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Post by racket on Oct 20, 2015 18:21:00 GMT -5
Hi Feathers
Interesting turb scroll configuration , could you post a pic of the scroll inlet please
Cheers John
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Feathers
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Posts: 169
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Post by Feathers on Oct 21, 2015 11:45:09 GMT -5
Hi Feathers Interesting turb scroll configuration , could you post a pic of the scroll inlet please I definitely will! But some bad news: the shaft is bent! Hard to come across a 50 year-old turbo in good condition, and no chance of finding a replacement part.
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Feathers
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Post by Feathers on Nov 29, 2015 0:41:03 GMT -5
We've been doing lots of work! Flanges, with captive studs, have been welded to the combustor casing. Another set of captive bolts secures this flange to the turbine inlet
We got some new hydraulic brakes off of a pit bike, fabricated a mount for them, and welded the caliper in place. Great improvement over mechanical brakes! We fabricated a mount for the engine, it holds to the back of the turbine inlet flange, and bolts to the bearing box of the rear axle very securely. THICK 1/4" steel plate used for this entire component. Engine mounted! Lots of parts, this is just a fraction of what our group ordered. Shiny AN fittings and ignition coils and other great bits. Mounting the fuel pump. There is a bung waiting to be welded in. All the tanks were made in house, and welded by yours truly. There will be a dip tube to make it to the bottom of the tank, from the inlet mid-tank. AND LAST BUT NOT LEAST! We just got a package from a friend on the other side of the world. Thanks for the turbine mark! We'll take good care of it (as best as we can at least ). We produced a near-perfect cad model of the turbine, so we can experiment with different configurations and implementations in the computer first Does anybody have a source for large (~7", ~180mm) V-band clamps? We can't find any. I've seen some on Racket's vehicles, and Anders bike. We're also in need of a FAT Stainless steel ring to use as the turbine shroud. Searching the internet high and low! Thanks all for your help, and thanks again Mark for the turbine! She's a LOOKER.
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Post by pitciblackscotland on Nov 29, 2015 1:08:23 GMT -5
Hi Austin, No worries glad to help out. Good to see the wheel getting use Cheers, Mark.
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Post by racket on Nov 29, 2015 2:34:02 GMT -5
Hi Feathers
Some of the large Garrett truck turbos have big V-band clamps holding their comp scrolls to the back plate, checkout a truck turbo overhaul shop.
With your shroud for the 3rd stage wheel , I used the same turb wheel for my first turbine bike and I ended up using a ring of flame cut 1" steel plate as both shroud and containment ring , at the temperatures you'll be using, heavy section steel is adequate if given a good coat of high temp exhaust paint , there isn't a ready made size of stainless pipe .
Cheers John
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Feathers
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Posts: 169
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Post by Feathers on Dec 6, 2015 18:37:10 GMT -5
Hey guys, We've been working on the power turbine section (mechanically at least). Seeing what kind of metal stock we have available, and what we can make work. Going for deep groove precision ball bearings on the shaft tunnel, with lubrication from the oil system, potentially. What would you suggest for oiling and cooling considerations? What has been done before? An exploded view of the assembly. Our resident lathe-man pulsedpropulsion has got his hands full. Meanwhile, I've been finishing up our FADEC unit. Its almost ready to be produced. Should be really nice to have an engine that sequences it's own startup! We're also having a nice carbon-fiber steering wheel made by our University's Formula SAE racing team. It will hold another circuit board with instrumentation, buttons, throttle, tachometer, etc. Getting more parts ordered as we speak!
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Post by racket on Dec 6, 2015 18:51:54 GMT -5
Hi Feathers
I noticed in the vid that your turb wheel is rotating in the opposite direction to your sprocket , is there gears in the housing ??
Nice electronics :-)
Cheers John
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Feathers
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Post by Feathers on Dec 7, 2015 3:24:08 GMT -5
Hi Racket,
The "medium" 20-tooth sprocket on mounted to the front of the shaft tunnel is just an idler, and is not driven. The driven sprocket rotates with the power turbine, and has only 8 teeth.
The idler is necessary because the c-20 turbine spins the wrong way for a direct drive in our application.
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Post by racket on Dec 7, 2015 3:38:24 GMT -5
Hi Feathers
Ah , a neat solution having the sprocket on the "outside" of the chain loop . :-)
Cheers John
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Feathers
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Post by Feathers on Dec 17, 2015 20:42:47 GMT -5
It should be a pretty simple fix.
We're just very concerned about two things:
A chain-off event would be completely catastrophic, of course. Racket, did you ever encounter anything like this? We'll be taking all the precautions we can to keep the chain tight and on track.
We're thinking of a hardwired "chain OK" system. This would be a stop switch, with a piece of teflon that rides the chain. If the chain leaves, the switch opens, and the fuel pump cutout relay opens, shutting down the engine.
Also, how do we need to care for our bearings? At the moment, we don't have any preload planned. Just a precision fit to the shaft tunnel. Both inner races will be "clamped" by the shaft assembly, with the outer races free to float axially by a few thousandths of an inch within the bearing tunnel.
Input on this setup welcome!
Thanks!
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Post by racket on Dec 17, 2015 21:33:12 GMT -5
Hi Feathers
Nope , never had any chain problems other than some stretch from too many full throttle takeoffs .
Your freepower rpm will be limited by the chain , so ~20,000 at max for quality racing kart chain , less for anything else , at these sort of rpm you don't need to worry too much about the bearings other than some lube and cooling air .
I don't think you'll need to worry about the freepower wheel even with chain off as your gas speeds will be relatively low , but if you feel the need for some sort of safety device then the one you propose sounds good .
Cheers John
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Feathers
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Post by Feathers on Dec 18, 2015 0:19:31 GMT -5
Sounds good John. Thanks as always for the advice I think we'll use some bleed air/oil for each bearing in the tunnel. We're going for some quality 6006 30mm X 55mm deep-groove bearings. We'll count on bleed air to scavenge the oil back to the reservoir, which will need a vent. Running #35 racing chain, hopefully that will work. We were wondering whether the freepower will reach dangerous speeds, and will probably implement some interlock to shut down the engine if we loose a chain.
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Post by racket on Dec 18, 2015 2:03:02 GMT -5
Hi Feathers
If you can get specs on max rpm and power limits for the #35 chain it'd be appreciated, so we can try and prevent any problems.
6006 bearings are huge for a freepower of your power output , get the "rattly" C3 ones which cope better with the extreme rpm .
If you use plenty of bleed air you only need a drop of oil every few seconds to lube the bearings , it can be a total loss system where the air/oil mix simply gets vented into the freepower space and burnt.
Cheers John
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Feathers
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Post by Feathers on Dec 18, 2015 10:56:07 GMT -5
I'll check up on our chain specs, they run regularly in single-speed 2-stroke 125cc racing karts, with very small output sprockets and engines that peg at 15-18krpm! I'm just glad our bearings won't be too small C3 it is. No issues with an oil bleed. Oil is cheap, turbines aren't. We'll try to keep it from leaking like a sieve and call it good. You mentioned in Anders Jet Bike thread that the C20 wheels are balanced as an assembly (which we'd suspected, there's LOTS of mass missing from the balancing ring on our wheel!) Since the turbine has such a shallow axial profile, is it possible that a careful static balancing would do the trick to run it on it's own? Just giving the drivetrain components a fighting chance in our inexperienced hands. Thanks,
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Post by racket on Dec 18, 2015 18:00:37 GMT -5
Hi Feathers
At the rpm you'll be doing and the size bearings you're using, there won't be a problem even if you don't do anything , a 6006 bearing has a basic static load rating of 8.3 kN and a dynamic loading of 13.8 kN , so even the roughest static balance will be more than enough :-)
Cheers John
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