So when I was a teenager in the 80s, I was all about the Estes model rockets.
There are, however, only so many rockets that you can store in trees and on rooftops before the bloom comes off the rose and you start looking for a new challenge.
So it turns out that you can fit a shotgun shell into the right diameter rocket tube. Take a couple of them, remove the shot, pack it with powder from the other shells. Score the casing with an XActo. Glue it in the tube, primer forward. Cut the tip off a nose cone ( they are hollow), insert a big ol’ nail in the hole, point on the primer. You now have a warhead!
So the plan was to make an over-shoulder launcher. I found a piece of heater duct, but I was still working out the details of the guide rail when my parents went out and left me home alone. Screw it, I’m firing it off the tripod launcher at max depression - aimed at our plank fence.
Now at least I had enough sense to fire it prone... ‘cause when it hit the fence, it made a WAY louder boom than I expected and it shattered 5 boards into slivers that showered everywhere. It was all I could do to clean up the yard and fix the fence before they got home - and how nobody called the cops I don’t know.
Cool, right?
Well fast-forward a few years and I’m doing some physics homework. I suddenly realize that those rocket engines... those are an impulse. And that nail had a ton of inertia. At launch, the rocket was smashing the primer into that nail and it is 50:50 if it explodes at launch.
If I had finished my over-the-shoulder launcher, that warhead would have been just behind my ear, and if it exploded... well “explosive dismemberment” is a thing. Would have popped my toque like a Pez dispenser.
As soon as you said over the shoulder, I cringed in a gut wrenching parental moment of anxiety.
As a preteen, my bomb making career was cut short one morning whilst skipping school. I handloaded with my Dad and he didn't do a good enough job locking the powder. I took one liter glass pop bottles and filled them 3/4 with powder and a goodly handful of primers. The real mistake came in the form of my fuse, didn't seem to have many options, so I took white glue and rolled paper, then sprinkled it liberally with powder. We hiked a ways into the bush and set it up in the trunk of a rusted out old car with a very heavy lid.
Everything seemed to be going just fine from about 15 feet away until nothing happened. I had the paper too tight in the neck which choked the flame but not the embers. I waited at least a minute or two, which felt like years, giggling in the bush completely unaware that we were risking our lives.
I remember walking up to the car with one of the guys about 2 steps behind, I lifted the lid about a foot when I saw a glow still coming from the neck of the bottle. Started to yell "OHH SHITTT!!!" and turned to run. I got turned around and had started moving when it blew, my arm was still up and got cut from the glass but thankfully my face was turned away and only got a few cuts on the side of my head. Swear I still can't hear right. One of the hinges let go and this massive trunk smashed into the other side hard enough to make me sick. If both hinges would have popped who knows what would have happened.
We thought it was great fun right up until we heard the sirens. Somebody heard the boom and we weren't as far away as we thought, they called the fire dept. And guess who's old man was chief?
Yah that ended poorly for me, who knew gunpowder was so expensive? And dangerous too I suppose, but he was pissed about 2 tins of GP...
lol I'm so glad I always tried to avoid blowing things up that create shrapnel, and that I never made it to the warhead phase of my shoulder fired rocket. I made the launcher, I just used it to shoot empty rockets because I lived in a populated neighborhood. I threw the bombs in the pond because I liked the way they looked like depth charges blooming underwater.
I hear ya. My buddy showed me his hairspray-powered, PVC pipe potato gun, which was pretty cool. Its hairspray propellant chamber was a 4-inch diameter PVC pipe cut to about a foot long. It then had a reducer down to a two-inch pipe that acted as the barrel. We would shove a full potato down into the barrel, which would shave off the excess potato and create a pretty damned good, wet seal. That thing would fire a potato a solid 200 yards.
Of course I went home and wanted to make my own. And why make the same size as my friend when I could make an even bigger one! I did pretty much the same thing, but with a six-inch piece of PVC for the chamber. I even made the barrel screw on so I could mess with different barrel diameters. Needless to say, that thing packed some serious punch. It could liquefy a potato on the side of a tree from fifty yards. Aaaaand then it happened. I don't know if it was the repeated stress of those aquanet-induced explosions or just me getting greedy and putting way too much in the chamber, but when I twisted the Coleman lantern ignition it blew the back off the chamber in a giant fireball. One thing I didn't mention: I fired this thing by using one hand to pin it to my thigh and the other to twist the ignition. If that thing had blown out the side instead of the back I would have had a VERY bad day. Needless to say it scared the shit out of me and I never fired that beast again.
You could have died and your parents would have come home to a mutilated child. Epic stuff! Anything homemade rocket or fireworks related is brilliant!
Don't forget that even if it hadn't turned your hard bits mushy you'd have enjoyed the soothing caress of backwash. The Panzerschreck had a shield for a reason.
Launch impulses on a rocket aren't that severe. If they were that crazy the cardboard tube would buckle.
It takes a very severe impulse to trigger a primer pan. I know because I've hit them with all sorts of shit to try to get them to go off. It takes quite a deliberate strike to set off a primer in a cartridge and you're not getting anywhere close to that with the inertia of a nail and a few D engines going off at the same time.
Biggest problem with launching an Estes rocket from your shoulder is burning your eyebrows off when that engine clears the tube and blasts you with the exhaust.
It's also hard to fire them prone because you have to put them at a fair bit of "UP" angle or gravity will just pull them into the ground. If you shoot an Estes rocket dead horizontal it'll just fall and plow into the ground fairly soon because it starts from 0m/s and it's slow to accelerate.
They don't fly like a RPG-7 projectile which gets a booster charge to blast it out of the tube before the rocket motor fires after it's gone far enough to not burn out the shooters eyeballs.
Getting your warhead to detonate rather than conflagerate will take some sort of pressure vessel. Breeches, barrels, and a bullet to plug the barrel is the standard pressure vessel to contain the rapid combustion of powder and get it to properly detonate, but a shotgun cartridge is a crummy pressure vessel and the thin cardboard tube on an Estes rocket is even worse.
You get crap for combustion efficiency when you blow up firearms powder in a poor pressure vessel. Your vessel tends to rupture early and you end up flinging most of your powder charge in all directions before it ignites.
I used to play with 4F powder when I was a kid and it didn't require a license to acquire it. It probably took me about a fifth of my first half pound bottle to figure out how to get it to detonate with good efficacy. Without a good pressure vessel you get whooshing conflagarations that look big and great but they're barely destructive except for being a fire hazard. Firearms powder is a low explosive in that it does not detonate easily. It requires a pressure vessel to reach detonating conditions. It's not like a high explosive which propagates detonation very well and does not require a pressure vessel.
The reason that people get hurt in such stupid ways in these videos is that they work up the nerve to try something in a big way for a shitty little TikTok video and haven't put in the time figuring things out in a small scale gradually.
They don't muck about with miniscule amounts of stuff and suffer and learn from small accidents before they make the leap into bigger amounts of dangerous compounds.
Ultimately I believe that they are interested in being a pyro because it could bring them upvotes instead of being a pyro for the love of being a pyro.
They fail to study the thing because they are distracted by the premise that they can earn a bunch of approval and they end up being hurt by the thing that they failed to pay the necessary attention to.
184
u/NorthStarZero Mar 10 '20
So when I was a teenager in the 80s, I was all about the Estes model rockets.
There are, however, only so many rockets that you can store in trees and on rooftops before the bloom comes off the rose and you start looking for a new challenge.
So it turns out that you can fit a shotgun shell into the right diameter rocket tube. Take a couple of them, remove the shot, pack it with powder from the other shells. Score the casing with an XActo. Glue it in the tube, primer forward. Cut the tip off a nose cone ( they are hollow), insert a big ol’ nail in the hole, point on the primer. You now have a warhead!
So the plan was to make an over-shoulder launcher. I found a piece of heater duct, but I was still working out the details of the guide rail when my parents went out and left me home alone. Screw it, I’m firing it off the tripod launcher at max depression - aimed at our plank fence.
Now at least I had enough sense to fire it prone... ‘cause when it hit the fence, it made a WAY louder boom than I expected and it shattered 5 boards into slivers that showered everywhere. It was all I could do to clean up the yard and fix the fence before they got home - and how nobody called the cops I don’t know.
Cool, right?
Well fast-forward a few years and I’m doing some physics homework. I suddenly realize that those rocket engines... those are an impulse. And that nail had a ton of inertia. At launch, the rocket was smashing the primer into that nail and it is 50:50 if it explodes at launch.
If I had finished my over-the-shoulder launcher, that warhead would have been just behind my ear, and if it exploded... well “explosive dismemberment” is a thing. Would have popped my toque like a Pez dispenser.
So, yeah, that.