Instructables

How to Dramatically Demonstrate a Combustion Reaction (Whoosh Bottle Experiment)

video How to Dramatically Demonstrate a Combustion Reaction (Whoosh Bottle Experiment)
The demonstration is performed with a dry five-gallon (20-Litre)water jug. A volume of 5.0 mL of methanol is added to the jug. The jug is capped and shaken for 30 seconds. After removing the top, excess ethanol is shaken from the jug, and placed in a stoppered container away from the demonstration table. Since these “Whoosh Bottle” demonstrations have caused a variety of accidents, it is imperative to protect against shattering when the ignition of the vapor in the jug occurs. After removing the top and drying the opening of the jug, place the jug on its side under the protection of a small three-sided safety shield1 that is lying on its side on the bench top. This allows for protection of both the demonstrator and audience when ignition occurs.

The demonstration is used to discuss the combustion process. I normally first ignite a small volume of ethanol on a watch glass (behind a safety shield) to describe the slow burning process of the vapors. This provides a sharp contrast to the ignition of a small volume of methanol vaporized in the jug. A variety of combustion/detonation processes may then be discussed.

Note
1. The standard three-sided safety shield, which is recommended for use in performing any hazardous demonstrations
Very cool. I remember doing this with the old Glass Water Bottles back in the mid-1970's when I was in school. We got some really great cobble stone flame effects. Good job!
John Smith6 years ago
Pulse jet?
HEY!!! somebody needs to make an instructable on how to make a pulsejet!
definately
That would be nice. Alot of them require machining, though.
not really just install a 1 way valve on the back and thats pretty much the only challenge
But it would melt(assuming you mean PVC). And if you mean stainless, the 1-way part would be hard to find. And even then it would probably have plastic in it that would melt. Of course you have valveless and valved designs, and the valveless ones wouldnt need a valve thing. But the sizes are pretty critical, i think. I wish i had a lathe and mill. Grizzly offers very nice mini lathes and mills. You can get a full mini lathe, and buy all the common accessories for it, for <$1000. Same with the mill. Not to mention the great customer service. I emailed them, asking what i'd need to start up a mini-lathe and mill, and they sent me back a "report" practically, naming everything I'd need for both of them, as well as other things too.
exactly what i thought. but it wouldn't last long. plastic will melt causing it to fail.
This would be a valveless pulse jet
yep that is what i would call this also :) a pulse jet (valveless). kiteman did an instructible on a very simple jam jar jet and then tried to create a metal one resulting in a cannon lol.
popscott34 years ago
a goast is inside the bottle!
zkcaj4 years ago
Tryed that at home with a close to empty mentholated spirits bottle.
it exploded and was extremely loud.
I used to do this with a rubbing alcohol bottle. You have to be careful to keep your fingers out of the way. Example: I was a little slow once and burned a good size circle on my thumb. It's funny now but it hurt quite a bit at the time ( I still laughed).
I guess that is one great way to light a cigar if you wanted to do it in style.
al_packer6 years ago
Dean Black told the Estes Industries R&D crew about this principle about 35 years ago. Back then it was a conical-top brake fluid can with a 1/4" (+/-) hole in the screw-on lid. The duration of the pulsing action depends, at least to some extent, on the thermal mass of the container. Thus an iron jug should function better than a plastic one.
Plasmana6 years ago
That is really cool! It looks like a jet!
Technically it is, a jet is defined as anything that shoots out heated gas. This could also be defined as a jet engine as a jet engine is a device which burns and shoots out hot gas rather than just a natural jet such as as a pulsar. This isnt a rocket however as it supplies it's own fuel but not it's own oxygen.
Okay, That is interesting, thanks for telling me!
I got the same effect as in the video by spraypainting into a plastic jug and lighting it. Sadly I used a small lighter and it burned all over my hand. Ouch! Also, if you take a 1 liter bottle, and light it on its side, it shoots a good 15 feet.
Pumpkin$6 years ago
ya that's what i was thinkin' too.....
Yenmangu6 years ago
what you have here is a very simple valveless pule jet engine(Y the reason you get the woosh woosh sound of the flame as though it is in a cycle is because of pressure differences and those are the pulses in a pulse jet engine. the pulse jets are very simple because they contain no moving parts(valvless) and are easy to opraate and maintain. the bad side with these is that they produce relativley low thrust. the v1 bombers of the war used a pulse jet engine to create the thrust but the reason they wern't all that popular was because they very often ran out of oomph mid-flight. some however did make it across the channel to england and they were called "buzz bombs" or similar because of the noise the engine made. imagine the woosh sound you get but much faster and louder. these are millions of explosions i think that are all going off at the same time thus creating the woosh woosh effect and the buzz from the v1 bombers. google pulse jet engines and check out some of the youtube videos of different engines and some go-karts with these jets attatched. rob
Konnrade6 years ago
Well this brings back memories. I used this concept in a middle school science project, but with 1 and 2L soda bottles, and with a cap with a small hole in it on them to work as a rocket nozzle. Hang it horizontally on a wire or string from some paper clips and "whoosh!", off it shoots.
schimmi6 years ago
hahaha, i can't remember what we did in chemistry but it was delayed woosh and our teacher told us we had to listen closely because it's quiet then BOOM. the whole room shook. everyone jumped
Nice. I like how you post a new thing every day, because when I get home from school I can always see one of your cool new videos.
Done it, but with a 20oz soda bottle. It does take a little longer to get it right too 'woosh'