Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
IT WORKS!!! theGreater and I have brought in the new year with a bang, a very loud bang. ME 1-05H works beautifully and has a surprising amount of recoil with just a light projectile (an empty soup can). Can't wait to test a full weight projectile in the monster! A video is soon to follow this post.
And here is the video of the cannon. Damage pics and videos to come soon.
[youtube][/youtube]
The high speed is low quality but it is really cool to see what the flame out of the barrel actually looks like.
So the howitzer performs flawlessly. The surprising thing is that even with the weight of the gun it has a surprising amount of recoil. Even with light projectiles (soup cans, as mentioned above) there is still a full 12" of recoil travel. We'll be attaching the recoil springs and pneumatic return tomorrow, as well as performing a full scale test. The past nights tests were with empty soup cans. The next test will have 7oz.'s of Plaster of Paris in the can with a heavy projectile test to follow. We will also be measuring the muzzle velocity of the cannon with our high speed camera. Unfortunately all experimentation will cease after this week due to college resuming. Keep a watch, though, on the weekends. This has been a successful build for the time we have worked on it. A big thanks to all who have posted, made suggestions, and/or have warned us about this build.
So yesterday theGreater and I shot Cerberus with a full scale projectile. The sound that came out of the cannon was deafening and we got some very valuable data from this test.
This is what we gathered.
Muzzle Velocity (approx.)- 650~670 FPS
Weight of Projectile- 7.2 Oz
Distance (approx) - 175 yards @ low trajectory (20~25 degrees)
This test was done with the meter pipe charged to 85 psi. and the chamber fan was left to run for 20 seconds.
By this afternoon I should have some damage pics posted along with the high speed shot of this test.
Looks VERY powerful for projectiles that size and weight. What are you planning to shoot at? Also are you using propane or MAPP? And how are you metering/measuring that? Can't wait to see the damage pics.
Here is a video of the cannon that has a full weight projectile (7oz). The high speed at the end is how we measured the muzzle velocity.
[youtube][/youtube]
I apologize, but I couldn't get around to making some damage pics or videos, there just wasn't anyway I could set up the cannon without theGreater not here ( too heavy), but theGreater will be back in tomorrow so we should be able to make some then.
Also are you using propane or MAPP? And how are you metering/measuring that?
We are using propane in the cannon (although MAPP would make for a nice boom ). We also have a proper metering pipe for the gun, but it just wasn't mounted to the cannon at that point of time.
Even with the bracing, we're going to replace the recoil springs with stouter ones and put bumpers at the end of the recoil rails to prevent a hard shock. get more springs for it. The ones we have definitely aren't giving the recoil reduction we'd hoped for. That being said, we definitely didn't foresee that amount of recoil in the designs. Luckily the gun itself probably weighs 80 lbs. Not necessarily light, but with the weight, the recoil probably isn't as bad as it could be with a lighter gun. Looking at muzzle brake designs. We're hoping to reduce the recoil by at least 25% Anyone have any suggestions for the construction? We're trying to keep it lightweight, yet effective.
A few pics to entertain.
Attachments
Here's the ammo. VERY simple design. The felt is 5/16th of an inch thick and is epoxied to the can. The "aerodynamic" bullet end is a fruit cup epoxied around the edges .
The chamber fan with spark gap farther back in the chamber. The propane inlet is the brass fitting on top of the chamber.
This is our recoil system. The springs are too long and bent down. The black rails are what the gun rides on while being shot.
A view from the front.
The Howitzer from the left.
Last edited by McCoytheGreater on Mon Feb 08, 2010 2:07 pm, edited 3 times in total.
For the muzzle break you could simply use a tee that fits onto your barrel and drill a hole in the center of it. I saw that at least once here on spudfiles but I don't know how it performs.
Edit:
something like that
Last edited by MRR on Sun Jan 03, 2010 6:39 am, edited 1 time in total.