SpudFiles

My son and I decided around Thanksgiving we wanted to build an advanced combustion gun over the Christmas holidays. We had built a couple of the basic hairspray models in the past years so we thought it was time to move up. The outcome was basically a slightly large Latke model L3 with a few personal touches. Nothing really innovative here, but a pretty nice presentation, if I do say so myself.

Features are:

- All "pressure rated" parts (please spare me the noob smackdown)
- 3800 CC chamber
- Standard ball valve propane metering
- Magnetic propane tank holder
- 3" combustion chamber opening with screw on interchangable barrel feature
- Stungun ignition, with multigap circuit board for spark source
- 80mm computer case fan, with 9v battery and switch mounted in project box
- 1" Ball valve rear air intake

Everything else is pretty much self explanatory in the pics. I've built a 3.5 ft, 1.5" general purpose sharpened spud barrel, a 3.5 ft slit 2" sched 40 sleeved in 2" sched 40 golfball barrel (man that was a job), a 5ft 2.5" tennis ball barrel and a 26" 3" tee shirt barrel. The only one of these that is optimum is the 2.5 which is roughly .8/1 ratio.

Shooting this thing is a little awkward in that we almost totally ignored human ergonomics in the design, something that won't happen next time. However, because the meter pipe is so well anchored down, it became a handy right hand holder with the left operating the firing stungun underneath.

While I haven't been able to do any performance testing, both golfballs and potatos exit Out Of Sight very quickly. Given the area we were shooting, I would estimate around 250-300 yds for the potatos and 350-400 yds for the golfballs. Tennis balls about the same as potatos. Haven't tried the tee-shirt barrel yet.

Wow very nice, you did your research. Looks great.

Nice shot with the rope by the way

Love the stand too

thats pretty good, most people (like my self) don't have the patience to build a cannon like that, it looks great.

Looks like a very well made advanced combustion. Do you know the capacities for the barrels that you use? It would seem to me from the pics that they could be a bit longer to gain maximum performance, my bet is that it is a loud SOB!
Nice work Starman- Welcome to Spudfiles

Edit: Fak, i missed the part in your post where you explained the ratios, apoligies.

Nice job, you definately did your research and you should be happy.

Most of the other new member dont search really and end up asking so many questions.

So you should be happy of yourself and your son.

Hope too see damage pics soon.

Also i dont recommend holding it by the meter because it might loosen or break and can damage our chamber.

Also the fittings dont have to be pressure rated in a combustion, but in a pneumatic, yes.

Welcome to spudfiles

Oh yes that little spud barrel is only 2.5/1, so I figure I'm only getting about 1/2 of my ultimate performance out of it. However, a 1.5/1 barrel is 87" and a .8/1 barrel is a manly 164" long...definitely special setup to test. This was purely for wowing the family which it more than did....yes it was nice and loud, about 16 gauge shotgun loud, not quite 12 gauge loud.

The golfball barrel obviously needs to be longer as well...Oh well that's what I get for going with a big chamber....

That is a really nice cannon! The only part i would change is that Clemson Crap on it. Jk, but really, you should put some GA Tech sticks on there...

very well made, I was picturing the scenario:

"You couldn't hit a bard door with that thing!"

"Oh yeah? watch me!"

FordGtMan wrote:That is a really nice cannon! The only part i would change is that Clemson Crap on it. Jk, but really, you should put some GA Tech sticks on there...

Yeah yeah I hear ya. Believe it or not I've already had someone want to buy the thing as a "gameroom decoration" ...he thought there could potentially be a market for stuff like this.... Color me a little dubious about that...

MERGED:

jackssmirkingrevenge wrote:very well made, I was picturing the scenario:

"You couldn't hit a bard door with that thing!"

"Oh yeah? watch me!"

Well my brother hit the bigger "barn door" with his hairspray model...so of course I had best him....

Absolutely beautiful - it's great to see someone who's really done their research when they were building and used all the right parts.

One slight niggle with it is that I can't see any pressure regulator in the metering system, which will mean that the changes in propane pressure from temperature changes will affect performance on different days. On warm days, your mix will be overly rich, and lean on cold days.

But, it will still be a lot better than the old spray can, which is very imprecise.

And I'm sure you and your son will get a lot of fun out of that.

starman wrote:he thought there could potentially be a market for stuff like this

There already is, SGTC was the biggest, but got shutdown early last year, now there are several smaller online stores, such as Spudfiles' favourite store, http://www.bcarms.com

Side note: Sorry but we don't allow double posting at SpudFiles, just edit your posts, or reply to multiple people in the same post.

Cheers.

MrCrowley wrote: Love the stand too

The stand was actually a trebuchet this time last year...one of those engineering week "see who can chuck something the furthest" kind of things. We just adapted it for artillery this year..

MERGED:

Ragnarok wrote: One slight niggle with it is that I can't see any pressure regulator in the metering system, which will mean that the changes in propane pressure from temperature changes will affect performance on different days. On warm days, your mix will be overly rich, and lean on cold days.

Yes very true. We were running out of time...I couldn't get my propane adapter threaded...Lord knows I tried hard enough. I have the regulator on the shelf awaiting next project.

I finally gave up on the absolute precision and clamped the hose directly on. My ideal gas load is 73 psi for this meter/chamber, which I can easily get if the temp is 55 F or above. Just have to quickly diddle the ball valve on loading... Its been far too cold of late...

Merged:

Re. SGTC and BCarms etc.

I'm aware of this stuff...was thinking more along the line of completed, painted, ready-to-go CUSTOMIZED guns for the rich folks with nothing else to do at their lake house.

Nice nice!
Very clean constructed!
One suggestion:
You should get spark gaps in different places in the chamber.
(like one in the front, one in the back and one in the middle.

psycix wrote:Nice nice!
Very clean constructed!
One suggestion:
You should get spark gaps in different places in the chamber.
(like one in the front, one in the back and one in the middle.

Thanks! Yeah I was running out of time on that as well. Rather than quickly rig something up I would be unhappy with, I kept it solid and simple. It's actually very reliable.

Yeah yeah I hear ya. Believe it or not I've already had someone what to buy the thing as a "gameroom decoration" ...he thought there could potentially be a market for stuff like this.... Color me a little dubious about that...

Hahaha, that must be my grandpa buying that! His living room is like a clemson gift shop. He now uses my other spudgun to "scare" off cyotes.