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Built a hybrid cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Unread postAuthor: SpudFarm » Fri Apr 16, 2010 11:31 am

I was going to shoot a APFSDS round on a big stump today. So I dragged it out and assembled it in the freezing cold winter air, cut a disk and set up the camera and aimed it at the stump and so on.
Then I was going to fuel it so I opened the propane valve and I WAS OUT OF PROPANE!
That is the things that makes me want to kill in life... Oh did I mention I had to carry a huge compressor down the stairs and also carry the stump down to my house from the woods? And I only get the sound of frustration.

Well, to get my mood up again I post some pics of the round. It is still in the section of my barrel it was made in on the photo, to load I just press the pipe with the ammo in against the breech of the barrel and push it out of the pipe and into the barrel.
Image
Image

Well, I am sorry I had to share my frustration. But everyone with a big cannon that needs to be assembled on site will understand how frustrating it is to get a misfire because of something that wasn't even a technical problem.

Hello again, I have thought of making a piston valve for this gun a long time now. I have started sketching.
What I plan on doing is just using a 2" elbow from the chamber into a section of pipe the same diameter as my chamber where the piston and all the other internals is.
I am going to use the chamber that I got pressure tested to construct the valve housing.

What I am basically asking about is general tips and opinions on the deign when it comes to the 2" elbow between the chamber/valve and perhaps tips on how to make it serviceable without to much effort.

Thanks.

Image

Please don't get mad at my tripple post.

I just fired the APFSDS round at a big stump at 5.5x mix.

I'll let the video do the talking.

[youtube]http://www.youtube.com/watch?v=vfpfYp0ZowA[/youtube]

Edited by jrrdw.
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Unread postAuthor: Heimo » Sat Apr 24, 2010 3:43 pm

very impressive 8)
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Unread postAuthor: SpudFarm » Mon Apr 26, 2010 8:59 am

Here's one more, Lead slug encased in a steel pipe fired at a range of 40m onto two stumps.
Nothing special really. just cloth sabot since it was only done since I was bored.


[youtube]http://www.youtube.com/watch?v=tri2sH63iS8[/youtube]
Thanks
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Unread postAuthor: Hotwired » Mon Apr 26, 2010 11:38 am

SpudFarm wrote:What I am basically asking about is general tips and opinions on the deign when it comes to the 2" elbow between the chamber/valve and perhaps tips on how to make it serviceable without to much effort.Image
But why do you want to?

Unless you muzzle load you're going to have to undo a similar connector to get the projectile in as you do already.

Then there's the weight of the piston assembly, issues with setting up the piston to resist the 100psi+ of the pre-ignition gas and the extra maintenance.

It might be more powerful, not because of the valve but because you're also increasing the chamber volume.
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Unread postAuthor: SpudFarm » Mon Apr 26, 2010 11:47 am

If I decide to try this I will probably just make a bolt assembly.
I will have to look through my options on it. The best thing would be a shed that the gun is placed in and shooting out through a hole in the wall.
This way the gun just needs propane and a burst disk along with the air and I would not have to assemble it before every shot.

I would like any other ideas that will let me keep it in one piece on the range without it rusting.:)
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Unread postAuthor: Technician1002 » Mon Apr 26, 2010 12:22 pm

Is there any reason that there is a large diameter chamber, a large diameter piston housing (cylinder) and a elbow between them with 1/4 (guessing) cross sectional area with a bend? I would think that elbow would eat a huge amount of energy by constriction of the flow from the chamber to the valve. The constriction would require the gas to flow at high rate through several changes in pipe size and a bend. Loss to turbulence has to be huge. Can the chamber and elbow be the same diameter?
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Unread postAuthor: SpudFarm » Mon Apr 26, 2010 1:03 pm

Technician1002 wrote:Can the chamber and elbow be the same diameter?


It is not impossible but it will be a long shot.
I would have to find pipe that is just as big as the chamber and then chop off 2" of the cannon itself. weld, cut 45 degrees and weld again and then start on the piston.

Then it would be easier to chop the chamber in the middle and attach another section of pipe to make it longer and just constructing a COAX.

I am planning another hybrid that will be much like Lardas HYGAC, he is even going to construct the parts that demands machine tools. I can trash that idea and order a much bigger chamber to make a coax..

I figured I should wait until I have shot a proper target to post this but I decided that the experienced of you will see the point anyway.

This is the first time I fire a full bore slug (DYI's suggestion) and I was suprised by the velocity it got. Around 200-250m/s to be... rough.

[youtube]http://www.youtube.com/watch?v=OqrQel53QZo[/youtube]

Edited by jrrdw.
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Last edited by SpudFarm on Sat Jun 19, 2010 6:18 pm, edited 1 time in total.
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Unread postAuthor: Ragnarok » Sat Jun 19, 2010 7:28 pm

That, sir, is a waste of 23 kJ. I would certainly have advocated a "proper target".

Nice nonetheless, but it just really isn't worth spending a projectile like that on targets that offer so little resistance to it.
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Unread postAuthor: SpudFarm » Sat Jun 19, 2010 7:51 pm

Ragnarok wrote:That, sir, is a waste of 23 kJ. I would certainly have advocated a "proper target".

Nice nonetheless, but it just really isn't worth spending a projectile like that on targets that offer so little resistance to it.


Hehe, it was mainly a shot to look if I could get the record for energy acivement in a "spud gun" made by ametueres.
The chrony got knocked over by the muzzle blast and I never got a reading.

Be sure that I will do this again. I never thought I could get a slug like that up to those speeds!

Also. A backstop would be nice when shooting near kilograms of lead at each shot.

Thanks.
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Unread postAuthor: mobile chernobyl » Sun Jun 20, 2010 1:54 pm

I would have to agree with Mr. Rag on that one. A golf ball would have easily done the same damage to that backstop out of your launcher.

I hope you were able to retrieve the round to at least melt it back into shape?

Also why not take it up to 10X? most of your shots so far seem to be in the 5.5X range. Is there a lack of adequate air supply? or just no need for that much power lol :shock:
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Unread postAuthor: SpudFarm » Sun Jun 20, 2010 2:15 pm

mobile chernobyl wrote:I would have to agree with Mr. Rag on that one. A golf ball would have easily done the same damage to that backstop out of your launcher.


As said, it was an attempt to get the highest recorded energy from a amateur build "spud" gun. The chrony didn't pick it up so..
I have an idea to shoot two 300g slugs connected with chain at a ATV frame later on.

The reason I don't just go for the 10x is firstly because I have one brass fitting that I would like to replace, I also need to get a proper target to use all that energy on something.
When I get my memory card back I will probably go full power on the watermelon.

Thanks.

This is for Ragnarok:

[youtube]http://www.youtube.com/watch?v=ksVTcVq4Fb0[/youtube]

Solid rock target. 6+ inches thick.

Edited by jrrdw.
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Unread postAuthor: SpudBlaster15 » Tue Jun 22, 2010 1:16 pm

Very impressive shot SpudFarm. High speed video makes the energy transfer so much more visible; you should continue to film launches like this.

Any idea what the amateur spudgunning muzzle energy record is? With these recent 20+kJ shots, you may have reached or exceeded it.
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Unread postAuthor: SpudFarm » Tue Jun 22, 2010 2:12 pm

SpudBlaster15 wrote:Very impressive shot SpudFarm. High speed video makes the energy transfer so much more visible; you should continue to film launches like this.

Any idea what the amateur spudgunning muzzle energy record is? With these recent 20+kJ shots, you may have reached or exceeded it.


Thank you, I will continue using the high speed function. I also want to make some sabot designs for penetrators and capture their exit from the muzzle at 1200fps.

I am planning to atleast do the steel penetrating record. DYI also mentioned that I might have gotten the record for highest muzzle energy. Atleast I havent seen a gas powered amateur built cannon reach higher levels of muzzle energy.
I will have to chrony the shots to make it slightly more "offical" though.
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Unread postAuthor: ramses » Tue Jun 22, 2010 3:12 pm

IIRC, Killjoy's FEAR had some monstrous muzzle energies. His chamber was around 63" of 6" sch 40 pipe (steel). Chamber volume around 30L. He only ever took it to around 6x with a barrel and projectile, but he did a 10x shot with just the burst disk [url]here.[/url]

Did I mention he has a 50' barrel?

He got 15kJ with 2 golfballs. If he used a lead slug, it would be rather hard to compete. Unless his PVC barrel exploded.
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Unread postAuthor: SpudFarm » Tue Jun 22, 2010 3:20 pm

ramses wrote:He got 15kJ with 2 golfballs. If he used a lead slug, it would be rather hard to compete. Unless his PVC barrel exploded.


The problem is that he isn't really shooting the thing. He have never given us any proper shots with heavy projectiles.
Also, I don't think he have chronyed any of his shots.
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