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DumHed
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Jet engine

In late '99 / early 2000 I built a basic turbine engine using a Toyota CT20 turbo and a combustion chamber made from various copper pipes and some sort of water heater casing I bought at a scrap metal shop.
It worked, but the chamber was too small to get the turbo up to a proper idle speed, although it did self sustain.
The flame extended too far past the end of the combustion chamber and caused the turbine to run too hot.

Recently I became inspired about turbines again so I put together a new engine on friday night (which might be a new record, 24 hours for a complete build? Smile)

I used a hotdog exhaust resonator as my combustion chamber, with a plate welded on one end to mount the fuel injector and spark plug, a steam pipe elbow on the other end with a flange for the turbo, and a pipe welded in the side to connect to the compressor outlet.

The fuel (LPG) is injected via a car LPG mixer ring, and the spark plug protrudes through the middle of it.

The engine fires up quite easily and was happy to sustain 10psi of pressure, but made some nasty noises at 12-13psi so I shut it down.







You may notice what looks to be a garden hose connected to the turbo oil feed Smile
I figured that since it has hydrodynamic bearings, as long as the pressure and flow are high enough, water should work instead of oil.
The end result is that yes it does, but the tap can't provide enough pressure for full power running.
I'll be building a proper oil system and changing to a larger turbo in much better condition this week.


I might have to bring it to the next event I can make it to Smile
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Post Mon Nov 21, 2005 3:45 pm 
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dyrodium
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YES please do! Very Happy
LOL i wonder what the neighbors will start thinking if someone built a pulsejet? Shocked
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Post Mon Nov 21, 2005 4:47 pm 
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DumHed
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I built a pulse jet back when I built the previous turbojet.

It was very audible from about 2km away Smile
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Post Mon Nov 21, 2005 11:33 pm 
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Glen
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holy crap thats awesome.

so does the air get sucked in one half of the turbo sent to the combustion chamber than back out the turbo?
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Post Mon Nov 21, 2005 11:49 pm 
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Big AL
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i seem to remember myth busters did a jet engine useing a vacume parts wouldhave worked if they had a slower fan and that one could have been mounted on a plane/robor Twisted Evil
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Post Mon Nov 21, 2005 11:56 pm 
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Glen
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id doubt it, arent the turbines in a vacuum plastic? youd probably end up melting them as soon as it started idling.

or did they make a ramjet or something? cant remember..

lol @ the pulsejet, people must have thought you where making some V-1s in the backyard Razz
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Post Mon Nov 21, 2005 11:59 pm 
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kkeerroo
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The Mythbusters jet engine didn't work because a jet engine is designed to create high pressure within the engine while a vacume motor (what they used) is designed to do the opposite.
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Post Tue Nov 22, 2005 3:30 pm 
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DumHed
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does anyone know of anything with a nice big planetary gearbox in it (or any other decent high torque reduction gearbox?)

What sort of reduction is in a circular saw?


I have a huge mega old school turbo that I pulled apart last night. I'm thinking about using its turbine to drive an output shaft via a gearbox so I can power a go kart or similar from the jet Smile
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Post Thu Nov 24, 2005 12:33 pm 
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Nick
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Circular saws usually just have two helical gears with not much reduction, plus they would probably not take the power. Big industrial saws have worm gear reduction.

Could you use the gearbox form a small motor bike via a belt drive? If your jet is anything like others I have heard of, you will need a huge reduction ratio! Stick the exhaust out the back of your kart and just use it as a jet...
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Post Thu Nov 24, 2005 1:23 pm 
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DumHed
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yeah I'll be trying it as a pure jet, but would also like to add the power turbine to it to see if I can make useful shaft horsepower.

I think the power turbine would be spinning at 40,000rpm or so (it's pretty big) so a 10:1 or even 5:1 reduction would be ok.

A planetary gearbox would be ideal for minimising axial loads on the turbine shaft, but I could also mount the gearbox in line with the shaft and have a coupling with some flexibility in between.
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Post Thu Nov 24, 2005 1:53 pm 
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Rotwang
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Winch gearbox? Auto trans , or off to that junk shop I told you about.

Post Thu Nov 24, 2005 2:17 pm 
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DumHed
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yeah I just realised that I have a winch gearbox.
I'm not sure how well they'd handle the high rpm but I'll have a look at it tonight.

I haven't ever looked inside an auto transmission, but that's also a good possibility.

There's a good junk shop near my work, but it's not as big as that one in Geelong. They don't have anything much, but I did find a cool 1960's lucas fuel injection pump which I think will work well as an oil pump once I replace the motor with one that works Smile
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Post Thu Nov 24, 2005 2:28 pm 
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DumHed
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OK I pulled apart the winch. I don't think it'll take any sort of high speed or sustained usage, but it's a pretty nice solid gearbox for low speed stuff Smile

I finally got a damaged centrifugal supercharger I have apart tonight, and that looks pretty promising. It's a very tough sort of planetary gearbox with a big pulley one the input (which would be the output in my case)

The output (or now input) shaft on it is bent, so I need to get it completely apart and machine up a new shaft for it.
Then I have the option of rebuilding it as a supercharger, or using it as a gearbox Smile

The oil pump I got didn't end up working out too well (a 1960's Lucas fuel injection pump with a dead motor) after I adapted a 100W scooter motor to it.
It does actually work, but seems to aerate the oil too much and give very sporadic output. I'll have to try it on something with lower viscosity.

I connected a power steering pump up to my drill, and even at low speed it pumps heaps of oil so I think that'll have to be the go.
I'll probably drive it from a whipper snipper engine so the whole thing can be self contained without electrical power.
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Post Thu Nov 24, 2005 11:11 pm 
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DumHed
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tonight I built the whipper snipper engine powered oil pump, which has a custom pulley on the engine driving a power steering pump via a short multi rib fan belt.

Hopefully it'll all work!

Last night I built the oil filter and pressure sensor setup, so once I have a couple more bits done it should all just plumb together Smile
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Post Thu Dec 01, 2005 10:44 pm 
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Knightrous
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mmmmmmmm, gas turbine
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Post Thu Dec 01, 2005 10:50 pm 
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