| The Cobra Striker is: |
| The sickest damn piston hybrid EVER! |
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86% |
[ 33 ] |
| A decent piston hybrid |
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7% |
[ 3 ] |
| Just another hybrid |
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0% |
[ 0 ] |
| Not at all impressive or special |
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0% |
[ 0 ] |
| Take your Striker and shove it! It sucks! |
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5% |
[ 2 ] |
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| Total Votes : 38 |
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| Author |
Message
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| Moonbogg |
 Posted: 09/22/2009 2:12 AM Post subject: Cobra Striker |
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Major General
Joined: 13 Oct 2008
Posts: 1355
3076.64 Spud Bux
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Lets start with the video!
http://www.youtube.com/watch?v=_rPbzu6R-ok
CANNON NAME: THE COBRA STRIKER
SPECS:
VALVE TYPE: BURST PISTON-VENTILATED (1" ID)
FUELING: 5x OXY/MAPP THRU 500PSI CHECK VALVES
C:B RATIO: 1.23:1
CHAMBER: 3 1/2" SCH40 X 10" (98.9cu in)
BARREL: 1 1/2" SCH10 X 36"
IGNITION: MULTI-GAP STUN GUN (150K VOLT)
HGDT ESTIMATED VELOCITY W/ GOLF BALL: 900FPS @3FT BARREL. 1030FPS @4FT BARREL. 1100FPS @5FT BARREL & 1160FPS@ 6FT BARREL.
MATERIALS:
6061-T6 ALUMINUM
B7 STUDS (5/16-24 FULL LENGTH)
GRADE 8 NUTS
POLYPROPYLENE
UHMW
STAINLESS PISTON GUIDE RODS
COST: TIME,SWEAT
MISC INFO: Cannon is in prototype form. Gaskets will be Copper (current PTFE gaskets stretch). Breech will not leak (solved). O2 will not be purged, but pressurized with gage. Cannon will utilize more robust sparking system, likely spark plugs due to extreme heat/pressure. Striker disagrees with chamber fans. Velocity to be verified and documented with existing 3ft barrel.
DESIGN EVOLUTION TO COMPLETION:
Last edited by Moonbogg on 10/02/2009 6:47 AM; edited 2 times in total |
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| GalFisk |
| Posted: 09/22/2009 3:49 AM Post subject: |
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Staff Sergeant
Joined: 28 Feb 2005
Posts: 104
381.00 Spud Bux
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| Aha, so that's how the valve works. I couldn't figure it out exactly from the description in the contest post. Nifty! |
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| jrrdw |
| Posted: 09/22/2009 5:32 AM Post subject: |
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Donating Moderator
Joined: 16 Nov 2005
Posts: 5522
9129.22 Spud Bux
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You should do chrony testing with the leak and then after the leak repair just to see how much power you were losing.
Really nice work!  |
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| qwerty |
| Posted: 09/22/2009 5:41 AM Post subject: |
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Colonel
Joined: 12 Apr 2009
Posts: 628
520.78 Spud Bux
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Man... thats a really nice piece of work and it got my vote but i still dont understand the difference between piston hybrids and normal hybrids because i know how normal hybrids work but not piston ones.
Is it a piston piloted by a burst disk when you fire the cannon? |
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| psycix |
| Posted: 09/22/2009 7:00 AM Post subject: |
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Donating Member
Joined: 25 Jun 2007
Posts: 3701
17.61 Spud Bux
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It is... shiny.
Good job on the breakbarrel, quite a challenge to make it seal and safe on those pressures. |
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| chenslee |
| Posted: 09/22/2009 7:07 AM Post subject: |
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Donating Member
Joined: 29 Jan 2009
Posts: 150
191.82 Spud Bux
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Oh, Moonbog. Beautiful work. I shat a brick when I saw it was you that made this!!
If you didn't use a mill or lathe on this (IIRC) how did you cut the chamfer on the breech sleeve?
What cad program are you using?
HAHAH. It looks like you did the same thing I did on a project awhile back. I was SURE I could find extra long socket head cap screws. Looks like you had to go with studs. I figured it was nuts and studs that were under the pretty black caps. |
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| jackssmirkingrevenge |
| Posted: 09/22/2009 12:11 PM Post subject: |
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aspiring machinist
Joined: 15 Mar 2007
Posts: 18051
32498.46 Spud Bux
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| Extremely well made, it certainly was a tough contender against chenslee's launcher. |
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| Moonbogg |
| Posted: 09/22/2009 13:13 PM Post subject: |
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Major General
Joined: 13 Oct 2008
Posts: 1355
3076.64 Spud Bux
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Thanks everyone! I am thrilled to have been able to place in this competition. It was great fun.
@Chenslee, the huge chamfer was made by using a bench top sander and holding the tube steady and rotating it to get the chamfer cut. After going through about 2 new sanding discs, I got it shaped and then used progressively finer sand paper by hand to smooth it out, then finally a rag and some compound. I tried a drill press with a buffing attachment, but I couldn't get the force needed to polish well, so I loaded a rag with compound, and started scrubbing.
The piston was the real PITA. I started with 1 1/4" round stock and drilled the thing out using progressively larger drill bits, all the way up to 1". |
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| Brian the brain |
| Posted: 09/22/2009 14:02 PM Post subject: |
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Dutch Spud Clan Leader
Joined: 05 Dec 2005
Posts: 2763
6458.86 Spud Bux
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Freaking awsome.
Now why didn't I see that breakbarrel picture in the contest?
Oh well...
I guess one vote wouldn't have made a huge difference..
I said his thing lacked creativity...I was dead wrong..
Unbelievable how you pulled this off without a machineshop...
Truely amazing! |
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| chenslee |
| Posted: 09/22/2009 14:38 PM Post subject: |
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Donating Member
Joined: 29 Jan 2009
Posts: 150
191.82 Spud Bux
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Wow. You have mad fab skills! I love the threadless pipe fittings. I'm still blown away by your internals.
I have tons of questions like:
What brand of clamp collars did you use? Where did you get them?
Where did you get your aluminum tubes?
Did you buff all this on your drill press or do you have a polishing wheel?
How did you cut the tank holes in what I assume is UHMW plastic?
Where did you get the black nut caps? |
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| Hotwired |
| Posted: 09/22/2009 15:56 PM Post subject: |
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UK Spudgunner
Joined: 13 Oct 2006
Posts: 2578
6346.06 Spud Bux
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That breech loading system scares me 
Seriously, I can see chamber flash coming out from there, how are you sealing it.
Aside from that, shine on  |
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| Moonbogg |
| Posted: 09/22/2009 15:57 PM Post subject: |
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Major General
Joined: 13 Oct 2008
Posts: 1355
3076.64 Spud Bux
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| chenslee wrote: | Wow. You have mad fab skills! I love the threadless pipe fittings. I'm still blown away by your internals.
I have tons of questions like:
What brand of clamp collars did you use? Where did you get them?
Where did you get your aluminum tubes?
Did you buff all this on your drill press or do you have a polishing wheel?
How did you cut the tank holes in what I assume is UHMW plastic?
Where did you get the black nut caps? |
Thank you.
Clamp collars are from McMaster. They are classified as structural tube/pipe fittings.
I ordered all aluminum parts in the diameters and thicknesses needed from an online small quantities metals store. This eliminates the need for mills and lathes. www.onlinemetals.com has all of it besides the 1 1/2"sch10 barrel. That came from mcmaster.
I started out buffing with a polishing wheel attached to a drill press. It didn't cut it because i couldn't press hard enough, so I QUICKLY discovered the best way by far is to do it ALL by hand. I used a rag and a buffing compound. Lots of pressure can be applied by laying the rag flat and rubbing the aluminum on it. Prepare to sweat.
Tank holes were cut by using a single drill press hole cutter from mc master. It has an adjustable blade that allows you to cut any size hole in sheet metal and plastic ranging from like 1 1/2 up to 7" or so. The tank holder material is polypropylene as it is super tough, rigid and very economical.
Black nut caps are from Mcmaster as well. |
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| jaythedogg |
| Posted: 09/22/2009 16:58 PM Post subject: |
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Private First Class
Joined: 06 Jun 2009
Posts: 32
108.38 Spud Bux
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| WOW!~ That is PURE SEX dude! Nice! |
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| chenslee |
| Posted: 09/22/2009 18:09 PM Post subject: |
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Donating Member
Joined: 29 Jan 2009
Posts: 150
191.82 Spud Bux
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McMaster FTW.
I ordered 8mm and 1/2" collars and got a mix of Ruland and Climax. Some spacers, o-rings, pressure gauge, and the constant force springs on my cannon were all from McMaster too.
I can't believe you HAND polished all of that. It makes me want to strip the paint off my plates and polish them like that. |
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| Moonbogg |
| Posted: 09/22/2009 18:26 PM Post subject: |
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Major General
Joined: 13 Oct 2008
Posts: 1355
3076.64 Spud Bux
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| chenslee wrote: | McMaster FTW.
I ordered 8mm and 1/2" collars and got a mix of Ruland and Climax. Some spacers, o-rings, pressure gauge, and the constant force springs on my cannon were all from McMaster too.
I can't believe you HAND polished all of that. It makes me want to strip the paint off my plates and polish them like that. |
I swear dude, you could polish that entire thing and it will look hella pimp. Take a fine grit sand paper to everything, removing any scratches. A good way to do it is to make sure the sanding is done in a uniform direction, this will make it look cleaner and shinier. Then buff away! After buffing with a medium grit paste, go for the polish! Do the tubes also! It will look amazing.
EDIT: to get into the grooves of those tubes you have, you could use a stick and wrap a cloth around it and put the paste on the cloth, then run it along inside the grooves with a nice, firm pressure. Then polish the same way. |
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