tapering tubes?

Moderator: Mike Everman

Post Reply
pezman
Posts: 613
Joined: Fri Oct 08, 2004 4:13 am
Antipspambot question: 0
Location: USA

tapering tubes?

Post by pezman » Sun Oct 17, 2004 2:59 am

I want to start fiddling with the creation of a "Bruno-O" high compression pulsejet. The only uflow models that show promise consists tapered tubes end to end. Anyone got ideas on how to make a tapered tube (1" id -> 0.5" id) about a half meter long?

I think that the engine will take some fiddling to get is to work, so I'm hoping for a really simple technique. Careful "squashing" of the tube was the only idea that I've had so far.

steve
Posts: 1029
Joined: Sun Jun 06, 2004 12:29 am
Antipspambot question: 0
Location: Clinton Conneticut / Melbourne Flordia
Contact:

Re: tapering tubes?

Post by steve » Sun Oct 17, 2004 3:22 am

how would you make one? a hammer, an anvil, and lots of patience

sounds like the tailpipe on the K-PT01b I built

http://www.pulse-jets.com/phpbb2/files/dsc01134.jpg
http://www.pulse-jets.com/phpbb2/files/dsc01041.jpg
http://www.pulse-jets.com/phpbb2/files/ ... nd_new.jpg
Image

larry cottrill
Posts: 4140
Joined: Sun Oct 05, 2003 1:17 am
Antipspambot question: 0
Location: Mingo, Iowa USA
Contact:

Re: tapering tubes?

Post by larry cottrill » Sun Oct 17, 2004 3:25 am

I think the best idea I ever saw posted on something like that was from somebody [probably Mark] who suggested visiting junk shops to find tapered tubular steel table legs. Of course, those will be almost a metre long, but you might readily find one that you can cut the proper piece out of. It depends, of course, on whether you feel you need precise dimensions or just something reasonably close. They will almost certainly be plated or painted, but I've never found that to be particularly troublesome when working with steel pieces.

If you live in or near a good-size city, just set aside a Saturday to go tour the shops - you probably already know where some of them are.

L Cottrill

pezman
Posts: 613
Joined: Fri Oct 08, 2004 4:13 am
Antipspambot question: 0
Location: USA

Re: tapering tubes?

Post by pezman » Sun Oct 17, 2004 5:51 am

The table thing is sheer genius. The dimensions just need to be close enough for govt. work -- if the design is too sensitive to geometry, then it probably won't throttle, won't operate when its too hot or cold etc., etc.

I'll grab a table for long sections and maybe a chair for some shorter sections. If I can get a prototype running then I can go back and build it properly.

If a working engine ends up looking anything like the model, then I've noticed that tapered light poles seem to be just about the right dimension for a big engine ;). The pulses would be two 40 Hz waves (out of phase) with lots of harmonics -- one way to make the local papers, probably.

Mark
Posts: 10753
Joined: Sat Oct 11, 2003 10:14 pm

Re: tapering tubes?

Post by Mark » Sun Oct 17, 2004 7:22 pm

I thought it was some likeable British fellow, I can't remember who suggested or posted a picture of some table legs. I suggested some tall flared stainless steel lamps I saw in a large hardware store in the lighting section that had ceiling fans, tall and short lamps, etc.

Mark

Hank
Posts: 539
Joined: Fri Oct 10, 2003 4:34 pm
Antipspambot question: 0
Location: Florida, USA

Re: tapering tubes?

Post by Hank » Thu Oct 21, 2004 12:45 am

[quote="steve"]how would you make one? a hammer, an anvil, and lots of patience

To which I might add a template and a clear vision in your mind of where you want to wind up as far as form.
You might want to research the processes involved in forming.
Hank

Bruno Ogorelec
Posts: 3542
Joined: Sat Oct 04, 2003 7:31 am
Antipspambot question: 0
Location: Zagreb, Croatia

Re: tapering tubes?

Post by Bruno Ogorelec » Thu Oct 21, 2004 9:16 am

steve wrote:how would you make one? a hammer, an anvil, and lots of patience
I'd add the instruction a friend of mine said he had seen in the manual for a Japanese bike that arrived in kit form and had to be put together by the buyer:

"The building of this bicycle should be attempted only in the state of complete emotional balance."

Mike Everman
Posts: 4930
Joined: Fri Oct 31, 2003 7:25 am
Antipspambot question: 0
Location: santa barbara, CA
Contact:

Re: tapering tubes?

Post by Mike Everman » Thu Oct 21, 2004 11:41 am

LOL! As well as the running of it.
Mike
__________________________
Follow my technical science blog at: http://mikeeverman.com/
Get alerts for the above on twitter at: http://twitter.com/mikeeverman

Mark
Posts: 10753
Joined: Sat Oct 11, 2003 10:14 pm

Re: tapering tubes?

Post by Mark » Thu Oct 21, 2004 1:30 pm

I love those Chinese instructions too. I got them with my two lathes, and other things I have ordered. The writing is flowery and as if a child were trying to caution you ever so gently about a serious potential hazard should you botch the assembly and/or use the device after having one too many beers.
Something like "do not enjoy beer while lathe is spinning." It's a riot to read the well-intentioned but laughable warnings, the incongruity. Maybe something like this too, "electricity can be about, do not think of something else if wiring is suspected, memory in a capacitor may last ."
I should get out my manuals again.
Mark

Mike Kirney
Posts: 517
Joined: Fri Oct 03, 2003 11:11 pm
Antipspambot question: 0
Location: Round Lake Centre, Ontario, Canada

Re: tapering tubes?

Post by Mike Kirney » Thu Oct 21, 2004 1:58 pm

Most tables are about 30" or 32" high, so the legs would be slightly shorter than that.
Trig IS fun.

Bruno Ogorelec
Posts: 3542
Joined: Sat Oct 04, 2003 7:31 am
Antipspambot question: 0
Location: Zagreb, Croatia

Re: tapering tubes?

Post by Bruno Ogorelec » Sat Oct 23, 2004 10:14 am

Mark wrote:I love those Chinese instructions too. I got them with my two lathes, and other things I have ordered. The writing is flowery and as if a child were trying to caution you ever so gently about a serious potential hazard should you botch the assembly and/or use the device after having one too many beers.
Something like "do not enjoy beer while lathe is spinning." It's a riot to read the well-intentioned but laughable warnings, the incongruity. Maybe something like this too, "electricity can be about, do not think of something else if wiring is suspected, memory in a capacitor may last ."
I should get out my manuals again.
Mark
A guy I know just sent me the text he took of a German website. The Germans have started manufacturing the Raven powered hang glider. Since the guy does not speak German, he pushed the text through Babelfish. Here's what he got:

courtesy of www.babelfish.altavista.com:

Who didn't dream yet to fly independently of mountain or hoist with its hanging glider where always it wants? But not with the power saw in the neck, but with a quiet and nevertheless strong engine belt, which well processes to handle easy and is fully everyday life suited.
Start from the level, the engine turn off and in the thermionics circle. If nothing more goes, comfortably by e-starter the hanging glider engine to start and home fly. No aufwaendigen back getting actions.
A Sightseeing flight in the vacation, with an engine belt, which fits comfortably into the trunk. Walk-fly or simply, the homeland from air explore. Which kite flier didn't dream yet about it?
With the Raven all this is in a simple manner feasible. The engine belt has enough thrust, in order to start from the level with zero wind. It is a minimum drive, which hardly worsens the aerodynamics and flight characteristics of the hanging glider. Thus also long thermikfluege with this minimum system with fun are feasible.
The harness is a modern front A riser with camera, radio and seitentasche. In order to achieve as good-natured a flight characteristics as possible with takeoff and landing, consciously without a central suspension one did.
Hand gas, Choke, starter button, engine circuit breakers and propeller brake are ergonomically positioned at the control console at the pilot shoulder. The pilot has so at any time all controls before eyes and full control of its Drachenmotor.
Der Raven is in less than five minutes and due to its easy handling a very good-natured foot-startable UL system. Randy Haney, thereby a completely balanced engine harness succeeded to the technical designer and manufacturer of the Raven, at which each ambitionierte hanging glider pilot can have its joy.
Motorized kite flies in its Urspruenglichsten form.

pezman
Posts: 613
Joined: Fri Oct 08, 2004 4:13 am
Antipspambot question: 0
Location: USA

Re: tapering tubes?

Post by pezman » Sat Oct 23, 2004 4:10 pm

lol

I'm glad I asked the question - not only got an answer, but the thread has taken such an interesting turn

Post Reply