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Small Brushless Outrunner w/o Speed Controller

Old 03-21-2007, 01:57 AM
  #1  
Lowrpm
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Default Small Brushless Outrunner w/o Speed Controller

Hi,
I'm brand new and I bet a some of you guys are gonna have fun with this post. I bought a small motor on Ebay thinking I could use it in my small pardon the phrase, "control line" planes. Been using a few small Hi Line cans with NimHd batteries. So then I read that the motor would be ruined running it w/o a controller.

So, how do I run this motor flat out for C/L? It's real small, 19 grams, 7A, and swings a 5/3 prop. Any advice would be appreciated, thanks.
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Old 03-21-2007, 01:58 AM
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skiman762
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Brushless motor are 3 phase you can run them without an ESC
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Old 03-21-2007, 07:04 PM
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Aero Ace Ace
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Brushless motors do require an ESC. You can't run them without one. I'm not sure how to run them without R/C control.
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Old 03-21-2007, 07:30 PM
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UncleBob
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You can run a brushed motor without an ESC.
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Old 03-21-2007, 09:42 PM
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pilotpete2
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A brushless DC motor will not run without the ESC, as it is the speed controller plus the commutator for the motor, the motor by itself is not complete.
Pete
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Old 03-21-2007, 10:25 PM
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Originally Posted by UncleBob View Post
You can run a brushed motor without an ESC.
Emphasis added
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Old 03-21-2007, 11:06 PM
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pilotpete2
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As UncleBob said, make it easy on yourself, get a brushed motor
Pete
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Old 03-22-2007, 12:17 AM
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Lowrpm
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Default Brushless Outrunner w/o Speed Controller

Originally Posted by Aero Ace Ace View Post
Brushless motors do require an ESC. You can't run them without one. I'm not sure how to run them without R/C control.
Thanks 3A, I'll have to figure it out. There's got to be a way. It sure is a cool looking little motor
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Old 03-22-2007, 12:35 AM
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Thanks all, have you guys seen this film? I bet this guy has an esc.

http://www.youtube.com/watch?v=CX05i2CXuko
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Old 03-22-2007, 12:39 AM
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UncleBob
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Brushless motors run on AC, batteries store and provide DC. You HAVE TO HAVE an ESC, but you might be able to rig a switch to pin the speed command to common and then to supply positive.

The switch is needed to arm the ESC, and I'm not sure it would even work. Use a brushed motor - they can be just as efficient at 100% anyway.
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Old 03-22-2007, 01:29 AM
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pilotpete2
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Originally Posted by UncleBob View Post
Brushless motors run on AC,
No, they are actually electronically commutated motors, or BLDC to be exact, and run on the same principle as brushed motors. Only commutated motors have a Kv rating
You can run one on a variable frequency drive, but starting is tricky, on normal fixed frequency AC 60/50 Hz, they won't start at all, they'll just sit there humming. Brushless motors have absolutley nothing in common with an AC induction motor and only a little similarity to an AC synchronous motor as they lack the AC synchronous motors ability to start in asynchronous mode to get up to synch speed.
Pete
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Old 03-22-2007, 05:12 PM
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UncleBob
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And I thought I was a hair splitter.

When they run, they're running on AC. The fact that the controller supplying the AC has to carefully hand-craft that AC to match the speed and phase of the motor is an implementation detail.

More to the point, they need an ESC.
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Old 03-22-2007, 09:55 PM
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Cyberwollf
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Brushless motors DO run on AC. No matter what frequency or how fast the current is switched it is still Alternating Current. Without it, there are no rotating flux waves to move the motor.
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Old 03-23-2007, 12:47 AM
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Originally Posted by UncleBob View Post
And I thought I was a hair splitter.
\

No, more of a "nit picker" ,when I hear "split a Hare" all I can see is Witch Hazel sharpening her knife to carve up Buggs Bunny
I appologize for getting a bit O.T.:o

Both of you are right in that a brushed or brushless DC motor creates it's own "AC" current thru the commutation process, the confusion arises because it is easy to think that the ESC and the motor are separate enties when they are not, they operate in a closed loop environment and will not function without the other. The input to the motor is the DC supply, not the 3 wires between the commutator and the coils. The important point to consider is that "brushless" motors operate on the commutation principle and are a relativlely recent development in the brushed/commutated motor family and are not classed as "AC" motors.
Here are some links with good info.
Brushless DC electric motor
Brushless DC electric motor - Wikipedia, the free encyclopedia

Now, no argument about the OP's problem, must have an ESC, or better yet, save the brushless motor and use a brushed motor

Regards to All,
Pete
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Old 03-23-2007, 12:59 AM
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Why does that link look so familiar? lol.
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Old 03-23-2007, 01:57 AM
  #16  
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Originally Posted by Lowrpm View Post
Hi,
I'm brand new and I bet a some of you guys are gonna have fun with this post. I bought a small motor on Ebay thinking I could use it in my small pardon the phrase, "control line" planes. Been using a few small Hi Line cans with NimHd batteries. So then I read that the motor would be ruined running it w/o a controller.

So, how do I run this motor flat out for C/L? It's real small, 19 grams, 7A, and swings a 5/3 prop. Any advice would be appreciated, thanks.
The motor needs a controller (ESC) to run at all. Most of us using brushless motors in C/L models use a timer to drive the ESC. There are C/L timers made by JMP and ZTron and you can get them from Bob Selman http://www.bsdmicrorc.com/products.cfm?catID=10006

Steve
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Old 03-23-2007, 06:22 AM
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Originally Posted by Lowrpm View Post
Thanks all, have you guys seen this film? I bet this guy has an esc.

http://www.youtube.com/watch?v=CX05i2CXuko
No ESC, it has a CARB.
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