I recently tried creating a jam jar jet with limited success. I used a salsa jar I bought at walmart and trilled a hole that was about an 3/4 on an inch in the lid. I placed some heet dry gas at the bottom, shook it up (with my finger over the hole, of course) and then lit it. After it ignited, there was just a blue flame that shot out of the top with a "Whoosh" noise to it, then it pretty much died. There was just a small blue flame at the top but that was about it. I think the hole may have been too big, but im not sure.
Also, I have read some articles about placing a copper tube in the jar and have it supported by wires. What is the point in that and is it needed.
Thanks
Jam Jar Troubleshoot
Moderator: Mike Everman
Jam Jar Troubleshoot
A 3/4 inch hole is too big! Make it a half inch or even 7/16. For small jars you have to make the hole even smaller. I would skip all the copper jazz, you only need a hole of the proper size and some methanol for fuel. Remember, don't put very much in, just enough to cover the bottom of the jar. Light fuse, get away fast. ha Don't burn your fingers. Everyone does though, there's a learning curve.
Your lid should seal tightly too. Remember you are trying to build feedback, not dampen it.
Your lid should seal tightly too. Remember you are trying to build feedback, not dampen it.
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Mike Everman
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No, no need for a tube.
Yes, your hole is too big.7/16" or 1/2" is better. You may get that big hole going with rubbing alcohol. In any case, try over and over, even when it doesn't work several times. Jam jars are about repitition when trying new things.
Yes, your hole is too big.7/16" or 1/2" is better. You may get that big hole going with rubbing alcohol. In any case, try over and over, even when it doesn't work several times. Jam jars are about repitition when trying new things.
Mike Often wrong, never unsure.
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If it is the Pace picante jar, about 6" height, that one runs well with a 7/16" hole. It is one of my favorite glass jars. It will only run about 8 to 10 seconds then will crack around the bottom from the heat build up.
For tinkering I usually put the jars in a pie plate. The HEET will often leak from the crack and start a little fire. Also when first testing unfamiliar jars it is a good idea to surround the jar with a 1/4 square wire mesh, as some will crack in unexpected ways.
Happy Jarring!
For tinkering I usually put the jars in a pie plate. The HEET will often leak from the crack and start a little fire. Also when first testing unfamiliar jars it is a good idea to surround the jar with a 1/4 square wire mesh, as some will crack in unexpected ways.
Happy Jarring!
Thanks for the help.
Is there any sort of formula to figure out what the size of the hole should be based on the dimensions of the jar. I was thinking about maybe trying a larger jar at some point (assuming i can get this thing running)
I also wrapped the jar in clear packaging tape in an attempt to keep all of the large pieces of glass together if the jar would break. It'd probably do nothing, but its still a nice piece of mind :P
Is there any sort of formula to figure out what the size of the hole should be based on the dimensions of the jar. I was thinking about maybe trying a larger jar at some point (assuming i can get this thing running)
I also wrapped the jar in clear packaging tape in an attempt to keep all of the large pieces of glass together if the jar would break. It'd probably do nothing, but its still a nice piece of mind :P
There is no formula that I know of. Mark may have one.
--I often use a 7/16" hole for a jar with a diameter 3" and height of about 6".
--So, if I have a 6" diameter by 12" height that equates to about 14/16" or properly 7/8"
1 unit chamber diameter to 2 unit height has been a good guide thus far.
7/16=.4375 for a 3" diameter chamber equates to:
about .1458 unit hole diameter per 1 unit of chamber diameter.
I notice in my jars, that they work better if they have a slightly larger bottom than top.
The tough part about putting them in water, is they float. This can be overcome, but is often added complexity.
--I often use a 7/16" hole for a jar with a diameter 3" and height of about 6".
--So, if I have a 6" diameter by 12" height that equates to about 14/16" or properly 7/8"
1 unit chamber diameter to 2 unit height has been a good guide thus far.
7/16=.4375 for a 3" diameter chamber equates to:
about .1458 unit hole diameter per 1 unit of chamber diameter.
I notice in my jars, that they work better if they have a slightly larger bottom than top.
The tough part about putting them in water, is they float. This can be overcome, but is often added complexity.
Generally, a larger hole is needed for a larger jar. But as Mike pointed out, if you use a different fuel, you might want a different sized hole too. I found ethanol, Everclear 190 proof, runs almost as well as methanol but the hole size just needs to be increased slightly. Ethanol, (C2H5OH), is a larger molecule than methanol, (CH3OH), so it needs more parts of air to burn one molecule of ethanol, relative to methanol. Methanol has a very wide range in which it will burn rich or lean, that makes it the most forgiving common fuel you can find.
In climates like mine, you will have better luck making the hole a little smaller in the hot humid summer. Sometimes you can be hard pressed in fact to get a jar to run when such conditions exist. In winter, you can get away with a little larger hole than normal too, because the jar really likes to run in cool, dry air. In fact, a smaller hole that worked fine in summer will often only give you a really energetic whoosh and flame-out more times than not, the jar unable to sustain combustion.
I guess another way to approach it would be to lessen/reduce the surface area of the pool of fuel in the bottom of the jar.
There are many variables, and I don't claim to know anything for certain. There is often a caveat, some exception to the rule. I'm still learning; jam jars are both simple and complex, I know that.
In climates like mine, you will have better luck making the hole a little smaller in the hot humid summer. Sometimes you can be hard pressed in fact to get a jar to run when such conditions exist. In winter, you can get away with a little larger hole than normal too, because the jar really likes to run in cool, dry air. In fact, a smaller hole that worked fine in summer will often only give you a really energetic whoosh and flame-out more times than not, the jar unable to sustain combustion.
I guess another way to approach it would be to lessen/reduce the surface area of the pool of fuel in the bottom of the jar.
There are many variables, and I don't claim to know anything for certain. There is often a caveat, some exception to the rule. I'm still learning; jam jars are both simple and complex, I know that.
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"It is my opinion that many jars have volume that doesn't contribute to gas flow. Dead space areas. The shape of the jar plays a key role in how long the jar will run when bottom fed."
That made me think what would happen if you had a jar with some dead end side channel tubes that couldn't refresh or breathe and get into the act other than acting as a slight gas spring/capacitor to the pulsations. It would be a curious experiment.
Then too, I want to try the party favors, the kind that are rolled up and uncoil when you blow into them.
Tomorrow my two Klein bottles should arrive, then I can try the U-turned snorkels that exhaust down the center of the jar and out the center of the bottom. I don't have high hopes, but I'm going to give it the old college try. Maybe I can lengthen the snorkels as a variable if they refuse to sustain, sleeve in an extention tube to make them a bit longer and that would also change the wide flare with a typical straight end exhaust/intake.
http://www.kleinbottle.com/baby_klein.htm
That made me think what would happen if you had a jar with some dead end side channel tubes that couldn't refresh or breathe and get into the act other than acting as a slight gas spring/capacitor to the pulsations. It would be a curious experiment.
Then too, I want to try the party favors, the kind that are rolled up and uncoil when you blow into them.
Tomorrow my two Klein bottles should arrive, then I can try the U-turned snorkels that exhaust down the center of the jar and out the center of the bottom. I don't have high hopes, but I'm going to give it the old college try. Maybe I can lengthen the snorkels as a variable if they refuse to sustain, sleeve in an extention tube to make them a bit longer and that would also change the wide flare with a typical straight end exhaust/intake.
http://www.kleinbottle.com/baby_klein.htm
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larry cottrill
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After you get the alcohol "inside" (ha) your Klein bottle snorkeler and coat the "inside" (ha) wall with it, you could light it off by setting it down on a sprig of your platinum wool in the middle of three little pedestals. For added excitement, the pedestals could be Sierpinski gaskets of appropriate height, for plentiful airflow to/from the center.
L Cottrill
L Cottrill
I was tinkering around with the jar again today and had better results. One problem I'm having is getting it to relight. I can start it the once and it make a loud whoosh followed by a weak few second "ba-ba-ba-ba" then it goes out. When I try relighting it, it doesn't even catch fire or anything. My fuel source is HEET dry gas.
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larry cottrill
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Flyer -
When they die out, they fill with a sort of "smoke" - I'm not sure why this happens with alcohol, but it does. You have to open them up and air them out before shaking and re-lighting.
Mark might have a tough time airing out his Klein snorkeler after a successful run. But then, the "inside wall" is really an outside surface, so it probably won't even need it ;-)
L Cottrill
When they die out, they fill with a sort of "smoke" - I'm not sure why this happens with alcohol, but it does. You have to open them up and air them out before shaking and re-lighting.
Mark might have a tough time airing out his Klein snorkeler after a successful run. But then, the "inside wall" is really an outside surface, so it probably won't even need it ;-)
L Cottrill