Introduction: The Terrible Idea: a Model Rocket Launcher
First of all, DON'T BUILD THIS. During all the experimentation with this thing, lots of stuff has gone wrong. This was the uninformed brainchild of an overconfident high school student. Any person in their right mind does not need one of these.
IF YOU DO BUILD THIS: Safety first, second, and third. Everyone involved wears thick long sleeved clothing, full face protection, gloves, etc. Have fire extinguishing things on hand. Shoot this in a huge empty field, preferably in the middle of the winter and very far from civilization. Have a clear area to run away if something goes wrong.
This build was originally designed to launch rockets for airsoft, but after many testing mishaps and the overall un-reliability of the system, I have decided that it is only fit for shooting for fun, not at other people. Also, it is most likely illegal in all civilized places, and generally isn't a toy. Any rockets you shoot out of this thing should be models without a payload.
I ran a few dozen rockets through this thing, with mixed results. The best rocket launched from this went somewhere in the neighborhood of 600 feet or so when launched at a 40 degree angle. We never found the rocket, and definitely alarmed the neighbors.
A few were designed to blast airsoft bb's out when they landed or ran out of fuel. The first one I made worked like a dream, but after that, they all failed more or less spectacularly, with one managing to coat the side of a tree in molten plastic. Not fun.
I can't pick out a specific launch that I would classify as the worst, but a few involved diving to the ground, or dropping the launcher and running away. Needless to say, operating this thing needs some serious safety gear.
I built it out of 4-inch diameter DWV-D drainpipe, held together with nothing but hot glue. It is approximately 4 and a half feet long, and weighs around ten pounds when empty.
This launcher is basically a more specialized version of Rwctt's launcher, made from lighter weight pipe, with a modified ignition system made from an Estes rocket engine ignitor. I do not have any construction pictures of the launcher, because at the time of construction, my camera was without a memory card. That's probably just as well. If you need instructions for something quite like this, go to the link below, his is safer, better designed, stronger, and better looking than mine.
You can find it here-----> https://www.instructables.com/id/PVC-Rocket-Launcher/
Step 1: Breaks Down for Portability
I made this in four parts. listed from top to bottom, these are: end cap spark arrestor, rear section with shoulder rest, middle coupler with ignition system, and the front section with rotating handle. All that is needed for break down is a small screwdriver or pair of pliers.
The end caps and spark arrestor were made out of cut tin cans and screwed in place.
The shoulder rest is just a piece of scrap wood glued to the body of the launcher.
I didn't want to cut the wires for the relatively nice Estes rocket ignitor unit, so I just stuck an extra piece of pipe on the side and jammed the excess wire in it. Obviously this was poor design and the wire should have been cut to length.
The spark arrestor cap serves two purposes:
- It contains all the wire connections and the rear of the rocket, which is easy to damage if exposed.
- It contains the backblast of the rocket and prevents it from burning things behind the shooter.
Step 2: Simple to Use, Provided It Doesn't Break
This launcher, when broken down, will fit in a big backpack The firing operation is very simple and can be detailed in only several steps:
- Insert rocket into assembled launcher.
- Remove end spark arrestor cap.
- Connect ignition clips to the wires on the bottom of the rocket. Replace end cap.
- Insert safety key into the hole on the ignitor box. depress key until light comes on.
- Aim and depress launch button to fire. Don't let go of the button until the rocket has left the tube (note: if it doesn't leave the tube, run)
- Remove safety key.
Step 3: Reflection on a Really Unadvised Project
I really am lucky I didn't seriously injure myself or start a forest fire with this.
Here is a list of the various problems and some possible solutions:
- Whenever it fired, the user would get a blast of hot gas and smoke in the face. Some kind of a backblast shield around the mouth of the launch tube would be helpful
- The rear parts of the launcher started to melt a few times. This is probably because I used a rear cap, so all the hot gas was somewhat contained.
- All the gas also deposited grey corrosion on any metal surface, so the electrical connections to fire the rockets always had to be cleaned with steel wool for reliable ignition.
- The interior of the tube was uneven due to the sloppy construction of the breakdown system, so on several occasions the rocket got stuck in the tube and exploded. Luckily the rockets would burn for a few seconds in the barrel before exploding, so I had time to throw the launcher, curse, and run away.
Overall, DO NOT TRY THIS AT HOME. This Instructable serves as a how-not-to and a cautionary tale. I share it with you in the spirit of honest project documentation. Cheers!