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Brushless motor suggestion for 5 lbs weapon on battlebot

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Old 11-12-2008, 07:21 PM
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Default Brushless motor suggestion for 5 lbs weapon on battlebot

I'm building a battlebot (floorsweeper) and i'm looking for a motor for the weapon. The weapon is 5lbs and 16 inches long. The voltage i'm going to be running is 14.4. My question is what brushless motor will work to spin the weapon up in 1 or 2 sec and spin around 7,000 rpm.
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Old 11-12-2008, 08:16 PM
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Default RE: Brushless motor suggestion for 5 lbs weapon on battlebot

What does the weapon look like? Is it a solid bar of metal or is the weight concentrated on the ends.
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Old 11-12-2008, 08:40 PM
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Default RE: Brushless motor suggestion for 5 lbs weapon on battlebot

it would be a solid bar with the weight distributed evenely
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Old 11-15-2008, 06:33 PM
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Default RE: Brushless motor suggestion for 5 lbs weapon on battlebot

Give me the bar dimensions and material and I'll do the math tonight. I won't recomend a motor but I'll give you the power range you should be looking at. If you could send me a PM that would be fantastic because I don't check this forum very often and I don't want to forget.
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Old 11-15-2008, 10:19 PM
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Default RE: Brushless motor suggestion for 5 lbs weapon on battlebot

Your not going to like the results, but I could have told you that right away. If you want to spin up your weapon that fast you need a huge motor. 8600 watts huge. I don't think you'll find an 11.5 horsepower out runner anywhere, let alone stay in your weight class with the batteries it will need or afford it.

I made a spreadsheet so that you could mess around with dimensions, rpm, time to get up to speed, etc. You can download it [link=http://cid-4a947c0fd105ba34.skydrive.live.com/self.aspx/Public/Spinner%20Motor.xls]here.[/link] I left out the inertia of the motor, shaft, and drivetrain as the shaft and motor are negligible and I assumed you are going to use a lightweight belt drive. I'm 99% sure my math is correct but if someone could check it that would be fantastic. I haven't done off center moment of inertia calculations in awhile.

Whats the weight class? Right now you have enough theoretical power to send a 200 pound bot flying 55 feet in the air.
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Old 11-16-2008, 08:46 AM
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Default RE: Brushless motor suggestion for 5 lbs weapon on battlebot

the weight class is 15 lbs
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