Submarine-Rocket launch : LUSENET : Junkyard Wars : One Thread

Build a two-man sub, have them go under and launch a rocket, or rockets. The highest height (or average height) of the rocket(s) launched wins.

Build the sub and launch tube and the rocket. Perhaps you'd make the rocket engines even.

-- Richard James Retey (, February 22, 2001


Man cut my big butt loose in a junkyard, I'd love a shot at this one. You could get barrels and weld them together I could see about four of them. In a smaller tube you could have the rocket, it could be inside its own barrel or even outside the sub, perhaps outside the sub would be best. The top of the rocket tube could be some sort of tenfoil that the rocket could burst through, you'd need a steel guide rod to keep the rocket from banging against the sides.

Too deep and the rocket may not make it to the surface. Some sort of bonus could be given for deeper launch, say ten feet deep vs three feet. You could also think about allowing them to build a two stage rocket, one stage to get them out of the water the other stage if it kicks in above the surface to go baby.

Everyone would have to be in some sort of bomb shelter because no one would know where in the hell the rocket is going when it reaches the surface, if it reaches the surface.

-- Richard James Retey (, February 22, 2001.

Wow, thats a lot! Building a sub was an excercise in itself for 10 hours and so was a rocket. Now adding the piece of how to keep the rocket dry (wet engines don't fire) and bouyant to get it to the surface is probably another 10 hours.

Modern submarines use a bubble of gas to surround a missle, or launch it from specialized containers. How you'd do that with junkyard parts is beyond me...


-- Brian Flynn (, February 22, 2001.

OK, I was told that one crew built a submarine in 6 hours. All they need to be is a couple of feet under water when they launch.

A plastic tube filled with air and some sort of thin top like a plastic film the rocket can burst through should send the rocket along with enough air to get to the surface. Maybe they'd need to light the rocket and open the top at the same time, this could be done if you had a tube in a barrel filled with air, if you opened up a hole in the side and on top at the same time what would happen? I guess water would want to push through and air would want to push out.

Hell a tube a couple of feet under water shouldn't be a problem launching a fifteen inch rocket. They can make the rocket out of PVC. saw off a couple of pieces of plastic off of an ink pen to gue on the side of the rocket to fit over the steel rod guide. Hell the rocket could be easily made in less than an hour.

Yes I think this can be done, in must be done. For God, and Country, the Queen and all that stuff and above all for JunkYard Wars...

-- Richard Retey (, February 22, 2001.

OK I've got it this time. And will check this for errors before I post.

Give the contestants a battery, rocket engine and fuse and I know I can get the dam thing out of the water in ten hours. First off did anyone say the sub had to be powered? You could have the contestants legs out the bottom of it and they could be the power.

If they have the time to build a powered sub fine. You could have a couple of air tubes surrounding the tube to fire the rocket, if you released them a half a second before igniting the rocket it should be a go. Remember the rocket doesn't need to be all that big, I was into building rockets when I was young. The air released by the surrounding tubes should be enough assistance.

I think this would be such a cool challenge and yes it could be done in the allotted time.

And now, it must be done, think of the kids, think of the good of our countries, my God man we just elected an idiot for President, we've got to do something.

-- Richard Retey (, February 22, 2001.

Well you do not need rocket engines. You could make a pressure rocket type contraption which will be pressurized before it leaves to go in the sub. If you wanted to get more complicated, you could devise a way to launch the rocket out of the water useing air power and when it gets out of the water ignite the rocket engine(s). this is just and idea, the teams would have to devise the method.

-- Robert (, February 22, 2001.

With a solid fuel rocket motor, the ignition of the rocket would make the pressure rise inside the launch tube. The trick would be to get it to go up and not sideways, which would not be healthy for anyone who might be in the line of fire. It's an intresting challenge, and it took the armed forces much longer than ten hours to work it out. They use the same system that they use for torpedoes, turned vertical, to kick the rockets out of a sub, and they fire them up as they clear the surface.

-- Waddy Thompson (, February 22, 2001.

Who has a model rocket and easy access to a pool? This would be a cool experiment to try. Put the rocket in a tub covered with plastic wrap. Run the ignitor wires out the bottom. A 9 volt battery later, the answer would be known.

-- Devin T. Ross (, February 23, 2001.

Devin T. Ross, EXACTLY! A piece of PVC pipe two feet long and six inches in diameter, an estees solid fuel rocket, or just go get the rocket engine, fit it into a one to one and a half inch piece of PVC pipe. Mount the a block of wood at the base to stand a launch rod, put the plastic at the top. Problem with the plastic, doesn't the air expand, wonder it it will hold under two feet of water?

Anyway the wire can be run to the bottom of the tube if the plactic holds the water shouldn't come up inside the tube. have to make something to hold the tube down, straps and concrete blocks should do the trick.

Now just make sure you didn't forget and go to a friends how where there is a screen roof, you wouldn't want to blow a hole in it would you.

Better make a snub nose rocket and have some sort of cover when you launch. But the rising gasses inside should blow the top off, you'd want the top to break free and not cling to the rocket... Interesting experiment.

-- Richard James Retey (, February 23, 2001.

I am going to attempt the experiment, my problem is with the launch. I could see trying to juggle a cam and a 9volt battery at the same time, then the rocket comes out of the water headed straight for me. Incase you've never seen one of those things, the little rockets, they really scoot.

Any suggestions on this will be appreciated. I don't have a camcorder may just take photos if I don't borrow one from someone.

-- Richard James Retey (, February 23, 2001.

Am going out today to get some stuff for the launch. A friend of mine, a plummer will get the 6-inch wide PVC, he asked if I wanted a cap, I said yes for one end. I am going to try and make it air tight, when I get the PVC will take it to the lake and see if the plastic wrap on top of the opening can stand the pressure of being one to two feet under water. Will have to secure it with some sort of clamp and perhaps a strip of rubber, if enough time may make some slight string groves in the side of the PVC. Don't know how many of you know this, but you can cut PVC with string.

Was thinking of compressed air and a way to open the top an instant prior to the launch but that is just to complicated. Heck am thinking the water holds the plastic down and the rocket never makes it to the top just exploding the PVC beneath the water. Would think the plastic would give first.

Have another good friend who said we can launch at his lake, he has a beautiful home way up on a hill from the lake. He will film it too, sure hope the rocket doesn't head to his house.

-- Richard James Retey (, February 24, 2001.

Its an interesting idea; will the water soak the rocket before the rocket clears the surface? My thought would be that as soon as you break the plastic wrap, the water is going to begin to pour in....very close timing whether it works or not. Does the rocket have the escape velocity to get out before the tube fills with water?

Some suggestions: Make diameter of the rocket fit the launch tube as closely as possible. Make the nose of the rocket as close to the top of the launch tube as possible, prehaps 2-3" down. Support the bottom of the rocket off the bottom of the tube some. All three will work to keep the water away from the fire.

Also, you might try "waterproofing" the rocket engines if the first attempts fail. A can of scotch guard should do the trick. Just don't spray too heavily....

Just a curiousity question - how deep could something like this be launched from? You mentioned 2 feet....could it be more?


-- Brian Flynn (, February 24, 2001.

Here's my $.02 worth about sub launching. Make the launch tube close to fitting the rocket's diameter, and make the fins on the rocket fold against the sides of the rocket. Cut the fins with a slight curve on the inside, and glue them on with a slight twist. This will make the rocket "spin stabilized" both in the water and when it breaks the water's surface. Cover the tube with a big balloon, which will expand into a bubble of gas when the rocket motor fires, which will help carry the rocket to the surface. The fins need to be flexible enough to not keep the rocket in the tube, maybe put a sleeve over them (milk carton stuff,) and a lip inside the top of the launch tube, or three screws barley into the inside of the tube, to pop the sleeve off when it gets to the end of the tube. It can be done, and don't worry about water getting into the motor after the motor fires, as pressure inside the rocket motor will keep it out. Mske the launch tube long enough to allow the rocket to gain some speed before it gets out of the tube, maybe 6 to 10 ft or so. The pressure of the water on the balloon at the top will not be any greater than the pressure at the water depth at the top of the tube, even if the bottom of the tube with a cap on it is 20 ft down in the water. Cross your fingers that the ignitor works right the first time. Weight the bottom of the tube, and put floats around the top, and it will float right side up without having to dive and anchor it to the bottom. Make the bottom anchor line where the line passes thru an eye at the bottom of the tube and comes up to the top of the tube, that way you can adjust the anchor line till it floats at the depth you want without getting out of the boat. Have fun, be careful, and remember to shout the famous "redneck's last words," " Hey Y'all, Watch This!"

-- Waddy Thompson (, February 25, 2001.

The tube would be a good idea but then you have to rember that water is denser than air and will try to push the launch tube over as you move. you might try to make an extendable one so when you move it is close to the sub, but when you are ready to launch you push it up by some means like an old fashion telescope.

-- Robert (, February 26, 2001.

It worked, thought I'd come back and mention it on this thread. I didn't find the rocket or I would have tried another launch. Am sure there is a depth to where this sort of launch wouldn't be successful. Probably two feet and beyond. Worried that water might seep into the tube I launched before the trash can was full, so the top of the launch tube was from only seven inches below the surface of the water. It appeared as if the rocket shot through the water, broke the surface and hung above the water about four to five inches for just a split second and then tore off. It was like it shot out, stopped to regain something??? and then took off again.

-- Richard James Retey (, March 25, 2001.

I was beginning to worry about you. It had been quite a while, but not really long enough for an extended hospital recovery (Hey You All, Watch This - you've got to love the image that produces). So, did you get pictures? I wonder if the pause you saw was real or an illusion? What was the exact system you tried - there were a lot of suggestions in this thread?

-- Devin T. Ross (, March 27, 2001.

It has been a good while since I did that launch. But it is still a little accomplishment that I am proud of. The people who come here have that pioneering spirit I mean how many people actually build something unusual from junk and make it work. Can't begin to explain how much fun it is to do something like that.

But use some common sense. I didn't realize how dangerous my experiment was till I did it and thank God my rocket came out of the water straight.

-- Richard James Retey (Swampie) (, January 29, 2003.

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