Simple Conduit Engine

[vturbine]

Well, it works out to almost exactly substituting 1/2" conduit for the inlet, 1-1/2" conduit for the CC, and 3/4" conduit for the tailpipe in Mike Everman's Ugly stick, with NO changes to lengths. This seems hard to believe. I may just have to build another non-functional engine to make sure

Here's what it looks like in numbers:

[PyroJoe]

It is interesting to compare the similarity of engines with each other, based on lengths.

[vturbine]

Very interesting, Joe!

Are these individually adjusted in scale in some way, or are they all shown at a fixed scale?

It looks like the baseline for all is the forward edge of the combustion chamber. Are the other lines averaged distances for other important junctions of the engines?

Are these all engines you have built, or are they just ones that you have found specs for?

[PyroJoe]

Most have been (fixed) scaled up or down to match lengths from the front of the CC to the end of the tail. The tail cone expansion line (red) was mostly derived from the Laird Chinese, and the Lockwood. Other engines matched well when brought in, The Raptor was a good one. Annes tail fit well. Erics engines hit pretty close to the lines. A couple are stripped from mystery motor images without given dimensions (the skewed ones), but all are known to run engines.

I noticed metiz last thermo type engine was good on length and the CC fit almost dead on, but his tail expansion started very much forward of the expansion line. He was willing to try shifting it back and it seems to be doing well. It is the last, but not least on the line-up. Some seem to be to long to fit well.

[vturbine]

The CC lengths agree very well, but intake lengths look pretty ragged. On the linears, I mean.

Do you have a list of these engines from top to bottom?

I wonder where my conduit duds fit in?

PS Has anyone else noticed that an engine that doesn't run uses more propane than one that does? How is that possible?

Where did that bottle go.....?

[PyroJoe]

At work, so I had to put this together mostly from (bit rotted) memory & not to be trusted as whole wheat. ha


Valved engine patterned from Eric B. valved PJ calculator

Midway redesigned tail

Midway

One of Eric B. engines

unknown

mystery engine stripped from a image

IAME Escopeta

I think this was one of Eric B. engines

Mini-Kentfield (mini kenny) (stripped from image)

Lockwood

Raptor

Chinese

Lady Anne

Pocket Jet

Dyna Jet (valved)

Thunderchine

M26 --- Bill Hinote

M1E --Bill H.

mini-Escopette ---Bill H.

Metiz--- Thermonese

[vturbine]

Thanks! That gives me a whole lot more lookups to read about!

Now for the EMT duds. Here are some "starting" moments captured on video for your viewing and audio pleasure of the Version 2 conduit engine. I had the camera handy today, so here's one where I just used a rosscojector snip tip on 3/32" copper pipe.

Notice the high pitched howling mode early on -- that's due, I believe, to a 7/64" hole I drilled in the lower outer corner of the CC while trying a radial injection. It was still open for this video. So the pulsejet is acting like it has two inlets. I've been able to sustain this mode very easily other times -- this time I kind of fumbled around with the injector. I do wonder if this kind of resonance can be used for something.

Moving on, and lowering the injector, we get to some other modes, the motorboat mode, and bang bang mode, which happens as the injector is brought toward the mouth of the inlet. Bang Bang mode usually puts out the injector sooner or later. It seems like backfiring out the inlet.

Motorboat mode is pretty stable until the engine heats. I can throttle it quite a bit, as you can hear. To keep it going I usually have to move the injector down as the temps rise.

Finally the resonance stops, and I think I'm in blowtorch mode, I try to pull the injector further down, and it pops out the mouth.

In later tries with this engine, I tried it with the injector centered (instead of against the edge of the inlet) and with the injector just inside to just outside the inlet mouth. This created other exciting modes, but always, sooner or later the injector got popped out (as in bang). I'll have to get that on video some time.

One thing I noticed in this video -- some plume at the inlet. I couldn't see that from where I was standing above the pulsejet. So it looks like it is almost running? But no glowing metal, of course.

http://www.youtube.com/watch?v=5bGIqZ-JPNg