Simple Golf-Ball Combustion - UPDATE 7 April '09

[mark.f]

Simple Golf-Ball Combustion Launcher
A.K.A. - "Practicannon"
_______________________________________________________________
See the post below for the upgrade information.

SPECIFICATIONS:

• Fuel: Metered propane, one main tank and one backup
• Ignition: Electronic grill igniter, wired to a three-gap spark-strip. Ignition points spaced evenly apart in center of chamber
• Mixing: Standard 12VDC computer fan from RadioShack
• Chamber: 14" of 4" SCH-40 PVC
• Barrel: 72" of 1-1/2" SDR-21 sleeved inside of 2" SCH-40

This was just a little ditty to build once the summer started. I designed it to simply shoot golfballs at a fast enough velocity to penetrate 3/4" plywood, but that is still as yet untested.

I built the ignition system to have three gaps spaced evenly apart in the center of the chamber, that way I would get three roughly spherical flame-fronts before burnout. I doubt it makes too much of a difference, but I was bored and I could, so I did.

The mixture fan is a standard RadioShack 12VDC fan, wired to run off two 9 volt batteries. I also wired a small red LED in parallel with the fan with a small ??? ohm resistor (forgot already) to signal when the fan was one. Ignition is provided by an electronic grill igniter which I mounted directly into a conduit box without modification, because I am lazy.

We'll have to see how it shoots later on today. Right now, my neighbor is on his tractor mowing his lawn(s), and I accidentally pulled a fan wire from a length of shrink wrap tubing whilst taking one of the pictures below, so I'll have to fix that soon. I'm gonna go out on a limb here and say that I'll have damage pictures and a video up by this evening, if I'm lucky. If you have any questions please ask them, because I didn't go over ever single little thing in this post.

Thanks for reading and have a great morning! The [excrement]-[intercourse]-load of pictures is below (used the uploader to appease PCGUY).

[starman]

Man, that chamber setup looks ALOT like what I'm building at the moment kind-of scarey actually.

You shouldn't have any trouble punching through 3/4" ply with this. You can also try adding a simple masking tape burst disk on your barrel male coupler...huge performance increase...even with 1X combustion.

This is 3 layers of 2" Scotch Painters Tape, trimmed with exacto knife.



When you replace that rope, you could use a guitar strap...easy to find and relatively cheap.

Nice job overall. Now why again do you have 2 propane tank holders? Seems like a lot of weight to carry around as you're not likely to ever run out (or only once or twice at the most) one tank in the usable life of this gun.

[mark.f]

Well, in short, because I can, and it looks cool and intimidating.

So, what are you building at the moment? Is it a golfball combustion?

[CS]

Great cannon and presentation.

Not sure if I see the reason behind a on board back up propane cylinder considering they are good for a few hundred shots each. A spare one in your garage or car should do. Plus it makes your chamber pretty bulky.

Props on the spark strip. While I'm sure they are not that hard to build I have yet to build and finish one.

Also great job on the project box. Looks nice.

Yeah as others have said you shouldn't have trouble punching holes in some 3/4" OSB. Sometimes I can get through 2 with my little ABS gun and it only has a 9-10" long 4" diameter chamber if I recall correctly. Plus it is a spray n' pray so yeah.

Great build, and thanks for posting!

[SpudFarm]

you call that simple? 8)

get a pic up of a advanced cannon

[starman]

So, what are you building at the moment? Is it a golfball combustion?

Noise cannons, using the burst disk barrel stumps you see in the pic. Should be ready to present here in a week or 2. Some July 4 block party gigs coming up.

I also have a 5' sleeved sdr 21 cam locked GB barrel that I'm using on my other gun....would also fit on my noise cannons as well...

[mark.f]

Thanks for all the compliments. Looks like I didn't get any videos tonight. spudfarm, I guess we have different opinions on what's advanced or not.

starman, you designed a cannon just for making noise?

[starman]

Thanks for all the compliments. Looks like I didn't get any videos tonight. spudfarm, I guess we have different opinions on what's advanced or not.

starman, you designed a cannon just for making noise?

I have indeed, a battery of 3 of them actually. Worked on applying the first coats of paint this evening.

I'll post them here when I finalize the design and make them presentable.

Oh yes.... they are LooouuuD.... 8)

[STHORNE]

very nice work. lol, "simple" my ass...

What you should do is put some handles on that baby and wire the ignition switch into one of the handles by modifying the bbq igniter (shown here)

Also, a paint job wouldn't hurt any
Again, nice work. Post some damage pics and videos mark!!!! Wanna see this thing in ACTION! lol

[mark.f]

I'm working on em (well, not really). I started to clean my truck yesterday (what I thought would be a simple one-hour endeavor), and that wound up lasting me until around 9 'o clock at night. I'll fix the fan lead and get some simple videos up today, hopefully. I've got nothing else to do...

Also, I've never really seen the use of painting. I've painted a few launchers, and it just wound up annoying me in the end. Even properly applied (sanded, primed, painted, recoated), it still scratches off quickly unless it's metal. Fusion is okay, but they have a rather limited selection of colors...

Like the ignition where it is, though. Maybe another day/month/year...

[STHORNE]

it still scratches off quickly unless it's metal.[/quote]

that's because you are forgetting the polyurethane (varnish) my friend. It comes in spray and brush. 1 coat of that over your final paint job and it will be protected for life. No more scratch marks, I promise

[mark.f]

I do have polyurethane, but I use that for woodworking. Besides, that's too much work to me. Better off with plain uncoated PVC.

[mark.f]

DR Style Update - 7 April 2009

For those of you who don't know what DR's (BewareOfDog's) style of launcher was, it was basically to to not over-complicate things, use cheap and readily available materials, and to be neat and clean in appearance.

While I might not have matched his style perfectly, I really wanted to get this cannon working again (salvaged the electronics for another project and never got around to replacing them), and I need it to make an art project, believe it or not.

I simply removed the spark strip and PC fan, mounted a cheapo wal-mart keychain fan on two of the 1/4"-20tpi bolts already in place (they don't sell my favorite camping fans anymore), enlarged a hole and threaded/epoxied in the lantern igniter, and that was that. I also removed the meter, added some quick disconnects to make it detachable, and even went so far as to get a "push to connect" female quick disconnect for easier fueling.

Some of you might disagree with the removal of the camlock couplings (*cough*starman*cough*), but take a look at it this way. You can't breech-load golfballs through a 2" cam-lock, and if you muzzle-load there's no real way to make sure the ball doesn't roll down the barrel. So, I threaded a 1/4"-20tpi screw into the back of the barrel. I simply insert the ball, and tighten down the screw to keep it in place.

The pictures of the update are below. I plan on having some long-overdue damage video and pictures up tomorrow (for real this time!), so stay tuned.

[King_TaTer]

Never got the chance to post on the original gun. I think this is a nice change from the brick it used to be but then again it's not so intimidating anymore. I also like the addition of the quick disconnect. Good work over all and I'm looking forward to the damage video and pictures.

[mark.f]

Thanks. The original version wasn't unwieldy, but it was a little cluttered.

I'll get something up tomorrow.