Plastic Soda Bottle + Alcohol = Rocket

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PulseDuuude
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Plastic Soda Bottle + Alcohol = Rocket

Post by PulseDuuude » Sun Aug 15, 2004 3:40 pm

In my younger and less sane days, I came up with a cheap bottle rocket...

Take a standard 2-litre soda bottle (empty and washed & dried) then drill a tiny hole centred on the bottom end (1/16-inch will work).

Clean out any bits of plastic from the drilling.

On the cap end place a piece of aluminum foil over the opening and a bit down the sides, but don't cover the threads, then screw the cap on. When you unscrew the cap the foil will stay in the cap. This serves to protect the cap gasket from the fire and heat.

You can fuel this little beasty with isopropyl alcohol 99% or methyl hydrate. Pour some alcohol into the prepared bottle, then cover both holes and shake the bottle thoroughly. Drain out any excess fuel! (Trust me on this! If you don't you'll have a nice stream of flaming fuel everywhere!)

Next, set the bottle upright on a fireproof launch surface with enough space under the bottle to get an ignition source to the small hole (Use something that will keep your fingers, eyes and other favourite body parts away from the rocket exhaust!)

When you light this sucker, it will take off with a FWEEEEEEET sound.

It has enough force to dent a gyprock ceiling so keep out of the way and have fun.
Jim

Mark
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Re: Plastic Soda Bottle + Alcohol = Rocket

Post by Mark » Sun Aug 15, 2004 8:20 pm

I use to do that too. Methanol is really peppy stuff when used for "whistling bottles." I use to put a double strand wire inside the bottle and light them with a piezo gas grill sparker, they would be 30 feet down range before you could even blink! You have captured the sound and spelling these bottles make when they hiss, it's almost ear piercing if you are next to a 3 liter plastic Coke bottle that is lit.
Mark
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PulseDuuude
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Re: Plastic Soda Bottle + Alcohol = Rocket

Post by PulseDuuude » Sun Aug 15, 2004 11:25 pm

Hi Mark,

Darn! And here I thought I had something origional...oh well.

I like your barbecue ignitor method...I'll have to keep an eye out for one at the surplus stores.
Jim

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Re: Plastic Soda Bottle + Alcohol = Rocket

Post by Stephen H » Fri Aug 20, 2004 2:00 pm

PulseDuuude wrote:Hi Mark,

Darn! And here I thought I had something origional...oh well.
ask anybody here, that seems to be impossible on this forum. eveything seems to be done sometime in the past

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Re: Plastic Soda Bottle + Alcohol = Rocket

Post by John Werner » Sat Jun 04, 2005 2:23 pm

PulseDuuude wrote:In my younger and less sane days, I came up with a cheap bottle rocket...

Take a standard 2-litre soda bottle (empty and washed & dried) then drill a tiny hole centred on the bottom end (1/16-inch will work).

Clean out any bits of plastic from the drilling.

On the cap end place a piece of aluminum foil over the opening and a bit down the sides, but don't cover the threads, then screw the cap on. When you unscrew the cap the foil will stay in the cap. This serves to protect the cap gasket from the fire and heat.

You can fuel this little beasty with isopropyl alcohol 99% or methyl hydrate. Pour some alcohol into the prepared bottle, then cover both holes and shake the bottle thoroughly. Drain out any excess fuel! (Trust me on this! If you don't you'll have a nice stream of flaming fuel everywhere!)

Next, set the bottle upright on a fireproof launch surface with enough space under the bottle to get an ignition source to the small hole (Use something that will keep your fingers, eyes and other favourite body parts away from the rocket exhaust!)

When you light this sucker, it will take off with a FWEEEEEEET sound.

It has enough force to dent a gyprock ceiling so keep out of the way and have fun.
====

You mention two holes, one in the bottom but nothing about the second hole. Where is the second hole placed?
JW

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Re: Plastic Soda Bottle + Alcohol = Rocket

Post by PulseDuuude » Sat Jun 04, 2005 2:54 pm

John Werner wrote:You mention two holes, one in the bottom but nothing about the second hole. Where is the second hole placed?
JW
Hi John,

I used a two(2)-litre soda bottle, maybe thats where the 2 hole idea came from?

Anyway you drill one hole in the bottom of the bottle and reinforce/insulate/line the bottle cap with aluminum foil before screwing it back onto the bottle.

Hope that clears thing up.
Jim

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re: Plastic Soda Bottle + Alcohol = Rocket

Post by Mark » Sat Jun 04, 2005 3:19 pm

I wonder if it would be possible to bore a hole in the top of the 2 liter bottle as well and use the escopette philosophy to redirect the flow in the same direction as the "nozzle" located in the cap. Maybe it would "cycle up" and throw the bottle farther by some means or maybe it would melt it from the extended time the flame might live in the bottle.
An "Escopette" "rocket" would be funny.
Mark
Last edited by Mark on Sat Jun 04, 2005 3:20 pm, edited 1 time in total.
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pezman
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re: Plastic Soda Bottle + Alcohol = Rocket

Post by pezman » Sat Jun 04, 2005 3:19 pm

I came across a site where a guy used hydrogen to generate the internal pressure for a water-rocket (as opposed to filling it with compressed air).
http://www.et.byu.edu/~wheeler/benchtop/hydropyro.php

Another variation would be to use propane etc. mixed at stoichiometric ratios.

Yet another variation would be to use PVC and fill it with a pressurized fuel-air mixture (e.g. water and propane-air at, say 90 psi) and then ignite it -- from a very safe distance. Supposedly, 4" schedule 80 can withstand a transient pressure of about 1100 psi, although it is rated at a much lower working pressure (like 194 psi). Assuming an initial pressure of 90 psi and a 10x increase in pressure due to combustion, you could get a peak internal pressure of 900 psi. My guess would be that you would be lucky to get a 7x increase (630 psi) and that it may even be lower due to heat losses etc. (on the other hand, the compression might compensate for these other losses a bit). Still, even a 500 psi water-rocket is likely to be a rather spectacular missile - or a spectacular fragment bomb if the PVC failed.
http://www.engineeringtoolbox.com/pvc-c ... 0_796.html

Here's a site that shows how to make a shaped nozzle in a PVC rocket tube (albeit for a conventional rocket motor) :
http://members.aol.com/ricbnakk/pvcmot1.html

... and here's a site that has some ideas on how to calculate ideal ratios of air/propane for propulsion:
http://www.burntlatke.com/ft_live.html

For rockets with elevated initial pressures, the calculation would obviously need to be scaled (e.g. for 6 atm pressure, multiply metering pipe length by 6).

Getting a pressurized-fueled water rocket to release and ignite in one smooth motion might be a little tricky ...

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Re: re: Plastic Soda Bottle + Alcohol = Rocket

Post by Mark » Sat Jun 04, 2005 9:44 pm

[quote="pezman"]I came across a site where a guy used hydrogen to generate the internal pressure for a water-rocket (as opposed to filling it with compressed air).
http://www.et.byu.edu/~wheeler/benchtop/hydropyro.php

I like his "Mr. Splitter" device. Very good presentation, a good sense of humor with those sissors.
Mark
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re: Plastic Soda Bottle + Alcohol = Rocket

Post by John Werner » Sun Jun 05, 2005 7:52 am

Good morning, it's 1:15am here in Denver.

It's interesting about the hydrogen rocket and I came across a hydrogen rocket kit at:

http://www.estesrockets.com

The hydrogen rocket is on page 35 of the pdf catalog.

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re: Plastic Soda Bottle + Alcohol = Rocket

Post by pezman » Sun Jun 05, 2005 2:10 pm

Hey, that gives me an idea -- using carbide crystals to generate acetylene fuel in the rocket. Just put a bag of crystals in the rocket (contained so that they don't fall into the nozzle), fill part-way with water, wait and then ignite the resulting acetylene/air mixture in the top of the bottle.

I launched a few methanol rockets last night for the kids -- they enjoyed it.

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Re: re: Plastic Soda Bottle + Alcohol = Rocket

Post by Ray » Mon Sep 05, 2005 6:44 pm

Ben wrote:It would be a good idea to use ABS or HDPE tubing for that sort of device, rather than PVC. PVC makes shrapnel, the other two don't.
Not to mention that PVC is transparent on an X-Ray...

Safety first guys...distance is your friend.

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re: Plastic Soda Bottle + Alcohol = Rocket

Post by steve » Mon Sep 05, 2005 7:19 pm

The other night we were having a good time shooting methanol fueled rockets through the hallways in my dorm.

it's probably the only type of rocket (besides a matchstick rocket) that you can make using only a pocket knife.

I'm trying to figure out the best way to stabilize them in flight without adding too much weight.
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re: Plastic Soda Bottle + Alcohol = Rocket

Post by mk » Tue Sep 06, 2005 8:57 pm

There simply must be a complicated solution for your purpose of stabilizing the rocket, Steve.
mk

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re: Plastic Soda Bottle + Alcohol = Rocket

Post by steve » Tue Sep 06, 2005 9:28 pm

yeah, the one I most want to try is fairly complicated, but it will be very lightweight and strong.

Another idea I'm toying with is taping several bottle sections together to make one long rocket. (more power, easier to stabilize in flight)

I also think it might be neat to fabricate a tiny nozzle out of a chunk of aluminium to boost the amount of available thrust. It would have to wiegh less then 2 grams if possible. I wonder how much that would increase thrust by?

It would be pretty amazing if I could get a rocket over 100 ft in the air on less then an eyedropper full of methanol!
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