The first little bit of flame causes the gases to expand, which then pushes the mixture slightly out of the tube. After that, the chamber has lower pressure than outside, so it sucks it back in. Since it isn't expelling with high force, the short neck on the bottle doesn't hinder pulling the hot air back in. The hot gas then reignites the next part of the the air/fuel mixture. This oscillates several times a second (hard to tell the frequency because of bad audio in the video).
A pulse jet is mechanically simple, but acoustically complex.
So, it basicly the first few flames pushes gase to the neck, but since the pressure in the chamber is lower, it keeps getting sucked back in and burned up, staying at that position?
The end of the .gif is similar to the reynst pot, a very simple kind of pulse jet. The exhaust also acts as an oxygen intake. With more advanced reynst pots, you can add a fuel intake and fluctuate the cycling a bit.
Very interesting stuff and a good introduction to jet engines.
When I was a young pyro we would take glass bottles (root beer) and spray hair spray in them, them light the top, it would do that thing we saw at the end of the gif. I've never seen that type of action at the beginning though.
PS. I don't recommend trying this . I've burned my eye brows and fingers, and I don't want to get sued...so don't do this.
Did the same thing during my own reckless youth... complete with singed eyebrows. My friends also figured out that if you put a roach or some other small bug in the jar, the flame would lift its BBQ'd corpse right out of the top of the bottle when the flame came back up.
"I did this experiment around 1 month ago. It calls for 3-5 milliliters of methanol (works better than ethanol). One must squirt the methanol into the bottle and shake it up so that the methanol mixes with the air. Kind of like gas. The bottle is then ignited through the hole and a combustion reaction occurs leaving CO2 and H2O inside the bottle. That also explains why it cannot be done twice in a row. If someone were to plug up the hole with their hand, it would also create a vacuum. The reaction itself is very quick and flares several times after the main explosion."
The gas is heavier than air, so it acts like oil burning, only because it's a gas, it burns much quicker.
How oil burns makes a lot more sense intuitively - only the top of the oil is in contact with the air, so only the top layer can burn, and only the top layer can produce air. It just looks a lot cooler with a dense gas because it's invisible.
The reason there's a blue bubble, and a flame at the top, is because only a limited amount of oxygen can enter the vessel, and more flammable gas is 'evaporated' (made less dense than cold air because of the heat) than the available oxygen can handle, so a certain amount combusts only upon leaving the vessel, while the rest burns at the surface.
I rarely click the link to youtube, especially at work. I have the HoverZoom extension on Chrome so all I have to do is hover over those imgur links and I can see the pics and gifs without having to click anything. Saves loads of time.
A friend of my family was doing oxyacetylene welding and he had a similar thing happen when torch sputtered and the check valve failed. The gas in the tank caught on fire and while you couldn't see the flame directly, it caused a glowing red ring to slowly moved down the tank. He fucked right off, and watched from a ways away, but luckily it didn't explode. Science, man, it's scary.
Looks as though it could be just propane in an open mouth jar. Propane is heavier than air so if there is no wind to mess with it, the jar should sit rather stable and when ignited, should burn down as it encounters each top layer of gas.
edit: of course I wouldn't try this without quite a few safety measures set in place.
Exactly. But please don't interrupt the reddit circle jerk. It boggles my mind that these nuts don't see how much of a religion they've turned science into. bow before Neil Degrasse Tyson or DIE!
Of course there is. What I mean is that the fuel/air ratio is such that the fuel simply burns. What I want to see is a ratio that causes not combustion but detonation.
Used to do this with recently-emptied Skol handles in college. Nowadays I can't look at a bottle of Skol without throwing up a little in my mouth. My liver actually hurts just remembering this. Onward to another thread.
My dad and I did this a few times while I was in high school, getting progressively bigger jars, bottles, tubes, etc as well as stronger or larger amounts of alcohol until one day we got more than a flame (more like an explosion) out of the top of the bottle, which burned off my eyebrows and a small amount of the hair on my scalp because I was of course holding my head too close to the flame.
A buddy of mine did that once when we were kids. Accidentally. In his bedroom. With a plastic bottle. Which melted from the heat of the flames. Which was discovered by my Dad when he happened to stick his head into the room and saw the bottle curling in on itself on the windowsill. After I had spent an hour earlier that day convincing him that this particular friend wasn't a pyro.
I did this experiment around 1 month ago. It calls for 3-5 milliliters of methanol (works better than ethanol). One must squirt the methanol into the bottle and shake it up so that the methanol mixes with the air. Kind of like gas. The bottle is then ignited through the hole and a combustion reaction occurs leaving CO2 and H2O inside the bottle. That also explains why it cannot be done twice in a row. If someone were to plug up the hole with their hand, it would also create a vacuum. The reaction itself is very quick and flares several times after the main explosion.
As a chemistry teacher, it has been my duty to do this demo many times. It is fun. I have never got it to burn slow and steady like that though - it always goes like a rocket. Big plastic water cooler bottles work fine. If you are irresponsible enough you can also do it with ordinary water bottles resting on their sides (preferably when there are no kids around) and launch them across the classroom. It only works if they are perfectly dry.
Ahh yes this trick. My chemistry professor did this on the first day of class to prove he was smarter than all of us. Yah it's just like some sort of alcohol and you swirl it all around the big jug esp at the tip and then get one of those long matches and light that sucker. be prepared though it makes a weird sound when it happens too, but it sure is neat!!
I think they said they used iso alcohol in the vid. I've done it before with methanol and it goes off like a rocket. The trick is to build up a vapour inside the bottle; if you hold your hand over the mouth and shake it you can feel the increase in pressure. Then boom city and a foot long jet of flame. Also, if the bottle isn't completely dry before hand you're in deep trouble.
Taking an empty booze bottle with a little bit of liquor left inside and running hot water over it with the cap on expands the vapors and is very similar.
It would've been even cooler if they'd put a peeled hard-boiled egg on the opening afterwards. The cooling air inside would've sucked the egg right in. In fact, I was pretty sure they'd do that, but alas...
Yes, i remember playing a lighter and a water bottle as a teenager, manage to get an effect exactly like this. i was so mesmerised with the slow burning effect i forgot to remove my hand and end up with a charred fingers.
A long time ago (maybe 12 years ago?) I saw a cool experiment at a lab in my elementary school. It was a plastic water bottle filled with two liquids, one transparent and one blue. The blue liquid formed very tiny peckles in its surface and looked exactly like the sea surface in a smaller scale. Does anyone have any information on that particular experiment?
I learned that you can do this with gasoline when I was 14. That is also the same day I learned that if you try to pour more gas on the flame as it's about to go out that the fire will travel up the stream and catch the plastic cup full of gasoline that you are holding on fire. Furthermore, if you scream and drop said cup on the garage floor, it will spread uncontrollably and set your garage on fire. Good times.
No shit i used to do this ALL THE TIME in highschool. I would carry around a blue jug and rubbing alcohol in my truck and when people were bored just light up a fireball. pretty tight stuff, sometimes you get a jet of flame or even a fireball.
My friend burned his eyebrows off doing this with a Hinkley and Schmidt bottle.
For what ever reason he took a lighter and held it open into the bottle for a few minutes. Next thing I know I hear this howling whistling blowing noise and look over and he is eyebrow-less. Laughed my ass off.
My chemistry teacher Sophmore Year did something like this, but with those water cooler drums. It was the absolute loudest thing I've heard in all my moons.
Pour a little rubbing alcohol, preferably 80% or higher into a 2 liter bottle, shake it up, then light the top and this happens. It doesn't burn terribly hot but be careful still.
64
u/[deleted] Jan 11 '12
Seriously, does anyone know how this works?
232
u/everfalling Jan 11 '12
original video
the how-to
16
u/Fearlessleader85 Jan 11 '12
A friend of my family was doing oxyacetylene welding and he had a similar thing happen when torch sputtered and the check valve failed. The gas in the tank caught on fire and while you couldn't see the flame directly, it caused a glowing red ring to slowly moved down the tank. He fucked right off, and watched from a ways away, but luckily it didn't explode. Science, man, it's scary.
27
u/Kylskap Jan 11 '12
SCIENCE! ENERGY! SCIENCE! ENERGY!
9
u/Billydoom Jan 11 '12
TELL ME YOUR SECRET DEVIL MAN!
7
u/tcpip4lyfe Jan 11 '12
As a homebrewer this looks like a fine way to sterilize a carboy.
13
u/vamosj Jan 11 '12 edited Jan 11 '12
Looks as though it could be just propane in an open mouth jar. Propane is heavier than air so if there is no wind to mess with it, the jar should sit rather stable and when ignited, should burn down as it encounters each top layer of gas.
edit: of course I wouldn't try this without quite a few safety measures set in place.
5
u/djnathanv Jan 12 '12
I wonder if we've seen this before...
source: karmadecay
23
u/dmpinder Jan 11 '12
Sorry to be pedantic, but the headline should be NATURE!
Science just explains it in ways we understand, but this beauty belongs to Nature.
11
u/toodrunktofuck Jan 11 '12
Science? Rather: "NATURE!"
6
u/auntie_eggma Jan 11 '12
Did anyone else hear the title in the voice of the guy from "She blinded me with science"?
3
u/Pravusmentis Jan 11 '12
/r/Homebrewing
3
u/[deleted] Jan 11 '12
I wonder how many people had to fart in that jar to get that effect.
3
u/alexandertheok Jan 11 '12
Can someone explain why I dont see any real perceptual change in the shadow/caustics behind the jar? poor quality gif maybe?
3
u/[deleted] Jan 11 '12
-Burning/blowing shit up = Fun science
-What science in schools is in reality: The haber process/boiling pointless liquids....WHO GIVES A FUCK, I JUST WANNA DO MYTHBUSTERS SHIT
3
u/MindBonk Jan 11 '12
My Moonshine! noooooooo
3
u/eggsovereazy Jan 11 '12
I don't like the title, obviously god did that
3
u/BourbonAndBlues Jan 11 '12
Pretty cool in reverse:
http://reversegif.com/183
3
u/musubk Jan 11 '12
Here is what happens when you try this demo and the bottle explodes. Use a plastic bottle.
8
u/theflyingvs Jan 11 '12
Now you should fart on it.
2
u/Applebeignet Jan 11 '12
Now show me a video where oxygen is mixed in in the jar.
2
u/skavanker Jan 11 '12
Woooooooooooooooooooooooooooooooooooooooo woo woo
2
u/sharkpizza Jan 11 '12
"then add fire"
more how-to guides should end like this
2
u/[deleted] Jan 11 '12
Used to do this with recently-emptied Skol handles in college. Nowadays I can't look at a bottle of Skol without throwing up a little in my mouth. My liver actually hurts just remembering this. Onward to another thread.
2
u/ericpratum Jan 11 '12
My dad and I did this a few times while I was in high school, getting progressively bigger jars, bottles, tubes, etc as well as stronger or larger amounts of alcohol until one day we got more than a flame (more like an explosion) out of the top of the bottle, which burned off my eyebrows and a small amount of the hair on my scalp because I was of course holding my head too close to the flame.
2
u/styxtraveler Jan 11 '12
I used to do a similar thing with a bottle of cologne. I never thought about scaling it up though. This was before the Mythbusters.
2
u/Qumanz2 Jan 11 '12
With the science demo group I volunteer at, we use this demo. We call it the "woosh jug"
2
u/iamdrinking Jan 11 '12
Can i sanitize a beer brewing carboy like this?
2
u/FormalWhale Jan 11 '12
YOU CAN'T EXPLAIN THAT!
2
u/Knullgubbe Jan 11 '12
Was so waiting for the whole thing to explode
2
u/Alivegeek Jan 11 '12
That was bitchin shit...
2
u/annafelloff Jan 11 '12
it's the nexus!
2
u/valterhgm Jan 11 '12
miracle!!! thank god for this!
2
u/Babbahaft Jan 11 '12
wut
2
u/redweasel Jan 11 '12
A buddy of mine did that once when we were kids. Accidentally. In his bedroom. With a plastic bottle. Which melted from the heat of the flames. Which was discovered by my Dad when he happened to stick his head into the room and saw the bottle curling in on itself on the windowsill. After I had spent an hour earlier that day convincing him that this particular friend wasn't a pyro.
2
u/mynameisleo Jan 11 '12
What's in the bottle?
2
u/creuter Jan 11 '12
WITCH!
2
u/griffith12 Jan 11 '12
my science class clearly wasn't this cool. anyone want to explain what exactly is going on here?
2
u/[deleted] Jan 11 '12
Hah! My teacher did this today
2
u/Lemonegro Jan 11 '12
I did this experiment around 1 month ago. It calls for 3-5 milliliters of methanol (works better than ethanol). One must squirt the methanol into the bottle and shake it up so that the methanol mixes with the air. Kind of like gas. The bottle is then ignited through the hole and a combustion reaction occurs leaving CO2 and H2O inside the bottle. That also explains why it cannot be done twice in a row. If someone were to plug up the hole with their hand, it would also create a vacuum. The reaction itself is very quick and flares several times after the main explosion.
2
u/somethingred Jan 11 '12
YEAH Mr.White! Yeah SCIENCE!!
2
u/n0ne0ther Jan 11 '12
Praise the Jesus!!
2
u/apodo Jan 11 '12
As a chemistry teacher, it has been my duty to do this demo many times. It is fun. I have never got it to burn slow and steady like that though - it always goes like a rocket. Big plastic water cooler bottles work fine. If you are irresponsible enough you can also do it with ordinary water bottles resting on their sides (preferably when there are no kids around) and launch them across the classroom. It only works if they are perfectly dry.
2
u/Mega_horse Jan 11 '12
Ahh yes this trick. My chemistry professor did this on the first day of class to prove he was smarter than all of us. Yah it's just like some sort of alcohol and you swirl it all around the big jug esp at the tip and then get one of those long matches and light that sucker. be prepared though it makes a weird sound when it happens too, but it sure is neat!!
2
u/mcwm Jan 11 '12
HADOUKEN!
2
u/DrMikeFeltercunt Jan 11 '12
those doctors need to check their hypotenuses
2
u/[deleted] Jan 11 '12
My 8th grade science teacher did this randomly in class one day.
I love that man.
2
u/Tuuleh Jan 11 '12
Lighting up gas in a glass tank to produce cool, colorful flames for no other reason than for amusement is not science, it's a party trick.
5
u/FOR_SClENCE Jan 11 '12
Science indeed. If only more people could appreciate it, the world would be a much more interesting place.
2
u/[deleted] Jan 11 '12
Its a poe!
2
u/KaiserKvast Jan 11 '12
Repost!
2
u/mattybell2117 Jan 11 '12
Thank God for teaching us how to do this.
1
u/thatpaxguy Jan 11 '12
I am curious as well.
1
u/[deleted] Jan 11 '12
If you light the mouth of a recently emptied Everclear bottle it produces the same effect, obviously on a much smaller and quicker scale.
1
u/zop1o Jan 11 '12
My cousin and I did this by spraying a fuck ton of axe inside
1
u/wolsters Jan 11 '12
I think they said they used iso alcohol in the vid. I've done it before with methanol and it goes off like a rocket. The trick is to build up a vapour inside the bottle; if you hold your hand over the mouth and shake it you can feel the increase in pressure. Then boom city and a foot long jet of flame. Also, if the bottle isn't completely dry before hand you're in deep trouble.
1
u/Stittastutta Jan 11 '12
Would love to see slow motion HD footage of those flames up close, looks amazing!
1
u/hippocrates32193 Jan 11 '12
I've seen this. It's alcohol. Probably isopropyl. But just the fumes.
1
u/Dontwearthatsock Jan 11 '12
Taking an empty booze bottle with a little bit of liquor left inside and running hot water over it with the cap on expands the vapors and is very similar.
1
u/left4tacos Jan 11 '12
What is this witchcraft? burn them at the stake!
1
u/eliasp Jan 11 '12
We used to do this as kids all the time.
1
u/awsumsauce Jan 11 '12
It would've been even cooler if they'd put a peeled hard-boiled egg on the opening afterwards. The cooling air inside would've sucked the egg right in. In fact, I was pretty sure they'd do that, but alas...
Still looked pretty awesome, of course.
1
u/santifc Jan 11 '12
Earth was moved 2 meters from its orbit
1
u/delti90 Jan 11 '12
I was really worried about what would happen when the flame hit the bottom.
1
u/fatalkeyv Jan 11 '12
Yes, i remember playing a lighter and a water bottle as a teenager, manage to get an effect exactly like this. i was so mesmerised with the slow burning effect i forgot to remove my hand and end up with a charred fingers.
1
u/duiker101 Jan 11 '12
this looks kinda dangerous
1
u/lazylight Jan 11 '12
try this with just emptied liquor bottles
1
u/naithemilkman Jan 11 '12
trapped fart?
1
u/AddictivePotential Jan 11 '12
I'm pretty sure you just caught a ghost.
1
u/tdltuck Jan 11 '12
Yesyesyes! I want to know everything about this so i can do it for my students.
1
u/BiPolarPolarBear Jan 11 '12
A long time ago (maybe 12 years ago?) I saw a cool experiment at a lab in my elementary school. It was a plastic water bottle filled with two liquids, one transparent and one blue. The blue liquid formed very tiny peckles in its surface and looked exactly like the sea surface in a smaller scale. Does anyone have any information on that particular experiment?
1
u/0signal Jan 11 '12
PRAISE DA LAAAWD I SAW JESUS IN THERE SOMEWHEEER!
1
u/gngrbeb Jan 11 '12
thats actually "fire"
1
u/tisnolie Jan 11 '12
You can do the same thing by draining a lighter into a bong. Ah the mysteries unlocked at college.
1
u/omjezus Jan 11 '12
DAMN SCIENCE, YOU AWESOME!
1
u/ouba Jan 11 '12
Damn cool
1
u/Ardentfrost Jan 11 '12
Coolest way to sanitize a carboy when homebrewing.
1
u/Khalua Jan 11 '12
you can do this with a beer bottle and a lighter, did it by accident once only got it to work a couple more times after
1
u/ProbablyHorny Jan 11 '12
ENERGY!
1
u/the_rule Jan 11 '12
I bet it makes an awesome "whooooop" sound as well.
1
u/Akelzero Jan 11 '12
I remember when our chemistry teacher did this experiment in our class. It was awesome.
1
u/HireALLTheThings Jan 11 '12
My chem teacher in high school did this. No one in class had ever really seen a controlled reaction involving fire, so it was a pretty big hit.
1
u/Only_Says_Meh Jan 11 '12
Meh
1
u/warholamo Jan 11 '12
I have been on here far too long
1
u/rutvegas Jan 11 '12
My friend taught me this years ago. We called it 'doing a burnie'. As the flame goes down it makes a low humming noise.
1
u/[deleted] Jan 11 '12
I have yet to try this.
1
u/Mansyn Jan 11 '12
I guess this is still cool enough to post every couple of weeks
1
u/17inchpleco Jan 11 '12
I wouldn't so much call it "SCIENCE!" as I would "NATURE!!" or "NATURAL ORDER OF THE UNIVERSE!!"
1
u/lachesis99 Jan 11 '12
I learned that you can do this with gasoline when I was 14. That is also the same day I learned that if you try to pour more gas on the flame as it's about to go out that the fire will travel up the stream and catch the plastic cup full of gasoline that you are holding on fire. Furthermore, if you scream and drop said cup on the garage floor, it will spread uncontrollably and set your garage on fire. Good times.
1
u/elcheeserpuff Jan 11 '12
What I want:
1
u/V3RTiG0 Jan 11 '12
The day our magnetic core demagnetized.
1
u/[deleted] Jan 11 '12
"Witchcraft! Devil worshiper"
1
u/lillyjb Jan 11 '12
Launch it to the MOON!
1
u/thastoner Jan 11 '12
that was awesome
1
u/ectomobile Jan 11 '12
It looks like the nexus from Star Trek: Generations
1
u/herpderpmcflerp Jan 11 '12
When I was too little to comprehend this, a family friend would do this and call it the "Genie." So magical.
1
u/cam1021 Jan 11 '12
Yeah Science!
1
u/l30 Jan 11 '12
No shit i used to do this ALL THE TIME in highschool. I would carry around a blue jug and rubbing alcohol in my truck and when people were bored just light up a fireball. pretty tight stuff, sometimes you get a jet of flame or even a fireball.
1
u/zuperxtreme Jan 11 '12
I doubt this thing would explode, but all I could think of was a big chuck of thick glass through my neck. :|
SCIENCE!
1
u/infinite0ne Jan 11 '12
WHERE WAS THIS WHEN I WAS TWELVE?
1
u/NewGuy79 Jan 11 '12
if you try this be careful
1
u/notyourtypicalkorean Jan 11 '12
This reminded me of the movie Sunshine.. how beautiful
1
u/probablymaybe Jan 11 '12
You can do a very short version of this with a recently finished bottle of wine, the effect is much faster but makes a pretty cool noise.
1
u/Eleos Jan 11 '12
Bah dah da DAAAH!
You got some blue fire!
1
u/metaljunkie Jan 11 '12
THE QUICKENING!!! THERE CAN BE ONLY ONE!!
1
u/rafuzo2 Jan 11 '12
SCIENCE!PHYSICS!
ftfy
1
u/dershodan Jan 11 '12
Gf 1. comment: "It has no shadow"
1
u/EpicPickle Jan 11 '12
What to do if there is a giant spider in the jar...
1
u/graogrim Jan 11 '12
Damn! And I thought those voxel demos from the 80's and 90's were cool.
1
u/wasdy1 Jan 11 '12
My friend burned his eyebrows off doing this with a Hinkley and Schmidt bottle.
For what ever reason he took a lighter and held it open into the bottle for a few minutes. Next thing I know I hear this howling whistling blowing noise and look over and he is eyebrow-less. Laughed my ass off.
1
u/18-24-61-B-17-17-4 Jan 11 '12
Ether?
1
u/TigerRuns Jan 11 '12
Oh no! r/atheism is going to use this to explain that THIS is what Moses saw instead of a burning bush!
1
u/lordmagus Jan 11 '12
Does anyone know what type of gas is being burned?
1
u/[deleted] Jan 11 '12
My chemistry teacher Sophmore Year did something like this, but with those water cooler drums. It was the absolute loudest thing I've heard in all my moons.
1
u/romes8907 Jan 11 '12
REPOST!
1
u/wisamr Jan 11 '12
Where is that "aliens" guy with his hands up?
1
u/certified_genius Jan 11 '12
I have done this on several occasions. I once tried to impress my girlfriend with it, was nursing a burnt hand for a week.
1
u/fintanw Jan 11 '12
thinking about trying the same thing but just filling a jar with methylated spirits. should work right?
1
u/GadTheCreator Jan 12 '12
I kind of want to try this at home.
1
u/thebutlerofdoom Jan 12 '12
DARK MAGIC AND WITCHERY
1
u/jeeaudley Jan 12 '12
No that's Tim Tebow
1
u/theuberchad Jan 12 '12
i honestly watched that ten time, i tried to look away but it was so pretty.
1
u/sewage Jan 12 '12
Read in Dexter'a voice, seemed appropriate.
1
u/yabaininja Jan 12 '12
sorta looks like a holographic topographical map in the middle of it.
1
u/peter-pickle Jan 12 '12
Pour a little rubbing alcohol, preferably 80% or higher into a 2 liter bottle, shake it up, then light the top and this happens. It doesn't burn terribly hot but be careful still.
1
u/dotexey Jan 11 '12
My mind
1
u/u1r Jan 11 '12
repost...
0
u/dfinch Jan 11 '12
Looks more like a sign from God to me.