The halitosis howitzer

[mklotz]

Ok, ok, it's a bit off topic. The content-purists can consider this to be a description of a single cylinder, non-reciprocating, internal combustion engine with electronic ignition.

If you want to get people's (especially younger people) attention at your next engine show or backyard barbecue, you just can't beat a small explosion. I've learned that the nanny-state frowns on 1" smoothbore, black powder cannons firing ball bearings through tree trunks so I built a safe cannon (actually a howitzer) that doesn't sacrifice that head-raising CRACK needed to get yourself noticed.

The top from a soft plastic 35mm canister is screwed to a block of wood. The piezoelectric sparking element is cannabalized from a commercial butane barbecue lighter and its two wires led through holes in the block to emerge into the cannister top (see detail in second photo. Arrange the wires so, when the piezo button is pressed, you get a nice juicy spark across the wires.

Fuel is provided from a pocket-sized cannister of aerosol breathspray. Spray a bit into the film cannister, immediately mount the cannister on its top on the howitzer, press the piezo button and the cannister will fly twenty to thirty feet with a very satisfying BANG!
The plastic film cannister won't do any damage if it hits something and, with the small amount of propellant, this is actually a pretty safe device.

Aerosol breathspray works well. It contains alcohol and the propellant is butane so it's fairly easy to get a proper mix of propellant and air in the cannister. Non-pressurized breathspray works too but you'll need to experiment a bit to get the right air-fuel mixture. Hairspray works well but leaves a sticky residue. Experiment - but resist the urge to try acetlyene.

If you have younger kids, ensure that they understand that this is Daddy's toy and lock it securely away when not in use.

Oh, one more thing. When testing the piezo element, don't touch the wires. DAMHIKT.

 

[rake60]

I have to like that Marv!

A few years back one of my boys friends built a potato cannon from PVC
pipe that used hair spray as a propellant. After an hour of launching
potatoes into the woods behind my house they were sitting in my living
room with the proud builder explaining to me just how his toy worked.
He clicked the grill lighter igniter and the residual isobutane in the
cannon created a blast that was powerful enough to take the curtains
off a window 8 feet away.

I don't suppose being on my knees laughing set much of as example for
the boys, but with the look on that kids face it was the only response
I could offer. LOL

Rick

 

[tattoomike68]

When I was a kid about 12 years old my friends and I all made tennis ball cannons from soup cans and duct tape and used rubbing alcohol to power them.

My folks took away all the fun stuff like that along with the nunchaku, throwing stars and other fun stuff we made. :cry:

 

[dparker]

Hello All: The film canister cannon was a Jr. High project for my son---lot of fun for me also. It is up on the shelf next to my model engines. As far as Spud Guns go a couple of stories--
My Brother in Law made one and was showing it off at a family reunion, some of our elder generation were interested in how it worked. B-I-L took the back end off and was showing the coleman lantern lighter and how it worked. Everyone was crowded around looking into the breech of the gun when he showed them how the spark worked---there was still some fumes from the starting ether remaining and it flashed. The crowd stepped back rather quickly but no real damage.
My experience was with the spud gun the B-I-L made for me, I was showing it to a friend with some apples as ammo. We used up all the apples by the time he wanted to try it so the next best thing he had was zucchini. We cut the zucchini to fit the barrel and he tried it. The gun did not fire the first few times he tried it, and each time he retried it he was more interested in it firing instead of aiming it, the muzzle would elevate a little. When it finally did fire, the zucchini took off across the yard, over the barn, across the street, up the driveway, into the open garage door, underneath the car and into the inside wall of the garage. He quickly gave me the gun (like a fool I took it) and ran over to the house. We thought it went through the bedroom window and may have hurt someone. The fellow was just coming out of the garage and looking around when my friend got there and said "Did you see a zucchini come over here?" The reply was "Yes, I just stepped into the garage and this zucchini came out from under my car and hit the wall." The explanation my friend gave was that he and his son had made a big slingshot and were trying it out and had the trajectory wrong. I was laughing too hard to be of any help to anybody.
Don

 

[lugnut]

Chuck, I think you proceeded in the right direction-----If there is a hazard in the way, you should remove it before proceeding :roll:
Mel

 

[JW]

When I was a kid about 12 years old my friends and I all made tennis ball cannons from soup cans and duct tape and used rubbing alcohol to power them.

My folks took away all the fun stuff like that along with the nunchaku, throwing stars and other fun stuff we made. :cry:

We called them polish cannons.

 

[rake60]

We called them polish cannons.

Oh yeah! Remember when Pepsi cans were tin?
6 Pepsi cans, a little duct tape and a can of lighter fluid.
If you didn't have a Polish Cannon and a blue/green bruise on the thumb
of your left hand from it kicking back when you lit it up, you were just
not a part of the crowd!

A good one would launch a tennis ball 200 yards. But you always
let your buddy light that one. You KNEW it was going to kick back!!! :wink:

I could tell you a little story about a metal Band-Aid box and a few
ounces of powdered aluminum...
That little stunt got me and a few of my friends in deeper trouble than we
had expected it to….. Oh to be 17 again! LOL

Rick

 

[Mcgyver]

great project that'll have the kids beside themselves they'll love it so much. made something very similar years, still sitting around in the shop somewhere.

problem is, where do you get those cool little black and grey containers ??

Don, I laughed pretty hard and your account, good story