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Spinning disk question

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Spinning disk question

Unread postAuthor: Carlman » Sat Jun 07, 2008 4:00 am

If i had a spinning disk that measured 8cm in diameter and i wanted the outside to be moving at 300km/hr how many RPM would the disk have to be spinning at?
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Unread postAuthor: jackssmirkingrevenge » Sat Jun 07, 2008 4:27 am

So, the disc has a circumference of (pi x diameter) around 0.00025 kilometres, so at 1 rpm the outside is travelling at 0.015 km/h

You want 300 km/h however, which means that your disc is going to have to be spinning at (300 / 0.015) the grand rate of 20,000 revolutions per minute.

Do I sense a centrifugal launcher in the works...?
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Unread postAuthor: SpudFarm » Sat Jun 07, 2008 4:36 am

mabe he is making something like the steam cannon mythbysters made?

(i saw only 3minutes of that episode)
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Unread postAuthor: Carlman » Sat Jun 07, 2008 4:38 am

jackssmirkingrevenge wrote:Do I sense a centrifugal launcher in the works...?


maybe...

your too good JSR! :roll:
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Unread postAuthor: SpudFarm » Sat Jun 07, 2008 4:39 am

you will need one hell of a thing to spin it.
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Unread postAuthor: Carlman » Sat Jun 07, 2008 4:42 am

spudfarm wrote:you will need one hell of a thing to spin it.


rc airplane motor and gears
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Unread postAuthor: SpudFarm » Sat Jun 07, 2008 4:43 am

frakin NICE!!
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Unread postAuthor: jackssmirkingrevenge » Sat Jun 07, 2008 4:51 am

Carlman wrote:rc airplane motor and gears


That will have to be quite a substantial motor, considering the load it will be under, I suggest you read up on the theory before attempting anything, or simply use the biggest motor you can find and go from there :wink:
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Unread postAuthor: Carlman » Sat Jun 07, 2008 4:52 am

just found this on ebay

link

worth getting?
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Unread postAuthor: SpudFarm » Sat Jun 07, 2008 4:53 am

oh i thought you was using a nitro engine
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Unread postAuthor: Carlman » Sat Jun 07, 2008 4:55 am

jackssmirkingrevenge wrote:
Carlman wrote:rc airplane motor and gears


That will have to be quite a substantial motor, considering the load it will be under, I suggest you read up on the theory before attempting anything, or simply use the biggest motor you can find and go from there :wink:


yea well that is the thing im debating on a hard slog at a centriugal lancher like the PEST or a tennis ball laucher style used for bbs.
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Unread postAuthor: jackssmirkingrevenge » Sat Jun 07, 2008 4:58 am

Looks good for the price.

Load Speed (rpm) : 39000


That should suit you fine, probably without a gearbox... now get your hands on some epoxy and carbon fibre matting and make yourself a lightweight yet strong disk :)
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Unread postAuthor: Carlman » Sat Jun 07, 2008 5:10 am

this could be fun :D
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Unread postAuthor: POLAND_SPUD » Sat Jun 07, 2008 6:33 am

put some pics when it's ready...
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Unread postAuthor: TurboSuper » Sat Jun 07, 2008 8:27 am

Hook it up to a Dremel, those things run at a clip of around 30,000 RPM at max speed.

I've even seen some knock-offs that claim to go up to 40,000 RPM.
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