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Post by racket on Sept 10, 2019 15:52:00 GMT -5
Hi John
There have been very few turbine engines made in the size you want because small turbines are too expensive compared to an IC engine , and turbines don't scale down well , the bulk of them are APUs with single shafts which produces a lightweight/expensive engine for a very specific aircraft requirement , two shaft engines are bigger, heavier, and more expensive again, so simply not made .
The other problem you'll have with any engine you find is "spares" if something goes wrong , so think carefully before handing over a lot of cash , you really need to see the engine running .
Cheers
John
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Post by aquaticharpy on Sept 27, 2019 20:37:51 GMT -5
What would be a good engine then. Say if I did have more room. Any output shaft rpm as long as its reasonable (2500 to 12000rpms) And about 100-1000hp. Something cheap with parts that are easily fabricatable or found and a good manual with it? Thanks Guys! Someday I hope to have a decent turbine car! Maybe something off a heli?
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Post by aquaticharpy on Sept 27, 2019 20:49:54 GMT -5
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Post by aquaticharpy on Sept 27, 2019 20:55:36 GMT -5
I have a chance to get a "rebuilt T50" looks brand new with control panel and such for 10k. How would that fare mounted to a 6 speed tranny? What's the output rpms and such? Thanks!
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Post by racket on Sept 27, 2019 23:12:13 GMT -5
Hi
None of those Links are suitable
A 2 shaft turbine engine doesn't need a 6 speed gearbox , single speed is sufficient for a car scenario , 2 speeds at most even for a relatively heavy vehicle.
The Boeing 502 engines are getting kinda old , the 553 is a better option ,............ but again I have to mention spares availability, ............limited and often very expensive for ALL turbine engines.
There aren't many turbine cars around because there really aren't many suitable engines, the engines that were made were very expensive when new , so by the time they become cheap enough for us to play with , they're seriously outdated and/or not worth playing with .................as I mentioned in an earlier email , be very careful about paying out cash for an engine without seeing it run , theres a lotta bullshit being sprayed around by the guys selling turbine engines on ebay .............theres just too many "zero time ??" engines that have obviously been "prettied up" to sell .
Cheers
John
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Post by aquaticharpy on Sept 28, 2019 9:01:39 GMT -5
How about a T50-B0-8A? And I would enjoy a 6 speed gearbox for a decent speed and acceleration. Perhaps a little tire squak.. what do you think? Would that turbine be suitable? What would you reccomend. And I do have axis to 5 axis cnc machining for many materials so parts arent an issue
Thanks
John
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Post by racket on Sept 28, 2019 17:07:30 GMT -5
Hi Yep , a T50-BO-8A would be OK for an automovtive application as long as it was all there and you inspect it running up to 100% before purchase . With ~300 hp at ~6,000 rpm you'll have ~263 ft lbs of torque at full speed , so ~525 ft lbs of torque at nil output rpm ( stalled) , with a 4:1 diff ratio and a straight connection between turbine and diff you'd have ~2,100 ft lbs of torque at the wheels , with a 2 foot diameter tyre , that equates to ~2,100 pounds of "thrust" .....................no need for a gearbox , .............yeh, I know you'd like 6 speeds , but unnecessary , it only complicates matters as well as making the machine less driveable , a single speed ( with reverse) 2 shaft turbine powered machine is a joy to ride/drive , no clutch , no gearchanging , just uninterupted smooth power. en.wikipedia.org/wiki/STP-Paxton_Turbocaren.wikipedia.org/wiki/Howmet_TXwww.autocar.co.uk/opinion/motorsport/insight-rover-brm-gas-turbine-powered-le-mans-racerAnd probably the best example to date of a single speed "homemade" turbine powered machines capability www.youtube.com/watch?time_continue=11&v=yD8YEGD6TW4As for machining parts yourself , generally the bits that let loose are turbine blades/NGV and bearings , you might be able to make other parts , but bearings for turbine engines can be very expensive . Cheers John |
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Post by aquaticharpy on Sept 28, 2019 18:07:28 GMT -5
So, rack and pinion 1 speed gear box. Would you reccomend a stall/torque converter for the best acceleration I could get? I'm running 14in tires and want good full throttle performance and the best acceleration as I could get.
Thanks!
Hope to get a turbine car soon! ^-^
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Post by racket on Sept 28, 2019 19:14:09 GMT -5
A torque converter will help with acceleration as it'll allow the freepower to be turning and producing some horsepower rather than just torque prior to "takeoff" ..............but it'll need to be a beefy convertor capable of handling a 600HP sized engine due to the torque convertor effects of the freepower turbine when stalled out with the gas producer at 100% ...................with our homemade turbine setups the initial acceleration is "retarded" a bit as we change over from just torque , which effectively does nothing , to shaft horsepower which represents work capability such as vehicle acceleration With a 6,000 rpm output from the engine it'll just be a straight connection to the diff , the "single speed gearbox" is already built into the T50 engine,.......... as a bare minimum, just fit a torque converter onto the output of the T50 and a tailshaft to the diff, if you need reversing capacity then you'll need to modify those minimum requirements. The Chrysler turbine car en.wikipedia.org/wiki/Chrysler_Turbine_Car needed a more complex gearbox setup because it was a grossly overweight vehicle for the modest power output , the engine in its final form was great, but they put it in a heavy family sedan rather than a lightweight sports car , a 140 HP engine in a 2 ton body :-( ..... if it'd been installed in a 1 ton or less vehicle it would have been a more balanced setup and much more successful . How you eventually need to set things up will depend on a number of factors,........... something to be discussed at a latter date :-) Cheers John |
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Post by aquaticharpy on Sept 28, 2019 22:35:56 GMT -5
I don't need reverse I guess. 1300lb is usually easy enough to push around. So I'm going to mount a turbine to a torque converter to a diff and be good? What about a neutral gear? Would you suppose the torque converter would act as a reverse gear? Be able to hit a certain rpm and go then I could back off the rpm for slow cruising? What would you reccomend as a rack and pinion gear ratio?
Thanks!
John
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Post by racket on Sept 28, 2019 23:22:56 GMT -5
You've got me confused here :-( Neutral gears are "bad" , it unloads the freepower turbine wheel which can be easily oversped unless theres some sort of fuel "govenor" attached to it. For simplicity and safety , the "best" scenario is a fixed connection between engine output shaft and the differential. 300 HP and 1,300 lbs to move will make for lively acceleration , my original turbine bike had 115 RWH and shifted a 616 lb bike with my 200 lb ass on it (816 lbs combined weight) up to ~120 mph in a 1/4 mile in ~12 secs www.youtube.com/watch?v=P-5PgWqgIJo speeds in kph not mph , no sound , my digital camera didn't have any and there was a limit of ~12 seconds of videoing back then .............how times have changed :-) One of the early turbine cars used a small electric motor to provide reverse gearing once the main engine was shut down . "Rack and pinion gearing  ??"............what/where are we talking about here . Cheers John |
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Post by aquaticharpy on Sept 29, 2019 9:01:03 GMT -5
Sorry for the confusion.
I forgot since it's a turbine spinning it backwards would be ok. I suppose I can do an electric reverse. A few hp electric motor should move 1500lb fine with me in it.
And ring* and pinion gearing, the gear ratios in the diff. Would we want 1:1 and let the torque converter handle takeoffs? And would the turbine have enough power for direct drive without dieing from lack of speed? (Say 2-3 mph traffic cruising)
Thanks!
John
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Post by aquaticharpy on Sept 29, 2019 11:28:40 GMT -5
Also what would we want the torque converter stall rpm to be at?
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Post by racket on Sept 29, 2019 16:58:47 GMT -5
As far as diff ratio is concerned , use a "normal" ratio for the top speed and/or acceleration rate you want assuming the vehicle had a 300 HP piston engine in it which rev'ed to the same output rpm as the turbine engine replacement .
Low speed cruising is just a function of how low you set the fueling to the combustor/s , with my 2 shaft kart as well as the bike , I found an idle which produced ~7 psi from the compressor was best , this gave a "coolish" interstage temperature and it only required a small touch on the throttle to get the kart/bike moving .................a number of the early turbine cars had highish idle settings to reduce "turbo lag" which resulted in the car actually getting up to a steady speed whenever the brakes weren't applied , to go slow you needed to keep your foot on the brakes.
The torque converter stall speed need not very high unless you were after max acceleration , a stall of ~1,000 rpm would probably be sufficient , remember that you'll be effectively running 2 torque converters as the freepower stage has its own torque converter characteristics, the "auto" torque converter is only there to provide some freepower rpm to aid in optimising acceleration , its not needed with a 300 HP turbine engine in a lightweight car
Theres a number of variables at play , the main one will be just how low an idle you can achieve with the engines gas producer stage and just how much it affects its rotors ability to accelerate quickly and how that affects driveability, lotsa unknowns .................but 2 shaft turbine engines have very fat power curves and a torque line thats as good as it gets .
To optmise the setup I really need to know what are the main performance parameters you want to achieve , exactly the same as if you used an SI engine
Cheers
John
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Post by aquaticharpy on Sept 30, 2019 0:09:39 GMT -5
I'm going for snappy acceleration when I want it, hence a higher torque converter, as well as good drivability in the 5-20mph range as well as decent acceleration going from say~ 50-100mph
A standard 'regular' diff would have a transmission attached so you had torquey low gears and fast high ones. A regular ratio I think would severely limit speed without a transmission attached to slow speed up the engine. I'm not too sure on that though.
Around 5mph idle is where I'd want to be most likely.
I'm still wondering as to why not a transmisison? It would give me good low speed gears and be able to keep the engine in the powerband with opportunity for high speed cruising as well. I might be thinking of this from too much of a piston engine perspective.. How fast would a 6k tire rpm translate to road speed?
Just trying to clear some things up. I'm still going to do what you said in terms of drivetrain. I trust an experienced man who owns a turbine bike more than a rookie just getting started on his first turbine vehicle.
Thank you very much!!
~John
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