Oct 16, 2012, 08:58 AM Registered User Chattanooga, Tennessee, United States Joined May 2003 27,208 Posts Original wind (723.9cc) has 96% more copper than the LRK wind (367.6cc). Pedantic professor again... how do you get this copper volume.. you can't fit almost a liter of copper in a tiny motor. I tried to calculate the volume: According to my chart AWG 18ga wire is 0.0403" diameter (= 0.102cm diameter)... thus radius is 0.051cm... square that and multiply by pi and you get cross section of 0.0082 square centimeters... multiply that by length of winding wire (116.8cm)... and you get 0.954cc.
 Oct 16, 2012, 09:24 AM Jack USA, ME, Ellsworth Joined May 2008 17,583 Posts Here is what I did: Volume of copper: Pi = 3.142, volume of cylinder = pi * r2 * h 8 strands of 0.24mm diameter x 2000mm (78") wire wrong answer = 3.142 x 0.12 x 0.12 x 2000 = 90.4896cc x 8 strands = 723.9cc of copper right answer = 3.142 x 0.12 x 0.12 x 2000 = 0.904896mm3 x 8 strands = 0.7239mm3 of copper 1 strand of 21 AWG 0.723mm x 1168mm (46") wrong answer = 3.142 x 0.3165 x 0.3165 x 1168 = 367.6cc of copper right answer = 3.142 x 0.3165 x 0.3165 x 1168 = 0.3676mm3 of copper I've been struggling with math for 70 years, I'm never surprised when I don't get it right. Jack Last edited by jackerbes; Oct 16, 2012 at 09:53 AM. Reason: Correct my bonehead math errors
 Oct 16, 2012, 09:39 AM Jack USA, ME, Ellsworth Joined May 2008 17,583 Posts It now occurs to me that my units should have been cubic millimeters, not centimeters... I have corrected it I think. Jack Last edited by jackerbes; Oct 16, 2012 at 09:54 AM.
 Oct 16, 2012, 05:10 PM Registered User Chattanooga, Tennessee, United States Joined May 2003 27,208 Posts Yes, Jack... the factor of 1000 was the missing bit... we didn't use exactly the same wire diameter, so we don't get exactly the same answer... but we both ended up in the correct order of magnitude!
 Oct 17, 2012, 01:10 PM What goes up must come down.. Canada, QC, Saint-Laurent Joined Jan 2002 1,739 Posts Interesting Jack...! I can't wait here for the results once it's all wind.. lot more copper!
 Dec 25, 2012, 05:37 PM 5,200 Led Lighted Bike-Bob P. USA, MA, Swansea Joined Mar 2003 2,958 Posts I just saw this in HK and spotted this motor. Has anyone tried one of these monsters? Hex DT-750's big brother. http://www.hobbyking.com/hobbyking/s...ner_900kv.html **Neons** Bob
 Dec 25, 2012, 08:03 PM Jack USA, ME, Ellsworth Joined May 2008 17,583 Posts I don't think it has been mentioned here before. Looking at the specs and dimensions it is nearly identical to the DT750, but they say it will handle twice as much current? Not sure I'll believe that until is has been proven by independent testing. DT750 - http://www.hobbyking.com/hobbyking/s...ner_750kv.html DT900 - http://www.hobbyking.com/hobbyking/s...ner_900kv.html Jack
 Dec 25, 2012, 08:49 PM Registered User St Catharines Canada Joined May 2002 943 Posts Theres also a 1000Kv that looks to be the same thickness as the D4023-850 where the 900 seems to be same as the DT 750. I've not tried either one but am interested in any info or tests anyone might do. Richard
 Dec 25, 2012, 10:13 PM Registered User Mexico, BC, Mexicali Joined Aug 2004 5,520 Posts My effort to 909Kv. DT750, 16T 21awg. No load: 11,000 rpm, 12.1V, 1.7A, 909 kv. APC 12x6e, 7500rpm, 11.2V, 24A, 263Watts, 1590g. http://www.rcgroups.com/forums/showt...=777998&page=5 To 400 watts is a cafe heater.
Dec 25, 2012, 11:01 PM
What goes up must come down..
Joined Jan 2002
1,739 Posts
Merry Xmas all!
MAnuel v I finally found some tests (wattmeter) around the L3010C motor that you post before (previous page) on youtube that too is "impressive" results for a stock motor!
I can only guess what you or Jack among other here with your nice rewind could do to this one by rewinding one it would almost need a new thread.
I just got one but I lack a good ESC or I have to find out how to properly hook an "opto" one I have on hands...
Here FYI:
 Turnigy L3010C-1300kv (420w) Thrust Test (1 min 25 sec)

Roger
Last edited by rodair; Dec 25, 2012 at 11:11 PM.
 Dec 26, 2012, 04:09 AM Registered User Antony (France) Joined Sep 2003 3,118 Posts Hi Rodair L3010C questions Could you measure the diameter of the stator tube to go in the flanged support ? Is the L3010C a 12N14P ? Is the stator 30x10 mm ? Are the magnets flat or curved ? Recent DT750 (4 bought in 2012): Stator is 34x7mm 12N, 14P flat Stator tube is around 9mm Rotor extra blue cylinder is around 10mm no flat, one set screw No connectors It seems that DT900 has a flat on the rotor small cylinder ? Louis Last edited by Fourdan; Dec 26, 2012 at 04:42 AM.
 Dec 26, 2012, 07:36 AM What goes up must come down.. Canada, QC, Saint-Laurent Joined Jan 2002 1,739 Posts Louis, physically the L3010C (1300kv) also under the name EDF in Europe, is a different motor than the DT750! The alum tube is only 7mm instead of 8mm on the one's thus smaller tube bearingd OD The bell is also smaller in dia. the stator and bell a little longer but not by much, finally same arrangement as for the magnets and poles 12Poles 14Magnets and came with 4mm bullet connectors installed. Maybe I'll post some pictures later but I really don't want to hi-jack this thread. So thanks for the heads up since it look like some previous made DT-750 (Jack post) for the bearings size thus for me a problem I thaught to just remove 2 set screw and try this one in my planes! I am now in a defferent ball park... furthermore "lock tight" will be a MUST to avoid the heavy torque of this one...and I can also forget about the bearings that I have in stock since they are not compatible! @ 7mm x 4mm x ?mm lg. and tiny. One will also have to be carefull when thigthening the set screw not much meat on the alum. bearing tube for the same matter. On the other hand this one will fit the alum. with heat sink extrusion motor mount for the 24gr. "blue motor" smaller motor that can attach to a 10mm sq. beam and it might the way to attach this one in a more secure less stressing way for the bearing tubes. I also order it's brother motor the 3010B one that is having a sturdy common mount and bigger bearings althogether...again let's not deviate from the DT-750 here. I hope this help...defeneatly mauel v is still the winner here with his rewind one! Roger
Dec 26, 2012, 09:33 AM
5,200 Led Lighted Bike-Bob P.
USA, MA, Swansea
Joined Mar 2003
2,958 Posts
Quote:
 Originally Posted by jackerbes I don't think it has been mentioned here before. Looking at the specs and dimensions it is nearly identical to the DT750, but they say it will handle twice as much current? Not sure I'll believe that until is has been proven by independent testing. DT750 - http://www.hobbyking.com/hobbyking/s...ner_750kv.html DT900 - http://www.hobbyking.com/hobbyking/s...ner_900kv.html Jack
Beng nearly identical motors there has to be some strong differences in the windings and weight.. It is a lot to get more power out of the DT-900 over the DT-750. If this DT-900 uses the same 7mm bearng as the 750 motors it will be a load of stress on them if the power claims are correct. I am still thinking maybe the tube can be reworked to take 2 rear bearings to make it a double row.

I wonder if the DT-900 is a better way to go than the DT-750 or 700? This is where I hope to see a side by side comparison sheet in operation tests. Or, would it be advisable to abandon the DT-900 and 750 series and just start a change over to the L3010C motors. I know very little about the L3010C motors. This is my only motor thread I am subscribed too. I will look at the new posted link on this motor also.

**Neons** Bob
Dec 26, 2012, 10:19 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,583 Posts
Quote:
 Originally Posted by **neons** Beng nearly identical motors there has to be some strong differences in the windings and weight.. It is a lot to get more power out of the DT-900 over the DT-750. If this DT-900 uses the same 7mm bearng as the 750 motors it will be a load of stress on them if the power claims are correct. I am still thinking maybe the tube can be reworked to take 2 rear bearings to make it a double row.
The later DAT-750's had the bearings increased from 7mm to 9mm O.D. And those are an OK size. Not optimal for long life or anything but OK. Most of us will damage bearings and replace often as they are cheap.

Quote:
 I wonder if the DT-900 is a better way to go than the DT-750 or 700? This is where I hope to see a side by side comparison sheet in operation tests. Or, would it be advisable to abandon the DT-900 and 750 series and just start a change over to the L3010C motors. I know very little about the L3010C motors. This is my only motor thread I am subscribed too. I will look at the new posted link on this motor also. **Neons** Bob
The 900 is certainly worth a try. It is the same weight as a DAT-750, probably has the bigger bearing tube, bigger bearings.

The L3010C is also worth a try. It is interesting that it is 4mm smaller in O.D. at 37mm, appear to have about the same stator height as the DAT-750, but is listed as weighing 87 grams or about 9-11 grams more than a 750. Weights are a good indicator of potential but HK is notorious for being a little inconsistent in reporting weights.

I think I'll always have an inordinate fondness for the larger diameter CD-ROM style motors because they are so easy to work on and I also think that their larger diameter contributes to their power. I say that because of the "longer lever" effect it you will when the out runner gearing effect is applied. The magnets are standing further from the center of the motor, they must have more leverage, no?

Jack