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| chinnerz |
 Posted: 06/26/2010 6:30 AM Post subject: |
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Lieutenant Colonel
Joined: 28 Dec 2009
Posts: 469
748.06 Spud Bux
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wow is that audio playing at 2kbs??
But that is an EPIC launcher you have there |
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| Moonbogg |
| Posted: 06/26/2010 11:41 AM Post subject: |
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Major General
Joined: 13 Oct 2008
Posts: 1355
3076.64 Spud Bux
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| Will the force pushing your bolt back be safe? The bolt better be super secure. |
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| Hotwired |
| Posted: 06/26/2010 15:43 PM Post subject: |
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UK Spudgunner
Joined: 13 Oct 2006
Posts: 2578
6346.06 Spud Bux
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That's some great machining and fabrication.
On the one hand I'd like to do something heavily machined and covered with o-rings myself but on the other, I have no real workspace or tooling so I'd probably have to pay someone to do it.
Another excuse I can use for not making another cannon anyway 
| Davidvaini wrote: | "really nice looking cannon, but who knows if it works since there is no video"
threads. |
I've got one of those.... I'll get round to a video someday though  |
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| frocksie |
| Posted: 06/26/2010 22:54 PM Post subject: |
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Sergeant
Joined: 23 Mar 2007
Posts: 91
50.43 Spud Bux
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The bolt is very strong. And the frame that retains the bolt is strong as well. I have no concerns whatsoever about the bolt or frame breaking.
Also, the pressure acting on the bolt will never be very high, as the golfball in the barrel starts moving at 3 psi, so the pressure acting on the bolt is far lower than the maximum chamber pressure immediately after ignition. |
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| Moonbogg |
| Posted: 06/27/2010 1:45 AM Post subject: |
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Major General
Joined: 13 Oct 2008
Posts: 1355
3076.64 Spud Bux
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| frocksie wrote: | The bolt is very strong. And the frame that retains the bolt is strong as well. I have no concerns whatsoever about the bolt or frame breaking.
Also, the pressure acting on the bolt will never be very high, as the golfball in the barrel starts moving at 3 psi, so the pressure acting on the bolt is far lower than the maximum chamber pressure immediately after ignition. |
So the high pressure is used for velocity purposes rather than a need to push hard, right? I mean, if one could find a gas with a faster expansion rate but with less energy, it could send the gofball just as fast, right? Like, if a 4x combustion shot expands at the same velocity as a 10x, then wouldn't a 4x be just about as fast with a light projectile? I think that may also be where a longer barrel comes into play. It gives the extra gas volume more time to accelerate the projectile. You see where I am a little confused? What benefits did HGDT show you for 10x vs something like 4x for a golf ball? |
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| SpudBlaster15 |
| Posted: 06/27/2010 4:13 AM Post subject: |
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Hybridian
Joined: 18 Oct 2006
Posts: 2372
295.89 Spud Bux
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| Moonbogg wrote: | | So the high pressure is used for velocity purposes rather than a need to push hard, right? I mean, if one could find a gas with a faster expansion rate but with less energy, it could send the gofball just as fast, right? Like, if a 4x combustion shot expands at the same velocity as a 10x, then wouldn't a 4x be just about as fast with a light projectile? |
The particle speed of the combustion gases does have some effect on the acceleration of the projectile, but it's not as significant as what you proposed. The actual expansion rate of the gas is mostly controlled by the movement of the projectile. Of course this changes once you start to approach the gas's local speed of sound, but that's a bit of a different topic...
The net force which causes the projectile to accelerate is almost entirely a result of system pressure; the inertia of fluid flows within the system has a much smaller effect. |
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| ramses |
| Posted: 06/28/2010 10:10 AM Post subject: |
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Major General
Joined: 29 May 2008
Posts: 1519
3981.54 Spud Bux
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That audio compression is horrible.
Nice cannon!
How are you securing the two tubes to the gas transfer spacer thing? Are the O-Rings on those tubes? |
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| frocksie |
| Posted: 06/29/2010 17:58 PM Post subject: |
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Sergeant
Joined: 23 Mar 2007
Posts: 91
50.43 Spud Bux
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| Quote: | | How are you securing the two tubes to the gas transfer spacer thing? Are the O-Rings on those tubes? |
No, the o-rings are only on the endcaps and the piston. The spacer is clamped in place with six bolts and sealed with bike innertube gaskets. This is able to seal because the contours of the spacer very closely match the contours of the barrel and spacer. Also, the rubber gaskets increase the friction between the barrel, spacer, and chamber, helping to hold the cannon together. |
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| Gun Freak |
| Posted: 10/08/2010 19:03 PM Post subject: |
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The Anti Hybrid
Joined: 25 Jan 2010
Posts: 4210
333.21 Spud Bux
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| Where's that video? |
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| Moonbogg |
| Posted: 10/09/2010 0:47 AM Post subject: |
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Major General
Joined: 13 Oct 2008
Posts: 1355
3076.64 Spud Bux
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| Yeah, I was looking forward to seeing this thing. Any progress? |
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| frocksie |
| Posted: 10/09/2010 10:32 AM Post subject: |
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Sergeant
Joined: 23 Mar 2007
Posts: 91
50.43 Spud Bux
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I hope to get a video up sometime in the next two months, but my camera is broken and I'm currently upgrading the ignition system.
The camera flash igntion coil circuit has been giving me problems so I think I will build a Wimshurst machine and use that as an ignition system. |
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| zeigs spud |
| Posted: 04/24/2011 15:34 PM Post subject: |
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Colonel
Joined: 04 Apr 2006
Posts: 654
751.13 Spud Bux
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| dangg that thing looks like it takes namesss. nice craftsmenship it looks pro. |
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| Hotwired |
| Posted: 04/24/2011 19:43 PM Post subject: |
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UK Spudgunner
Joined: 13 Oct 2006
Posts: 2578
6346.06 Spud Bux
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| frocksie wrote: | | The camera flash igntion coil circuit has been giving me problems so I think I will build a Wimshurst machine and use that as an ignition system. |
Sounds like a hindrance.
What's not working with the ignition coil system. |
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| Tobin |
| Posted: 04/25/2011 4:23 AM Post subject: |
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Private First Class
Joined: 16 Aug 2010
Posts: 38
110.01 Spud Bux
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| Thats a really nice cannon, looking forward to se some videos! |
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| frocksie |
| Posted: 04/25/2011 13:13 PM Post subject: |
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Sergeant
Joined: 23 Mar 2007
Posts: 91
50.43 Spud Bux
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| Quote: | | What's not working with the ignition coil system. |
My coil had a short in it so it wasn't producing consistent sparks. When it did spark, the sparks were weak, too weak to ignite higher mixes.
| Quote: | | Sounds like a hindrance. |
Sure it's not the most compact system out there, but it's pretty cool and I have always wanted to build one. Also, I needed a project for tech class, and a Wimshurst fit the bill.
The Wimshurst is nearly done; all I have to do is finish the control system and motor assembly. Hopefully I'll be able to finish it in the next three weeks. |
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