30 years ago I was a teenager a friend of mine had a giant plot of empty land in his family, and so we'd go out there and do stupid teenager things things like playing with fireworks and building and shooting potato cannons.

We'd discovered dry ice bombs alongside internet plans for potato cannons, and in our infinite wisdom we tried to build a dry ice bomb powered potato cannon. In our mind the sudden increase of air pressure would've sent the payload going ridiculously far.

Thankfully when we went to use it the first time, we were smart enough to run as far as we could before it went off. It was far far more pressure than the pipe could handle and it sent little bits of PVC shrapnel flying everywhere.

Has anyone tried supplementing the hairspray with the sort of canned oxygen you can find at ski resorts?

Best my pals and I ever did was engine starter fluid and like 40PSI of air with a duct tape diaphragm to hold the air in. We shot old D batteries wrapped in duct tape out of it. Shot it at a stop sign once and it made a perfect hole with sign peeled back like shooting BB guns at a coke can. The whole thing was stupidly dangerous.

Not a traditional spud gun, but my father (who has been a welder for his whole life) built a couple differently sized cannons out of aluminum (one fired wine corks and the other was about tennis ball-sized). We used acetylene gas. Honestly kind of terrifying and incredibly dangerous, not recommended. They only come out on independence day.

We built one using acetylene as the source gas generated from calcium carbide and water, ignited by a spark gap from an electric fence. The combustion chamber was a 40 gallon oil drum and the barrel was a 20’ scaffold pole.

Round 1 worked a treat, firing a champagne cork sized wooden baton far away into the distance.

Round 2 was a disaster. Calcium carbide needs water to react into acetylene. Our method involved putting a few pints of water into the oil drum (on its side), then a few rocks of calcium carbide, then the igniter, and finally the scaffold pole resting under it’s own weight in the small, off centre oil drum aperture.

On this second round the end of the pole was accidentally submerged in the puddle and the wooden baton got jammed. This meant the explosion forced water up the gun barrel — a pole just resting there in the mouth of the oil drum — launching the entire pole down the garden. It must have gone a good 50 feet or so. This is a steel javelin weighing a good 30lbs.

Round 3 ruptured the oil drum. It sounded like a bomb going off.

I was surprised to see hairspray as the recommended fuel, since that what we used growing up 30 years ago, with no particular engineering expertise. I assumed there would be more advanced options now (if for no other reason, because hairspray smells!)

I find the 99% isopropyl alcohol from the pharmacy works well, and it's cheap too. Also, I'd get funny looks buying hairspray, when I have very little hair.

Aren't many hairsprays just propane? I think its just a convenient option, otherwise you need a tank and/or a hose of something else

I always used starting fluid

https://www.petes-tools.com/what-is-starter-fluid/

Friends and I used MAPP gas mixed with oxygen...had a pretty good kick but you were really just rolling the dice on the ratio

The way to do this with oxy-fuel is to light the torch, adjust to a neutral flame, then extinguish the flame. The resulting gas coming out of the torch should be pretty close to stoichometric, and should be treated with extreme care.

Thats how you make a bomb. With pure oxygen you can add /much/ more fuel in, and it detonates rather than deflagrates.

Search on youtube for some hydrogeh/oxygen baloon explosions to see what I mean.

The rated pressure is for water, and the rating assumes the pipe is in perfect condition. And no, constant vs shock pressure doesn't make it safer.

If you nick it, drop it on something, etc - the rating no longer applies.

Over the years numerous shops have used PVC pipe "because the compressor only goes up to 100psi and the pipe says 250", that sort of thing...and had the pipework explode and injure/kill people.

~100 psi in a PVC pipe is enough to tear through a sheet of drywall and then fatally injure someone.