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What it is and how to make it:

Boredom sometimes gets the best of you when you have a bag full of fireworks left over from the 4th of July holiday. My husband and I were about 16 or so when we got bored one day and made a rocket that launches about 200-300 feet in the air. Not too shabby of a distance for two old vegetable cans, water and some black cats. Through these steps we created a firecracker water rocket. We call it, The Frocket!


**DISCLAIMER**

Most of us know how to not get ourselves hurt and stay out of the way of a launching or falling tin can, BUT, I will say it anyway...

FIREWORKS CAN BE DANGEROUS! Every single firework has a warning label saying so. Don't try to relight a failed firecracker with a shorter fuse, just toss it out and use another. Don't put your head over the cans as you are lighting the fuse and stay there; the can WILL bust you in the jaw. Heads up when the can flies into the air, it could come down and hit you. Be careful around the sharp edges of the can where it was opened and where you drill the hole; it can slice you open and it will hurt.

Step 1: What You Need

I made the Frocket by using the following materials:

  • (1) 8.25 ounce fruit can with pull tab top
  • (1) 6 ounce tomato paste can
  • (1) Regular fire cracker per launch you desire
  • Water
  • A lighter or other fire source for lighting the fuse
  • A drill with a 7/32 bit, or a medium size phillips head screw driver will work

**It doesn't matter what size cans you use as long as one will fit inside the other and the narrower the small can, the better the launch will be. The two cans should have just a small amount of room in between them when put together. You could also use a "Rotel" or condensed soup can with a regular vegetable can**

Step 2: Preparing the Frocket

Peel the label off of your cans (or at least the small one). Turn the smaller can upside down and drill or poke a hole into the center of it that is the same size as the fire cracker. I just used a black cat brand regular fire cracker and the hole was just a little bigger than a 7/32 size bit. I used a screw driver to help make the hole a little bigger. Don't make the hole too much bigger than the fire cracker. You want the can to be able to hold onto the top part of the fire cracker, and not fall through.

You can use a screw driver to help make the hole slightly larger if it is a bit too small. Also, if you make it a bit too big, you may be able to come from the underside of the can and bend some of the can back to make it a tight fit.

Step 3: Final Preperations for the Launch

Insert the fire cracker into the bottom of the small can until just the tip of it is showing. Add water to the larger can. This will be somewhere between 1/8 and half full. In all of our launches we got about the same height no matter how much water we used. After water has been added to the larger can, insert the smaller can into it with the fire cracker sticking up. The can will sink to the bottom without any force.

Step 4: 3... 2... 1... LIFT OFF!!

Now, light the firecracker on the Frocket, step back and watch it launch 200- 300 feet into the air.

Step 5: Refueling...

Each time you want to relaunch your Frocket, simply load another fire cracker, add water, insert the small can into the larger one, and ignite. Happy Launching!!
heres my method: use bottle rockets with the sticks removed and i find it goes pretty high up when it pops
Very amazing. So glad you posted this, my grandpa was telling me about this once, but they did it with empty beer cans back in the 30's.
just wondering, how could you ever get up to 200-300 ft? i have exactly the same cans, and by chance my firecrackers are black cat too. however, the highest i got was about 20 ft, and the others around 10 ft. (I didn't expect it to ever get up to 200 ft, but i thought maybe more than 10 ft.)
Most likely the culprit is the size of your cans. Either using bigger cans, or the more likely truth, would be the size difference between the two cans. My two cans fit perfectly inside of one another with almost no wiggle room to speak of. The water will make a seal and if they are sized correctly, the explosion of the black cat will have no where else to go but way way up. Otherwise, I have found that it loses some of it's force and won't go as high. We used to get the same effect you are describing when we would simply drop the firework into the water (with the waterproof wicks of course). Let me know if i can be of any more help.
I am happy to say it worked a lot better actually, in recent launches, going more than high enough to impress any watchers. However I'm still interested in the physics behind this. As you say, I think the water is the seal, creating a small chamber of air inside the smaller can. When the firecracker explodes, the explosion has nowhere to go, except up. However, if thats how it works, and I can't see any other way it might, then I don't think the cans must be similar in size at all. All the similarity of size might help is the larger can directing the smaller can as it leaves, and reducing the spin, making it go straighter. as long as the water is there, the seal is complete. In fact, I just went outside, put some water in a peanut butter cap, and successfully launched the can. It didn't go as far as I've seen it go, but I don't think it was the change in launch pads, as it did manage a respectable distance. So I don't believe the size difference matters. I'm probably going to try next time with a smaller can, so it's lighter and might go farther. Thanks for the idea though!
Damn, i was just about to put this on here but then i saw this
my ones never flew as high but that is probably because i did not use black cat.
I've been doing this since I was a little boy. (about 40 years ago) Use a bucket with about an inch and a half of water in it instead of the second can. It will be more stable and fly cleaner. We even got a little freaky with it. We used an empty propane bottle with the top cut off, (small camp stove size) and an M-80 (when you could get the real M-80s, (1/4 stick)) Serious sick fun! Very good ible anyway.
Oh yes, I was sure that other kids have done similar things with firecrackers, I just haven't seen anything like it on the internet, so I figured I'd share my technique ;-). As far as your method goes... did you still use a can with the firework in the same method, just have a larger bucket with water? Or bigger containers for both and use bigger firecrackers? Empty propane bottles huh? Ahh the good 'ol days when kids could actually be kids and out of sight was out of mind. It sure is a different world now, even from when I was a kid (15 years ago). We used to run around on 3 acres of land with gasoline soaked newspaper on long sticks (torches) while chasing each other. Now, it seems like going out in the front yard without supervision is something that is forbidden, and we live out in the country!!
Same rocket. Use the bucket instead of the launch can. And... Aaah yes, the good ole days. Blowing up the neighbor's mail box with M-80's (of course we got caught, who else was around to do it) Playing cowboys and indians or army with crossman pellet guns. My brother still has a bb rolling around in his scalp
i used to the same sort of thing but what i would do is make a hole just big enough for the fuse, stick the fuse through the hole from the inside, and fold it over so the firecracker would hang on its own ( the green fuses work better for this one ) and when you light the fuse, it will burn down and fall to the bottom of the can and then go boom. it usually makes it go much higher. by the way i like the name.
Thanks for the comment. We did try a few of the green fused water proof ones (because we had them lying around), but for our technique, the good 'ol "no time to run" black cats seemed to have worked better. Never tried doing it your method though. Thanks again!
That is very cool, but... what's the water for?
It basically creates a seal around the "combustion chamber" and allows the small can to travel farther than it would, otherwise, travel.

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Bio: My name is Danielle. I am 24 years old and live in Oklahoma. I have a wonderful husband and an oober smart American Pit Bull ... More »
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