Proposed Design - The Short Lady Revealed

Moderator: Mike Everman

Re: Proposed Design - The Short Lady Revealed

Postby larry cottrill » Sat Sep 18, 2004 10:39 pm

steve wrote:Of course I would be interested!

the sheet metal I am using is about .037 inches thick mild steel (sorry, no stainless!) I can weld them together if you want me to, I'll probably tack weld them anyway so they hold their shape.

total weight at the moment is 22.7 oz.

That sounds excellent for thickness; I'd opt for the tack welded form. Sounds like the finished weight won't be too bad, actually.

Figure out the costs [don't forget the shipping!], what form of payment you want, and and when you think you can fabricate, and email me with the info and your address, etc. When you've got them ready, you should be able to ship by ordinary postal mail if you pack them well, or use UPS or FedEx if you like.

Thanks!

Just got back from the Promise Keeper's conference in Des Moines, where I've been last evening and all day today. Otherwise, I'd have replied sooner. About 12,500 guys, I guess.

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Re: Proposed Design - The Short Lady Revealed

Postby steve » Sat Sep 18, 2004 11:25 pm

OK sounds good. I'll worry about the shipping, fabricating etc after I get mine running. (please let it work please let it work please let it work please let it work please let it work!!!!!!!!!!!!!!!!)

anyway, I just measured the ID on the so-called 3/4" conduit and discovered it is 2mm too wide. Do you think I should try to roll a sheet metal version to the correct dimentions or am I being too anal-retentive again?

We should probably come up with a better name for this thing then "the short lady" how about the steve-O-dyne? just kidding ;-)
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Re: Proposed Design - The Short Lady Revealed

Postby larry cottrill » Sun Sep 19, 2004 3:37 am

steve wrote:... I just measured the ID on the so-called 3/4" conduit and discovered it is 2mm too wide. Do you think I should try to roll a sheet metal version to the correct dimensions or am I being too anal-retentive again?

Don't worry about it. That's my fault, for not making a new measurement of it and just going from memory. Rats! Anyway, the important thing is just getting the centerline lengths of the two segments right. Just go from that with the conduit, and I'll try to correct the drawing sometime soon.

We should probably come up with a better name for this thing then "the short lady" how about the steve-O-dyne? just kidding ;-)
My trade name for marketing was going to be Reynstodyne Fokus(TM); generically I call it the 'focused wave valveless pulsejet', as on the drawing. If you ever want to manufacture them under license, you can call yours whatever you want, and pay me 5% of wholesale or 10% of retail per unit sold ;-)

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Re: Proposed Design - The Short Lady Revealed

Postby Bruno Ogorelec » Sun Sep 19, 2004 11:43 am

I was wondering; why 'Reynstodyne'? To me it does not look like owing a particular debt to F. H. Reynst's designs. To my historian's eye, it looks like belonging to the family of 'sidewinders', together with the Logan, the NRL, the Thermojet etc.
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Re: Proposed Design - The Short Lady Revealed

Postby Mike Everman » Sun Sep 19, 2004 4:42 pm

I agree, the Reynst is a two hole breather, but no exhaust comes out the intake. I think that should be the criteria for something with Reynst heritage... Though it's the source of great pleasure when Larry adds 'odyne and TM to his developments. LOL
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Re: Proposed Design - The Short Lady Revealed

Postby Bruno Ogorelec » Sun Sep 19, 2004 4:54 pm

Mike Everman wrote:it's the source of great pleasure when Larry adds 'odyne and TM to his developments. LOL


Yes, it sure is. Never fails to raise a chuckle.
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Re: Proposed Design - The Short Lady Revealed

Postby steve » Sun Sep 19, 2004 4:59 pm

I just made my own intake diagram with the revised ID of 21mm and the walls of the conduit shown to scale.

Do you see any problems with the slight changes?

BTW do you know what the small angle at the end is supposed to be? Is it critical or could It just be cut parallel with the centerline of the CC? I'm asking because the revised ID threw it off slightly.

the dimention lines became fuzzy when I converted to .jpeg, I could post a bitmap instead if you are having trouble reading anything.
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Re: Proposed Design - The Short Lady Revealed

Postby steve » Mon Sep 20, 2004 2:25 am

Here's some more goodies I cooked up- Enjoy!

ps. Larry If you like the rendered stuff I could make some of the Elektra too for your book.
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Re: Proposed Design - The Short Lady Revealed

Postby larry cottrill » Mon Sep 20, 2004 3:47 am

steve wrote:Here's some more goodies I cooked up- Enjoy!

ps. Larry If you like the rendered stuff I could make some of the Elektra too for your book.

Steve, that looks great! Sure, it would be nice to have renderings of the Elektra sisters. No hurry -- I can't work very fast on the book, anyway.

As to your other question: I'd rather see the raked-back angle there than a face parallel to the main axis. The angle doesn't need exactness, however -- you just want to 'hit the spot' with that pressure node point at the centerlines where they cross. The raked angle is just an attempt to make it unlikely that we'll get flame ejection out through there. If we can, we want nothing but some of the pressure wave leaking out through that pipe!

Again, nice work.

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Re: Proposed Design - The Short Lady Revealed

Postby larry cottrill » Mon Sep 20, 2004 12:22 pm

Bruno Ogorelec wrote:I was wondering; why 'Reynstodyne'? To me it does not look like owing a particular debt to F. H. Reynst's designs. To my historian's eye, it looks like belonging to the family of 'sidewinders', together with the Logan, the NRL, the Thermojet etc.


Mike Everman wrote:I agree, the Reynst is a two hole breather, but no exhaust comes out the intake. I think that should be the criteria for something with Reynst heritage... Though it's the source of great pleasure when Larry adds 'odyne and TM to his developments. LOL

I plead guilty only to the usage being confusing -- I have never meant the Reynstodyne name to imply that the derivation is from the Reynst Pot per se. [Of course, I have never read Reynst -- just seen the copy that Ben Brockert got and had it in my hands a few minutes.]

For the name, I appeal to something more fundamental than the refined geometry of a specific device. To me, the significance of Reynst is the realization that breathing and valving could be done behind the expansion zone, rather than out in front of it. That, for me, was a revolutionary concept to consider. It's really quite profound when you think about it -- it takes you out of the realm of trying to block outward flow with an inefficient rectifier of some kind [the "original" Pulsodyne(TM) idea that I had, back before I knew that valveless pulsejets had already been thought of!] and into a design that gets the entire reaction energy developed against a hard wall at the front. That is different from any rectifier design, different from Schubert, and even from the Logan [though theoretically, if you bent back the Logan intake pipe, you would have that part of it]. The other aspect, as Mike said, is to develop separation between mass and wave ejection, at least as much as possible at the intake. That way, you get all of the explosion mass momentum transferred into moving the cold piston mass you've taken in behind.

The Reynst Pot is simply that principle taken to a high degree of optimization; it is not the only possible geometry to exploit the priciple.

So, to me, any engine that breathes from the rear, reflects all wave energy to the rear to optimise the reaction force in the thrust direction and tries to keep the explosion mass flow concentrated on moving the cold air piston sum up to what I have previously termed a 'Reynst pattern engine', and my 'trade name' for that will always be 'Reynstodyne', regardless of the specifics of the geometry.

Not 'derived from the Reynst Pot' but 'working from the Reynst pattern' is the key definition. It is perhaps not as clear in the Focused Wave Engine as in some other designs because here there is no distinction between the chamber and the exhaust nozzle. You can be sure, though, that the 'constant volume expansion' all takes place forward of the intake, so the breathing of the device is still typical of 'Reynst pattern' operation.

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Re: Proposed Design - The Short Lady Revealed

Postby Bruno Ogorelec » Mon Sep 20, 2004 5:19 pm

Larry, I am impressed by your pledoyer for the Reynst pot. I am an ardent supporter of that principle, but I could not have put together such an impassioned plea in its favor. The only think I would add is a few musty phrases, for that is my trademark.

In fact, you may have spurred me into a rethinking of the Reynst idea.

Not reading Reynst is your loss, however. You must, at some point. Preferably away from distraction, with a glass of good vintage by your side. A corpulent red will do, I think. It will fit the tone of the book.

Reynst is a classic in the best sense of the word. A Dickens of propulsion engineering, as it were. In fact, one has to be careful before accepting his writing as engineering documents, though much of it is quite rigorous. At times, it is difficult to separate the science and the fancy, especially when he writes of 'cold combustion'.

There's brilliance there, too. I was taken aback to discover that he invented (quite independently, it seems) the concept of the fanjet.
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Re: Proposed Design - The Short Lady Revealed

Postby steve » Mon Sep 20, 2004 8:12 pm

Construction Update:
the Intake flare and spark plug mount are now complete.

I tried to "blacksmith" the flare by heating and hammering and in the process gained a new appreciation for the flare you made on the fomychin! I soon gave up on that and made a sheet metal flare instead. At least with the sheet metal I can hit the correct dimentions more exactly.

tomarrow I will hopefully start cutting and bending the intake to shape.
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Re: Proposed Design - The Short Lady Revealed

Postby larry cottrill » Mon Sep 20, 2004 8:19 pm

steve wrote:Construction Update:
the Intake flare and spark plug mount are now complete.

I tried to "blacksmith" the flare by heating and hammering and in the process gained a new appreciation for the flare you made on the fomychin! I soon gave up on that and made a sheet metal flare instead. At least with the sheet metal I can hit the correct dimentions more exactly.

tomarrow I will hopefully start cutting and bending the intake to shape.

Steve -

As always, nice work [even with the gargantuan spark plug] -- don't choke now ...

Sometime you'll have to describe in detail how you go about making your 'sheet metal flares'. Looks like it works well for you. Good picture of work in progress, too.

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Re: Proposed Design - The Short Lady Revealed

Postby Mark » Tue Sep 21, 2004 12:58 am

Steve,
Just for fun, if you haven't put the side port on yet, spray a few misty shots of methanol down the tail pipe and then honk it, (light the tail with a match and listen to the loud reving bark it makes. I don't know why I like to do that with my creations, but it hints at what will occur with a constant combustion.
While I don't know it is possible, it would be stupendous to get a long narrow shape to jam jar at a high intensity. An example of breathing through one end only is this design. It blurrs the notion of a single snorkel breather.
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Re: Proposed Design - The Short Lady Revealed

Postby larry cottrill » Tue Sep 21, 2004 12:26 pm

Mark wrote:While I don't know it is possible, it would be stupendous to get a long narrow shape to jam jar at a high intensity. An example of breathing through one end only is this design. It blurrs the notion of a single snorkel breather.
Mark

Mark, I have to disagree with you, though my problem may be just semantic. This does not exactly 'breathe through one end only' -- if you narrow your gaze to the engine proper, it clearly separates the intake and tailpipe, i.e. it is a 'two hole breather' as you put it. It is actually not hard to imagine this one having the cylindrical tailpipe replaced by a narrow cone and ending up with the 'folded Lockwood' design that I [and others] have envisioned before. As it is, it's a sort of 'concentric Thermojet'. It's amusing to see that they apparently just blow the fuel in from the side. This is the first time I've ever seen a [presumably] scale drawing of such a geometry, after speculating about it.

Mark, I think this is an extremely nice design. It has the 'concentric Thermojet' basic geometry, a well-developed thrust augmentor, and an outer shroud which seems to be nothing but heat recovery. I wonder if this is another example of a 'space heater', like the railroad pulsejet for track thawing that you posted a while ago. Do you know what this one was actually used for?

This makes me want to pick up my 'Long Tall Sally' engine again, although I now think that chamber is too, well ... 'Long'. I ended up with a bunch of breathing holes clustered around the nozzle point. All I'd have to do is provide an outer sleeve with a flare and weld it on, and I'd have a working model of this beast, sans augmentor and outer shroud. Tuning the length of the intake sleeve would be the only tricky part.

Thanks! I continue to be amazed at the stuff you come up with that's already been built by somebody! You must have quite a book collection ...

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