What is a pressure jet?

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Mark
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Post by Mark » Wed Jul 07, 2004 11:11 pm

Yes, my Logan will purr or just barely gurgle and it is fun to like you say give it the gas and watch the side port blue flame extend out an inch or two, with little eddies curling back on the main flame near the tip of the fire, whining as best it can, screeching loud for so small.
With MAPP gas it is more fussy, and will flame out if you give it too much gas or modulate it up or down too quickly.
Propane I never got to work, maybe if the fuel line took a path through the flame somewhere to preheat it perhaps.
I was thinking it would be neat to have a small device like the Logan screw directly on top of a propane canister with a piezo sparker like my sweating torch head which has a trigger start that releases the gas and simultaneously spark starts it all in the singel trigger action. Imagine instant noise!
Mark

steve
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Post by steve » Thu Jul 08, 2004 12:03 am

I just ran some more tests and aparently you don't need any spark after all. I started it about 10 times using the blowtorch at the tailpipe. Aparently you don't need starting air either! It started accidentally when I was turning on the acetlyne and that's how I discovered this neat trick. the easiest way to do it intentionally is by turning the torch knob up slowly (with the blowtorch at the tailpipe) untill it catches (it should take about 1-2 secconds to do so). you may have to have the engine horizontal to do this, although I havent tested it at an angle yet. at any rate, I can now demonstrate this engine any place where there is an oxy torch.

I got some more neat pics too:
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Post by Mike Everman » Thu Jul 08, 2004 12:28 am

Very nice pics, Steve!
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Post by steve » Thu Jul 08, 2004 12:59 am

Mike Everman wrote:Very nice pics, Steve!
thanks! Photography just happens to be one of my many other hobbies.

I scanned in some other pics that you might enjoy:

I use a 35mm for this stuff, the digital stays home
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Mark
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Post by Mark » Thu Jul 08, 2004 2:42 am

steve wrote:I just ran some more tests and aparently you don't need any spark after all. I started it about 10 times using the blowtorch at the tailpipe. Aparently you don't need starting air either! It started accidentally when I was turning on the acetlyne and that's how I discovered this neat trick. the easiest way to do it intentionally is by turning the torch knob up slowly (with the blowtorch at the tailpipe) untill it catches (it should take about 1-2 secconds to do so). you may have to have the engine horizontal to do this, although I havent tested it at an angle yet. at any rate, I can now demonstrate this engine any place where there is an oxy torch.

I got some more neat pics too:
Acetylene is very forgiving, it's almost cheating. I think it might be fun to try in a tiny jam jar device using it instead of methanol. And I would stress the word tiny. It can go off with a bang as I am sure you have found. You would like jam jars, and methanol can be bought at most any auto store that sells additives, or you can buy it at Walmart under the name HEET. It is about 75 cents a 12 ounce bottle.
I found this color chart, you can see zinc emits a white flame with a greenish tint. If you want a fascinating intense color, try using some copper tubing. That was a nice picture of your jet running.
Mark


http://chemistry.about.com/library/weekly/aa110401a.htm

steve
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Post by steve » Wed Jul 14, 2004 6:23 pm

I just figured out how to post video so I thought I'd post this:
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Post by Mark » Wed Jul 14, 2004 11:43 pm

Nice documentary videos Steve of your pulsejetting episodes. I hope you keep it up and continue entertaining us.
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Post by Mike Everman » Wed Jul 14, 2004 11:47 pm

A little bit under 400 Hz. Very nice. I'd like to see one at 2x scale; should run easily on propane.
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Re: What is a pressure jet?

Post by NanoSoft » Fri Sep 03, 2004 11:41 pm

I just had to build one of these things even though i am working on tons of other jet projects. At the farm we have more pipe fittings then your average hardware store so i decided to put them to good use. I got mine to work on acytelene. I think when i get time i will build a 2x scaled up version and try it out. Me little one doesn't produce much thrust but some. Out the tailpipe i can feel the hot air blowing from 2 feet back which is't bad for its size. Ou the inlet theres double. Its the equivelent of a weak airgun. Mark, i wan't to thank you for coming up with this simple design. I wonder why the side port produces more thrust then the exhaust. Any idears. Thanks

Nanosoft

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Re: What is a pressure jet?

Post by steve » Sat Sep 04, 2004 2:11 am

the thrust produced is quite good for it's size especially if you were to add a curved augmentor to the intake so it points rearward. I would love to make a lightweight sheet metal equivilant fueled by methanol and mount it on a small CL plane. It would be great because it only makes about as much noise as a .049 model aircraft engine rather then deafening your audience like most pulsejets.

I look foward to seeing to 2X version! good luck!
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Re: What is a pressure jet?

Post by NanoSoft » Sun Sep 05, 2004 4:22 am

I started and finished my logan x2 in 1 hour or so today. It took longer then i thought it would because i decided to weld this one up and not just make it out of pipes. It works!! Actually it works quite well on acytelene. It revs up and down with even a broader range then the previous one. It idles down to where you can hardly hear it and then in seconds you can rev it up to full throttle which is deafingly load. I tryed propane but couldn't get it to sustain for more then a second. Tommorow i will play with the lenghts of the exhaust and intake and try to make it work. Here are some pics of the engine. Tommorow i also plan to post a video of it running at idle and full blast on acytelene and hopefully propane.

Nanosoft
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Nanosoft's Logan engine
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Mike Everman
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Re: What is a pressure jet?

Post by Mike Everman » Sun Sep 05, 2004 2:45 pm

Great! You did a bit different fuel feed, can you trry the original style with propane before you change anything?
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Re: What is a pressure jet?

Post by Mark » Sun Sep 05, 2004 3:14 pm

Another little Logan is born on the forum. What is that you used for a combustion chamber, it almost looks like a cartridge with a firing pin? I don't know why the side port makes more thrust than the tailpipe, perhaps it is that the proportions on a small jet are more similar and the exhaust takes the path of least resistance. It could be that my proportions are off, I just tinkered until I found something that ran.
Good work on the 2X, it sounds like you had fun reving it up and down, and making lots of noise ala acetylene.
I was thinking if you subjected some propane coils to the fire and then injected the hot high velocity propane gases into the side port, it would act to staunch some of the escaping side port thrust and at the same time make the propane burn better. In a recent combustion book I was reading, it stated pre-heating the propane dramatically increases the flame speed.
Mark

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Re: What is a pressure jet?

Post by NanoSoft » Sun Sep 05, 2004 5:57 pm

I moved this topic to a more proper place in the valveless section seeing how this isn't really a pressurejet. Thanks

Nanosoft

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