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Post by racket on May 30, 2012 20:17:59 GMT -5
Hi Jamie
Yep , a centrif kart clutch would be the way to go so as to maximise acceleration of the kart , a good quality racing clutch should suffice .
The original aim of building the kart was to show its possible to build a freepowered kart with decent horsepower without the need/expense or complication of a gearbox , it satisfied those requirements.
The sheet metal scroll was not only to minimise weight but also to maximise mass flow through a relatively slow spinning turbine wheel of limited proportions , I was able to flow ~1.1lbs/sec thru the wheel with that setup whereas it would have been less with a cast iron scroll with configuration more suitable to a higher revving turbo wheel .
The bypass of gases exiting the gas producer was necessary due to the gas producer ( TV84 turbo off my turbine bike ) being too large for the Cummins freepower to swallow, ~40% of the gases were fed thru the bypass jet nozzle the remaining 60% thru the freepower , the gas producer can't differentiate between a jet nozzle or a freepower , all it feels is a certain restriction downstream , I just needed to size the jetnozzle correctly to produce the required "backpressure" ....................in most cases it wouldn't be necessary to have that bypass as we'd want all of the gas producers exhaust to feed thru the freepower to maximise horsepower but in my case the gas producer was too big and the horsepower being produced by the freepower was probably at the limit of the karting chain's capacity.
Cheers
John
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sven
Veteran Member
Joined: February 2012
Posts: 102
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Post by sven on Sept 8, 2012 6:33:10 GMT -5
Hi John
I think its a good (simple)solution to make free power unit out of large turbocharger, what to think is it good enough powering motorbike with similar free power unit, or adding gearbox is necessary? Or is it simply to too small scroll(turbine wheel) to power larger and heavier bike even with gearbox, maybe its gonna be underpowered. My plan is use holset he55 as a gas producer and free power unit gonna use holset Hy55 turbine wheel.
Sven
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Post by racket on Sept 8, 2012 18:26:12 GMT -5
Hi Sven
The freepower wheel needs to have a flow area about twice the gas producer's turbine wheel flow area due to the lower gas density and velocities .
An undersized freepower will surge the gas producer and wreck it :-(
Horsepower output and freepower size will depend on your gas producers output , so make the pure jet engine , measure thrust , temperatures and pressures to determine what size the freepower needs to be
Cheers
John
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Post by racket on Mar 17, 2015 4:36:33 GMT -5
Found this pic of the karts first road test whilst digging through the archives , lotsa stuff I'd forgotten about :-)  Cheers John |
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Post by pitciblackscotland on Mar 17, 2015 5:01:33 GMT -5
Hi John, Nice pic there with your brother on the right. Would be nice to see that kart flying down the road again. Cheers, Mark  |
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Post by racket on Mar 17, 2015 19:40:56 GMT -5
Hi Mark
LOL...... I don't look a day older ;-)
Its a shame someone hasn't done a "proper" freepowered kart with 150 hp , now thats something that would move along, this one was a very basic/simple setup without gearbox , I can only imagine a gearbox'ed ones performance ............heh heh , maybe we talk Andrew into cannibalising good ol' Frank to make one .
Cheers
John
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Post by pitciblackscotland on Mar 17, 2015 22:17:37 GMT -5
Hi John, No No!!! that's what Andrew will say maybe someone will build a 150 hp turbine kart Cheers, Mark. |
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Post by racket on Mar 18, 2015 0:01:59 GMT -5
Hi Mark
LOL, Smithy could make a 200 HP kart using the existing GT6041 gas producer ;-)
Cheers
John
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Post by enginewhisperer on Mar 18, 2015 0:13:29 GMT -5
I do have a kart frame and a GT6041 too  it's very tempting - just got a few other projects in the way at the moment. btw the 6041 isn't going to end up in the boat. It'll be getting a piston engine for now (turbine assisted though, and around 400hp |
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Post by Johansson on Mar 18, 2015 1:00:11 GMT -5
it's very tempting - just got a few other projects in the way at the moment. That exact phrase must be crossing my mind 5 times every day... |
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Post by enginewhisperer on Mar 18, 2015 2:00:55 GMT -5
I think I might get it every 5 minutes Eventually a few of the projects merge together and become one bigger, better one though I also tend to work by collecting parts over time, until something comes together as a workable solution for a problem, and then that project takes priority! |
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Chuks
Senior Member
Joined: August 2015
Posts: 498 
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Post by Chuks on Aug 19, 2015 10:39:17 GMT -5
Hi everyone! Wanna a question that have been bordering me, can a turbo jet engine be used to power a bike? If yes is it gonna be as powerful as the wonderful ones I have been seeing here? Please tell me about it?  |
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Post by racket on Aug 19, 2015 16:47:31 GMT -5
Hi
It depends on the airflow rate of the jet engine as to how much horsepower can be produced from attaching a freepower wheel
Cheers
John
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rolandsean
Member
Joined: September 2020
Posts: 13
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Post by rolandsean on Oct 19, 2020 8:38:28 GMT -5
Scroll was fixed to the shaft tunnel using the standard Vband arrangement . The 2 red plastic covers on brass fittings at the sprocket end of the shaft tunnel are where bleed air from the gasifiers combustor and bleed lube from the main lube pressure system are supplied to the shaft tunnel . Lubrication is total loss , a supply of a few drops /min is all thats required , the bleed air forces the lube thru the bearings and out into the turbine ducting . The bleed air also supplied an "air seal" around the shaft behind the sprocket to prevent lube leakage , the majority of the bleed air exiting at the turbine wheel prevents hot gases entering the bearing space , keeping bearing temperatures at reasonable levels. Total weight of freepower stage including mounts was 8 kgs -~18 lbs John, do you have more pictures of the construction of the oil bearing housing? I will need to construct something of the sorts and I planned on having sealed bearings, I have never heard of a total loss oil system used like this and it makes sense to use for this. Any info on your R&D for bleed air design and such. I am sure it has been covered somewhere in here so if you could link me to a good build and design that would be much appreciated. Very cool build. |
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rolandsean
Member
Joined: September 2020
Posts: 13
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Post by rolandsean on Oct 19, 2020 8:47:58 GMT -5
Hi Richard Theres some video of the kart runs on Youtube www.youtube.com/watch?v=F-fci_AlNMU , acceleration was kinda slow initially , as with most single ratio freepowered turbines , but picked up once the freepowers rpm rose and it started producing horsepower rather than just torque . From a standing start it took ~5.1 seconds to cover the first 50 metres-55 yards , but only 2.4 seconds from 50 to 100 metres . The kart is now with a new owner , but I'm in the planning stage for another , using either my 9/94 engine, www.youtube.com/watch?v=8Y8jpaDTkEY , with afterburner, or a "fan " engine I'm considering building using a transonic first stage axial comp wheel flowing ~10 lbs/sec powered by a 4th stage Allison C20 freepower wheel with gas energy coming from the 9/94 engine or a DIY gas turbine engine made from a new/reman Garrett GT60 turbo I have sitting in the shed , the GT60 turbo weighs a lot and would probably require something more substantial than the usual lightweight kart chassis .................LOL, mind you , both setups will need something substantial for the projected ~500 lbs of thrust, project for 2011 year :-) Cheers John Sorry John, another question: when using a freepower wheel to produce shaft power, is the exhaust still usable exiting the freepower wheel to, say, run an afterburner? If not, is it because of too low of velocity or what prevents its use as such? Thanks |
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