Even the Cheapest Jet Should Breathe Like a Reynst!

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Re: All New WIP Photos Now On Site

Postby Anthony » Wed Apr 21, 2004 11:58 pm

Larry Cottrill wrote:OK, I managed to get the minivan working again in record time, for a mere $703.50, and just now I got the Elektra I page updated with all the remaining 'under construction' photos:

http://www.cottrillcyclodyne.com/ElektraI/ElektraI.html

The next time I post pictures of Elektra I here, there will be some kind of blue flame erupting from it somewhere!

L Cottrill


No doubt you're gonna suceed!
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"Pumping Up" - The Cottrill Postulate

Postby larry cottrill » Thu Apr 22, 2004 5:05 pm

Larry Cottrill wrote:
Rossco wrote:I have posted before about being able to get my engines going much harder by "pumping them up".
What i mean by this is get it going as hard as it will, self sustaining. While running, and hot, give the intake a sudden blast of air (as high pressure and volume as you can). At the same time crank the gas up a bit, then let it sustain at this new level. I can do it about 5 times with mine, and at a guess, i get about twice the thrust and heat level than at the highest throttle position that it would self sustain at originaly.
My theory on this is that all of my current engines have undersized intakes. By doing this to them it induces a lower intake phase pressure, and therefor suck more air, and will hence tollerate more fuel!

Rossco

Rossco -

I doubt that you can hang this on "undersizing" of the intake [OK, maybe you can in its final condition, where you can't 'pump it up' further, but the intake must be doing OK up to that point!]. I do agree that there must be a lowering of average pressure in the suction phase of the cycle. What I mean by this is that it could be that the deepest pressure isn't lowerered further, but rather that the low part of the pressure graph is made broader in time value under 'pumped' conditions.

What I'm saying is, the pressure curve of an engine running hard may not be a vertically magnified version of the pressure curve of the very same engine running easy. There!

Whatever the exact situation is, it has to mean that you're getting a better energy conversion per cycle than at the last plateau [more work in the same period of time]. It all boils down to the momentum you actually achieve in the tailpipe 'piston' - more momentum means more thrust, but also means a more powerful draw at the front end [all other things being equal].

What this observation proves is that it is not necessary to alter system geometry to achieve stable operation at various power levels. I have usually assumed that an engine runs up [in the first few cycles] until it reaches a limiting condition where negative feedback catches up and we have a stable condition beyond which we can't go. Obviously, this is not true [in the case of your engine, at least] and that is important. It means that we should not necessarily give up on a design that sustains in a 'weak' thrust condition - it may simply be operating in the lowest stable state that we can find [or, some low stable state we happened upon]!

Remember that if your engine were in motion, the action you're describing would not involve coordination between an artificial air source and the fuel valve, but merely a careful synchronization of air- and fuel-throttling. ['merely' - ha!]

The next time you get this to work, you should see if temporarily restricting the air causes a step downward to a lower-powered stable state, and try the same with fuel restriction, i.e. is the transition air-led or fuel-led, or must it be a coordinated adjustment? Even if the theory isn't quite immediately grasped, a set of practical guidelines for how it works could be invaluable.

L Cottrill


At the risk of once again providing proof of myself as an utter fool, I propose The Cottrill Postulate:

For any given self-sustaining pulsejet where the fuel input is an independent variable, there will be a stable operating state at a definite average machine temperature for any given energy input level [rate of fuel consumption], with higher average temperatures corresponding to higher input levels.

There - I've said it. What this means is that your engine will eventually achieve a certain stable rate of heat radiation [average temp] where it will throttle down its intake air if it becomes hotter, and conversely, increase its intake air if it becomes cooler, so that it always tries to return to equilibrium for a particular fuel input level. If, then, you can bump it up to a higher temperature, you will achieve a stable state of equilibrium between energy input [fuel consumption] and energy output [radiated heat and air movement]. You do this by setting up more fuel delivery and excess air until the operating temperature comes up, and then you can relax the fuel back to a level that will be at equilibrium at the higher output point while the engine controls its own air input to achieve the stable state [thermal equilibrium] at that new level.

I feel confident that to seasoned practitioners such as Bill Hinote, M, and some others, my Postulate will seem obvious and practically trivial. But for guys like us, it might be helpful to have in mind while searching for such desirable features as throttleability.

Also keep in mind that this statement does not imply that there is a high degree of linearity or that there aren't limits as to how high or low you can go -- merely that for any one design there is no one "perfect" operating point [constituting the only condition where it will work], but rather a range of values that will satisfy a stable running condition.

Basically, I think that any pulsejet can be run hard or easy -- you just have to discover how to properly set up the exact running condition for the power level you want.

It is harder to apply this to a carbureted engine, since the fuel input loses its 'independent variable' aspect, and tries to track the air input in a roughly proportional manner. In theory, the principle still applies, though - your method of control would be trickier, imposing tight synchronization of air and fuel delivery [since the carburetor action will not be perfectly linear].

L Cottrill
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Re: "Pumping Up" - The Cottrill Postulate

Postby hinote » Thu Apr 22, 2004 5:41 pm

Larry Cottrill wrote:

At the risk of once again providing proof of myself as an utter fool, I propose The Cottrill Postulate:

For any given self-sustaining pulsejet where the fuel input is an independent variable, there will be a stable operating state at a definite average machine temperature for any given energy input level [rate of fuel consumption], with higher average temperatures corresponding to higher input levels.

There - I've said it. What this means is that your engine will eventually achieve a certain stable rate of heat radiation [average temp] where it will throttle down its intake air if it becomes hotter, and conversely, increase its intake air if it becomes cooler, so that it always tries to return to equilibrium for a particular fuel input level. If, then, you can bump it up to a higher temperature, you will achieve stable state of equilibrium between energy input [fuel consumption] and energy output [radiated heat and air movement]. You do this by setting up more fuel delivery and excess air until the operating temperature comes up, and then you can relax the fuel back to a level that will be at equilibrium at the higher output point while the engine controls its own air input to achieve the stable state [thermal equiliobrium] at that new level.

I feel confident that to seasoned practitioners such as Bill Hinote, M, and some others, my Postulate will seem obvious and practically trivial. But for guys like us, it might be helpful to have in mind while searching for such desirable features as throttleability.

Basically, I think that any pulsejet can be run hard or easy -- you just have to discover how to properly set up the exact running condition for the power level you want.

It is harder to apply this to a carbureted engine, since the fuel input loses its 'independent variable' aspect, and tries to track the air input in a roughly proportional manner. In theory, the principle still applies, though - your method of control would be trickier, imposing tight synchronization of air and fuel delivery [since the carburetor action will not be perfectly linear].

L Cottrill


Larry:

As the observer/operator of a sweet-running pulsejet (the QD), I can assure you that your observations are spot-on.

Operation of the fueling "throttle" (currently a ball-valve, to M.'s disgust!) results in immediate changes in power, and it's obvious the airflow is automatically following suit. The heat flux moves a little more slowly--in the case of the QD it takes 2 or 3 seconds to notice the change in color due to the metal heating/cooling, and more than 10 seconds for it to re-stabilize.

There doesn't seem to be any limit to how fast the engine will accept changes in fueling rate--to the operator the response is immediate and the newly established level of power is totally stable.

Bill H.
Acoustic Propulsion Concepts
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MAPPing Better Bang and Howls

Postby larry cottrill » Fri Apr 23, 2004 1:20 pm

I tried it again last night, though my time was limited, using MAPP gas for fuel. The difference in fuel energy between MAPP and propane is easily observed. I got some really good bangs, along with some ghostly howls. The odor is the natural smell of acetylene, rather than the ethane odor of artificially-flavored propane. I ran constant spark for all testing.

The best explosions were when I 'bumped' the gas quickly on and off again by quickly turning the regulator screw in and back out, between once and twice per second. Attempts at steadily trickling gas in always ended up in a weak, fully internalized howling mode OR the 'giant blowtorch' mode with a huge flame billowing out the back, i.e. no internal combustion at all.

The really silly thing was I hadn't prepared by charging up the compressed air tank on my old Dynajet starter, so I had no air supply to try driving it with - rats! When I happened upon 'howling' type operation, I think that would be a good time to ease some air in. Because I wasn't ready for that, I didn't get the good sounding buzzing operation that I had the other night with propane. I think, realistically, we're probably going to need air to start this engine, whether I like it or not. Someone has said recently that relatively little air is needed [for small engines], suggesting that even a hair drier would be usable, and I might try that or have the shop vac handy. I'm sure that the leaf blower would simply be overkill in this case.

I think another interesting time to start phasing air in would be when you get the engine flooded with fuel gas [the giant blowtorch] -- introducing mixing air at that point might have quite an impact on what's happening. However, I think this would be a poor starting method, though at the moment I wouldn't turn it down if I ended up with a running engine!

I had to quit when the fuel cylinder was so iced up it didn't have enough vapor pressure left to get through the regulator. It appears that these small torch cylinders are completely inadequate for this work! But, it's obviously worth trying again, with some air available, while I still have some of both fuels left. It is also entirely possible that I haven't given the propane a fair chance yet, and that better technique in tweaking the gas on and off would get better bangs than what I saw before.

Some of the bangs throw flame out the intake; some do not. My preliminary observation is that rich, yellow bursts tend to backfire through the intake, while good blue blasts seem to head out the tailpipe more or less exclusively. It's hard to really watch both places at once, though, so this observation may be influenced a good deal by wishful thinking.

More this weekend, if the weather cooperates. It has been better than predicted the last few days, though it's been a little cool in the evenings for doing this kind of work.

L Cottrill
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Postby Mike Everman » Fri Apr 23, 2004 1:58 pm

Larry, I keep expecting you to say that you've:
A: flared the intake a bit
B: squeezed an impedence taper into the intake pipe and,
C: squeezed a throat into the exhaust just aft of the CC

It's my opinion that straight pipes on this is just going to be frustrating, but you've created a very watchable process! Thanks.
Mike
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Postby larry cottrill » Fri Apr 23, 2004 2:26 pm

Mike Everman wrote:Larry, I keep expecting you to say that you've:
A: flared the intake a bit
B: squeezed an impedence taper into the intake pipe and,
C: squeezed a throat into the exhaust just aft of the CC

It's my opinion that straight pipes on this is just going to be frustrating, but you've created a very watchable process! Thanks.

Mike -

Well, I've considered both A and B. C never occurred to me because I don't think of that as a feature in an engine with a combustion chamber section way larger than the tailpipe. But, I could try that. What would I be going after -- better acceleration of the blast into the tailpipe gas mass? Or more of a 'diffuser' effect, as in the Lockwood or Chinese?

I'm sure the intake flare would be a really good enhancement - of course, the time to mess with it would have been BEFORE welding the pipe in, and I really couldn't think of a very good way to accomplish it. I guess I could just heat the rim and work it out with an ordinary ball peen hammer. Or, heck, I could just build up a nice one out of J-B Weld or fireplace cement! But, yes, I think that would be a definite improvement.

But first, another thing I could try would be an oversize version of my castle nut-and-setscrew variable impedance inlet. It would take a .75 inch nut and screw, but those shouldn't be tough to get. This design has some of the advantage of a flare [because of the way I file the grooves in the notches] and a wide range of adjustment. The only trick would be finding a good way to mount it so it could be easily removed.

I think, though, that a better place for a pinch in the inlet pipe would be right down close to the chamber, where the fuel pipe terminates -- that would create both a sort of 'venturi' [perhaps optimizing mixing a little] and a sort of 'cold flow ejector' using the fuel flow to help pull air in during starting. [I'm not sure where along the pipe you were thinking this would go.]

The only problem I have with any of this, of course, is the introduction of more variables. However, any or all of them would be simple to do. The adjustable inlet has the advantage that the effect is reversible, which tube pinches really are not!

Thanks!

L Cottrill
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With more air, some good growls

Postby larry cottrill » Tue Apr 27, 2004 2:17 am

I tried the engine again tonight with propane, but this time with boosted air. I started out with the blow dryer, which is pretty feeble. However, it did create some good howls, which I thought promising enough to warrant dragging out the mighty Black and Decker Leaf Hog.

I also decided that I was having very poor control over the fuel delivery by just trying to adjust the pressure regulator. So, I quickly added a fair-sized brass body needle valve to the circuit. This allows me to set a fixed pressure to the valve and then use the valve for flow adjustment. This turned out to be a far better scheme for accurate adjustment, and I wish I had done it much sooner.

I set up the test with constant spark, 10 PSI at the needle valve, my left hand on the valve and the leaf blower in my right hand. This worked reasonably well, except that it's hard to maintain a constant relationship between the leaf blower and the engine intake. The tests pretty well convinced me that I can get all the air I need! The action was best when I could get just the right trickle of air from the edge of the blower nozzle into the intake. The blower is very noisy, but to my astonishment, the sound muffs I was using practically cancelled the high-pitched whine while letting the bangs and hoots of the engine through plainly! The muffs are definitely the way to go when the blower is in use.

However, all I got was some impressive pulsejet-like growls when I managed to get the air positioned just right -- not enough to get anything up to red heat or burn off any galvanizing, but impressive sounding, anyway. Obviously not strong enough yet to drive sustaining operation. There were occasionally really good bangs, when I'd let the blower drift around, or when I tried a kind of sweeping motion of the air stream across the intake face. On some bangs [very rich], there was visible flame ejected from the intake stack, especially right after a quick passage of the blower stream.

Next time, I'll go back to using what remains of the MAPP gas and try the same sort of technique. With plenty of air at my disposal, I'm more sure than ever that the flow of fuel gas is too restricted for propane to be delivered effectively. It should take a lot less MAPP to get the same energy or higher.

L Cottrill
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Postby Mike Everman » Tue Apr 27, 2004 3:13 am

Hi, Larry. Fun stuff. WRT the inlet taper, I was suggesting a uniform taper (not a pinch), squeezed more at the opening, keeping the flare at the inlet. I'd try that first. Should be about a 15% reduction in area from CC to inlet, according to my tribal knowledge unwritten rules of thumb. :-P. I'll check early in the thread for your intake diameter, and I have a calculator to tell what the measurement across the flats needs to be for this taper, but I didn't bring home my computer.
Mike
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Postby larry cottrill » Tue Apr 27, 2004 12:22 pm

Mike Everman wrote:Hi, Larry. Fun stuff. WRT the inlet taper, I was suggesting a uniform taper (not a pinch), squeezed more at the opening, keeping the flare at the inlet. I'd try that first. Should be about a 15% reduction in area from CC to inlet, according to my tribal knowledge unwritten rules of thumb. :-P. I'll check early in the thread for your intake diameter, and I have a calculator to tell what the measurement across the flats needs to be for this taper, but I didn't bring home my computer.

Mike -

Thanks. I'm sure what you're suggesting would be helpful, though it would be hard for me to do a very smooth job of it at this point. I'm starting a new thread in a moment that will address what I think the main problem really is.

The inlet ID is just a hair over .75 inch, probably .78 or something on that order.

Stay tuned.

L Cottrill
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Postby Mike Everman » Tue Apr 27, 2004 4:11 pm

Larry,
With a starting ID of .78", for 15% taper, you would progressively squish down to an opening flat-to-flat of .37"

See photo, I used a press, but you could do it in one minute with a vise and a couple of blocks of wood. Note how I just push off center of the blocks to get more crush at one end. Put a stop block at one end so you don't crush the root.

Of course you are right, mixing is paramount, but once you get that, I believe you will need the impedence of the tapered inlet, then tackle the exhaust tube.
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Postby larry cottrill » Tue Apr 27, 2004 5:29 pm

Mike Everman wrote:Larry,
With a starting ID of .78", for 15% taper, you would progressively squish down to an opening flat-to-flat of .37"

. . .

Of course you are right, mixing is paramount, but once you get that, I believe you will need the impedence of the tapered inlet, then tackle the exhaust tube.

Mike -

Thanks. Well, that's a fair amount of squeeze. But, still camparing with the Dynajet [you've got to forgive me here, Mike -- it's the only engine that works that I've ever gotten my hands on!] it makes sense, in terms of the ratio of tailpipe area to inlet area [almost 4:1 for the Dynajet!]. So it doesn't strike me as particularly extreme.

However, I'm going to hold off a bit, and here's why: The first shot I'll try at turbulating the flow will be to create turbulence upstream of the fuel entrance. I'll use some kind of little 'Christmas tree' gimmick slid down into the pipe. Even though I'll try to make this fairly 'low profile', it will obviously introduce some flow impedence of its own, and who knows how close it might come to being about right? If that doesn't seem to produce desirable results, I'll go to more extreme measures, i.e. a bluff body or two in the bottom of the chamber where the forward flow is, and then apply your taper to the unhindered stack.

Do I understand that you want the taper closing toward the top of the stack [the inlet], a la Lockwood intake? It seems that way, since you warned earlier about leaving a flare there. I know a flared inlet would have been a good idea in the first place, but wasn't sure of a good way to get it.

What do you think of the plan of inducing turbulence before fuel induction? As I see it, my turbulator would run right down to the station where the fuel enters. It could even go beyond, of course, if it doesn't seem too draggy.

L Cottrill
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Closer ... closer ...

Postby larry cottrill » Mon May 03, 2004 1:22 am

Ran another couple of test sessions yesterday [again about 60 degF weather] until I once again iced up what's left of the propane and MAPP cylinders. This time I inserted my 'hex sleeve anchor' turbulator in the intake and managed to get some pretty good roars, though still not nearly enough power to take off and sustain. Here's what I think I learned yesterday.

For a given level of fuel input, getting the EXACT airflow needed is quite critical. It is extremely easy to overblow this engine with starting air. Using the leaf blower was very difficult -- it turned out that the shop vac was much easier to handle, but even with that it was difficult to angle the nozzle just right to get just the trickle of air needed. My earlier guestimates of starting air requirement were way too high, at least with the turbulator anywhere in the intake.

The location of the turbulator makes a big difference in the kind of combustion action you get. Basically, it seems to work better the deeper into the intake you slide it. At first, with it high in the stack [by which I mean, fairly near the inlet] it had a barely noticeable effect; when you get it down in the middle of the path, its action seems much better [that is actually about the relationship to the fuel outlet I had shown in my original drawing in my thread on that subject, re-shown below]. Farther down might even be better, so that the fuel is introduced in the laminar flow and then mixed up later as it all gets vortexed together behind the blades.

I found that it was possible to observe the combustion in the chamber by looking right 'down the chute' through the intake stack from a safe distance above and behind. In the common situation of a too-rich mixture, the yellow flame is firing right beneath the fuel port, inside the stack! When air is removed and brought back in, unburned fuel gas has accumulated for a split second and generates a bang that comes out both the exhaust and intake. This can be blue, or very rich and bright yellow with a very loud report.

In the odd moment when you get the air just right for a while, you can see the blue flame racing past the angled cutoff face at the bottom of the stack, just as it should! If you can hold this a little while, you start to get some heating of the tailpipe; the galvanizing is still there, but it now looks like grey primer. At any rate, it was fun to see good combustion moving right past that port, with nary a feather running up the dark walls of the stack!

That's about all I was able to find out. In such cool conditions, it's hard to keep the propane or MAPP flowing very well for very long. I got lots of good bangs and roars, even some higher pitched brief squeals. I did get myself a 20 lb tank of propane Saturday and I now have my old high flow volume Victor regulator set up with the proper stem to connect it, plus the gauge and needle valve needed. Next time, I should be able to run a lot longer! I don't know if a large MAPP tank uses the exact same left-hand threaded stem or not. It is somewhat easier to get good noises out of MAPP gas, but the ambient temperature may have something to do with that.

L Cottrill
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Latest Test Observations

Postby larry cottrill » Wed May 05, 2004 4:30 pm

Yesterday afternoon I tried the first test session using my 20lb propane tank and the high flow regulator. What a difference! I got lots of good bangs and reasonably good roars, but still not self-sustaining operation. The heat of the pipe after running a few minutes might have been just barely red hot, but not enough to see in daylight [and I couldn't re-run at dusk due to other commitments]. The main lessons learned seem to be:

The observation from my last test that only a trickle of air is needed now seems erroneous. I believe that conclusion was the result of self-limited fuel flow due to the restrictions in the regulator and cooling of the fuel cylinder. In this latest test, I found it was possible to provide so much fuel flow that the mixture would not ignite, even with maximum air supplied from the leaf blower! On several occasions, I actually had to back off the fuel flow to re-establish ignition.

I get the best operation from the highest air volume I can supply -- the B&D Leaf Hog at full force and zero spacing from the intake face. [Remember that at this point, there is no intake flare or taper, just a slightly rounded edge on a straight pipe.] When I get the fuel set up right for the air volume delivered, I get a nice roar of maybe a little under 200 hz. As the air supply is pulled back slowly, this gets weaker and is soon drowned out by the blower noise, then dies.

At this high air volume, my turbulator doesn't seem to help much, though it seemed highly effective at low air flows. This seemed mystifying at first, but I think the explanation might be that the leaf blower with its short snout [i.e. extension nozzle not used] contributes significant turbulence of its own, which carries down through the stack some distance before smoothing out. That might also explain the rapid 'tapering off' of power as the blower is backed away from the port [of course, I realize that the velocity is dropping off also].

Another factor that might help a lot in the 'transition' from blown air to self-breathing would be an intake flare. Everyone agrees that this detail is critical to success with all or most valveless designs. And, of course, Mike Everman's suggestion of tapering the intake could still be tried [the idea being to raise the input impedance significantly].

There are occasional super loud bangs [MUCH louder than the cyclical roar] that deliver enough force to shake the engine on its mounts AND produce a pressure wave out through the intake. When this happens, you can feel the impact right up through the leaf blower, going into your hand like the recoil of a small pistol -- highly amusing the first time or two, believe me! But, the condition under which this happens is almost perfectly predictable: it occurs whenever the air stream is briefly interrupted and then resumed. So, it must be from the accumulation of rich mixture [since fuel is still flowing] and the sudden reintroduction of excess air. This is probably to be expected under a configuration where fuel flows constantly and forced air can be varied moment-by-moment.

With plenty of air and fuel, good roaring operation is definitely achieved -- what I got in earlier tests were mere howls by comparison. Nevertheless, it is disappointing that no combination of air and fuel tried resulted in sustaining operation. The one gratifying thing is that, regardless of power level achieved, I can still observe the desired passage of exhaust gas past the bottom of the intake stack [well, OK -- I can't see it at MAXIMUM power, because the snout of the leaf blower is in the way!]. It's just very cool to look down in there and see the little circle of rearward-heading blue flame. I almost consider this vindication of the main point of the Elektra design -- and really it will be, if the thing ever sustains itself!

At this point, I'm pretty confident that I can deliver all the fuel needed to make it run. I can urge a little more velocity [and probably a lot less turbulence] out of the leaf blower by snapping on the long nozzle. I could easily do the intake flare [not necessarily permanent] and/or the intake taper [permanent unless I decide to cut and re-weld]. So, there are still some things left to try.

L Cottrill
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Postby jmhdx » Wed May 05, 2004 10:01 pm

Excellent stuff. Does the gas really prefer to jump the gap.
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Tonight's tests: Good Roars But No Cigars

Postby larry cottrill » Tue May 11, 2004 2:34 am

Tonight I tried two basic changes: First, I used an 'intake flare' which I carved from a funnel-shaped polyethylene bottle neck a few days ago. This is held in place snugly around the top of the intake tube via a hose clamp. For the next test run, I tried setting up a couple of chunks of 2x4 lumber in the vise to squeeze a long diffuser and venturi in the pipe. I used this with the flare still in place. I did not go as far yet as Mike Everman suggested with this -- it is just slightly elliptical so far, not really 'flattened' at the sides. But it is enough to be a significant though small area reduction.

What I was able to do in both runs is get full grease Dynajet roar operation, and some areas of red hot metal within less than a minute after leaning out the mixture. The red hot zones are the flat sides of the chamber, the first few inches of exhaust pipe and the very bottom half inch or so of the intake tube, down inside the chamber where the exhaust slips around it to get to the pipe. Looking down in there, it is something to see -- the red hot rim with thick blue fire streaming past the hole. It's still a thrill for me just to watch it do that! However, I still only get the best running power with the nozzle of the blower right down on the intake, and then you can't see it in action any more 'from the inside out', of course.

If this thing would ever take off and sustain, I guarantee you it would NOT resemble your average 'hamster breathing through a straw'. But, aye, there's the rub. Yes, I can get a horrendous roar -- from under my sound muffs, it sounds just like the Dynajet: a hard, sharp, nasty waveshape. Yes, I can run it like that till metal starts to glow. Yes, I even get a little frost on the propane tank. But try as I might, I cannot find a fuel setting that will let it keep running when I pull the air away. If I back the blower off slowly, it either quits [if set for rich running] or slowly fades into weaker pulsing, rapidly devolving into dull howling, and then 'blowtorch' mode operation [if set lean]. No matter what 'in between' setting I try, it won't catch and go on its own. Perhaps my technique with the blower is poor. Maybe the intake still just isn't right. Who knows?

I now have some fairly good video of it 'running' like that, and should have a couple of still shots to post before the end of the week.

What it appears to boil down to is this: It simply does not seem to develop a really good suction wave on its own.

L Cottrill
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larry cottrill
 
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Joined: Sun Oct 05, 2003 1:17 am
Location: Mingo, Iowa USA

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