www.pulse-jets.com

My neighbor is gone
Time to test, put a sparkplug in it today, built my mini spark unit, fired the plug, added air, opened the gas and WHAM it went, almost blew the vice it was clamped in off the bench.
I thought, well, if a bang can do that, what happens when it runs, lotta bangs, and it should blow it off the bench ?
Needs a lot of air to run, but when its warm, it will run alone, and I got it to flameout today too. So I guess Im on the right track, and metiz, your right, Its a bit LOUD.
Will try to get the mixture right, kind of hard without a proper jet and an airbleed sys. to tune.
I was thinking, maybe a petrol jet with an airbleed, and try some regular from the gastation.
I just dont know how much vacuum is in the intake on the motor, and I would need to make a venturi for it too, as you want a low pressure area around the jet tube.
I will make the intake a bit larger, and make the venturi the same size the intake tube is now, so It wont get starved for air.
You adjust the amount of gas with the jet, and the emulsion tube hole size lets ya bleed air into the gas before it enters the intake, tunable sys. to try on this motor,
Dont know if anyone else has tried this, but it was just something that popped into the empty space on top of my shoulders today.

Turn on the spark, puff of air to pull the gas up the line, and it should run, if not, tune the jets and the airbleed. Simple. I will try this out, but first in an empty intake tube,
To check how the airbleed oxygenates the out coming gas mixture, Hope the reverse pulses dont push the gas (and fire) back up into the tank . It shouldn't, as the jet tube is sitting in a lowpressure area, and it dosnt care which way the air is blowing. But PJ air has fire with it. Think Ill take this thing somewhere, where if it blows, it wont hurt anybody.
Man, what a long POST.

Good job,
Looks like the combustion chamber could be a couple of centimeters shorter, but it starts easy enough. The problem I encountered with air bleed systems is there is on average about 1 to 2 psi of pressure near the CC. If the system is moved far away from the CC then the intake typically will be misting/wasteing considerable fuel on the outflow. Liquid fueling has a tough set of variables to overcome before it becomes efficient. Let us know how you get along with it.

PyroJoe wrote:Good job,
Looks like the combustion chamber could be a couple of centimeters shorter, but it starts easy enough. The problem I encountered with air bleed systems is there is on average about 1 to 2 psi of pressure near the CC. If the system is moved far away from the CC then the intake typically will be misting/wasteing considerable fuel on the outflow. Liquid fueling has a tough set of variables to overcome before it becomes efficient. Let us know how you get along with it.

Joe, I will keep yall posted,
Ran it today at 5pm. LOL, the neighbor from 800mtrs away came by(a friend of mine), and asked what I was doin today, I said, nothin much, just tryin my PJ motor.
He asked me If I knew of anybody doing land grating today, Hmm, around here? Not that I know of, why ? He said, because I heard something like a land grater 20 min. ago, and was lookin to see who was building a house in the area.
He asked me, whats that ya workin on, My PJ motor I said, Whats that do? Kinda like a Jet Engine, thrust and noise, but Im just testing it.

Can ya crank it up? Sure I said. You know me, lol But stand back, and plug your ears Dude, he said,WHAT, from that little thing? Brrrrr AAAAAAAAAAAMMMMMMM
20sec. went by. Schitt was that loud man. Than he was lookin at it intensely, How the F*ck did that, do that? He called his wife, and asked her if she heard something like what happened an hour ago. ya,she said, who is building, lol, Frank, he has a pipe that carries sound, or something, I dont know what it is, but it looks cool, and it almost blew itself out of the vice its clamped in, come on over, and check it out. His wife came over, and brought a schitt load of beer with her.
Now, I an toasted, GErman beer kicks ass yall, and , no I wont fire my PJ when Im a toasted (Buzzed) to dangerous for a misstake.

Well, time fror me to go, ZZZZZ

Frank

Here's another take, haven't had time to fully compare with Joe's stuff, nor the "Hinote Criteria"...

http://exrocketman.blogspot.fr/2012/05/ ... s-for.html

Read that link three times over the last few weeks. One of the few weak spots is the chamber volume, and the angle into the tailpipe are not well defined.

Aerodynamic valving was not well considered. Trying to discover the best TSFC without adequate throttle range would be difficult IMO.

There was mention of multiple intakes which can hedge the performance somewhat into the blended bodies area.

There was no mention of cold beverages as needed for fire supression and self medication.

PyroJoe wrote:cold beverages as needed for … self medication.

That shows a disgraceful lack of scientific rigour, I'll agree.

Mind you, cold beverages are out for the moment round here, we're having a shitty summer. Turned up at work a week ago, 3°C and sleet. It's hot chocolate and oxy-acetylene weather.

Well, I guess I qualify as a Beginner, as I just started building a PJ Motor not to long ago.
Pyro, I did a motor using your CALIBER Method, added a bit of tuning to the Intake tract, and I now have a lockwood that starts and self sustains with not even a blow of air to it.
I built it, showed you it, and you said I should add a taper to the exhaust entrance, I did that, I tuned the intake as I know how flow works, and the thing just bursts to life in seconds.
https://www.youtube.com/watch?v=nkhv5v5 ... e=youtu.be

A DB test of it for ya.
and a few pics.

Good to hear you got it humming along. That dB meter was extra icing on the cake!

Just to be clear, does tail expansion increase the efficiency of the engine? How much should the intake be flared, and would replacing the exhaust pipe and intake with truncated cones be a bad idea?

Just to be clear, does tail expansion increase the efficiency of the engine?
-From the concepts I have read, a tail expansion helps when the engine is run static. (sitting still)
-When the engine is moving at a fast speed, the expansion is less needed.
-It also helps the pressure in the combustion chamber fall faster in the cycle.

How much should the intake be flared,
-Somewhere between 13% to 25% of the intake diameter

and would replacing the exhaust pipe and intake with truncated cones be a bad idea?
-from my experience I would only use truncated cones on the back 1/2 of the tailpipe.

@ PyroJoe: Thanks, have you done much experimentation with longer cones? I understand most people avoid them because they are more difficult to make than cylinders, especially long ones that have a very shallow slope (the one I was thinking of would have a slope of .05 or less). I noticed that the CC of the FWE is designed differently than most other pulsejets, is there a reason for that?

Yes, I have worked with shallow cones in many configurations. My work typically has revealed the need to maintain the Helmholtz properties of the CC as a chamber and the -inertial pumping- characteristics of a pipe for the tail. But I would recommend anyone to test it and come to their own reasoning.

PyroJoe wrote:Yes, I have worked with shallow cones in many configurations. My work typically has revealed the need to maintain the Helmholtz properties of the CC as a chamber and the -inertial pumping- characteristics of a pipe for the tail. But I would recommend anyone to test it and come to their own reasoning.

Thanks! I'll take your word for it until I get good enough at engine fabrication that it doesn't take me forever to weld one.

Based upon your designs, i designed a pulsejet with 4 intake's, as seen in the image included, after hopefully getting the version underneath working i'll bend the intake pipes to the front. I'm not sure whether this will work if someone could please point out any mistakes that would be very appreciated.
I don't know how i'm gonna make the fueling system but i'll get back to you once i've thought of something.
The volume in the intake tubes is the same as it would be had i used a single tube, they have the same height as a single one would have but a different diameter.
Thanks in advance!
The designs: http://puu.sh/nv0bo/a7d650a37a.png
the file was too big to attach

Sorry for the late reply. It should look similar to this drawing. Thanks, and let us know how it goes