Bride of Kazooenstein runs yellow hot!

[luc]

Heyyy Mike,

Congradulations with your engine. Now ... You need to put numbers on that engine; i.e : Thrust figure, throtleling span and SFC. But again ... Congradulations.

As for Mark's bottle picture ???? You mind telling me what the hell is this or what are you trying to do ???? A Home made terorist bomb?????... He he he.

Anyway....Good work guys,

Cya,

Luc

[Mike Everman]

Thanks Luc! Mark, if you reply to that here, your hijack will be complete! ;-P

Status report:
I just ran the 2" Bride again last night. It definitely needs a minute of air fed growling before it wants to take off. On the high power side, it is much stronger than my electric leaf blower (out the tail)! It's quite impressive to behold, but it's got to be burning a lot of fuel. The hope is that it is not, of course. Beyond that, I can't quantify it, buy I'll be able to by this weekend. It's my goal to post thrust and SFC numbers by this weekend.

I now have two that are the same except the new one was squeezed .10" less than it's predecessor in the two critical spots, inlet and throat. The previous one starts easier and quicker, the more open one takes some coaxing, but seems to have a good deal more thrust when you get it going really loud. Both idle down to a level you can hold a conversation over, and I must get a handfull of ear protectors for spectators; I'm noticing it's hard to plug your ears and reach out to feel the blast!

For the record, here is the plan for the "as built" Kazooenstein, circular equivalent. If you build this engine, it will run. It's a nice managable size for fun. I plan to sell a full step-by-step plan set for $10 to fund more work, but you could build it easily from this and my previous threads on the subject.

[Bruno Ogorelec]

I plan to sell a full step-by-step plan set for $10 to fund more work, but you could build it easily from this and my previous threads on the subject.

Mike, my ¢2 worth: It will be much more attractive to fans who want to build the thing if you provide the dims for the bent version, using an off-the shelf U-bend -- or with some kind of a thrust deflector.

Most people will want to power something with their engine eventually, even if it is something entirely silly. It won't serve them well if it pushes in opposite directions.

You might try an Escopette-style recuperator made out of an off-the-shelf U-tube. I cannot think of a deflector that would be esier to make.

[Mike Everman]

Recouperation will certainly be covered, and I'm leaning toward a Messerschmidt type for flight. I will certainly diagram method and dimension of the smash, and anything else I can think of! I want to create a document that pulls together and organizes all I've posted and learned about this thing. The intrepid can find all needed here, but highly fragmented, to be sure. I posted a long while ago the tool for estimating the smash dims for a given dia; but while it works in practice I think Larry's treatment is more accurate and I'm re-doing it with that soon.

[jmhdx]

I dont offer congratulations too freely but think maybe some are due here, youv'e almost created a benchmark engine that will be reffered to for years as long as plenty of folks can actually build it. I hope you havent given up on your original design brief though as the crushed pipe design could be easily built anywhere. I appreciate the difficulty in kazooing the front end and despite my confidence elsewhere I cannot offer a fueling solution, although crimping a washer in would produce a turbulent void in front of cc.
I would be happy to buy plans from you and happier still to buy a Kazoo ready built. Have you thought about production?.
If the project is completed air modellers will have an almost disposable, light weight, maintenance free jet engine. Quite something.
Regards,
Mike.

[Mike Everman]

Oops double post.

[Mike Everman]

Thanks very much for the kind words, Mike!

I do have plans for manufacturing them in 3, 2 and hopefully 1" versions. The 3" got finicky on me as I was dreaming of making a production version of it, so I went back to the books for a while and now understand why it's funky, and I'm left with more questions... The mixed scaling, boundary layer corrections and the 2" that proves it out are the result of my current state of understanding. Now that I know the cylindrical inlet on the 2" works well and without a sneaky injector, I will make a fully weldless one, to see if it's viable; stay tuned! You may recall I cut off the Kazooish intake cause I got impatient and screwed it up! I have no doubt this engine has model aircraft potential, when I manage to liquid fuel it.

I am bending a mixed scale 1" (.88" ID) tonight. It is 36" inches long. Thin walled tubing is on the way here. This should be the acid test for my scaling and corrections. I'll start with a smashed intake, and move to the washers, leeetle holes and tubular inlet if no joy. I'll post video of the starting attempt before the week is out.

The spectrum attached is of me blowing into the spark plug hole, flute like on the unbent raw 1" tube. It is 37" long and the hole is at L*20% O-scope on my laptop only heard 634 Hz. Faaaascinating.

[larry cottrill]

Mike -

I ran the circular cross-section equivalent plan through uflow1d [program recommended by Graham]. I particularly wanted to see hot vs cold start characteristics, which were, oddly enough, not really all that different. What I did notice, though, is the wonderful progression of pressure waves through the engine. If I remember rightly, you start getting decent low pressure in the chamber at under .002 second after expansion starts. The mass flow from both ends of the pipe is very smooth throughout the expected cycle time, and seems [to me] actually more balanced than the 40/60 thrust ratio generally quoted would suggest.

Of course, many assumptions about temperature and starting pressure had to be made for these runs; who knows how close to reality it might be? But, it certainly looked nice -- the pressure wave in the Elektra seemed downright chaotic by comparison.

Very nice development - just needs some bracing of the pipe against that high bending moment at the nozzle. That shouldn't be difficult, though it needs to allow unimpeded longitudinal movement at the point of support, of course.

Nice work!

L Cottrill

[Mike Everman]

Hey, Larry. I suspected you were UFLOW literate. I could have sent you the model! Graham has helped me a lot with that, and I owe him a handful of ales when I go to the UK. In fact, his money is no good around here either!
If I had to guess, and I'll know for sure soon, this engine is about 75-25 by feel.
As to the bending, It was turned so the flat was horizontal, and the throat is about 1/4" thick there. I now turn it vertical and I can rigid mount it at the front bulkhead only, without tail support. (I fired it up to red hot again and bent it back!)
If you start with a 220KPa pulse in the cc, you get a 140KPa peak at the end of the cycle. Very small changes to the inlet dia can bring it off of this sweet spot. Cool stuff.

[Mark]

Perhaps you should have named it the Lavitra-stein or the Nitinol-o'-dyne.
It's nice to have a pulsejet that can remember it's shape and bend back when red hot.
Mark

[Dave]

Mike,

Although I have not posted to the forum recently I have been following yours with great interest.

I too look forward to seeing thrust and other numbers and would also very much appreciate any additional information on “the booksâ€

[larry cottrill]

As to the bending, It was turned so the flat was horizontal, and the throat is about 1/4" thick there. I now turn it vertical and I can rigid mount it at the front bulkhead only, without tail support. (I fired it up to red hot again and bent it back!)

Sorry, Mike -- I understand what you're saying, but when you start talking about vehicle propulsion, that doesn't count. In an aircraft, the inertial forces can be many times the gravitational ones. And, they can be in any direction: pitch, yaw and roll ... or any combination thereof. And, the direction and combination of forces can change quite abruptly.

When hot, your flattened tailpipe acts as a long massive cantilever on a soft 'hinge' near the end of the chamber. With the engine running properly, the nozzle zone will always be the hottest, i.e. weakest point. That was observable on the Dynajet, even in flight where the cooling was "practically ideal". I think the best thing to do would be to provide a support near the center of mass of the flattened section. That way, you try to take up the entire inertial load of that part of the engine mass in isolation. This is not perfectly correct, of course, since even the heat-weakened nozzle will still carry a small part of the load in shear, but at least it will theoretically null the bending moment at the nozzle [which now appears as a tension load on one sidewall of the narrow passage and a compression load on the other].

Since the vehicle is capable of sharp turning accelerations [rotational forces in the yaw and pitch directions], there will still be brief episodes of shear at the nozzle zone, as a function of the moment of inertia around my suggested support point. However, with the lightness of material that you have, and the amount of metal cross-section of the tube at the nozzle, this force should not be a serious problem even in the highest G maneuvers, I would think.

This gives you a simply achieved pattern of two-point support: a rigid mounting at or about the front plate, and a sliding fit lateral containment type mounting at the half-point of the flattened tail section.

L Cottrill

[luc]

Hi Mike,

In honoring your good work, I could not resiste drawing your engine in SolidWorks 3D ... He he he. Also, in The version I have, there is a Sheet Metal module included. So ... I took the liberty to do a little test to see how I could deploye each engine sections ... he he he.

Look at the results Mike.

So, this mean that in the futur, if you guys requires some little Wizard jobs to deploye your engines for productions drawings, I will be glad to do it ... Once you know the tricks and trade, it basically take aprx. 5 minutes to do it.

Here ... have a look ...

Cya,

Luc

[Mike Everman]

Cool, Luc! I'll trade you... my Solidworks model is a thin wall sweep, table driven with a variety of LH designs that have been posted on the forum, including Lockwood patent and production drawings. I haven't messed with the sheet metal functions much. Looks Great!

[Mike Everman]

Built a 1" Kazoo, with length scale at an overall length of 36". It has boundary layer compensation at the inlet to the CC and throat, amounting to 1.5mm thickness.

I put some meth in it and it did the pop pop pop pop looodle. First one so far to do multiple pops on meth for me, so I was encouraged. I used the small torch cylinder valve. Nice satisfying bangs with a little compressed air feed needed. Just pops when the spark goes, about 2 Hz. Nothing approaching resonance.

I checked dimensions and I blew one big. The tail is squashed way too far, I'm going to have to open it up or make another. I'll keep trying though, and the spreadsheet is fixed.

I've got some thin wall 1" tube coming, .035 wall actually. I'm looking for thinner, like .015" or .020. I need to make the fuel feed more hi-fi. I'll have it running (if it's going to...) by this weekend. I just need to get this out of my system and move on!