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| Carlman |
 Posted: 06/07/2008 3:00 AM Post subject: Spinning disk question |
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The Aussie
Joined: 24 Nov 2007
Posts: 1170
375.30 Spud Bux
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| 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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| jackssmirkingrevenge |
| Posted: 06/07/2008 3:27 AM Post subject: |
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space monkey
Joined: 15 Mar 2007
Posts: 6981
11122.02 Spud Bux
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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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| SpudFarm |
| Posted: 06/07/2008 3:36 AM Post subject: |
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Hybrid Guy
Joined: 04 Nov 2006
Posts: 2094
1180.73 Spud Bux
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mabe he is making something like the steam cannon mythbysters made?
(i saw only 3minutes of that episode) |
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| Carlman |
| Posted: 06/07/2008 3:38 AM Post subject: |
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The Aussie
Joined: 24 Nov 2007
Posts: 1170
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| jackssmirkingrevenge wrote: | | Do I sense a centrifugal launcher in the works...? |
maybe...
your too good JSR!  |
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| SpudFarm |
| Posted: 06/07/2008 3:39 AM Post subject: |
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Hybrid Guy
Joined: 04 Nov 2006
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| you will need one hell of a thing to spin it. |
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| Carlman |
| Posted: 06/07/2008 3:42 AM Post subject: |
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The Aussie
Joined: 24 Nov 2007
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| spudfarm wrote: | | you will need one hell of a thing to spin it. |
rc airplane motor and gears |
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| SpudFarm |
| Posted: 06/07/2008 3:43 AM Post subject: |
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Hybrid Guy
Joined: 04 Nov 2006
Posts: 2094
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| jackssmirkingrevenge |
| Posted: 06/07/2008 3:51 AM Post subject: |
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space monkey
Joined: 15 Mar 2007
Posts: 6981
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| 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  |
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| Carlman |
| Posted: 06/07/2008 3:52 AM Post subject: |
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The Aussie
Joined: 24 Nov 2007
Posts: 1170
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just found this on ebay
link
worth getting? |
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| SpudFarm |
| Posted: 06/07/2008 3:53 AM Post subject: |
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Hybrid Guy
Joined: 04 Nov 2006
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| oh i thought you was using a nitro engine |
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| Carlman |
| Posted: 06/07/2008 3:55 AM Post subject: |
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The Aussie
Joined: 24 Nov 2007
Posts: 1170
375.30 Spud Bux
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| 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 |
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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| jackssmirkingrevenge |
| Posted: 06/07/2008 3:58 AM Post subject: |
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space monkey
Joined: 15 Mar 2007
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Looks good for the price.
| Quote: | | 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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| Carlman |
| Posted: 06/07/2008 4:10 AM Post subject: |
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The Aussie
Joined: 24 Nov 2007
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this could be fun  |
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| POLAND_SPUD |
| Posted: 06/07/2008 5:33 AM Post subject: |
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Brigadier General
Joined: 13 Oct 2007
Posts: 969
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| put some pics when it's ready... |
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| TurboSuper |
| Posted: 06/07/2008 7:27 AM Post subject: |
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Brigadier General
Joined: 16 Jun 2005
Posts: 785
1273.63 Spud Bux
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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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