RPG

[cowboy]

Well my Introduction has turned into a discussion about making an RPG so I thought I would just start one here. Basically the design that I am thinking of would be comparable to what they had in WW2. Basically a tube that you load a rocket in, have a breech door that closes, and basically have a model rocket type projectile with an explosive tip. I am moving at the end of august to an area where I can safely make, and test my theory without fears of the BATF busting down my door, and me shooting a few of them thinking that we are being invaded. Anywho I just wanted to see what other people thought of the idea of having a home made RPG. Also I would probably fire it as a Sabot round.


Edit: I finally decided to deal with the mac version of paintbrush as my main computer is down at the moment, and made a rough sketch of my idea so far. Let me know what you think

[TheFallen]

I wouldn't go for a sabot round, you need seriously high velocities to make them effective.

Nor would I have a breach, the recoil will hurt a lot. research recoilless rifles.

[Enkidu]

I've got a small collection of books on shoulder fired projectiles. I've uploaded it to rapidshare. I've got a few other files scattered around my hard drives... when I come across them I'll post them as well. Some (all?) of the 'homemade' titles are either crap or toys. My hopes for an 'rpg' doesn't include either of those qualifications.

Its been a while since I looked into this project with any diligence. After I finish my current projects, I'll begin again on this one. (The first is 90% done, the second is only about 30 or 40% finished. No telling when I'll get to this one. ) However, I'll try to keep up with this thread.

Some files I want that I don't have are the patents for the Panzershreck, the RPG-7 (patents for any of the RPG series actually) and the M72 LAW. Of course, any other patents (or books) pertaining to would be helpful. If anybody finds the patents for any RPG, I've got a Russian-speaking friend (Russian is his native language) who can, I suppose, help us out with translation.

Here are a few of my qualifications for the shoulder fired projectile weapon:

• Accurate to 100 meters. I.e., it's accurate enough to hit an SUV sized target at 100 meters.
• The launcher must be reusable.
• Lots of safety systems in place... I'll go deeper into that aspect later.
• The warhead must be an HE/shaped charge. It can have interchangeable warheads to include fragmentation rounds, but a 37mm grenade does that job just as well, so that's just a plus.
• Shape of the projectile is similar to the LAW or RPG-7. (This part actually was a major sticking point when I worked on this project.)

I've got other qualifications, but I seem to have misplaced some notes. Also, I have a really bad habit of making notes in my head.

If this project really gets underway and y'all are working together at all, y'all will have to decide many, many small (and not-so-small) details. For instance, fins, body design, body material, ignition system, etc, etc, etc. The list literally goes on for miles. I worked on this project for a while with only two other persons, and, let me tell you, we spent most of our time arguing.

@TheFallen: What exactly are you dissing about the sabot round? I think you may be confusing the sabot (the thing that 'carries' the projectile) with anti-armor flechette rounds or something similar.

Finally, the link to my upload.

http://rapidshare.com/files/38182917/Rocket.rar

[cowboy]

Thanks for the books. They are d/ling as i type this. TheFallen the reason I am gunna go with Sabot rounds is recently I bought a .54 cal ML rifle, and tried several different types of rounds through it and the Sabot round performed the best. When I started investigating the Sabot round I found out the military uses Sabot rounds in several different weapons, and they preform beautifully. The way i am thinking of doing it is have a model rocket type projectile, and have a lightweight foam type sabot around it that engages rifling in the steel tube, and then detaches when it comes out of the tube. the advantage of having an electric igniter is I can remotely test it behind cover. If I made a breech block it would have holes drilled in it kinda like a blast shield that would increase propulsion, and reduce the back blast. The amount of recoil would increase slightly but the increase in propulsion would be worth it. On a personal note my wife wants me to let you guys know she hates all of you because you guys encourage me(she is crazy, for some reason she thinks I will blow myself up).

[Enkidu]

Cowboy... paragraph breaks are your friend. It's easier for us to follow your train of thought.

Look to past (and maybe a few present) models of whatever it is that you want to make. If you want to make a shoulder fired rocket launcher... look to the Bazooka, LAW, RPG, etc. They were designed by people and governments with a lot more money and put into research than we have. They've got good ideas, and you don't want to reinvent the wheel.

I don't think rifling is the way to go. First, do you know of any other launchers that have rifling? AFAIK (or assume ), all the launchers are smooth bore. Second, how are you going to rifle the tube? Rifling the barrel of a rifle is hard enough and requires special tools. How are you going to rifle a 3" wide tube? If you were to 'rifle' the actual projectile, like a shotgun slug, you wouldn't be able to use the sabot design. The 'rifled missile' was an idea proposed by one of my buddies... we nixed it on several grounds. The idea might be worth revisiting, but I doubt it.

You are right to think that the projectile needs to spin to stay stable. IMHO the only way to effectively do that is to through fins. The fins could be canted, or you could use what we called 'thrust vectoring fins.' Thrust vectoring fins angle the hot gases as they emerge from the the nozzle; in fact those fins are actually part of the nozzle. I have a patent on that somewhere... I think.

I saw a Future Weapons in which they had fitted the LAW (errr... or something similar) with a bag of saltwater(?) so that it can be fired from inside a building. If you fire it with your back up against a wall without the bag, you get all kinds of nasty internal injuries. With the bag in place, you can be closer to a wall. I think that idea is probably best if you're worried about backblast.

You are also right to be worried that you won't be able to get enough thrust for a successful launch. I often postulated to my friends that our rocket would end up in the dirt 10 meters in front of us. The right propellant should be able to solve that problem. I have no idea what the right propellant is.

Of course, the apparatus for launching the projectile is only half the battle. You've got to find both a propellant and a energetic filler for the warhead!

The following are some observations about launching the projectile out of the tube. The Bazooka, LAW, and some RPG models ignite the engine inside the tube. The RPG-7 uses a boosting charge to launch the rocket out a ways (10m? can't remember) and then the engine carries the rocket the rest of the way to its target. The British PIAT was a spring loaded launcher. It was crap, but very simple.

Your wife is right to be worried. Just tonight, I got some nasty stuff in my eye (Acetone + Sodium Bicarbinate + Polyvinyl Nitrate). Always wear goggles and follow all safety precautions! There are a lot of corpses and amputees out there. Remember, chicks dig scars, but not missing fingers or eyeballs. I think someone from RS said that...

Edit: Do you have and know how to use CAD/CAM software? Solidworks is nice if you don't. Both my buddies know how to use it (although I've not learned), so I've got a few drawings... I must figure out where those went.

BTW... it's a good thing your not leaving the great state of Texas for a while. It will probably take you that long to get a working model up. I must say that last time we attempt this, it was so complicated that after months of work, the project was put on hold indefinitely. Safety is the biggest issue. So, if you're really dedicated to seeing the final product... be prepared for a shitload of work and failures.

[TheFallen]

Free CAD software, Google SketchUp.

You'll need a fins or spin stabilized rocket, preferably both.

Find me a bazooka/LAW that uses sabots rounds. None. Why? Because you need the velocity of a 120mmm cannon to make it work. LAWs use HESH/HEAT or shaped charges.

The main consideration here is the warhead and how to trigger it.