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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Alan Buck on January 24, 2010, 10:19:04 AM

Title: cobalt motor question
Post by: Alan Buck on January 24, 2010, 10:19:04 AM
I have one new in the box. is any good for anything in c/l flying. it is a CEM cobalt motor  cem 0506  thanks
Title: Re: cobalt motor question
Post by: Alan Hahn on January 24, 2010, 10:48:43 AM
Alan,
I am not that acquainted with this motor, but from what I can find, it is a brushed motor with a kV in the 2000 rpm/volt range.

Probably means that you would be flying with 2s Lipo pack to get rpm's in the 10-12000 rpm range.

I have an Astro 05 Cobalt motor that I use to fly in an old Goldberg Electra RC powered glider. I am not sure if the two are similar, but I bet they are.

I think the motor can handle ~20A or so max, so that would give you ~160watts of input power. My SuperClown setup was running somewhat higher than that, so I am guessing that you are probably going to be marginal with that size plane.

The downside is that this motor is relatively heavy for its power handling capabilities (~5-6 oz if I got the specs right) compared to a brushless motor. Also you need a brushed controller if you don't already have one.

My guess is that it probably would be cheaper in the long run to go to a brushless setup--this depends if you already have the ESC and battery in hand. If you don't then buying a brushed setup with a 2s pack is probably a dead-end system. You won't have a governor mode capability (AFAIK) for example.

So although it might be fun to try, my advice is to go brushless.

Maybe others have more experience with this and would have a better idea of a suitable setup and airframe.

Alan
Title: Re: cobalt motor question
Post by: Dennis Adamisin on January 24, 2010, 01:14:17 PM
I agree with all Alan said (no surprise there!) and add this: With a high winding cobalt it seems logical to add a gearbox - however I tried that with a brushless inrunner last summer and the gearbox lasted 10 flights!  Thus I think you are better off with direct drive and probably a smallish prop - maybe a 7x4.

Its possible to plug the motor directly into the battery but DON'T DO IT with Lipo's - you will go dangerously deep into discharge ruining the batteries or worse.   Use an ESC with a Lipo cut-off voltage mode.  Then I suggest writing to Wil Hubin and asking him to build a suitable timer - I'd think a normal timer would do the deed but check with Wil to be sure.

Title: Re: cobalt motor question
Post by: Alan Buck on January 24, 2010, 06:05:42 PM
Alan & Dennis, Thanks for your answers. I thought it was heavy for use on a super clown Thank you