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large hybrid

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: SpudFarm » Sat Jan 23, 2010 2:21 pm

Might my hybrid chamber be of interest? Never using it anymore, It's a shame to let it rust to its death...

I will be happy to sell any part of the cannon. PM for more info.

Edit:
Forgot the link..
http://www.spudfiles.com/forums/upgbh10x-t18898.html
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Unread postAuthor: artillerycreations » Wed Jan 27, 2010 5:55 pm

Update. I have attached a scale drawing of what i'm wanting to build. To recap on updates specs. 20' 3 inch barrel. 33.5'' long 6'' pipe chamber with one piece sleeved inside the other for a combined 3/8ths wall thickness. Two spark plug gaps. Stun gun ignition, with remote switch (any ideas?). 4 total holes in chamber, all of which are through 1.25'' endplates. 2-1/4'' female or male quick connects on chamber (which would work better?). Manometric metering using a 0-10psi gauge for fuel allowing for more fuel pressure than I will ever need as this gun will be used primarily between 4-9x. Compressed air for venting will be used if necessary.

The endplates will be 7'' square with four pieces of 3.5''x3.5'' angle iron welded to box in the chamber. I hope this will add rigidity and strength to the chamber and take stress off the pipe. It should also help keep the endplates from blowing off. I was in the process of designing a recoil system for the gun but then I realized I could save myself lots of time, money, and complexity by using materials I already had to build it strong enough to take the recoil. Therefore I will be using a muzzle brake complemented by the ability of the gun to roll upon firing.

Due to the pivot point being attached on the bottom of the gun, the muzzle will want to rise on firing. My muzzle brake will vent upwards and to the sides at a 45 degree angle to the barrel. This should correct its tendency to rise when fired.

I will be using a car jack to raise and lower the barrel for different trajectories. This system will be similar to mobile chernobyl's and credit goes to him for the inspiration. While not in the picture, I figured you guys could just use your imaginations. :wink:

Any ideas on putting a burst disk in a 3 inch coupling would be greatly appreciated. I’m not sure if it will hold the around 7200lbs of force that will be acting on it at 1000psi without flexing and blowing out of the gun prematurely. Let me clarify a bit. I’m worried that there is a threshold and once I get to it, using stronger disks wouldn’t matter. They wouldn't "burst" and let the air go by at say 800psi; they would more or less crumple and be blown out of the groove at 400psi. This would mean that using any kind of a stronger disk would be a waste of time because it would just be blown out at 400psi no matter what. Am I correct in this fear?

I will be using 2'' pipe for all bracing and there will be a 4' long sleeve, 3.5'' i.d. that the barrel will slide into. This will allow for the barrel to be unscrewed without binding and for projectiles to be breech loaded by simply sliding the barrel into the sleeve and then once loaded screwing it back on.

Just so you guys know, I am 100% aware of the power this gun will produce, and i also have lots of land to play with it on out in the country. There are lots of people around me that are gun freaks and shoot thousands of shells each day with deer rifles so I won't stick out a bit. :lol:

I am totally serious about this. I wouldn't have spent time drawing the picture to scale (every pixel is 1/4'' which is hard to do when the barrel is 240'' long) or writing this huge post if I wasn't completely serious. I want to know if this is feasible/reasonable, or if i’m totally lost on the concept. Thanks in advance for all comments.
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1unit     .25 inch     scale cannon drawing.jpg

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Unread postAuthor: artillerycreations » Sat Jan 30, 2010 6:37 pm

Anyone care to share a comment or anything. Im looking for input.
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Unread postAuthor: ramses » Sun Jan 31, 2010 2:03 pm

The disk shouldn't be pulled out of the groove as long as it is held securely.

Be prepared for the cannon to fly back quite a ways from recoil.

I can't wait for the damage pics...

:twisted: :twisted:
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Unread postAuthor: spudtyrrant » Sun Jan 31, 2010 3:02 pm

artillerycreations wrote: this gun will be used primarily between 4-9x.


artillerycreations wrote: I’m not sure if it will hold the around 7200lbs of force that will be acting on it at 1000psi without flexing and blowing out of the gun prematurely.


If you think you have 1000psi in a gun(pre-ignition)that is going to be used at 4-9x you know less about hybrids than i thought.

If I was you I would build a smaller scale version and learn a little bit about hybrids before i go jumping to the big boys

The real point is if you are ready to build a gun like this, you shouldn't need to ask us questions
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Unread postAuthor: McCoytheGreater » Sun Jan 31, 2010 3:53 pm

spudtyrrant wrote:If I was you I would build a smaller scale version and learn a little bit about hybrids before i go jumping to the big boys


Definitely give it some consideration. Build a small one if you haven't built a hybrid before. Granted I haven't built a hybrid before, but when i do it'll definitely be a small one. I have, however, built a large gun, and there are some monster recoil forces. You will DEFINITELY need more support for the barrel. At a 10ft barrel length, even with the bracing we originally planned, we had to add another support, so i can only imagine the stresses with a 20ft barrel. As stated above, try the 3" chamber first before you go full scale with this thing. A half scale will definitely give you an idea of what you're working with. O, and be careful with the endcaps. They could blow out. :wink:
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Unread postAuthor: artillerycreations » Mon Feb 01, 2010 11:50 pm

Spudtyrrant, you must have misunderstood as i didn't mean 1000psi before ignition. What i meant is that a disk that would burst at 1000psi would fail at much less pressure due to lack of something to grab onto in the groove in the coupling. This would occur post-ignition. I have done my homework and hoped I would get the benefit of the doubt.

Recoil would be massive on a gun of this size but at 750lbs(rough estimate) recoil shouldn't be quite as bad, and being allowed to roll should help.

McCoy, thanks for bringing up barrel support. The first 4 foot of the barrel would be in a sleeve, leaving the last 16 feet or so unsupported. I need to look into that.
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Unread postAuthor: spudtyrrant » Tue Feb 02, 2010 12:36 am

artillerycreations wrote:Spudtyrrant, you must have misunderstood as i didn't mean 1000psi before ignition. What i meant is that a disk that would burst at 1000psi would fail at much less pressure due to lack of something to grab onto in the groove in the coupling. This would occur post-ignition. I have done my homework and hoped I would get the benefit of the doubt.
I am inclined to say that it is not as much misunderstood as it was misstated, but even so: the amount of friction holding the disk in the coupling only increases upon combustion, so the disk will always fail far before it will "slip" out, even at this scale.

I still think it would be a wise decision to create a smaller scale version before going full scale, i have no doubt that you know the numbers and understand the power this cannon will produce, but it is better to get some first hand experience with hybirds before you go making the hybrid monstrosity from hell :wink:
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Unread postAuthor: McCoytheGreater » Tue Feb 02, 2010 2:28 am

[quote="artillerycreations"
McCoy, thanks for bringing up barrel support. The first 4 foot of the barrel would be in a sleeve, leaving the last 16 feet or so unsupported. I need to look into that.[/quote]

Definitely. With our 10' barrel we had 7' unsupported in the original plan. We had to add a barrel support to the top of the gun. The 3" barrel drooped about 4 inches before we put it on. That's only with roughly 5' of unsupported barrel.
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CIMG0133 [800x600].jpg
Barrel support (black with silver hanger) on top of the gun/carriage assembly.
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Unread postAuthor: artillerycreations » Tue Feb 02, 2010 3:14 am

I checked and I don't think I will have a problem with barrel droop. I have a gun that uses a 15' 3 inch pvc barrel and it does droop some but I will be using sch40 steel on this hybrid (of course :roll: ) and it doesnt seem like there will be a problem.
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Unread postAuthor: artillerycreations » Mon Feb 22, 2010 7:17 pm

I am considering using an 80 cf empty high pressure cylinder. In the attached file i would cut the neck to accept 3'' pipe inside of it. It would be a short stub of pipe with a coupling on it to house the burst disk. The coupling as well as the pipe would be welded to the cylinder and this area would be gusseted. Any comments on going this route compared to pipe?
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