No-weld pipe fitting valveless

[steve]

you could try a bigger flare on the intake, maybe.

I would love to see that thing glowing!

[Mike Everman]

Oh, it'll glow, I'm almost there. the nipples I used needed a lot of grinding out. They are smooth now, but I didn't get to try it. Odd, Mark, but I reaaaally grunted this thing together, ran it yesterday, and today I could take it apart by hand. I think I just learned to tighten it up again after some hotness.

I'll try again soon. One thing that might have been hurting it beyond this loosening and what must be resulting leakiness, is that the paint was burning on the tailpipe, and that smoke was going in the intake, perhaps choking it with ick. I'll lay it down next time.

Mark, did you preserve the 29" dimension with your oh so out of spec long CC?

[Mark]

Mike,
For my tail I have a 24" pipe, the combustion chamber is way off because I don't have a smaller one, from tip of bell to tip of bell is a whopping 9 1/4". And my intake is too long too, I'm using a 5 1/2" piece.
I tried an 18 inch exhaust pipe for the heck of it and there was not enough confinement to get it to rev/run with forced air with that proportion. Then I tried a shorter snorkel. I think the combustion chamber is just too big. I meant to pick one up yesterday but forgot, but I did get some propane and I am dwelling on using this regulator on my tank to better control or modulate the gas pressure.
Fear not, I will get there, and I think I have some 1 inch elbows so I will be right behind you when you get your Lockwood Pipewood running.
Funny, with this new propane tank I have, you can turn the gas knob on and nothing comes out, in fact I was startled to find it wasn't even screwed tight when I got it home. I guess these new ones activate only after you screw your fitting into them. All new to me.
I only had some fatter gas fuel line going into the snorkel, some 1/4 inch stuff and it wasn't bent to lay smooth against the walls, and that too may have interfered with the resonance a bit. I will get some of my thin copper tubing and use that next time. As it was, with air compressor air fed in about two inches from the intake, it sounded every bit a pulsejet, but alas I couldn't wean it off the air. Little dimensional changes mean a lot with these valveless designs.
It took me a long time to find a window of opportunity for my two Logans, and I didn't have any plans. I just felt my way around in the dark. One small thing, I don't think it matters much, but I am using 2 different kinds of bells, one is rounded like your bells and the other a more streamline neck.
Mark

[Mike Everman]

OK, it runs in the bent configuration with a 1.5" pipe that replaces the expander section, simulating the first linear, but bent. The two 90's seem not to effect it. Turns out my fueling isn't quite right, and I keep having to go back to the bent back and flattened stinger, manually and randomly positioned. (have I qualified that enough?) I'm not going any further until this fueling is reliable. Then I'll put the expansion back on and get some thrust data with and without, for kicks.

[pezman]

I tossed together two of these -- one with a 1" diameter chamber and another with a 2" diameter chamber. Both worked reasonably well. The 1-incher didn't seem to generate much thrust. The 2-incher occasionally roared very nicely.

The only problem that I had was that I was using a 1# propane tank and feeding propane at a rate that would make it run made for lots of frost, which eventually messed up the fueling situation.

This is a neat design. I think that I'll try to knock together a pair of these, put 90's on the intakes and point them at each other to see if they synchronize and generate any compression.

I also discovered that the Wal-Mart cocktail shaker has the right dimensions to make one of these puppies. I hope to have a weld-less, stainless version of this engine soon.

[Mark]

Mike, it would be funny to go even farther and do a 360 loop. You are the Pipe Master now. I wish I had a fuel stinger hooked up to a microscope fine and fast focus knobs of some sort, so that I could feed it in and out and not have to hassel with hose clamps and wacky arrangements. It's bad enough having such a funny looking jet, let alone one draped in a nightmare of time consuming adjustment features.
Mark

[Mike Everman]

Cool, Pez! What did you do for injector and where? Mine seems to like the fuel jet to point at the inside of the front "dome" somewhere near the intake. Once it was very hot, it would run with a simple 3/16" brake line tube from the side, but throttlability was poor.

Pictures?

[pezman]

Ok, I'll post evidence as soon as I get the new and improved version done.

For the trial run, I just used a stinger made from a flexi-spout salvged from an old pump-oiler and throttled using the valve on an old torch that I had hacked up. The valve and nozzle were spliced together using a short length of pneumatic hose. I just probed around a bit to see if I could find a sweet spot -- and on the 2"-er I occasionally found some really sweet spots. The 1"er ran, but it was kind of feeble thrust-wise. Ignition was accomplished using a MAPP torch as a "pilot", so no spark plugs.

I think that the nozzle on the stinger might be a little large. The whole system would get so cold that the fuel pressure really dropped and that spoiled the ram-air effect of the stinger, caused fuel leaks etc. I'm hoping to put togther a fancier valve and tubing system over the next few days, w/ 1/4" copper tubing wrapped around the jet for heating the propane (and cooling the jet) and using my 0.6mm nozzles for fuel delivery.

[Mike Everman]

I'll draw it up when I get a minute, but some detail on the folded design (which runs quite strong) is this:

The 1" elbows turn out to be about an equivalent linear run of 2.75"
Use two 1" nipples, 2" long. Tighten until 1" of the nipples are exposed (so the threads engage .5"; this seems typical of all of the tapered thread joints).

You then can add a 1" pipe, threaded at one end and 15.6 long over all.

If you do the expander tail, the 1.5" tailpipe, 12" long over-all is close enough, and you need another 2" long nipple and a reducer.

[Bruno Ogorelec]

I think that I'll try to knock together a pair of these, put 90's on the intakes and point them at each other to see if they synchronize and generate any compression.

Mike, it would be funny to go even farther and do a 360 loop.

Yes and no.

You can easily (well, relatively easily) do that with a valve-type engine. The valveless is trickier because it blows back through the intake. So, one engine would suck in what the other would blow out. No fresh air would get in and the engine would die.

Have you seen the sketches of the paired engines that J.A.C. Kentfield did? See the complication he went to? The reason is to divorce the gas flow from the pressure wave.

On the intake side, you want the blast to get from one pipe to the other, so that it helps pump fresh air, but you want hot gas to get out of the loop and generate thrust. So, a trick is needed to separate the two.

[Mark]

One thing fun to try would be to have the intake and 360 loop exhaust end meet, but slightly off center and gapped so that some of the exhaust might go back into sustaining and energizing the circulation.
Mark
PS Remember there have been several 360 looped valveless engines done in the past, and a few posted on Ken's site here. I don't think the engine minds too much as long as the distance covered is the same as if it were stretched out. I don't think anyone in the forum has done it yet though.
As for a 360 regenerative effect, I have a vague idea but must head off to work now.

[Mark]

I remember in Foa's book "Elements of Flight Propulsion" there are some wave engines that seem kind of interesting but more complex than I would want, I would like to avoid the moving parts . But they do use the 360 looped effect to pump energy back into the system.
Mark

[Mike Everman]

It's only 17" long now. A 360 would make it almost all fittings. Haa ha. Right now it's a nice compact leaf blower. I think this will be the powerplant for my Turbo 3000 bicycle. ;-)

[Mark]

There was a band here in Pensacola with a funny name. The band's name was: "This Bike is a Pipebomb." Maybe you could design a plumbing pipe bicycle frame and start a band entitled: "This Bike is a Pulsejet." I like the idea of using the structure/frame of the bike for the pulsejet, a dual purpose bike with hotdog cooking capability.
Mark
http://www.punknews.org/reviews.php?op= ... ew&id=3577

[Mike Everman]

Yeah, you could cook yer buns on it too. ha ha