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| mattyzip77 |
 Posted: 05/09/2012 16:09 PM Post subject: |
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Spudder Extraordinaire
Joined: 28 Jun 2011
Posts: 1247
734.05 Spud Bux
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| Awesome video crowley!! I need to get a camera. I recently moved and have 46 acres of land to shoot my cannons!! I recently put a golf ball through both sides of a 55 gallon steel drum with my asco launcher!! |
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| jackssmirkingrevenge |
| Posted: 05/09/2012 22:51 PM Post subject: |
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aspiring machinist
Joined: 15 Mar 2007
Posts: 21776
40609.37 Spud Bux
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Good stuff MrC 
With regards to stabilisation, at the ranges you were shooting at even a plain rod would likely have been adequate. Some testing I had done here showed that it took a couple of metres for the projectile to have tumbled significantly.
You really need some better support material for your darts though, I suggest a hole punch and some balsa sheet |
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| MrCrowley |
| Posted: 05/09/2012 23:04 PM Post subject: |
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Kaleun
Joined: 23 Jun 2006
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12528.86 Spud Bux
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| Quote: | | With regards to stabilisation, at the ranges you were shooting at even a plain rod would likely have been adequate. Some testing I had done here showed that it took a couple of metres for the projectile to have tumbled significantly. | Well I tried 5m, as seen in the video, and I got good penetration. I think the dart was wobbling in the air from the turbulence as I pointed out it entered on an angle. The entry hole was no bigger than point-blank shots with the same projectile so I'm pretty sure it wasn't too badly affected. I can probably try 10m tomorrow, I would have done so first up but you can see there's a truck behind and to the left of the target.
| Quote: | | I suggest a hole punch and some balsa sheet |
And arrange them like baffles? Not sure how you meant for them to be arranged but if they're disks with the projectile going through the middle, wont they jam/break up inside the barrel?
I think the way I had arranged it, the cotton balls they weren't doing a bad job. I put one at the tip of the projectile and I assume this is the cotton ball that I always find intact after the launch whereas the cotton balls that surround the shaft are usually in tatters. It's actually surprisingly difficult to poke a hole through the cotton balls with the crossbow bolt and I think this is why it survives the launch.
Edit: Thanks for digging this up by the way. Me and DYI aren't alone  |
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| jackssmirkingrevenge |
| Posted: 05/09/2012 23:21 PM Post subject: |
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aspiring machinist
Joined: 15 Mar 2007
Posts: 21776
40609.37 Spud Bux
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| MrCrowley wrote: | | And arrange them like baffles? Not sure how you meant for them to be arranged but if they're disks with the projectile going through the middle, wont they jam/break up inside the barrel? |
My suggestion would be to use a hole punch to cut out some disks, meat tray foam would also be a good candidate (of if you're feeling hardcore: http://www.depronfoam.com/ )
Punch out a barrel diameter disk, with a bolt shaft diameter hole in the middle. Then cut the disks in half, and slip them into the barrel as a pair. Make sure the split is perpendicular to the previous pair.
That should keep the projectile steady in the barrel and fly apart once it leaves the muzzle.
I make no secret of my misadventures either |
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| MrCrowley |
| Posted: 05/10/2012 2:40 AM Post subject: |
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Kaleun
Joined: 23 Jun 2006
Posts: 10042
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| Actually meat tray foam would be good; especially if cut at a diameter slightly larger than the barrel so it folds inwards to form a cone and reduce the chance of the disk slipping out of place. |
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| Gun Freak |
| Posted: 05/10/2012 15:19 PM Post subject: |
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The Anti Hybrid
Joined: 25 Jan 2010
Posts: 4527
761.70 Spud Bux
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| ramses |
| Posted: 05/10/2012 19:27 PM Post subject: |
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Major General
Joined: 29 May 2008
Posts: 1653
4344.04 Spud Bux
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| jackssmirkingrevenge |
| Posted: 05/10/2012 19:40 PM Post subject: |
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aspiring machinist
Joined: 15 Mar 2007
Posts: 21776
40609.37 Spud Bux
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| hehe... I don't believe I've seen that before, backstory? |
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| ramses |
| Posted: 05/12/2012 18:10 PM Post subject: |
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Major General
Joined: 29 May 2008
Posts: 1653
4344.04 Spud Bux
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AAh, I should probably make a thread.
Long story short, we built a robot to throw the first pitch at a baseball game (using a 4" piston valved cannon)
Someone decided to test it in the school, I though 'meh'. He aimed about 4' above the top of our foam backstop at 60 feet and fired at about 30 PSI.
The baseball flew 300 feet down the hallway, bounced off the ceiling, went through two tempered glass doors, across 2 parking lots and into our athletic practice fields.
The Custodian on duty (this was Saturday) then gave us all pops and thanked us for the overtime.
Last edited by ramses on 05/16/2012 19:13 PM; edited 1 time in total |
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| jackssmirkingrevenge |
| Posted: 05/13/2012 23:31 PM Post subject: |
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aspiring machinist
Joined: 15 Mar 2007
Posts: 21776
40609.37 Spud Bux
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hehe excellent bit of a mini-mythbusters event then  |
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| jackssmirkingrevenge |
| Posted: 05/18/2012 23:47 PM Post subject: |
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aspiring machinist
Joined: 15 Mar 2007
Posts: 21776
40609.37 Spud Bux
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double tap, awesome |
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| DYI |
| Posted: 05/19/2012 8:54 AM Post subject: |
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Rear Brigadier
Joined: 07 Jul 2007
Posts: 2845
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| jackssmirkingrevenge |
| Posted: 05/19/2012 9:31 AM Post subject: |
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aspiring machinist
Joined: 15 Mar 2007
Posts: 21776
40609.37 Spud Bux
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| Nice one, Mr Smith any chance of putting a barrel on it? |
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| DYI |
| Posted: 05/19/2012 11:06 AM Post subject: |
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Rear Brigadier
Joined: 07 Jul 2007
Posts: 2845
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| There will be a barrel, but don't hold your breath. There's a lot of work left to do (including extensive modification to the chamber - there were a number of sealing issues). Probably two weeks or so, and I haven't even ordered the materials yet. |
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| Labtecpower |
| Posted: 05/19/2012 11:19 AM Post subject: |
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Brigadier General
Joined: 20 Feb 2010
Posts: 1117
2281.60 Spud Bux
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what velocity and energy figures are you expecting?
And about the rich mixture, what kind of performance increase is to be expected if you put a slighly richer (I have no idea about concentrations) mix in a butane-air hybrid?
seems a bit like a piece-of-string question to me, hope this is clear 
I have tried gaseq, but I can't get it to work right |
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