A Speculation: The Hinote Criteria and the 'Logan Point'

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A Speculation: The Hinote Criteria and the 'Logan Point'

Post by larry cottrill » Tue Aug 17, 2004 4:40 pm

hinote wrote:I've done some basic research on this engine type (Chinese/Thermojet valveless); I believe it obeys rules somewhat similar to the rest of the operating valveless engines--a combination of resonant (acoustic) and gas-dynamic effects. The real trick appears to be in the intake tube, and how to relate its length and location to the rest of the engine.

If you look at the "standard" Chinese dimensions (currently being re-posted on the thread, "Nord 1500 Project"), you'll find the distance from the front of the engine to the mouth of the intake is very close to 1/3 the length of the engine (all calcs should be made to include open-end correction factor of .6R); this figure is reinforced by the Thermojet drawing that has appeared from time to time on this Forum.

The length of the intake tube itself is subject to some variation, but (again using the "standard" Chinese as a benchmark) the measurement appears to be L/5 (use an end-correction factor for both ends on this one). This figure is at odds with the L/4 spec used on the Thermojet drawing, but I would tend to "copy the Chinese" because of its greater success.
The above is quoted from close to the tail end of my "For a Close Shave ..." thread. This is extremely interesting stuff, because it is an observation by a careful builder who has had considerable success with small engines, Bill Hinote. I dubbed these two factors, L/3 for the intake pipe port station and L/5 for the intake pipe length, the 'Hinote Criteria". I have not built enough engines to validate the criteria, but they are observed from successful valveless examples as empirical data, so I don't have any reason to fault them.

An engine that I did not mention in my "What Makes the Great Engines Great?" thread was the Logan, for two reasons: the most obvious being that I have no direct experience with it, the other being that I have never heard of it achieving very high thrust or propelling anything. It is, however, fascinating in itself for a short handful of very good reasons: (a) All parameters considered, it is arguably the simplest valveless engine to put together; (b) It is graphically simple -- a sort of what you see is what you get kind of design; and (c) It still seems to carry an aura of mystery with it that never seems to be abated.

Part of the mystery seems to be that the Logan appears to be more capable than most valveless types of running continuously while "breathing through a straw"; that is, it disagrees with my observation of the "great engines" having big, low impedance intakes! The Logan intake always seems to be kind of a long, narrow pipe protruding exactly sideways [transverse flow path], with the fuel simply introduced at some point along the way.

I believe that, speculatively building on the empirical 'Hinote Criteria' we can derive a proper theory for the Logan and turn it into a simple, effective propulsive device at almost any scale desired. The following is 100% hypothesis, that is yet to be proven:

Let's assume that Bill's observations of points along the acoustic length are essentially correct. I believe that they are, but that the most fundamentally important point has yet to be expressed -- I believe that the absolutely most critical point on these kinds of engines is the point at which the intake pressure wave merges with [or diverges from] the main pipe pressure wave. Why? Because that is the only point where the two have any direct influence on each other! Particularly, it is the only point at which the intake directly "senses the feedback" of the low pressure wave from the main body of the engine. And, the Hinote Criteria lead us to the exact point where that sensing will be optimized: the L/8 point [measured from the closed end of the pipe]. That station, I believe, turns out to be the "Logan Point" of a closed pipe engine.

The classic picture of the Logan shows it as a smooth teardrop with a stretched tailpipe, plus the absolutely transverse skinny pipe. I believe [and Mark's threaded pipe experiments tend to bear this out] that none of this is really important to whether the engine will cycle. What IS important [and never shown in the classic drawing] is WHERE to put that tiny intake pipe.

Set the Logan aside for a moment and imagine the classic Thermojet layout -- a chamber with two absolutely straight and parallel pipes, usually of somewhat different diameters. Lay this out according to the Hinote Criteria: the intake pipe's external end is at L/3 and the intake pipe length is at L/5. Where does that put the inside end of the intake pipe in relation to the front end plate? Well, it has to be at 33% MINUS 20% = 13% of the overall length L. My hypothesis is that this distance is actually ideally 12.5%, or L/8 for perfect synchronization at resonance.

Now, here is the secret to how the whole mess works together: The pressure wave is a STATIC pressure wave! The same holds for the low-pressure wave that returns after the blast wave leaves the pipe. That means that, at any given instant in time, it is pushing [or pulling] in all directions equally, including, but not limited to, the transverse direction in the pipe. If this speculation is true, consider what this means: If the inside opening of the intake pipe is at the ideal Logan Point, it doesn't matter what direction the intake pipe is aimed from that point, for static operation! It can be a classic Logan intake, ending at the side wall of the chamber; it can be a Rossco intake penetrating from the front end right down the center; it can be a Chinese intake with a diffuser stopping at the wall of the rear cone; it can be an NRL design with the intake pipe practically penetrating clear through the space; it can be an Elektra intake poised in front of the exhaust; it can be a Fo Mi Chin intake cutting into the tailpipe. It doesn't matter whether the engine is flashlight shaped, straight or multi-coned -- if you're in the right place, you're in the right place! All you need to know is that the wave is moving through an essentially same-temperature environment from one end of the pipe to the other [not strictly true, but close enough] and the point can be predicted as the 12.5% point.

Once you have this, you can experiment with everything else. The length of the intake will probably need to be about Bill's L/5, but probably ideally a little more or less. The L/3 wave path length will be about right, but will vary with the average temp you actually achieve in the pipe [after all, in all these engines, that air column will be far cooler than the gas condition at the engine interior!]. But the point where the two wave paths intersect is the absolute magic that must be satisfied very closely for things to start and keep running. I'd bet that if Mark and Steve would measure their fully operational pipe Logans, they will find a reasonably close fit to the mark.

Note that in wavelength terms, this defines the Logan Point as the 1/32 wavelength station, with the intake pipe corrected path length = 1/20 wave, since we are relating to a 1/4 wave pipe [closed pipe]. The total wave path length from end plate to intake entrance [with end correction] would be 1/12 wave.

This will be tested, as close as I can cut and weld it, in the Elektra II engine design. I hope that others will try to validate and/or refute this hypothesis. If it is true, it would mean that the crudest valveless pipe designs imaginable will at least run if the Logan Point is used as the starting point for the rest of the design. I also believe that a classic Logan design would run with a much larger intake than originally shown, providing a simple design that is fit for actual propulsion use. The intake could be bent back, "Chinese" style, for full recovery of the pressure wave component of thrust, of course. None of this should be taken to mean that other design parameters are unimportant, just that closely hitting the Logan Point will be crucial to success.

L Cottrill

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Re: A Speculation: The Hinote Criteria and the 'Logan Point'

Post by hinote » Tue Aug 17, 2004 5:47 pm

Larry Cottrill wrote:
The above is quoted from close to the tail end of my "For a Close Shave ..." thread. This is extremely interesting stuff, because it is an observation by a careful builder who has had considerable success with small engines, Bill Hinote. I dubbed these two factors, L/3 for the intake pipe port station and L/5 for the intake pipe length, the 'Hinote Criteria". I have not built enough engines to validate the criteria, but they are observed from successful valveless examples as empirical data, so I don't have any reason to fault them.

L Cottrill
Larry, thank you for adding my name to my recent speculation--creating the term "Hinote Criteria".

I should caution you that adding your speculation on top of mine is probably going to create the most speculative pulsejet theories yet.

Do I hear laughter from the Portland area?

Given my recent (and ongoing) debacles on this Forum, one should move carefully along these particular paths to pulsejet truth.

Besides, the Escopeta recently posted here seems to respond to a somewhat different set of rules. The concept is similar, but the numbers seem different. Could this account for its excellent performance?

Bill H.
Acoustic Propulsion Concepts

P.S.: Personally, your theory makes a lot of sense to me--but whether the actual numbers are correct is something I can only speculate on.

There's that word again!

Only construction of operating engines can prove (or disprove) all this.

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Re: A Speculation: The Hinote Criteria and the 'Logan Point'

Post by tufty » Wed Aug 18, 2004 8:08 am

hinote wrote: I should caution you that adding your speculation on top of mine is probably going to create the most speculative pulsejet theories yet.
I speculate that this is highly probable.
hinote wrote: Only construction of operating engines can prove (or disprove) all this.
Indeed. Now, I have the 'horizontal bong', which refused to fire up yesterday, probably due to the high humidity (hell, it was raining at the time I was trying it), but which has adjustable intake and exhaust lengths. It's a relatively trivial matter to match these up to Larry's speculation (A quick bit of spreadsheet on the newton gives me an overall length of 105cm and an intake stack extension of 4cm). It's worth a try (indeed, I intend to try it later today, weather and other commitments permitting).

Simon

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Re: A Speculation: The Hinote Criteria and the 'Logan Point'

Post by larry cottrill » Wed Aug 18, 2004 2:27 pm

tufty wrote:Indeed. Now, I have the 'horizontal bong', which refused to fire up yesterday, probably due to the high humidity (hell, it was raining at the time I was trying it), but which has adjustable intake and exhaust lengths. It's a relatively trivial matter to match these up to Larry's speculation (A quick bit of spreadsheet on the newton gives me an overall length of 105cm and an intake stack extension of 4cm). It's worth a try (indeed, I intend to try it later today, weather and other commitments permitting).

Simon
Simon -

That's wonderful! Sounds like a great way to try this out. I for one will be eagerly awaiting news from this test.

Thanks!

L Cottrill

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Re: A Speculation: The Hinote Criteria and the 'Logan Point'

Post by Mark » Wed Aug 18, 2004 3:56 pm

Larry,
That's some good food for thought, it does make you wonder why Logan wasn't elbowing his side port. I'm still toying with the long reach ratchet for your Chin-O'-Dyne; after some thought, I feel certain it could be done on the cheap with some sort of improvised extension adapter.
Here's a picture out of my book "Pulsating Combustion Proceedings." (D.J. Brown, 1971). It was to be used to melt snow at remote railroad switching stations, if I recall. I don't like the intrusion into the combustion chamber, but I think they were looking for reliable starting.
Mark
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Re: A Speculation: The Hinote Criteria and the 'Logan Point'

Post by Viv » Wed Aug 18, 2004 4:49 pm

Mark wrote:Larry,
That's some good food for thought, it does make you wonder why Logan wasn't elbowing his side port. I'm still toying with the long reach ratchet for your Chin-O'-Dyne; after some thought, I feel certain it could be done on the cheap with some sort of improvised extension adapter.
Here's a picture out of my book "Pulsating Combustion Proceedings." (D.J. Brown, 1971). It was to be used to melt snow at remote railroad switching stations, if I recall. I don't like the intrusion into the combustion chamber, but I think they were looking for reliable starting.
Mark
Mark you are an absolute Star!! thats the NRL engine! I have been looking for more info on this baby for a while, can I have what ever you have on it as we were going to do a construction drawing for every one.

Brill I am so happy!

Viv
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Re: A Speculation: The Hinote Criteria and the 'Logan Point'

Post by larry cottrill » Wed Aug 18, 2004 4:55 pm

Mark wrote:Larry,
That's some good food for thought, it does make you wonder why Logan wasn't elbowing his side port. I'm still toying with the long reach ratchet for your Chin-O'-Dyne; after some thought, I feel certain it could be done on the cheap with some sort of improvised extension adapter.
Here's a picture out of my book "Pulsating Combustion Proceedings." (D.J. Brown, 1971). It was to be used to melt snow at remote railroad switching stations, if I recall. I don't like the intrusion into the combustion chamber, but I think they were looking for reliable starting.
Mark
Mark -

It was either you or Bruno [sorry I can't remember] who sent me that before in a private email. I believe this is the railroad snow melter.

This is especially nice, because we have a well-detailed dimensioned drawing -- so, we can check this lady out against the criteria, except for one little thing: They don't dimension the outer end of the intake tube!!!. For that, we will have to resort to crude scaling, alas.

If this is the engine I think it is, it is usually stated that the intake goes almost clear through the chamber. The drawing clearly shows that this is not so: The intake tube is cut away at the rear almost at the top of the chamber, just below where it cuts in! So, that point, acoustically speaking, is the inside end of the intake tube. The remaining portion of the tube protruding down in is apparently acting as just a 'blast shield' for the intake and perhaps a flow guide for the intake air stream within the chamber.

To get the 'Logan Point' they're using, we would add the first 1.5 inch and the 4.3 inch shown at the top, plus another .7 inch to get us to the centerline of the 1 inch OD tube. Roughly scaling, I get approx. 8.8 inches for the length of the intake pipe, from the 'Logan Point' to the intake flare [which I find shockingly minute in this engine!]. I did my scaling from a printout of the posted photo, so accuracy of this value is obviously limited, and is probably in error on the short side, due to the crude method used. The only other datum we need is the internal total length, shown as 41.75 inches. So we have:

Logan Point:
Logan point = ( 1.5 + 4.3 + .7 ) / 41.75 = .156 or the 16% station
[12.5% hypothesized]

Hinote Criteria:
Length of intake pipe [uncorrected, approximate] = 8.8 / 41.75 = .211 or 21% of L
[20% hypothesized]
Acoustic station if intake port [uncorrected, approximate] = ( 1.5 + 4.3 + .7 + 8.8 ) / 41.75 = .366 or 37% of L
[33% hypothesized]

So, this engine approximately fits the Hinote Criteria, with a significantly larger proportion of the main tube in front of their chosen "Logan Point" than predicted by my hypothesis. The largest variations from the anticipated values amount to only 4 % of the length, however.

We apparently don't know a lot about this engine. Was it designed on fully theoretical grounds, or mostly by experimentation, or a combination? I would have to assume that any optimization was probably more for heat output and good cold starting than maximum thrust output. Physical ruggedness appears to be a high priority, as would be expected for a piece of gear handled by burly RR men. Note especially that the spark gap is made as long as they can get it to jump reliably -- almost a fifth of an inch [5mm]! This is what you want in a zero-compression chamber, the longest possible spark, NOT the hottest! We aren't sure [unless they say something in Mark's textbook] whether the engine was successful at self-starting or had to be compressed air driven [however, there is an AIR INLET indicated at the side of the fuel stem -- that must have been needed for something!].

At any rate, the dimensions are not wildly far from my and Bill's expectations for this type of engine configuration. Basically, the intake pipe is located just a bit rearward of where we would have 'called it'. This may or may not be due to adjustments while perfecting the design with working models; we obviously have no way of knowing the exact development approach.

L Cottrill

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Re: A Speculation: The Hinote Criteria and the 'Logan Point'

Post by Viv » Wed Aug 18, 2004 5:06 pm

Larry Cottrill wrote:
Mark wrote:Larry,
That's some good food for thought, it does make you wonder why Logan wasn't elbowing his side port. I'm still toying with the long reach ratchet for your Chin-O'-Dyne; after some thought, I feel certain it could be done on the cheap with some sort of improvised extension adapter.
Here's a picture out of my book "Pulsating Combustion Proceedings." (D.J. Brown, 1971). It was to be used to melt snow at remote railroad switching stations, if I recall. I don't like the intrusion into the combustion chamber, but I think they were looking for reliable starting.
Mark
Mark -

It was either you or Bruno [sorry I can't remember] who sent me that before in a private email. I believe this is the railroad snow melter.

This is especially nice, because we have a well-detailed dimensioned drawing -- so, we can check this lady out against the criteria, except for one little thing: They don't dimension the outer end of the intake tube!!!. For that, we will have to resort to crude scaling, alas.

If this is the engine I think it is, it is usually stated that the intake goes almost clear through the chamber. The drawing clearly shows that this is not so: The intake tube is cut away at the rear almost at the top of the chamber, just below where it cuts in! So, that point, acoustically speaking, is the inside end of the intake tube. The remaining portion of the tube protruding down in is apparently acting as just a 'blast shield' for the intake and perhaps a flow guide for the intake air stream within the chamber.

To get the 'Logan Point' they're using, we would add the first 1.5 in and the 4.3 in shown at the top, plus another .7 inch to get us to the centerline of the 1 inch OD tube. Roughly scaling, I get approx. 8.8 inches for the length of the intake pipe, from the 'Logan Point' to the intake flare [which I find shockingly minute in this engine!]. I did my scaling from a printout of the posted photo, so accuracy of this value is obviously limited, and is probably in error on the short side, due to the crude method used. The only other datum we need is the internal total length, shown as 41.75 inches. So we have:

Logan Point:
Logan point = ( 1.5 + 4.3 + .7 ) / 41.75 = .156 or the 16% station
[12.5% hypothesized]

Hinote Criteria:
Length of intake pipe [uncorrected, approximate] = 8.8 / 41.75 = .211 or 21% of L
[20% hypothesized]
Acoustic station if intake port [uncorrected, approximate] = ( 1.5 + 4.3 + .7 + 8.8 ) / 41.75 = .366 or 37% of L
[33% hypothesized]

So, this engine approximately fits the Hinote Criteria, with a significantly larger proportion of the main tube in front of their chosen "Logan Point" than predicted by my hypothesis. The largest variations from the anticipated values amount to only 4 % of the length, however.

We apparently don't know a lot about this engine. Was it designed on fully theoretical grounds, or mostly by experimentation, or a combination? I would have to assume that any optimization was probably more for heat output and good cold starting than maximum thrust output. Physical ruggedness appears to be a high priority, as would be expected for a piece of gear handled by burly RR men. Note especially that the spark gap is made as long as they can get it to jump reliably -- almost a fifth of an inch [5mm]! This is what you want in a zero-compression chamber, the longest possible spark, NOT the hottest! We aren't sure [unless they say something in Mark's textbook] whether the engine was successful at self-starting or had to be compressed air driven [however, there is an AIR INLET indicated at the side of the fuel stem -- that must have been needed for something!].

At any rate, the dimensions are not wildly far from my and Bill's expectations for this type of engine configuration. Basically, the intake pipe is located just a bit rearward of where we would have 'called it'. This may or may not be due to adjustments while perfecting the design with working models; we obviously have no way of knowing the exact development approach.

L Cottrill
Larry
This engine was not developed by burly rail road men as you put it but by the Naval research laboritory staff at NRL Washington, it is mentioned in a number of papers from that source but I cant get to the ones I want as I am not in the blasted navy!

It dates from about 1954 in my referances when it was used in a pressure gain experiment for turbines, interestingly the engine was copied from yet another navy project to save time but I dont have any info for that one.

I think it crops up in a few other places too but I have never seen diemensions only pictures.

It is reputed to have a very good performance and will run on gas or diesal, now we can build it and find out:-)

Viv
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Re: A Speculation: The Hinote Criteria and the 'Logan Point'

Post by Viv » Wed Aug 18, 2004 5:14 pm

And one more thing, look at the tail pipe cone section real close? in the photo it is only tack welded on to the tail pipe not seam welded, also the drawing shows the engine drawn with a thickness to the material but the tail cone is just drawn as thin lines.

It looks as if it was just added to a previous version of the engine and the plans updated roughly rather than redrawn properly

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Why There, Anyway?

Post by larry cottrill » Wed Aug 18, 2004 5:32 pm

Someone should have asked why my choice of the L/8 point should be better than any other point. I can't answer that in terms of harmonic frequency waves, etc. because I don't know enough to do so. However, looking at the problem philosophically, I think I have an answer as to exactly why some point must be better than any other point along the engine's length.

First of all, we know we need a point somewhere near the combustion zone of the engine, so that a fresh charge of air/fuel mixture will be ready for use when the engine suction is developed. On an engine of this type, we expect [somehow] that the explosion will occur right up against the front plate of the engine, and that the gases will temporarily undergo 'constant volume expansion' [essentially, a rapid increase in static pressure] before expanding rearward in the more usual sense of the word. Long before the gases really get moving, there will be a pressure wave propagated rearward -- eventually, this will be followed by a pressure trough echoed back in the forward direction. This is the point, however, where I have to deviate from the usual explanation.

An important characteristic of the wave and trough 'system' is usually not mentioned: The pressure wave passes every engine station once on its way out; the pressure trough, however, passes through the entire length of the engine TWICE, because it is almost perfectly reflected by the front plate. So, the trough moves forward, is echoed off the front end of the chamber, and moves rearward again! Every station of the engine will see the trough pass twice, except the very front end station of the engine main tube.

This, I believe, is the key. What we need for breathing is TIME -- time for the static pressure in the bottom of the intake tube [which is behaving as a half-wave oscillator between two pressure antinodes] to accelerate as much of the contained mass as possible into the chamber area for the next explosion. The front end will give us a very intense trough, as it turns around -- but NOT for very long. A station farther back toward the center of the main tube will see the trough pass in two discrete stages, separated by significant time. What we want for our ideal Logan Point, however, is to provide fuel/air mixture where we have established low density in the chamber AND the maximum possible time of exposure to the pressure trough -- a couple of thousandths of a second in a small engine, if we can get it.

So, what I hypothesize is that the ideal point is where the trailing edge of the forward-running trough begins its pressure rise just as the leading edge of the rearward-running reflected trough begins its pressure drop. The wave, seen over time at that station, will look like a long plateau or perhaps an inverted 'two-humped camel' where the static pressure never rises very close to ambient pressure between 'humps'. In other words, we want the point in the pipe where the initial trough and reflected trough combine to provide the largest period of time well below ambient pressure that we can get.

Whether that really turns out to be L/8 or not can be determined by experiment for a given case -- the best such a criterion can be is a sort of "rule of thumb" value, anyway -- just a place to start that will probably at least get things working.

L Cottrill

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Re: A Speculation: The Hinote Criteria and the 'Logan Point'

Post by larry cottrill » Wed Aug 18, 2004 5:52 pm

Viv wrote:
Larry
This engine was not developed by burly rail road men as you put it but by the Naval research laboritory staff at NRL Washington, it is mentioned in a number of papers from that source but I cant get to the ones I want as I am not in the blasted navy!

It dates from about 1954 in my referances when it was used in a pressure gain experiment for turbines, interestingly the engine was copied from yet another navy project to save time but I dont have any info for that one.

I think it crops up in a few other places too but I have never seen diemensions only pictures.

It is reputed to have a very good performance and will run on gas or diesal, now we can build it and find out:-)

Viv
Ah -- so this one is the famous NRL engine. Thank you, thank you! And again, for pointing out the tail-end detail, although I don't think that changes things much from a purely acoustic standpoint. Or, maybe you feel that it changes things radically, and that's why you're bringing this out. That would tend to blow some pretty high-calibre holes in my hypothesis; Rossco has said that his observations are that leaks in tailpipes don't matter acoustically -- the thing simply resonates on the full internal length you end up with, no matter how sloppy your extension sleeves are. Would you agree or challenge that idea? Or would you assert that this case is not at all equivalent to 'leaky sleeves', since there's absolutely no overlap?

And now, who has pics and dimensions of the railroad snow melter that I thought this was? It must be out there somewhere!

L Cottrill

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Re: A Speculation: The Hinote Criteria and the 'Logan Point'

Post by Viv » Wed Aug 18, 2004 8:44 pm

Larry Cottrill wrote:
Viv wrote:
Larry
This engine was not developed by burly rail road men as you put it but by the Naval research laboritory staff at NRL Washington, it is mentioned in a number of papers from that source but I cant get to the ones I want as I am not in the blasted navy!

It dates from about 1954 in my referances when it was used in a pressure gain experiment for turbines, interestingly the engine was copied from yet another navy project to save time but I dont have any info for that one.

I think it crops up in a few other places too but I have never seen diemensions only pictures.

It is reputed to have a very good performance and will run on gas or diesal, now we can build it and find out:-)

Viv
Ah -- so this one is the famous NRL engine. Thank you, thank you! And again, for pointing out the tail-end detail, although I don't think that changes things much from a purely acoustic standpoint. Or, maybe you feel that it changes things radically, and that's why you're bringing this out. That would tend to blow some pretty high-calibre holes in my hypothesis; Rossco has said that his observations are that leaks in tailpipes don't matter acoustically -- the thing simply resonates on the full internal length you end up with, no matter how sloppy your extension sleeves are. Would you agree or challenge that idea? Or would you assert that this case is not at all equivalent to 'leaky sleeves', since there's absolutely no overlap?

And now, who has pics and dimensions of the railroad snow melter that I thought this was? It must be out there somewhere!

L Cottrill
I am interested in the history and results of the rail road application the same as i am interested in all attempts at using pulse jets, although we never hear much about the lenox (spelling) heaters) so I am with Larry any body come across any thing?

As to leaks well we found on the BCVP testing they made a differance! but it depends on the size of the leak and were it is:-) its going to have an effect no matter how small thats for sure.

In some cases you can ignore it as its contribution is minor but some you cant, for instance the pressure jet needs a hole drilled in it to lock up a harmonic in the third stage intake or the motor wont lock up and resonate properly, thats worth nearly half its rated thrust output on some motors due to them being nearer off toone than on toone:-)

NRL did a lot of work on the quite it seems we just need to liberate the information from there library.

Viv
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Re: A Speculation: The Hinote Criteria and the 'Logan Point'

Post by Mark » Thu Aug 19, 2004 4:19 am

"In Canada railway track switches must be protected from failure caused by snow or ice." The snow melter made 3.25 lbs thrust at 250.000 BTU/hour rating using propane as the fuel. "The inlet valve was simplified so that it could be fashioned from an Inconel tube. The proportions of the combustion chamber and tail pipe were changed to allow fabrication from standard stainless steel tube sections and fittings." The fuel supply pressure was 5 psig. Levels of about 130 db have been measured.
I thought this was funny. "It is believed that the heater can be located as close as 1000 feet to a residence."
"A solid state timer is incorporated to control the ignition and auxillary air during starting." "The fuel nozzle used is a simple tube of 0.125" bore mounted on the side of the intake elbow discharging concentrically with the intake into the combustion chamber."
Anyway, that's about all the snow melter fun facts I have.
Mark
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sam
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Re: A Speculation: The Hinote Criteria and the 'Logan Point'

Post by sam » Thu Aug 19, 2004 9:08 am

Hi everybody - I've been away for ages so haven't been very prominent lately (anyone remember me?). It seems like lots has been going on in my absence. Larry - I need a bit longer to think about what your saying with regards to the "logan point" but I think it sounds plausable.
Mark - did you get that stuff from the "first international symposium on pulsating combustion"? I think I have a copy of that somewhere too. The engine is based on the US Navy NRL project as you correctly pointed out. Porter's work in this area was on pulsating combustion for acheiving a pressure gain in gas turbines (similar to what Kentfield was trying to do). I've attached a copy of the report (1.3Mb) if you dont already have it.
sam

PS - Grahame - i owe u some results i know. sorry! My email stopped working so i've lost everyones addresses and also the files you sent me. if your still interested then send me a geometry file again and i'll see what i can do. can you also tell me what fuel your using and roughly where its injected. my new address is sam_mas0n@hotmail.com (sorry again) .
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larry cottrill
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Re: A Speculation: The Hinote Criteria and the 'Logan Point'

Post by larry cottrill » Thu Aug 19, 2004 1:09 pm

Mark wrote:"In Canada railway track switches must be protected from failure caused by snow or ice." The snow melter made 3.25 lbs thrust at 250.000 BTU/hour rating using propane as the fuel. "The inlet valve was simplified so that it could be fashioned from an Inconel tube. The proportions of the combustion chamber and tail pipe were changed to allow fabrication from standard stainless steel tube sections and fittings." The fuel supply pressure was 5 psig. Levels of about 130 db have been measured.
I thought this was funny. "It is believed that the heater can be located as close as 1000 feet to a residence."
"A solid state timer is incorporated to control the ignition and auxillary air during starting." "The fuel nozzle used is a simple tube of 0.125" bore mounted on the side of the intake elbow discharging concentrically with the intake into the combustion chamber."
Anyway, that's about all the snow melter fun facts I have.
Mark
Mark -

Thanks! That's the first time I've ever seen a drawing, and it's fascinating -- far different from what I expected. It is an NRL engine [or clone] mounted inside a huge augmentor feeding a rectangular duct embedded between the rail ties! Apparently, the cutesie-pie outlet stacks attempt to distribute hot air in several directions in the space between the rails.

I almost laughed aloud when I spotted the two sections of RR iron, and realized that the partially hidden rectangle represents a crosstie!!! What a wonderful view into the inner workings of a technological marvel ...

L Cottrill

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