Spudfiles gets a facelift!

Long running potato cannon forum Spudfiles has recieved a major overhaul and now includes a Nerf showcase, and discussion section. I was lucky enough to kick off the Nerf showcase with the Remedy Metal Longshot #2.

Spudfiles was my first port of call while I was learning to build potato cannons and is probably the richest source of information on available for that type of thing. The community there is supportive of progress and a few individuals are constantly pushing the envelope for what can be done to shoot various projectiles using air or combustion power (or in the case of mad scientists, both). Safety is also strong message pushed by spudfiles community which is really great, senior forum members often steer less clued-up users in the right direction so that everyone can enjoy spudding without any worries.

If you're in to potato cannons, air guns, or Nerf basters, do check out the newly refreshed Spudfiles and join the community. I have been a part of the forum since before I even touched a Nerf gun, and I think it will be interesting seeing the hardcore spudders' input in to the Nerf sections, perhaps we will see some direction of progression that no one has ever tried before?

Edit: Posting this at 2am? Yes, that is correct. I finished work an hour ago. This is one of the reasons why I don't post regularly.

Air cannon project: Upgrades!

It's a rainy Thursday afternoon, and I have nothing better to do other than work on my cannon a little. I decided that the simple design I built the other day was far too long to be practical for transport and trying to aim it was awful. So, I made two changes that has fixed that and should give me a little more power too.

First, I changed the chamber to an over-under layout, so that the length of the chamber is essentially halved. Using two 90 degree bends gives me a flat area to put my shoulder to achieve better aim, and the added volume of the bends slightly increases the overall chamber volume. not only that, but I can now stand the cannon on it's end for storage without risking damage to the fill valve, which is now under the main valve instead of at the end of the cannon.

Tin foil burst panel to be seated between the
back of the barrel and the o-ring on the other half

Secondly I wanted to be able to remove the barrel for storage and breech loading capabilities. I was originally going to cut the barrel and add in a simple male/female threaded fitting, but I was lucky enough to find a union coupling of the correct size at Bunnings, which means I can also add in a tin foil burst disc, sandwiched in the coupling. The burst disc won't break until a certain amount of pressure has built up behind it, allowing more time for the ball valve to be opened which will increase flow and increase initial acceleration of the projectile. Having the barrel removable also means I could build different barrels for it, possibly a Nerf dart barrel? A vortex mortar? Or even a paintball bazooka barrel? Oh the possibilities... Testing with projectiles might happen on the weekend, if the weather is good.

VERA: another video!

What does the world's largest, most powerful "potato cannon" look like? It's bright yellow and sits on the back of a truck trailer, of course. If you've been reading this blog since the very early days (over a year ago now! missed my own blog's cake day, whoops!), you may remember the initial testing video of project "VERA" or "Variable Energy Research Accelerator". This was only a video of the testing stage and was eventually taken down, so I removed the post the other day when I found out there was to be updated details.

Basically, VERA is a research tool developed to test projectiles that are of an odd shape with less violent acceleration forces. It uses the same technology used by hybrid potato cannons, that is, compressed flammable gas and air ignited by electrical arc, which in turn expands and builds pressure in the combustion chamber until the burst disc ruptures, unleashing the burning pressurized gasses upon the projectile. It's 19" bore x 40 foot long barrel might be a bit large for a potato though, so as in this video, other projectiles are launched with the aid of a sabot (a shell to guide it out the barrel) which is caught by a sabot catcher after the projectile has left the barrel.

Anyway, since this video was posted on the spudfiles forum today, I thought I should share it. After all, potato cannons can be park of this blog too, and I promise you, you will be stunned.

A simple air cannon

Remember how I said I might build an air cannon this weekend? Well I did, for less than $30 AU. This design is probably one of the cheapest, simplest and most reliable potato cannon designs you could possibly build. All parts are rated to at least 12 bar (174psi), which is a ton more power than needed for a bit of fun.

You should have seen the looks I got when I pulled this out of the garage...

This thing is over 2 metres long, has a 30.25mm I.D barrel, 50mm I.D pressure chamber, simple ball valve operation and a schrader valve as the fill valve (car tyre valve). So far, I've done test shots using potato ammo at 50, 60 and 75psi and the results so far have been AWESOME. This cannon at 75psi is as powerful as my old propane cannon of the same caliber. I'm pretty interested to see the results of taking it up to 150psi, but I need a decent compressor to test that. I may need to add barrel rifling to stop the potatoes from going out of control too...

While at the moment it remains in an unpainted, rather crude look with bootlace to attach the shoulder strap, this cannon can easily be changed to an under/over layout with a threaded barrel for breach loading, so in the near future I might either upgrade this, or build bigger and perhaps go to a 45mm I.D barrel with a 65mm I.D chamber. Even then, I doubt that kind of setup would take more than $40 and 30 minutes work. So, I guess now you know that I don't just screw around with Nerf blasters, I also try to put vegetables in to low orbits!