Turn Empty Water Bottles Into Alcohol Fueled Rockets

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video Turn Empty Water Bottles Into Alcohol Fueled Rockets
Not long ago I was challenged to create a project using a water bottle that could be displayed in a one minute long video. While I missed the one minute mark, I think I still managed to make a pretty entertaining device.

The rocket and launcher featured in the above video function off of a very simple concept of igniting a flammable vapor using a replacement barbecue igniter to propel the bottle through the air. The parts for this project should cost no more than $15, with the igniter taking up the majority of that price tag at about $10. The bottles can be reused many times until the heat from repeated shots eventually warps the plastic.

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Thanks for reading!
tahuwahu7 months ago
Very cool - nice work ;)
Samuel kos9 months ago
I've made this and it so much fun thank you for posting this!
I absolutely love this launcher. It's simple, easy to make and FUN! This launcher inspired me to modify it and post an instructable of my design. Thank You!
hassannaeem10112 months ago
Is it possible to use a lighter instead of a replacement barbecue igniter. Such as this:
yes it is possible to use a gas lighter as a substitute
it is also possible to use perfume as a fuel
simplebotics10 months ago
Halo 4 "Sticky Detonator!"
Great! Allow me to share my riff on this elegantly simple design. Throw in a PVC tee, grill igniter fits into the the rear, add a short piece of PVC for a pistol grip. I wouldn't recommend starting fluid, alcohol (70% and 90%) works as advertised.
NightHawkInLight (author)  crispyjones1 year ago
Looks good!
damato321 year ago
I made this with two handles for a more gun-like design, per my kids' request (see picture attached). But we had difficulty getting it to ignite. I got it to work twice, but in both cases the blast was pretty big and I got singed a bit. I'll keep trying to get he right mix (atomizing is indeed key - we used 91% alcohol as shown). In the meantime, we decided to use a bottle half the size as the one shown in the video above. The bottle doesn't slide down much, but if fits perfectly and now we can blast these off pretty easily. I found the trick to be pouring about 1/2oz of alcohol into the bottle, then shaking it vigorously (with the cap off) and then pouring our all excess so that the bottle only has a slight coating of the alcohol. Thanks for sharing. This is one of the best Instructables projects we've done.
Alcohol Rocket Gun.jpg
NightHawkInLight (author)  damato321 year ago
Very cool. Since posting this instructible several people have mentioned the great idea of using another bottle that has been cut off and inserted over the pipe to act as a blast shield. Perhaps a 2 liter so it's plenty large to catch the flame and block any spray.
This is simple enough to make and awesome enough to be worth making!!! :)
I found a similar igniter in a gas water heater and used methylated spirits as the fuel.
It worked well :)
So we made one of these yesterday evening with a 'barrel' length of about 20" or so. We had a very difficult time getting it to fire with alcohol (we used 91% isopropanol) and only got one actual ignition.

Any tips to getting it to fire consistently with rubbing alcohol?

After our frustration, we switched over to propane + 1 liter coke bottle (stronger plastic than a water bottle). We just used a propane torch, put the nozzle in the bottle, give it 1 - 2 seconds of fuel, and it shot perfectly every time, at least until we broke the bottle.

But I still want to get it to fire more consistently via rubbing alcohol.
The key is to find the right amount of fuel. Too little or too much and it won't burn. Between trials be sure to blow fresh air into the bottle or there won't be enough oxygen to burn the fresh fuel. Once you find the amount you need it's just a matter of consistency.
The trick is to atomize the fuel. We did this by pouring a quarter tsp or so of fuel into a 24oz pop bottle and then spraying a few bursts of air into it with an air-compressor. Camp fuel is by far the best fuel I have found for this. Gasoline works but camp fuel smells better. Finally, a single wrap of electrical tape around the pipe and cram the bottle pretty hard onto it.

It is important that the bottle sticks onto the pipe because the explosive force is magnified under compression.

A nose cone and fins help a lot. Keep fins on the small side. Expect 30-40 shots out of a bottle before it must be retired.

We get launches 150' up and 400' distance.

Caution: Sometimes there is residual fuel and enough air to fire again. Discovered this indoors. Ooops.
Edgar1 year ago
Voted, and a Link gone to this Blog.
eljohn31 year ago
Great make! The only thing I would suggest is adding a disk of plastic or cardboard in front of the duct tape to divert the flaming exhaust and prevent scorched knuckles (basically a little launch pad).
fjr_scoot1 year ago
Almost every time I see a gas grill along the road that someone has thrown away, it's because the burner has corroded. The igniters are mostly still good. Just sayin': good source for igniters
flavrt1 year ago
Just speculating wildly, but it would also probably be best to not try this at home with acetone, gasoline, or over-proof rum, right?
NightHawkInLight (author)  flavrt1 year ago
Acetone would probably melt the bottle, gasoline would be difficult to find the right fuel/air mix for and would stink up the place, 140 or higher proof rum would work fine, if you didn't care to drink it.
quite a waste of rum, I would say :-)
I've done all sorts of bottle rockets over the years... denatured alcohol was best, next isopropyl is next. Gasoline burns too hot and the mixture is difficult to get, the bottles warp and melt. Acetone and MEK are also hot... and more explosive than burning... you want a burn that lasts for a few milliseconds but isn't too hot.

My favorite is a 3-liter bottle where the lid has two 1/8 (3mm) inch diameter holes drilled about 1/8 inch (3mm) apart. Use one tablespoon of fuel. Lay it at a slight incline OUTSIDE on cement. Light... about a 20" (50mm) fireball and 80 foot (24m) flight. You can stick the two probes into the holes... give yourself some distance... or your arm won't have much hair left.

Remember... don't do this at home... go to your friends home. :o)
I have been shooting bottle across my yard for kicks for some time now. I just use a lighter. But I get the best distance from Heat fuel treatment. I am going to make this project and I am expecting even a greater distance.
mbourhan1 year ago
I'd recommend against anything like acetone or gasoline, contact with either has been show to be carcinogenic. They're also a bit more dangerous as their burn rate can be explosive.

Perhaps aerosolized cigarette lighter fluid would work. (Like they use in Zippos). It can cause skin irritation, but has no warnings on the package about carcinogens... I've also seen hairspray or even aerosol sanitizer (high proof alcohol) used in potato gun / launchers. Could be fun to experiment with.
Naptha - The lighter fluid you're mentioning - Is the most volatile part of the liquid petroleum distillate.

All of the other fluids you mentioned are carcinogens as well.
If the bottle had a little weight added, it would fly farther.
Have you considered sending a bottle to the moon with this?
mudfish1 year ago
raypsi1 year ago
gr8 job and vblog I like to use disposable flash camera's guts. Have you tried finns and or nose cones, on the bottles? Nose cone to reduce the aerodynamic drap and finns to stabilize it in flight.
Range can be dramatically improved by adding fins and a nose cone.
KateinNH1 year ago
I see references to using gasoline or acetone. I can't for the life of me imagine why anyone would want to fool with these highly volatile substances, particularly gasoline when there's so much else available, possibly not offering as much kick, but hey, whatever. I've seen the results of people fooling with gasoline and its not pretty -- if they manage to survive and not burn the entire neighborhood down.

Please leave the gasoline to automobiles and be safe, a bottle rocket isn't worth it.
marshall p1 year ago
Interesting -- Had tried this with two litre bottles of HHO when we were experimenting with that . Didn't plug the end of the bottle but just laid it down on it's side on my truck tailgate and lit it with a bbq lighter -- after my ears settled down a bit i had to go 200 feet to find the bottle and had to get a new lighter as this one had the tip broken off . That was just pure HHO then by a mistake i took too long to light the mix and fresh oxygen diluted the mix and when i lit it off there was a bang like dynamite went off and i couldent find any of the bottle except for the neck . So be careful with HHO gas .
lethink1 year ago
I bought an igniter from Home Depot and its base has to large of a diameter to fit in a 3/4 inch OD pvc pipe but the pipe barely fits in a water bottle. Did you hog out the inside of your pipe? I'm thinking about using a straight connector for a larger diameter slot to drop in the igniter.

Awesome video. Looking foward to building a couple of these with my kiddos this weekend.
NightHawkInLight (author)  lethink1 year ago
Some bottles are a tighter fit than others, it won't make a difference in performance. I did not have to widen the pipe for the igniter, but if yours doesn't fit just use some sand paper.
This is extremely rad. Love your instructables and I love that you include videos (meaning catering to those of us who learn by watching). I wonder how much more efficient it would be if you "salted out" the alcohol to make it more pure?
NightHawkInLight (author)  Pat_Maroney1 year ago
Thanks, I prefer video myself. The purity of the alcohol will not make a difference in performance. The vapor is what burns, and only if it is in the correct ratio to the oxygen that is in the bottle. Purer alcohol may create vapor slightly faster, but there's only so much oxygen to go around so the end result will be the same. If you want it to be a more measured process you can fill a spray bottle with alcohol and add it to the bottle with a fine mist rather than pouring it in and shaking.
Again, great video and congrats on getting featured front page! 200K is just around the corner now!
I love your projects. I've tried to make a few, but I have a tough time finding the igniters you always use. Where do you suggest I look?
NightHawkInLight (author)  ElectroFlex1 year ago
Any hardware store that sells barbecues should carry replacement igniters. Otherwise they can be purchased online.

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