Worlds simplest valveless?

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Mike Everman
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Post by Mike Everman » Tue Dec 02, 2003 9:32 pm

Oh, if it's the latter, that's what I'm going to build!
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hinote
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Post by hinote » Tue Dec 02, 2003 9:39 pm

Mike Everman wrote:Which baflles you? The more I look at the unequal, the more I like it. Perhaps the exhausts are offset just the right amount for thier pulses to be in phase with each other? Wouldn't doubled pressure waves on a single engine make potential for a big augmenter throat?
I have a much more mundane theory:

I think the combustion chamber nestles into the smaller diameter at the front of the megaphone better--the total package has the least frontal area when it's bent there.

Must be something--even the Enics drone engine is bent like that.

Bill H.
Acoustic Propulsion Concepts, Inc.

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Post by Pieter van Boven » Tue Dec 02, 2003 9:51 pm

I don't know, but knowing how this GS-1 looks it could have something to do with these few words I reffered to.

"Un nouveau developpement dans le domaine des pulsos a haut vitesse fut alors entrepis sous la direction de l'ingenieur Pierre Servanty. Cette machine comportait mettant a profit des proprietes connues des ondes de choc. Des essais au banc avec ce type de pulso de 60 kg de poussee permirent de realiser 0,85m
Ce propulseur pesant 14kg
etait equivalent a un moteur conventionnel de 300 cv. Malgre une grande avance dans cette nouvelle technique, la snecma a du abandonner les travaux par manque de credits."

probably I am wrong, maybe not..
To be honest, my french is to bad to understand this piece of information. :)

Pieter.

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Post by Bruno Ogorelec » Tue Dec 02, 2003 10:50 pm

Pieter van Boven wrote:To be honest, my french is to bad to understand this piece of information.
Pieter, my French is probably even worse -- I can only really understand the words pertaining to matters erotic. Still, I think I have discovered the meaning of the crucial words here.

The text says, "Des essais au banc avec ce type de pulso de 60 kg de poussee permirent de realiser 0,85m. Ce propulseur pesant 14kg
etait equivalent a un moteur conventionnel de 300 cv."

What it means is that 60 kg thrust was measured on the stand, with the engine weighing 14 kg. The thrust equals the power output of 300 HP of a conventional engine. It permits the attainment of Mach 0.85. The 'm' should have been written as 'M'.

I have learned from other sources that a specially streamlined Escopette engine has indeed atatined the speed of Mach 0.85 -- probably powering a drone.

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Lift vs. speed

Post by Bruno Ogorelec » Tue Dec 02, 2003 11:27 pm

This discussion has prompted me to review an exchange of opinion and information with a man who used to frequent the forum often but has long since dropped from sight – Milisavljevic. Months ago, we talked a lot about Escopette, Ecrevisse and Lockwood and he seemed to be of the opinion that the Escopette was suited for relatively higher speeds – meaning flight -- while the Ecrevisse and Lockwood performed better at low speed, implying lift. He was fascinated by the Lockwood engine that is the least conspicuously present in the public reference sources – the big lifter the company thought would be used in the VTOL ‘sled’. Looks like Bertin and Servanty eventually had similar thoughts about Ecrevisse, even though its early days were devoted to the pursuit of speed in various streamlined configurations.

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Lift vs. speed

Post by milisavljevic » Wed Dec 03, 2003 4:50 am

DELETED.
Last edited by milisavljevic on Wed Aug 18, 2004 8:31 pm, edited 1 time in total.

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Post by Mike Everman » Wed Dec 03, 2003 5:48 am

Milisavljevic,
Ah, what could be better than juicy, copious detail! Thank you for chiming in.
In what form is your predictive model? I'd be fascinated to see. I've been using excel and I've created one that tells you how far to smash a tube to change the area to a desired amount (see the first design on this thread, also an n-intake and rectantular construction converter. All allow you to select which of the two engines from the Kentfield paper you want to emulate, single or four-pipe. With areas and surface/volume reporting. There is no corrections for scaling, unfortunately; I have no good data for a first cut on that, but you can specify a 4" Kentfield and it will give you all the dimensions to use. I am assuming that some lengths would be proportionately less as the scale diminishes, but I'm just guessing. Any data or knowledge for scaling corrections? Everyone wants a smallish valveless, I'd like for my utility to do a good job at dimensions.
I am very interested in the dimensions of this SNECMA Ecrevisse. The more I look at the design, the more I like it. For a simple engine, there is a lot going on, things that Lockwood should have adopted but didn't. It's the best architecture, I want to build one (but a bit smaller). :-D
Mike
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Post by Mark » Wed Dec 03, 2003 3:27 pm

George wrote:Re hy!

Trying to send more photos of the écrevisse:
It would make a nice picture for a pulsejet calendar. It looks life-like almost and it must have been interesting to watch it hover around on its leash, I swear it looks like it is trying to find/sense a way to escape the building or stay out of the reach of the people below; it brings to mind the children's movie, The Red Balloon.
Mark

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Post by Pieter van Boven » Wed Dec 03, 2003 5:29 pm

Milisavljevic, I would realy like to receive the dimensions of the SNECMA "Ecrivisse".
Thanks in advance,

Pieter.

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SNECMA PJ

Post by George » Thu Dec 04, 2003 2:36 pm

Hello !

There is that i have for all the SNECMA PJ, informations taken in SNECMA documents (see excel file).

The ecrevisse i shown is a C type, unfortunately i have no plans for it.

But i have the plans of the A and B types, soon on line... if Bruno do not kill me before !
Attachments
Snecma prod.xls
(15.5 KiB) Downloaded 317 times

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Post by Mike Everman » Thu Dec 04, 2003 5:50 pm

I can't wait to take a look, George, thanks. I only have a moment, and this is the "world's simplest valveless thread, after all so here's one I'd like to make in the hydroforming rig I'm making. I may change it to the ecrevesse style in the VTOL picture; would make this even simpler. Just need proper proportions.
Attachments
kentfield proportional 2-pipe, diverted.jpg
kentfield proportional 2-pipe, diverted.jpg (20.74 KiB) Viewed 7063 times
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Post by Viv » Thu Dec 04, 2003 10:54 pm

Mike Everman wrote:I can't wait to take a look, George, thanks. I only have a moment, and this is the "world's simplest valveless thread, after all so here's one I'd like to make in the hydroforming rig I'm making. I may change it to the ecrevesse style in the VTOL picture; would make this even simpler. Just need proper proportions.
*!!!!! * * *,,, *! I wish I had thaught of that one:-(

Bastard bastard bastard,,, bastard!

Viv
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Monsieur le commentaire

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Post by Viv » Thu Dec 04, 2003 11:05 pm

Viv wrote:
Mike Everman wrote:I can't wait to take a look, George, thanks. I only have a moment, and this is the "world's simplest valveless thread, after all so here's one I'd like to make in the hydroforming rig I'm making. I may change it to the ecrevesse style in the VTOL picture; would make this even simpler. Just need proper proportions.
*!!!!! * * *,,, *! I wish I had thaught of that one:-(

Bastard bastard bastard,,, bastard!

Viv
Well fucking hell! I didn't know the forum edited out "*", so whats wrong with the anglo saxon "*", were I come from thats almost a term of endearment:-)

Glad to see "bastard" made it through, on a lighter note I lived up in Nottingham for a while and you just cant use the B word up there.

I coudn't work out why i was upsetting people untill a friend took me off to one side and explained!

Around Oxford if you call some one the B word you are just being friendly! "how are ya you old bastard" for instance!

In Nottinghamshire they take it a little more literally it seems:-(

Viv
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Monsieur le commentaire

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words and meanings

Post by Nick » Thu Dec 04, 2003 11:27 pm

words can catch you out!, as a teenager and im sure all UK smokers or ex smokers will recall cigarettes had many names in the late 70's all quite acceptable and recognizable.
Image the my confusion and the consternation of Friends from the US and Canada whom i met when whilst on a working holday in Luxumbourg when i by way of simple curtusy when lighting one up would ask if they "....wanted a FAG!!!".
someone realised what the problem was and thereafter i refered to fags as cigarettes!!!!. :)

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Post by Bruno Ogorelec » Thu Dec 04, 2003 11:36 pm

Reminds me of the Herman's Hermits song of the 1960s, 'No Milk Today'. A big hit in its day. Anyway, there's a line in the lyrics, saying "The company was gay/we turn'd night into day". Just a couple of decades later, it meant something completely different.

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