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big 4X chamber concept

Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
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Unread postAuthor: Moonbogg » Mon Aug 22, 2011 5:58 pm

The pop off valve was my original idea, and i moved away from it because it was suggested that it might not be fast enough to fully dump the pilot. But its OK if it doesn't fully dump it. It would serve the function of preventing too much additional pressure build up in the pilot, hindering opening speed more than necessary. Now, will it be fast enough to even alleviate at least some pressure in time? Who knows. But I am just about willing to go for it.
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Unread postAuthor: Fnord » Mon Aug 22, 2011 6:10 pm

Honestly MB, if it were me building it, this is what I would do. I did not list any dimensions but it's very likely you can use all standard pipe/tubing in this design.

Do you really need those big flanges? If you wanted to add a fan I can see why but otherwise I think you're better off without them. You'll be able to service the piston just fine.
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toolie hyb.gif
Black is weld bead, red is neoprene.

Also at this time I'd like to point out GODDAMMI$# $#%#OFA!$#*&)^$FUC%^ YOU MICROSOFT!! I WANT THE OLD MSPAINT BACK!
I'm a pc, and windows 7 was NOT my idea!
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Unread postAuthor: jackssmirkingrevenge » Mon Aug 22, 2011 8:23 pm

Moonbogg wrote:The pop off valve was my original idea, and i moved away from it because it was suggested that it might not be fast enough to fully dump the pilot.


Why not have the piston dump the pilot area by function of its movement?
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Unread postAuthor: Gun Freak » Mon Aug 22, 2011 8:51 pm

Looks rather difficult to machine that certain fill path, but I'm sure there's a way around it. Looks good to me jack.
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Unread postAuthor: Technician1002 » Mon Aug 22, 2011 9:32 pm

The standard proceedure to machine that fill path is to drill the radial hole all the way from the outside, then add a plug to cap it off. It is nto difficult and you can see this on many items such as Carburators with a set of plugs press fit into the body.
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Unread postAuthor: jackssmirkingrevenge » Mon Aug 22, 2011 11:08 pm

Gun Freak wrote:Looks rather difficult to machine that certain fill path, but I'm sure there's a way around it.


As Tech pointed out there are easy ways to get it done, in any case the pressure valve can be incorporated into the piston to avoid making extra holes in the chamber cap.

Image wrote:GODDAMMI$# $#%#OFA!$#*&)^$FUC%^ YOU MICROSOFT!! I WANT THE OLD MSPAINT BACK!


Having used the MS Paint in Windows 7, I concur wholeheartedly with that statement.

The way you drew it though, won't the piston just pop out of the pilot? Or is there an unseen stopper somewhere?
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Unread postAuthor: Moonbogg » Mon Aug 22, 2011 11:24 pm

Fnord wrote:Honestly MB, if it were me building it, this is what I would do. I did not list any dimensions but it's very likely you can use all standard pipe/tubing in this design.

Do you really need those big flanges? If you wanted to add a fan I can see why but otherwise I think you're better off without them. You'll be able to service the piston just fine.


That looks good. We would need a way to stop the piston from moving forward too much. I would also be concerned about a heavy (.6lb) piston slamming into the back of a plate that thin with welds along the edges. Welding destroys aluminum's strength and I can't spend the money to re heat treat this time around. I like the concept though.

JSR, yours looks good as well. How would I support the piston rod? Once it comes out the back it will cantilever and hand downward, and if it bounces back the end will slam into the edge of the pilot vent hole. Supporting the piston rod to be rigid enough while not blocking the flow in that tube will be difficult and complicated. Also, the long support tube is a huge cantilever and with the force of a slamming piston, will try to flex a lot and put insane stress on the back end of that tube and will probably bend or crack unless insanely thick. Not to mention the difficulty in machining something with that long and narrow of an ID.
These are great ideas, they are just difficult to implement in a practical way without spending a fortune.
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Unread postAuthor: jackssmirkingrevenge » Mon Aug 22, 2011 11:33 pm

Moonbogg wrote: These are great ideas, they are just difficult to implement in a practical way without spending a fortune.


Oh ye of little faith ;)
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sawnoffpiston.png
The o-ring on the small end of the piston should be floating in order to allow air to enter the pilot and not flow out once the pressure source is disconnected. Simple radial supports at the piston end of the tube should be enough to prevent whiplash without disturbing flow significantly.
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Unread postAuthor: Technician1002 » Tue Aug 23, 2011 12:08 am

Fnord wrote:Honestly MB, if it were me building it, this is what I would do. I did not list any dimensions but it's very likely you can use all standard pipe/tubing in this design.

Do you really need those big flanges? If you wanted to add a fan I can see why but otherwise I think you're better off without them. You'll be able to service the piston just fine.


I'll have to do the edits when I have more time to show the design I had in mind. It was very much like this one, except to save moving mass, the valve is not a toolie design but instead a short hockey puck piston. Think of those dimensions but the piston shortened and the bumper and piston cylinder hang off the breech of the valve inside the chamber. To service the valve, the valve assy is flange mounted on the front of the chamber. It would unbolt, or unscrew if threaded flange is used, and removed out the front for service.

It would not be a QDV, but a normal piston valve.
Fans don't survive in hybrids.

Due to time a very fast edit. Pilot tube from the pilot to the front flange is not shows. Supports do not seal the flow. Pilot can be opened for service.

Edit. Attached wrong picture. Updated.
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Last edited by Technician1002 on Tue Aug 23, 2011 12:31 am, edited 2 times in total.
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Unread postAuthor: Moonbogg » Tue Aug 23, 2011 12:10 am

OK JSR, that last one made me tingle a little bit. I like that idea. So far, that along with the toolie idea from Fnord I really like. Thanks for the help and for getting me thinking, really. My lone brain can't produce the best cannon, so this feedback from everyone is really getting the juices flowing.

I can use my original piston housing, have the piston a QDV style like you show and have it enter the barrel, and have a bolted tube for the center part. Even a threaded pipe for that section would be cheap and work.

EDIT: Tech, wish I could envision what your saying with your last post. The more ideas the better!
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Unread postAuthor: jackssmirkingrevenge » Tue Aug 23, 2011 12:31 am

Moonbogg wrote:Thanks for the help and for getting me thinking, really. My lone brain can't produce the best cannon, so this feedback from everyone is really getting the juices flowing.


Sometimes it's incredible how much more clearly you can develop ideas by simply bouncing them off someone like minded, that's why I love this forum :D

Technician1002 wrote:Pilot tube from the pilot to the front flange is not shows. Supports do not seal the flow. Pilot can be opened for service.


That would need a pop-off on the front flange for maximum efficiency.

Here's a more "buildable" version of my previous design, unfortunately it requires epoxy which I know Moonbogg is not a fan of...
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Unread postAuthor: Technician1002 » Tue Aug 23, 2011 12:32 am

Bump. Used wrong pic. Just updated it. Low mass hockey puck piston and the pilot tube would go to the removable (muzzle end) flange with the valve body. The valve body would hang off the end of the outlet pipe.

Sorry I didn't draw in the pilot.
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Edited JSR photo. Pilot would go through the front flange supporting the valve.
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Unread postAuthor: Moonbogg » Tue Aug 23, 2011 1:03 am

Tech, how would the pilot vent? This is all looking better and better.
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Unread postAuthor: Technician1002 » Tue Aug 23, 2011 1:11 am

A tube would run from the pilot area up to the removable face plate so the plate, valve assy, and pilot would be all one unit that could be reomved out the front for service and disassembled for service. This would emiminate problems with sealing a tube out the breech as only one opening into the chamber is needed.

Super cheezy pilot sketch added.
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Unread postAuthor: Moonbogg » Tue Aug 23, 2011 1:21 am

So the tube is used to fill the pilot. The cannon fires, then does the the pilot have a way to vent? If it vents out of that tube how does the tube hole pressure but release it when fired?

Edit: I REALLY like how it hangs off instead of needing a huge flange with vent slots like my original design. I could use bolts hanging off the flange and use a nut to secure the now much smaller piston housing. You just took my piston housing and made it way better. Man, this is great. But how does it vent?
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Last edited by Moonbogg on Tue Aug 23, 2011 1:24 am, edited 1 time in total.
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