Original Schmidt Tube

[Andrew Parker]

Has any work been done on perfecting the original Schmidt Tube design? It was a broad straight tube which narrowed slightly as it approached the closed(valved) end. He also used a very difficult to manufacture valve array which did not last very long. When Argus was given the task to manufacture Schmidt's pulse-jet, they created an entirely new design. IIRC, Schmidt was convinced that his original design was achieving detonation, but his research was not accepted. The claims and counter claims between Schmidt and the Argus engineers makes for some interesting reading. Unfortunately, I don't remember where my copy is and I don't remember the title. I was reminded of it after the mention, lately, of the low tech detonation tubes and the Argus reproductions.


Andrew Parker

[Viv]

If you find them and it is in english i would love to read them Andrew.

I have all ways felt the Schmidt tube wa s a completly differant engine, you can see it is trying to be a PDE.

Diedricht (spelling) did the production engineering on the Argus engine and I would say it is not a Schmidt engine anymore!

The Argus is a completly differant animal and we should list it as such.

Viv

[Bruno Ogorelec]

This is what the original Schmidt tube looked like in section.

Bruno

[Viv]

This is what the original Schmidt tube looked like in section.

Bruno

Is that it! come on Bruno I say something completely contentious and all you can manage is a mild little picture? not even a small rebuke.

I was expecting a tirade at least, a comment accusing me of talking out of my hat! but no just a rather mild "heres a picture of a Schmidt tube"

Gone are the days when even the merest mention of any thing more complex than a box of matches to start a pulse jet would have had you frothing at the mouth.

Whats up mate you been smoking some of Marks wacky backy?

Viv:-)

[Bruce]

It is interesting to note that Tharatt experimented with engines very similar to the Schmidt tube but didn't seem to consider them any better or worse than the more traditional layouts.

I think the bottom line is that the "propulsive duct" doesn't differ much in thrust or TSFC regardless of how you shape it (within reason). Although there are some small benefits to be gained from providing some post-combustion confinement of the burning air/fuel charge (by way of using a smaller tailpipe/larger combustion chamber), this is offset to a greater or lesser degree by other factors.

It's pretty much accepted that what Schmidt observed was not a detonation but a form of radially propogating flame-front with multiple points of ignition.

[Viv]

From the point of vuew of DDT it is a differant story the taper works to accelerate the flame front, but as with all PDEs it is totaly dependant on the f/a ratio.

Get it wrong and it will fizzle.

Viv

[Bruno Ogorelec]

Viv,

Alas, no new weed is involved.

I'm just older and wiser now. Also, the ugly stuff that's found its way into the forum since my fiery debates has left a sour taste in my mouth. I am no longer that strongly interested in a debate actually yielding a result.

I am no longer strongly troubled to see people not thinking straight. As far as I'm concerned, they can think a pulsejet will be better if fired by powdered escargot and ignited by a conduit to the ozone layer.

These days, I conduct most of my discussions off forum anyway.

Further, I have been cured of the illusion that one of my concepts will be developed into a practical machine by some enthusiast on the forum. I will apparently have to do it myself. As I can do absolutely nothing about it at the moment -- it will take me a few years -- the urgency of my drive has lessened a lot. It's all become just another goddamn hobby.

That's where all the mildness is coming from.

Bruno

[Viv]

So how do you propose to support this conduit all the way up to the ozone layer?

Will it have to be timed?

and what is the calorific value of powdered escargot? do you think it better than say granulated escargot?

Viv

[Bruno Ogorelec]

>So how do you propose to support this conduit all the way up to the ozone layer?

With an escargot-powered UAV, of course.

>Will it have to be timed?

No. I have quit the idea of timing ever since my early youth, when I overheard a wise man pronounce, "Time flies!" The idea, coming from a sage, excited me very much and I spent weeks running after flies with a stopwatch in my hand. It proved completely fruitless.

> and what is the calorific value of powdered escargot? do you think it better than say granulated escargot?

Powdered escargot (if soaked in saltpeter before drying and powdering) will work if compressed into a solid pellet. If granulated, will give uneven, surging combustion due to air pockets in the granulate and may blow up your engine. You need your fuel to be slow. That's the whole point of picking escargot.

Bruno

[Andrew Parker]

If you find them and it is in english i would love to read them Andrew.
Viv

Viv,

I scrounged up my photocopies. They are in English. The articles are titled:

"On the History and Development of the Schmidtrohr," Paul Schmidt, p. 375-399

"Development of the V-1 Pulsejet," Fritz Gosslau, p. 400-418

I do not know the title of the publication. I suspect that it is from an AGARD seminar reviewing aerospace projects from * (World War II) Germany. Perhaps Mark can track it down for us? It was probably from the late forties or early fifties, as the participants were the actual engineers and managers of those projects.


Andrew Parker

[roland2001]

[Mike Everman]

I think I would rather never be near one of those running.