For those who like potato guns

[New Zealand]

 

100 lbs = 45.45 kg.

1000 fps = 304.8 m/s

Energy = 0.5 * 45.45 * 304.8^2 = 2.11 MJ

 

...wow... now THAT is a real gun lol

[chilehed]

For comparison, my design goal is 100 lbs to 1000 fps (680 mph).

Damn... can I come over and watch?

 

 

edit... Something's not right here. 1.5 MJ compared to "2+" MJ for a significantly smaller projectile that's slower as well?

 

PUMPKIN

10 lbs = 4.545 kg.

600 mph = 268.2 m/s

Energy = 0.5 * 4.545 * 268.2^2 = 196 kJ

 

Mine

100 lbs = 45.45 kg.

1000 fps = 304.8 m/s

Energy = 0.5 * 45.45 * 304.8^2 = 2.11 MJ

Sure enough, I screwed that one up. Misplaced the decimal.

[InigoMontoya]

Still have a lot of work to do to fully characterize the gun but.... She lives.

 

[pic deleted]

Edited December 18, 2010 by InigoMontoya

[Cap'n Refsmmat]

What exactly am I seeing there? It's impressive, but... what're the fiery bits doing?

[InigoMontoya]

Nothing particularly exciting, just a combustion mechanics test. No projectile, just gases burning.

 

Still, observers 1200' away and well behind the muzzle stated that not only was it loud, they *felt* the muzzle blast.

[Cap'n Refsmmat]

Hang on... is that the barrel of the gun on the right? It was yellow in your earlier pictures, but it looks rather green.

 

I was confused because I saw a ring of fire sort of hovering in mid-air, but if that's the end of the barrel, that makes more sense...

[InigoMontoya]

Yes, that's the barrel of the gun. The lighting isn't the greatest (you're looking at the "shadow side"), but other than that all I can do is shrug and say "bad lighting" for why it has a green tint. I assure you it's still yellow.

[Cap'n Refsmmat]

Impressive. You do realize that we'll need high-speed video once you start shooting at targets.

 

I almost feel bad for the flight data recorders.

[InigoMontoya]

[Meh, nevermind]

Edited December 18, 2010 by InigoMontoya

[TonyMcC]

This potato gun could obviously fire potatoes by the sackfull. If you used the bolts at the muzzle to hold a grid of strong wire it could easily be converted into a potato chip producer of industrial proportions. Patent it and make some money!

[Cap'n Refsmmat]

http://xkcd.com/421/

 

[FX]

I've been working on a project for a number of years now. It's *almost* completed. In short, I believe it will be the world's most powerful gun powered by "hardware store-level technology". Not the largest, mind you, but the most powerful. Muzzle energy should be in excess of 2 MJ.

 

That is quite simply ... awesome.

[InigoMontoya]

A more recent photo....

 

[Cap'n Refsmmat]

That needs to go on the 2012 Spud Gun Wall Calendar.

[FX]

OK that is incredibly awesome. I want to see video now!

[TonyMcC]

Gosh - that trailer must have good brakes!

[InigoMontoya]

Somebody asked me for an update so I figured I'd give it here....

 

There's not really tooo much to report as work has been incredibly busy and things are only getting worse (will probably be working 7 days a week next month). VERA (the gun) is a side project so she has been largely neglected during this time. Granted, "insanely busy" is a good problem to have these days so I'm not complaining, but it doesn't help my dreams for VERA come to completion.

 

HOWEVER....

 

Right now there's a video that's working it's way through our public affairs office. It was supposed to have been a rough cut of a marketing video but it too has been overtaken by events and there's a desire to get something out there fast. So the rough cut will be the final cut. In any event, I expect the video to be released in about a month. When that happens I'll put it up on youtube and put a link in this thread.

Edited April 9, 2011 by InigoMontoya

[Hal.]

Inigo ,

 

Why is there a preference for propane / air mixtures ?

 

I like to throw a few numbers into my calculator to see what I get , can you say what the amount of propane used is per explosion ?

 

Would it be possible to use acetylene / oxygen mixtures ?

Edited April 9, 2011 by hal_2011

[InigoMontoya]

Why is there a preference for propane / air mixtures ?

Propane/air results in a very stable, well behaved combustion.

 

Oh, and it's dirt cheap and everybody is familiar with it. It's nice to be able to turn to the safety department and be completely honest when I say, "This gun is safer to operate than your backyard BBQ grill."

 

can you say what the amount of propane used is per explosion ?

Off the top of my head? Meh... Something like 3 or 4 pounds.

 

Would it be possible to use acetylene / oxygen mixtures ?

Depends on your definition of possible. Could I pump acetylene/oxygen into the gun? Sure. Would I want to? Hell no. I want a deflagration, not a detonation. Acetylene and oxygen would assuredly detonate. That's bad.

Edited April 10, 2011 by InigoMontoya

[Hal.]

Inigo , Would a propane / oxygen mixture give an unwanted detonation ?

[InigoMontoya]

Inigo , Would a propane / oxygen mixture give an unwanted detonation ?

I can't speak authoritatively on that front, but I believe it would. Mind you, a bit of O2 to augment the burn would probably be OK, but as O2 levels rise so too would the odds of detonation.

[Hal.]

Inigo , one more question while you have the spare time , What is the technical reason that classes Vera as a gun ?

[InigoMontoya]

Inigo , one more question while you have the spare time , What is the technical reason that classes Vera as a gun ?

I'm not sure I understand the question. Can you rephrase?

[Hal.]

Inigo , Why is Vera a gun and not for instance a jet engine ?

 

Has it to do with the fact she has or has not got a projectile ?

 

 

[InigoMontoya]

Inigo , Why is Vera a gun and not for instance a jet engine ?

 

Has it to do with the fact she has or has not got a projectile ?

Huh? Why do we call guns "guns" and not "jet engines?"

 

You've got me thoroughly confused.