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Mike Everman wrote:Then there's one where I got concerned that the tail throat region would just melt, but had a nice length reduction as a feature...

Gary Robinson and I tried that one some years ago. It ran very poorly. Seems that having the exhaust throat close to chamber bottom doesn't really work.

But, it sure looked impressive...

Well that got this forum working really well ,

lots of input ,some positive, some negative and some really brilliant ideas.

Guess im just going to have to build something along these lines and see what happens , will keep you all informed, be it a failure or a success (but dont hold your breath)

thanks to all of you for your replies.

If you want a really easy manufacturing process for the 'cap' for an experimental pattern of this kind of pulse jet - have a look at used oil filter bodies.
I have been collecting them for my scrap bin - others see scrap I see
Pulse Jets ( apparently quite a common affliction ). Anyway can you spot
the candidate for a Renyst makeover?

Hey great idea , although they are very thin steel and wont last long,

your idea provoked another idea

almost all vehicles, prior to the spin on filters had cartridge filters , these were mounted in cans that are of heavier gauge steel and some are very pulse jet cc shaped and even have the hole for the sparkplug ready made

great stuff

Mike Everman wrote:Then there's one where I got concerned that the tail throat region would just melt, but had a nice length reduction as a feature...

Reminds me of one of mine from way back on the old forum, which see.

L Cottrill

yeah, there it is, Larry. I think the teardrop/flare section at the tail throat is essential, but whose to say...

Hi all - just playing about in the garage - not really serious - just having fun.Just mostly getting my fabrication skills honed.
Putting the fuel and air in from the front really didn't get anything into the chamber - it basically just flowed around and then out the other side. I could have used mutliple fuel pipes etc - but I think it would have done the same.The Argus engineers had sort of a deflector dome thingy that guided the flow into the combustion chamber.Anyway I then decided to place the fuel and air in where the spark plug would normally go - made up a really gumby injector and tried that.Really easy to get some decent
bangs but that was about it. Really hard to get it to rumble ( flame off the injector etc) - and when I got that - adjustment of the outer intake and fuel postion only got a slight buzzing of resonance.
However the interesting thing was that it occasionally did sustained really slow motion pulsation of about 1 second duration cycles.Really funny to watch and more like pretend detonation ( "Bang") rather than the ("boomph" ) of pulsation.
This effort was really to see if the oil filter bodies could "hack" it.

Yo man, i'm trying to find Mike E's gouger, in this instance it might be just what you need? Who knows! This thing is crazy!
With these designs I feel strange trying to get around the fact when sliding the dome forward or backward, not only are you changing CC volume quite rapidly, but also your intake length. I like what your doing man good work!

GOT IT!
http://www.pulse-jets.com/phpbb2/download.php?id=8809

Hey jutte
that really is great , im going to go to the maintenance shop and see if they will give me some old filters

your comment about the gas coming out of the other side really excited me , im more convinced than ever that we need a circular tube manifold,

This may be no more than a piece of copper plumbing pipe with at least 4 small rocscoe style injetors probably 6 would be better , all this could be silver soldered at this stage ,

It would look something like a spider with a big hole in the centre of its body

They would need to be calibrated to give equal flame , this can be done in the back yard at night , by just pinching them a little its quite east to get two equal flames , 6 would be harder but im sure doable.

Its getting dark here right now , ill post a video of a couple of double d

anyway great job ,

I haven't tried this yet;

weld a small steel tube on the side of the exhaust at an angle towards the exit. Try using shop air, it should pull air into the intake.

Hagen

Ok heres a vid
these are kinda modified double d , a bit too much spread, but lots of entrained air,

hell looking at the vid, i ask myself is that really what i need ?

more confused than ever

anyone like to comment ?

thats the neighbours dog barking at the end , they hate me, so does the dog , especially after the solid fuel rocket episode but thats another story

I think everyone forgot my concentric PJ.

http://www.pulse-jets.com/phpbb2/viewto ... concentric


Check it out let me know what you think.

Cheers.

Here is a drawing.

http://www.pulse-jets.com/phpbb2/viewtopic.php?t=2572

Hi Hagen,
Nice engine - did you ever find out how much thrust it was making?

Hi Jutte,

It was only putting out a few pounds of thrust. I haven't tinkered with it very much and I'm sure there are alot of areas that I could impove upon. The interesting thing for me is when I first had a good run I was using very little fuel, but it was very hard to start with my old set up. I unfortunatly didn't have a way to measure thrust or fuel consumption at the time, and it had a very narrow range of throttle.

When I shorten the intake and exhaust it ran like a standard PJ and I could give it large amounts of fuel ect...

I need to get it running again back the old way so I can do more measurements.

If you read the posts you will see a picture of the CC only barely glowing, and this was after a few minutes of running. That really interested me, because it goes against all the other PJ's ever made (I think).

If you try to do something simular, make sure if you are using screws to hold the intake to the exhaust that you have to somehow make sure the screws can't back them selves out. It would be a good idea to use stainless for the exhaust because the tip is in the CC and does not get any real cooling.