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Cell count on brushless motors .

Old 04-15-2009, 07:56 PM
  #51  
BEX
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My results were very clos too , 36A on the 12x6 , and 37A on the 10x10.
But with the 10x10 it took forever for the plane to get to flying speed. Luckily i had 200 m of road.
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Old 04-15-2009, 08:41 PM
  #52  
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Originally Posted by BEX View Post
But with the 10x10 it took forever for the plane to get to flying speed. Luckily i had 200 m of road.

yea, funny how that is even when you have over 2:1 thrust...LOL

SK
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Old 04-15-2009, 11:10 PM
  #53  
kyleservicetech
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bex
The esc is rated 2S-6S , i ran 5S through it.
I ordered a couple of props to try get more from the motor , i think the 12x8 will be the ticket.

Out of curiosity, what brand of ESC is this? I've got five different Castle Creations ESC's, run them at their rated maximum current rating, and they only get slightly warm at their rated power output.

If you overvoltage these ESC units, they can blow a Fet, when that happens, things get nasty real quick. You will likely see a very hot spot on the ESC shrink wrap where the Fet has failed.

How ever, even the CC ESC units can run hot, if you are trying to use the ESC internal Battery Elimination Circuit (BEC) to power your radio. Or, if you are using a separate battery to power your radio, make danged certain to disconnect the ESC RED wire to your receiver! If you don't do this, you wind up with the ESC BEC circuit trying to charge your receiver battery. And, the five volt regulator on the ESC will get hot. Don't ask how I know.:o
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Old 04-16-2009, 08:12 AM
  #54  
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The Esc that I used is the Pulso DLU 60A , no BEC.
http://www.rcmaterial.com/pdfs/Manual_ESCPulso_EN.pdf

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Old 06-18-2009, 05:32 AM
  #55  
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Hey BEX,

Just wondering if you ever came to a conclusion on the best prop to use with the 42-40-1000 on 3-cell, or 4-cells?

I have one and can only get 300 watts out of it using an APC 11x7E and 3-cells. I've grilled the manufacturer on their specs but they won't give me a straight answer. I think their specs are way off.
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Old 06-18-2009, 07:15 AM
  #56  
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Originally Posted by Tony C View Post
Hey BEX,

Just wondering if you ever came to a conclusion on the best prop to use with the 42-40-1000 on 3-cell, or 4-cells?

I have one and can only get 300 watts out of it using an APC 11x7E and 3-cells. I've grilled the manufacturer on their specs but they won't give me a straight answer. I think their specs are way off.
that looks like a 4cell motor... Kinda weak on 3 cells prob prop higher....

here's a review I found helpful

Prop tests on fully charger 3 cell 2100mAh D9 lipo battery:

APC E 11x8.5 7400rpm 30Amps 2.6lb thrust 59mph pitch speed
APC E 12x6 7400rpm 30Amps 3.2lb thrust 42mph pitch speed
APC E 12x8 7100rpm 33Amps 3.4lb thrust 53mph pitch speed

Would recommend APC E 10x7 prop if using 4 cell lipo. I have not tested on 4 cells but would expect 33A to 35A current draw and around 9800rpm(3.5 lB thrust and 64mph pitch)
(or 11x5.5e prop for similar results)

SK
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Old 06-18-2009, 05:17 PM
  #57  
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Thanks, miniteve2003.

That's exactly the info I needed. And it confirms what I thought: Great planes specs are way off on this motor! (This is just my opinion - anyone interested should form their own). They are claiming a good 36% better performance than I am getting with the 42-40-1000 on 3-cells. And what I am getting matches up with everyone else. I guess I will have to go with 4-cells to get what spec said I would get on three.

It really bugs me that Great Planes would advertise such specs and then not meet them - or at least come close. I use to have a lot of confidence in Great Planes, but I bet next time I go with a Scorpion.

Tony C

Last edited by Tony C; 06-18-2009 at 05:36 PM.
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Old 06-18-2009, 06:14 PM
  #58  
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Originally Posted by Tony C View Post
Thanks, miniteve2003.

That's exactly the info I needed. And it confirms what I thought: Great planes specs are way off on this motor! (This is just my opinion - anyone interested should form their own). They are claiming a good 36% better performance than I am getting with the 42-40-1000 on 3-cells. And what I am getting matches up with everyone else. I guess I will have to go with 4-cells to get what spec said I would get on three.

It really bugs me that Great Planes would advertise such specs and then not meet them - or at least come close. I use to have a lot of confidence in Great Planes, but I bet next time I go with a Scorpion.

Tony C

LOL... and Here I though you were using a turnigy 42-40-1000kv motor...LOL

I once used a 28mm inrunner of Great planes... and then bought a hxt 28mm of the same specs... and they were near identical in performance...

If your going to be using a 3cell pack, it's prob best to stay in the 35mm range... the 42's are pretty much the same on watts, however they will be able to take a bit more heat, and a bit more RPM's... for certain applications... but they are heavier so it can become a tossup...

SK
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Old 06-18-2009, 06:22 PM
  #59  
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here's the specs for the GP's one... it looks pretty close to the turnigy one, however it does say it allows for higher amps (prob not good though)

Can Diameter: 1.65" (42mm)
Can Length: 1.57" (40mm)
Shaft Diameter: .20" (5mm)
Shaft Length: .67" (17mm)
RPM/V (kV Rating): 1000
Weight: 4.4oz (125g)
Propeller: 10.5E-11x7E
Input Voltage: 11.1-14.5V
Max. Constant Current: 45A
Max. Surge Current: 50A
Max. Constant Watts: 666W
No Load Current: 2.5A


lets see...

11.1 x 50a = 555watts...
14.8 x 50a = 740watts... "hear dangerzone theme song"...LOL

more like
14.8x 40-45amps = 600-666watts.... sounds about right...

SK
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Old 06-18-2009, 06:54 PM
  #60  
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Here are the REST of the specs though:

11x7E, 8970 rpm, 44.5 amps, on 3-cell

And I can't get anywhere close to that on 3-cells. I pull only 28.6 amps on 3 cells with same prop.

Here's where I'm getting the rest of the specs (note-the 42-40-1000 is on the right column): http://www.electrifly.com/motors/mot...ire-42-40.html

I'm about to pull my hair out (what's left of it - lol). I can't decide if I have a bad motor or if this is just the best it can do. I hate to get a warranty replacement and have it perform exactly the same or worse.
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Old 06-18-2009, 07:14 PM
  #61  
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Originally Posted by Tony C View Post
Here are the REST of the specs though:

11x7E, 8970 rpm, 44.5 amps, on 3-cell

And I can't get anywhere close to that on 3-cells. I pull only 28.6 amps on 3 cells with same prop.

Here's where I'm getting the rest of the specs (note-the 42-40-1000 is on the right column): http://www.electrifly.com/motors/mot...ire-42-40.html

I'm about to pull my hair out (what's left of it - lol). I can't decide if I have a bad motor or if this is just the best it can do. I hate to get a warranty replacement and have it perform exactly the same or worse.
hmm... sounds like it's hitting the same/similar specs to the 800kv version... wonder if it got mis-labled

SK
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Old 06-18-2009, 07:31 PM
  #62  
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Originally Posted by ministeve2003 View Post
hmm... sounds like it's hitting the same/similar specs to the 800kv version... wonder if it got mis-labled

SK

That's a possibility I hadn't thought of. I'll get some rpm measurements without the prop, later today, and see if I can tell. And thank you for taking the time to look at those specs.

Actually I just looked at the "no load current" specs for both and I am getting exactly what they are getting for the 1000kv (2.5 amps), so that would tend to indicate it is a 1000kv as labeled
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Old 06-18-2009, 08:25 PM
  #63  
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Something doesn't seem to add up here. I've been playing around in Drive Calculator using the motor specs from the Electrifly web site. It predicts about 37 amps for both the 11x7e 3 cell schenario and 10x5e 4 cell schenario for 1000 Kv motor compared to the approximately 45 amps shown on the web site. It also predicts about 27 amps for the three setups for the 800 Kv motor as well compared to values in the low 30's they show.

I'm wondering if their published values are NOT from measurements but are rather predictions from some (incorrectly used) drive system calculator program.
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Old 06-18-2009, 08:54 PM
  #64  
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Originally Posted by MustangMan View Post
I'm wondering if their published values are NOT from measurements but are rather predictions from some (incorrectly used) drive system calculator program.
I have an email from product support claiming they actually tested the motors (Great Planes 42-40-1000): Here is exactly what the email said:

"I did some of the testing on the Rimfire line of motors when they were being developed. We went back through our old data and I can tell you that the numbers we saw (42-40-1000, 11x7E, 11.1V, 8970rpm) were consistent in that series of runs. We were testing with a power supply so we did not have the "drop-off" that modelers experience with battery packs so that may skew the numbers a bit."

Even if they were delivering a full 11.1 volts to the speed control, that still doesn't account for the 36% difference I, and some other's, seem to be getting.

But I agree with MustangMan, something does not add up. I think my motor (and probably more GP 42-40-1000's) just plain don't come anywhere close to spec

Last edited by Tony C; 06-18-2009 at 09:15 PM.
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Old 06-19-2009, 12:03 AM
  #65  
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here's the specs for the GP's one... it looks pretty close to the turnigy one, however it does say it allows for higher amps (prob not good though)

Can Diameter: 1.65" (42mm)
Can Length: 1.57" (40mm)
Shaft Diameter: .20" (5mm)
Shaft Length: .67" (17mm)
RPM/V (kV Rating): 1000
Weight: 4.4oz (125g)
Propeller: 10.5E-11x7E
Input Voltage: 11.1-14.5V
Max. Constant Current: 45A
Max. Surge Current: 50A
Max. Constant Watts: 666W
No Load Current: 2.5A

Lets see, 660 watts, motor weighs in at 4.4 ounces. If you divide the factory "rated watts" by the motor weight in ounces, you get a kind of a performance indicator. This motor comes out to 150 watts per ounce of motor weight. In my personal opinion, any motor running over 100 watts per ounce of motor weight had better be very well cooled, or never run at full power for long (or both). Or the motor could look kind of funny after a flight. :o
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