Pipe organ stuff

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Mark
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Pipe organ stuff

Post by Mark » Wed Nov 17, 2004 3:34 am

I wonder if someone got their hands on a pipe organ if they could make a valveless device out of one of the pipes or some sort of honking snorkeler, something that would sustain pulsating combustion?
Some ideas along the way.
Mark

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Key of F.

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The big boys

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steve
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Re: Pipe organ stuff

Post by steve » Wed Nov 17, 2004 3:43 am

you can always tell when someone has the pulsejetting disease by its most obvious simptom: The sight of a round hollow object is almost always accompanied by the phrase "Hey, I bet I could make a pulsejet out of that!"

(Just a hunch, but I think Marks got it)

:-)

It does kind of look Like it could be made to run though...
Image

Al Belli
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Re: Pipe organ stuff

Post by Al Belli » Wed Nov 17, 2004 1:27 pm

Hi,

The pipes in a " classic " pipe organ are made from a lead alloy, and would melt. More modern organ pipes were made from zinc.
The pipe material must be " dead " as far as vibrationally-excited resonances, since the pipe's voice is purely an air resonant tone.

Al Belli

larry cottrill
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Re: Pipe organ stuff

Post by larry cottrill » Wed Nov 17, 2004 1:28 pm

The problem with using an actual organ pipe would be materials - the metal ones are generally tin or brass or some such, with soldered seams. The square wooden ones are, well, wood. There's nothing that says you couldn't base a pulsejet design on organ pipe design, though, in some way.

I have built wooden organ pipes out of popsicle sticks, one for each of my sons when they were little, and they worked great as little whistles [until they get wet at the breathing end] - these were closed pipes, so not as high-pitched as you might imagine.

A 32-foot organ pipe is a thing of wonder to behold, especially a big wood diapason all stained and varnished on the outside. You could home-build really nice wooden ones with something like birch plywood, if you can figure out where to get big enough pieces.

L Cottrill

Mark
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Re: Pipe organ stuff

Post by Mark » Wed Nov 17, 2004 3:33 pm

Here's a history of pipe. I hate you all for bursting my pipe organ idea.

http://www.encyclopedia.com/html/p1/pipe.asp

Here at least is someone who might have a high temperature pipe organ.

http://thebase.weblogger.com/stories/storyReader$3365


http://www.lhpo.org/lhpo_images3.html

Mark
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Mike Kirney
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Re: Pipe organ stuff

Post by Mike Kirney » Mon Nov 22, 2004 7:40 am

It's interesting how the pitch changes with the force of the draft up the pipe. Would it be a change in airflow velocity that alters the frequency of vibration?

Larry, do you think those square organ pipes could be make out of solid pine? I have a whole bunch of 6 foot and 8 foot s4s pine that is about 7/8" by 7 1/4" (nominal 1 x 8). I have some tounge and groove pine that is about 5/8" thick, 5" wide, and some pieces are 12 feet long. I have yet another pile of rough 1 x 8 pine with some pieces 17 feet in length. Can you suggest a workable L/W ratio for square wooden resonant tubes?
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Re: Pipe organ stuff

Post by Mike Kirney » Mon Nov 22, 2004 7:46 am

Maybe you could set an organ pipe some distance back from an augmented pulsejet and use that airflow to generate a note. You could choose a jet whose frequency complements that of the pipe somehow and create some otherworldly sonic effect. By the way, what did you do with all your knocked-down trees from the hurricane?
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Re: Pipe organ stuff

Post by larry cottrill » Mon Nov 22, 2004 2:05 pm

Mike Kirney wrote:It's interesting how the pitch changes with the force of the draft up the pipe. Would it be a change in airflow velocity that alters the frequency of vibration?

Larry, do you think those square organ pipes could be make out of solid pine? I have a whole bunch of 6 foot and 8 foot s4s pine that is about 7/8" by 7 1/4" (nominal 1 x 8). I have some tounge and groove pine that is about 5/8" thick, 5" wide, and some pieces are 12 feet long. I have yet another pile of rough 1 x 8 pine with some pieces 17 feet in length. Can you suggest a workable L/W ratio for square wooden resonant tubes?
Mike -

I have never understood what exactly alters the frequency of an 'overblown' pipe. The classic tracker-action organs of Bach's day were all driven by low-pressure sources, and the sound is clean and wondrous. I have heard recordings of several German organs that were played by Bach himself, and the sound is fabulous, to this day!

Of course you could make an experimental pipe out of that stuff, though it's a bit massive by organ-building standards. Organ pipes are built over a wide range of L/D ratios, the ratio affecting the tonality, i.e. what 'voice' the pipe will have. This is also affected by such things as small tunable vent pipes piercing the closed end, tapered vs straight pipe, etc. Keep in mind that a big pipe requires a HUGE air volume to sound!

Unlike pulsejets, organ pipes scale perfectly if all are operated under the same pressure. A tiny 'flute' pipe a couple inches long will have the same voice as a 16-footer, with the internal dimensions exactly scaled. Of course, this assumes that the material is identical and the wall thickness is to scale, too, at least approximately. [I think that scaling the wall thickness becomes less critical with the smallest pipes, because you and I can't hear the upper harmonics, anyway, but a professional might point out some flaw in this assumption.]

Making even little pipes and hearing them work is fascinating. The critical part is the labial ["lip"], the knife-edge going across the top of the open mouth of the pipe. You have to get the air flow as precisely aimed at that knife-edge as you can manage, and perfectly uniform flow across its width - much easier to do with a small pipe than a big one. This need for uniform flow is the reason for the large 'diffuser' section at the bottom of the pipe.

Organ pipes are very ancient, organs with keyboards appearing before the ancient Greek civilization. The pressure was regulated with water pressure, somehow, so the ancient organ was known to the Greeks as the hydraulos.

L Cottrill

Bruno Ogorelec
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Re: Pipe organ stuff

Post by Bruno Ogorelec » Mon Nov 22, 2004 4:47 pm

Mike Kirney wrote:Larry, do you think those square organ pipes could be make out of solid pine? I have a whole bunch of 6 foot and 8 foot s4s pine that is about 7/8" by 7 1/4" (nominal 1 x 8). I have some tounge and groove pine that is about 5/8" thick, 5" wide, and some pieces are 12 feet long. I have yet another pile of rough 1 x 8 pine with some pieces 17 feet in length. Can you suggest a workable L/W ratio for square wooden resonant tubes?
If yo have some long square-section pieces or can make them, building tubes out of wood is a cinch using the bird-mouth technique.

It's a curious but very neat method that boat builders appear to have forgotten and rediscovered several times over the centuries. They have always needed a way to build strong hollow spars, but it is fairly difficult to do without this trick.

It should be a good way to build organ tubes, too.

Al Belli
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Re: Bird mouth technique

Post by Al Belli » Mon Nov 22, 2004 5:13 pm

Hi,

For this technique of building wooden pipes, see- http://www.duckworksmagazine.com/r/arti ... h/mast.htm

Al Belli

Bruno Ogorelec
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Re: Pipe organ stuff

Post by Bruno Ogorelec » Mon Nov 22, 2004 5:51 pm

Thanks, Al! I only knew the rule of thumb, which is OK for simple jobs, but I'd be hard pressed to work out a taper.

What I love about this trick is that it is incredibly simple, yet works exceedingly well. It increases the glue joint area by almost 50 percent and the interlocking resists delamination far more strongly than a butt joint. It can also be used to make oval spars.

I always thought that a hardwood pulsejet built this way would be a funny thing to have. The 'voice' would probably be quite something. A century ago, in these parts, rebellious peasants were making cherry wood canons. They could not afford cast iron or steel. They were reportedly quite effective. I've seen a few. Very quaint. You'd sooner expect them to hold rum than fire lead balls and iron nails..

BTW, Mike, when I wrote 'square section' I really meant 'rectangular section'. A slip of the pen (keyboard?). Square section would not be good for this purpose.

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