Worlds simplest valveless?

[Graham C. Williams]

SNECMA boys tested that with 19 PJ in the same tuyere... no one PJ runs at the same time than an over.

Dear George.
What a great picture.
As I recall from the SNECMA report (1st symposium of non-steady combustion, Sheffield) they found this configuration worked best with odd numbers of combustors and many times would not work at all with even numbers of combustors.
Graham.

[Mark]

SNECMA boys tested that with 19 PJ in the same tuyere... no one PJ runs at the same time than an over.

Dear George.
What a great picture.
As I recall from the SNECMA report (1st symposium of non-steady combustion, Sheffield) they found this configuration worked best with odd numbers of combustors and many times would not work at all with even numbers of combustors.
Graham.

I have a tall book entitled "First International Symposium on Pulsating Combustion" 1971 Proceedings Edited by D.J. Brown
It took place September 20-23, 1971 University of Sheffield, Sheffield, England.
Fear me! For I have this book. Well, ok, it's just another book. Perhaps like rocketry, there is little new under the sun. Yet perhaps, for the tinkerer, creativity and exotic applications abound. Why just a day ago I read a sales pitch for a pulsejet, it was being pitched on Ebay as a way to break your lease agreement.
Mark

[Graham C. Williams]

Dear mark.
You on the weed again?
Graham.

[Bruno Ogorelec]

Dear all.
First you have to ask yourself 'what type of pulse combustor you want to make'? Kentfield separates the high load from the low load.

An interesting point. However, he also makes a case for the Ecrevisse/Lockwood layout both as low-load and high-load engine. I think you can use most pulsejets in both 'modes' but they have to be tuned specifically for one role or the other. Pusshing the loading up involves harnessing as much of the resonance possibilities as possible. Tuning a high-load engine appears to be fraught with problems, as each increment of power brings its own problems with it. At some point, the exercise becomes self-defeating. That's how I interpret the often cryptic and oblique references to success I find in the research papers.

As for the point you made in a later posting -- even and odd number of engines -- the problem is probably in the tendency of pairs to tend towards coupled operation. In order for that to succeed, they have to be tuned to do so. an untuned pair will often just refuse to work.

Having an odd number of engines may well be much easier because they will behave in the opposite manner. They will fight attempts at coupling. I am almost absolutely certain that three or five engines will always fire separately, out of wavelength-imposed sequence, catching the resonance only by accident, at random intervals and very briefly.

However, with a large number of engines, the point may become moot.

Long ago, I proposed that the best way to pair the engines would not be to use two, but four, in the configuration old motorcycle buffs will recognize as 'Square Four'. The four occupy the corners of a square and fire together in diagonal pairs, A and C together, followed by B-D and back to A-C. This will do much to average out the differences among individual pulses, which must be the bigbear of paired pulsejets. also, firing in diagonal pairs will eliminate the rocking couple and make the engine vibrate only in the fore-and-aft line, making it very easy to mount it in a shock-absorbing way.

[Graham C. Williams]

Dear Bruno.
Perhaps Mark would be good enough to supply us with the exact findings of the French Team?
Graham

[Bruno Ogorelec]

For ‘Pusshing’, read ‘pushing’, of course. And ‘bigbear’ is ‘bugbear’. I must be more excited than usual…

[Mark]

Dear mark.
You on the weed again?
Graham.

Weed? I'm on life on planet earth. That's pretty much a weed in and of itself. Any ideas how we got here? All these orbital positions, all these stars in the sky. Just where are we? Who decided to include our great minds in this big picture? I say it is a trick. A million years from now, what will mankind realize? How much are we allowed to know? How many brains has the Creator invited to the party? Imagine the suffering, the animals that killed people today, the people that killed animals today, what love on a grand scale! Weed wouldn't put a dent in these feelings. Life forms on planet earth are red in tooth and claw. Pulsejets are but a diversion. As Mark Twain says, it's killing all down the line.
Mark

[Mike Everman]

Trippy, dude.

[Mark]

Trippy, dude.

6 months is the average time an employee lasts at a slaughter yard. I am thinking the experience somehow damages these workers, as does soldiers who kill, it must take awhile to assimilate it all. CNN did an interesting documentary on how hard it is for those that have to see and do things we would rather not.
To me it's funny, we like to view action movies and yet, I doubt any of us would be thrilled to see someone die dramatically in real life. It's not really something most would enjoy. The horror...
Mark

[Mark]

Dear Bruno.
Perhaps Mark would be good enough to supply us with the exact findings of the French Team?
Graham

I swear I don't have anything more on the French, all I know is what you know: Marconet, the escopette, the ecrevisse, and the escargot.
How much more can we mine on pulsejets really?
Mark

[Bruno Ogorelec]

I swear I don't have anything more on the French, all I know is what you know: Marconet, the escopette, the ecrevisse, and the escargot. How much more can we mine on pulsejets really?

Well, I am surprised at how much new turned up in the last six months, given that I have been collecting this stuff for years. There seems to be an inexhaustible supply. But, not many saw full-scale development of the type given to Escopette, Ecrevisse and Lockwood. A lot of them were conceived, tested briefly and abandoned -- whether they seemed to offer potential for more or not -- because the times were against it.

Look at the Argus valveless. They were at it full tilt when orders came from the War Ministry to concentrate on a valved design along Schmidt lines. In the Third Reich, when the War Ministry said 'jump' you asked 'how high?'. You didn't think twice.

Time and again, I have seen similar stories. Development is a long and expensive process. Companies do not exist to make interesting things, but to make profit. If money is to be made in making baby cots, a company turns to baby cots, rather than persisting in a quixotic project of a jet engine that no one else seems to be interested in.

To my mind, engines like the Saunders Roe, Argus, Reynst etc. etc. deserve attention as candidates for development. What I am afraid, however, is that they are not going to be developed today, either. The whole field is just too black magicky for serious money to become interested. Scaling down turbojets seems like a much safer bet to the people who have to make decisions on allotment of serious money.

[Psignorian]

This says to me that the R&D for future pulsejet-kind is up to us. That's a scary thought. o.O

[Mike Everman]

OH, no not scary at all! It means there is little competition with those of the deep pockets... Any tremendous out of the box breakthrough is yours without fear that a thinktank at GE is already there or working on it. Yes, it's black art, but an art you can optimize in your garage, unlike nanotech or DNA research. These engines are beatifully organic, they breathe, they consume, they shout out to the heavens, each is the seed for the next...

[George]

Hi guys !

News from France: i've scanned and give to Bruno all the SNECMA documents i have, i think he would better than me find inside what could interrest all of you !


here's the Ecrevisse A original plan for X-mass:

[Bruno Ogorelec]

Ah, what great massage for my ego! what a beautiful present for Christmas, too!

OK, I promise to try to digest everything and make it available to everyone interested.

George, a sincere thank you on behalf of the entire forum. You have contributed priceless stuff.