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RC Electric Motor needed for non rc sciencel project?

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Old 07-23-2013, 01:45 AM
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Xsfacade
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Default RC Electric Motor needed for non rc sciencel project?

I hope this is the correct posting location since my searching found nothing similar. I need help in a bad way trying to find the correct motor to run an attached disk approximately 10.25" in diameter with a total weight of no more then 4 pounds. This is a science experiment in gravity requiring high rpm that can be adjusted. I may need two motors counter rotating for a gyroscope effect so that has to be considered as well. The attached disk will have weights at the outer edge. Size is important due to space so an outrunner design that is relatively flat will help. I am guessing at this point on required rpm so the higher the better. One other issue is air flow due to a required sealed containment vessel and a possible vacuum enviornment for added benefits to lengthy to explain here. I have looked at kinds of motors and RC keeps coming up. I interested in simplicity the most so I can focus on experimental measurements. Oh yeah I cannot get it paid for by school and at last check Bill Gates has not replied to my request for adoption so money is a factor
Any free advice is very welcomed.
Thanks
Jason
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Old 07-23-2013, 06:37 AM
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Default RE: RC Electric Motor needed for non rc sciencel project?

With discs that heavy you'll probably burn up an RC motor trying to get them started. If you can do the experiment with a constant speed motor, look into using a starter motor for a motorcycle or ATV or either the starters we use for glow engines. They run on straight 12v power and can handle quite a load. How many RPM do you need?
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Old 07-23-2013, 08:09 AM
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Default RE: RC Electric Motor needed for non rc sciencel project?

Well, let's think. If an OFNA Nexx10SC weighs 4.5 pounds and uses a brushed motor, then why not use that one: http://www.amainhobbies.com/product_...FShp7Aod7kUA3g
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Old 07-23-2013, 08:13 PM
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Default RE: RC Electric Motor needed for non rc sciencel project?

Turning a 1 ounce tire to move a vehicle that weighs 4 pounds is not the same thing as turning a 4 pound wheel.
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Old 07-23-2013, 11:25 PM
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Default RE: RC Electric Motor needed for non rc sciencel project?

I really want to stay away from brushed motors due to other parts of experiment involving high current since brushes are carbon and if I need to seal it the brush dust will really give voltage a path. I am very aware of spinning mass equations but not aware of other things like all the different types of brushless motors that don't cost a fortune. If school paid for it I would just order the specs I need with their money but that is not the case yet. I need to show proof of theory before I can ask for financial help from anyone. I have looked very closely at the Bolan oven hood motors made in Germany. They are only 1000rpm but I can boost that with high power magnets for next to nothing. They are also of an outrunner design which adds to the centripital forces I need. The only issue is they are a little heavier then I want before I add magnets. Brushless motor is the definate design I need to stick with. Any other ideas?

Motor size no bigger then 3"x3" and rpm abover 5k if possible. The other part is the control system to modulate the pwm signals.
Thanks
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Old 07-23-2013, 11:55 PM
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Default RE: RC Electric Motor needed for non rc sciencel project?

"The other part is the control system to modulate the pwm signals.
Thanks"

That's actually fairly easy. In the R/C hobby market, you will find servo testers, and even digital readouts.
The readouts show between 1000 and 2000 for the "standard" range of servo travel, or the pulse with in ms.
Jomar (Electronic Model Systems) is one source.
The servo tester plus the usual ESC with a built in BEC and an appropriate battery plus the motor
can get the job done. A four pound disk has a lot of inertia to overcome with the usual model A/C motors.
This would require an extremely slow spinup and spindown, as well as support bearings.



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