www.pulse-jets.com

Not sure where to put this, but I just found a cool video regarding the jam-jar jet, it adds a diffuser using a plumbing part to make it much more powerful:

http://www.youtube.com/watch?v=fciwFk0IfF8

it might help with yours

Wish I filmed that well, or sounded that good...

Audio would be nice.

As promised in another Thread; Construction details.
Pretty simple stuff. The vent holes were made with an "I" drill. not 1/4" ( .635cm ) as I had thought, but it was in the ball park ( a large park.... )

The OD of the rod is Very close to 1/2" ( 1.27cm )

Totally weld-less and no sealant, Just get it all tight.

Use a water jacket for prolonged running.

What is the size of the CC? it might still be written on it lol but it might have burnt off! good going with the threaded pipe idea

Go back one page in this thread. It is about about 1/4 of the way down.

Or I could quote my self...

Ok final edit ( I hope ); Approximate dimensions.

CC: 2"ID x 3" long
Tail Pipe: 16" x 3/8"ID
Vents: 1/4" qty 2

Approximate should be read with emphasis.

And I did add 16.5" to the tail pipe to make it go.

Have to go find /Thunder Hawk/ plans now....
Cheers

Pulled out my favourite jars the other day, haven't played with them for ages. Only have 95% ethanol to hand, methanol is hard to come by over here and it's not time to run the "laboratory" distillation apparatus yet, so I don't even have any "heads" lying about. 66% humidity, but both of them ran themselves dry after a bit of messing about (and the usual burned fingers due to a foolish "lighting the bigmouth handheld" incident).

I'd almost forgotten how much fun they are.

Fun they are, but some what mysterious to me in some ways. My little tin can starts up like a typical JJ and ramps up to a real zip like a little thermo. It has even heated it's CC partially red, and run totally dry. Impressive to me because I've been using old oiled fuel made for 2 stroke model airplane engines, even the oil burns off... I have been fiddling with more of these little cans, and something was not adding up. I pulled out the calipers for a closer look at the best one. The vent holes average ( not so round... ) at about .280 dia, and so does the hole in the coupler that I use for holding the 3/8 ID tubing in place, this is at variance with the previously posted specks. Serves me right using a tape measure, and missing the whole coupler MUST be smaller than the tube it goes in thing. The CC after measurement seems to be about 10 cubic inches, however I suspect a math error on this value, and there are some dimensions around the cap and threads that must be estimated, so 10 is a guess Given....

One thing that seems to favor good running is having the tail pipe penetrate the CC past the plane of the vent holes. Further testing is needed to help quantify this result.

When I returned to start another round of experiments yesterday evening, the fuel can ( 1 us Ga ) was sitting in an oil/goo puddle and had clearly ruptured. The leak is small and involves rust. Vibration may have been a factor in the final demise of this vessel, also the heat lately... Some of the remaining //fuel// was used for some runs that were less than great. With some experimental configurations, (could be a factor). Clearly the condition of this stuff was not good from the get go. Now I am wondering what kind of performance I can get out of new fuel. I also realize that I have to retest everything with said new fuel. The old stuff still burns fine in the bigger jets so I will salvage what I can ( read as have fun burning it up ), and move on...


Cheers.

Missed one thing I am planing on making some test units out of pipe, so I have greater control of dimensions and can add internal structures &c.

Still looking for a better way to film/record this stuff.

Cheers

The other day I tried something with the last of my nitro rich fuel.

see pictures.
Obviously the work of a nut case....

It ran. Briefly, Maybe 10 to 20 cycles but this little runt ran. Not loud or hard. but it ran...

SO new fuel just went way up on my priority list.

Cheers

I've done a few of those in the past too. I had better luck by not drilling the hole out quite all the way, yet airing them out is more difficult with a slightly smaller opening. The very first time I encountered this Reynst jam jar action, I didn't even recognize it for what it was. I was toying with a yellow plastic lemon, the kind that holds lemon juice or something that tastes like inferior lemon juice.
I had removed the tiny nozzle insert and was putting a few drops of methanol in it and letting it rocket away, just another "whistling bottle" to me. One time I just held it upright and lit the top, and instead of the sudden whoosh and flame-out, it putted along for several seconds just like a jam jar or rather a lemon jar. ha
Later in my quest to know more about pulsejets, I ordered a copy of Reynst's book "Pulsating Combustion" and was so delighted with the jam jar idea presented in his book. It afforded me weeks of entertainment, and still today I like to imagine new jam jar aspects to toy with. I showed my brother one of my first real jam jars and he was quite taken by it. He thought I had discovered something fascinating. Right after the demo I revealed to him it was something I found in a "new" book I was reading. But it was he who gave me his Dynaj-Jet a few years before and somehow I again became interested in pulsesjets, being bored one day.

My first jam jar was a lemon. Oh!
http://farm2.static.flickr.com/1070/105 ... 9a.jpg?v=0
I like to use straight methanol for jam jarring.
http://www.brasslite.com/SiteImages/Misc/HEET.html

That's funny, Truly funny. Odd too, my first Lemon was a car...

I think I might have hesitated to warm up a plastic bottle like that.. maybe ... but probably not.

I just ordered some .004 stainless, I am thinking of trying a //Valvi-Jar// that name will never last...


I will report back on what hilarity ensues.

I had better luck by not drilling the hole out quite all the way, yet airing them out is more difficult with a slightly smaller opening.

It was the drill in the chuck... not scientifically selected.
Yah airing out is an issue on the little guys...


P.S. yes I spun the hell out of it in the vice, sloppy work on my part, But then I was just goofing off...

Cheers

I was fiddling around with my new camera last night (1am ish ) with some old, slightly corrupt PVC primer.

Results .... such as they are..... Here ... .. ... http://www.youtube.com/watch?v=aiSpdbpKWcA

Cheers.

hehe pvc primer....got to give that a go

That was a nice effect. I liked the ejecting sparks and wobble.

http://docs.google.com/viewer?a=v&q=cac ... pQbHx_vjpw

Vapor Pressure
(mm Hg):
400 @ 104° F Based on
first boiling component-
Acetone

Ha ha, Ghrey, that's some fun stuff. Pretty energetic, that first one with the long pipe. I love the array of bottles, tubes and cans. That's one of the cool things about jamjars is you can play with them at 1am, though more than once I've had a gun shot go off that rings the garage door. "ooops, F--k! sorry neighbor.." whose bedroom window (open) is about ten feet away... good times.