is interesting. My guess is that the 12x3.8 propeller is more efficient than the others you tested, and that this increase in propeller efficiency is more signifficant than the loss you see as higher motor temp. When that is said, I think 12x3.8 might be a little too much for the 2217/20, and especially if you are going to add payload to the craft.
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Old Jan 01, 2012, 06:32 PM
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Eagle Lake, Minnesota
Joined Apr 2003
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Quote:
Originally Posted by JanHenning View Post
I'm using these motors a lot, and they run relatively cool on my MK/4S setup with 11x4.7 SF.

I think your low amp/high temp observation is interesting. My guess is that the 12x3.8 propeller is more efficient than the others you tested, and that this increase in propeller efficiency is more signifficant than the loss you see as higher motor temp. When that is said, I think 12x3.8 might be a little too much for the 2217/20, and especially if you are going to add payload to the craft.
I agree, the 12-3.8's for payload application is a bit over the top for the 2217-20's I don't have an MK setup but I run the AXI 2217-20's on 3s with my 3.5 lb tricopter spinning the APC 10-3.8SF and the motors come down pretty much cold. I started with the 11-4.7SF prop but I like the way the 10-3.8SF matches my disc loading, it just responds better. Great motors

Mike
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Old Jan 02, 2012, 03:54 AM
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Quote:
Originally Posted by JanHenning View Post
My guess is that the 12x3.8 propeller is more efficient than the others you tested, and that this increase in propeller efficiency is more signifficant than the loss you see as higher motor temp.
That has sense, may be the way to go, as I want to add payload, is to lower the timming from 24 to 12 in order to accomodate it to the new weight and common rpm use (a non acrobatic UFO few times run at full power or full rpm).
Jan, can you tell me the weigh and rotor numbers of your ufo as well as an aproximate value of the engines temperature after a long hovering?
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Old Jan 02, 2012, 04:24 AM
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Norge, Vestfold, Tønsberg
Joined Apr 2010
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The weight of the craft included payload is 3100 grams, and it has 6 motors in a Y6 configuration. I have never measured, since they are really never that warm, but my guess is 10-20 degrees above ambient temperature.
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Old Jan 07, 2012, 08:12 AM
limburg Netherlands
Joined Aug 2004
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payload

Quote:
Originally Posted by elossam View Post
Hi friends.
I made today several flying test with ghe following equipment. DJI wokong, droidworx CX4, herkules II esc, 4s 3300 bat, 4 axi 2217/20 engines and three different airscrews that reported the following numbers:
Graupner 10x5 : 18.5 A/h 9 min. Flying time. 45°c temperature inside the engines.
Graupner 11x5: 17.5 A/h 9.5 min Flying time. 38°c temperature inside the engines.
APC 12x3.8: 15 A/h 11 min Flying time. 60°c temperature inside the engines.

Al flights where done at outdors temp of about 10°c and hovering all the time. The setting in the esc includes a 24 degree timming as recomended by AXI for this engines.

The question are:
1) Why a lower total amp. consumption whith the APC generates higher engine temperature?
2) A friends exactly equal equipment and settings with the graupner 10x5 but a different brand of flying board instead of DJI gets the same numbers but absolutely zero increase of engine temperature over the outdoors temperature. Is the DJI specially agressive with the engines may be due to a faster comunication of variations to the engines? Have heard something so related to MK with the last firm but refered to the esc temperatures. Any idea?
Nice setup!! what is the total weight and how many payload is acceptebel.
Can you place a photo about the connection between the DJI and Herkules?
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