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First Attempt: Homemade Valveless Pulsejet

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First Attempt: Homemade Valveless Pulsejet

Unread postAuthor: DR » Sun Feb 15, 2009 2:41 am

Bored with the thought of making yet ANOTHER combustion or pneumatic cannon and entirely embarrassed for being SO bored, that I made a rubber-band gun... I wanted to try something entirely different.

Jam-Jar jets are kinda cool, but are difficult to start and usually crack after cycling for less than 20 seconds. There are several sites where you can buy a pulse-jet, one of them being ebay. My wife surprised me, this Valentine's Day, by buying me one off of ebay. - But, little did she know, that I was already in the process of figuring out how to make one myself, out of common and readily available materials.


<a href="http://i43.tinypic.com/29nf5ut.jpg"><img src="http://s5.tinypic.com/29nf5ut_th.jpg"></a> <a href="http://i44.tinypic.com/awb7u1.jpg"><img src="http://i44.tinypic.com/awb7u1_th.jpg"></a> <a href="http://i39.tinypic.com/14b6avs.jpg"><img src="http://i39.tinypic.com/14b6avs_th.jpg"> <a href="http://i42.tinypic.com/34pds2u.jpg"><img src="http://i42.tinypic.com/34pds2u_th.jpg"></a>

The spark plug was tapped into the end of the combustion chamber, with the same tap that I had always used for my hybrid combustion launchers. It was really unnecessary though, as the thermojet will start with a hand-held propane torch.

This ran with a less-than half-full 1 lb. disposable propane bottle and STILL was able to run for over two minutes... And there's STILL a significant amount of fuel, left in the cylinder. A properly designed "engine" of this size will (supposedly) consume 5.5 LBS. / HR. / LB. THRUST ... (Spec's from the similar-sized one that was purchased from ebay)

I have NO clue as to how much thrust it was putting out, but I do know that it was obnoxiously loud. It resonated throughout the entire garage, spittin' sparks and freakin' out every animal in our house.

<b>These are The #@*$</b> - Until you've seen and heard one (up close), you have no idea how much fun a simple thing like this can be.

No memory card for the camera, so I set it on VGA, so that I would have over 20 min. worth of video-capture.

Here's a super-crappy video of it running: <a href="http://www.youtube.com/watch?v=2VA-LvaaNcU">Homemade Valveless Pulsejet</a>
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Unread postAuthor: inonickname » Sun Feb 15, 2009 2:49 am

Sweet. You feed propane into the two shorter exhausts from the chamber don't you? I think I've seen that one somewhere before. I'm currently building a lockwood hiller, but I need dad to refill the mig's bottles..

Cool automatic spudgun without ammo ( :? ). Still, awesome.
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Unread postAuthor: starman » Sun Feb 15, 2009 2:54 am

Your wife bought you a Vday pulse jet...? She is definitely a keeper DR!!.. :wink:

Cool project, although count me one of those that wouldn't mind seeing yet another one of your combustion gun creations.
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Unread postAuthor: Brian the brain » Sun Feb 15, 2009 4:53 am

Without a mini dragster to propell, this is just a very elaborate way of building a lightbulb.A loud one at that. :D

Nice build, I like the high frequenty over bigger pulsejets.This seems more consistent, more jetlike.

Like I said, not much use for it, other than the accomplishment itself, and coolness of it. 8)
You must be thinking of ways to make it more powerful as we speak, or do you plan on upscaling this, like you did with your cannons?

With all that heat development, you could always turn it into an aluminiumsmelt oven. :?
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Unread postAuthor: POLAND_SPUD » Sun Feb 15, 2009 6:03 am

LOL you have a very nice wife
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Unread postAuthor: inonickname » Sun Feb 15, 2009 6:40 am

POLAND_SPUD wrote:LOL you have a very nice wife


Agree, we want your wife's babies! :roll:

I'd love to see a thermometer reading and thrust measurement.. But like what Brian said, why not use it to power a mini forge for small scale precision stuff?
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Unread postAuthor: TurboSuper » Sun Feb 15, 2009 9:16 am

That is awesome! You really gotta measure the thrust, that could be a sweet addition to some various things :D
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Unread postAuthor: Sticky_Tape » Sun Feb 15, 2009 11:39 am

[youtube]http://www.youtube.com/watch?v=J6yzqatuzUk[/youtube]
Fast forward to 1:50 that is one fast rc plane.
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You can tell how awesome a cannon is by the pressure used.
http://www.spudfiles.com/forums/high-pr ... 12803.html
xnt rnm ne z ahtbg
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Unread postAuthor: starman » Sun Feb 15, 2009 12:26 pm

Sticky_Tape wrote:Fast forward to 1:50 that is one fast rc plane.


...and one good RC flyer. To maintain control of that thing at those speeds was a feat unto itself.
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