Jet Snowmobile Project/Team

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luc
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Jet Snowmobile Project/Team

Post by luc » Tue Mar 04, 2014 2:02 pm

Hi members,

Long time no chat and I'm glad to be back ... :wink:

I've been asked to put to gether a team and build a Jet powered snomobile using "Thrust" (Not torque) to accelerate and race 1/4 miles, and one of the criteria is that IT MUST BE an "Homebuilt (DIY)" turbine.

Now, I found this on Internet that I find pretty interesting and basically a jet engine using six (6) turbos, all of them having a common combustion chamber and exhaust. You will understand that before putting something like that together, I need to make certain it WILL (CAN) work so we are not gona waist money and time putting this together if this concept has no chances of working.

So here are my questions to you fellow experts and friends ;

1 - Will this work?
2 - If yes, can it be started by spinning only one turbo, then, the remaining 5 will follow, or we have to spin all 6 of them at start?
3 - Still if yes, and as no turbo are perfectly identical even if the same models, do you think one or more might spin faster to the point of stalling others, or they will all follow each other on acceleration?

Interesting concept and I'm ready to give it a try, but I just want to make certain it has chances to perform.

Thanks for your comments and answers guys :wink: :wink: ,

Regards,
Attachments
Radial 6 Turbines.jpg
Luc
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racketmotorman
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Re: Jet Snowmobile Project/Team

Post by racketmotorman » Wed Mar 05, 2014 8:27 am

Hi Luc

LOL........good to see you getting back into burning kero :-)

To answer your questions about Sals design ......

1 ...........theoretically , yes.

2 ..........no , all turbos will need to be spooled up together , with only one turbo being spooled up the air from its compressor will enter the single combustor and bleed out through the remaining non spinning compressors rather than going through the flametube into its turbine stage and/or the other turb stages .

3.......... if all the turbos are the same model with similar compressors/turbines as well as comp/turb scroll A/Rs , the slight variations shouldn't mean a big difference between individual turbo rpm .


The greatest problem could be getting an ever distribution of gas flow to the individual turbine stages .

Theres a twin turbo engine of similar design thats already running , its was built by Nick Haddock a number of years ago but finally installed in a vehicle only recently , mass flow of >4 lbs/sec .

Hope to hear more of your project :-)

Cheers
John

luc
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Re: Jet Snowmobile Project/Team

Post by luc » Wed Mar 05, 2014 2:05 pm

Heyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy .... My Good Buddy Racketmotorman,

Geee I'm glad to here from you man .... And thanks for the answer buddy ... Most appreciated.

Now, I do and fully understand your answer about "Spooling up the turbos together so air does not escape from the other NON turning turbos"; But whal about if I cap the 5 others turbo's compressor inlet so air could not flow through???? I think this might solve the problem for as the first turbo get spooled, air would be forced to flow through the flame tube as it CAN NOT go out through the other turbos, although all 6 of them would spin from the initial combustion.

NOTE : We both understand the 5 "Capped" turbo's compressors would cavitate for a while and until the cap is remove.

Then, and once a primary or initial combustion is established, it would just be a question of removing each "Compressor Caps" one after the other.

Of coarse, this is easier said and wrote ... Then done, and I do understand this. But Ruffly speaking and if I would get the hang of it, you think this would work????

ALWAYS a pleasure chating with you John,

Best regards,
Luc
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Re: Jet Snowmobile Project/Team

Post by racketmotorman » Wed Mar 05, 2014 9:39 pm

Hi Luc

Nope , that won't work :-(

By splitting the hot gases exiting the flametube into 6 parts , there won't be enough energy going to the one turbine wheel spinning its compressor wheel and attempting to supply air to the combustor , you'd need to blank off the other 5 turbine stages as well as the compressors to have any hope of getting the engine running , ......................... much easier to fit impingement air start to all comp wheels and spool them all up together.

How big is this engine going to be ??

What sized turbos ??

The guys on the JATO Site http://jetandturbineowners.proboards.com/ would be very interested in this build , maybe a build Thread on there as well,......... please :-)

Cheers
John

luc
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Re: Jet Snowmobile Project/Team

Post by luc » Thu Mar 06, 2014 12:39 am

Hi John,

Okeyy ... I beleive you if you say so, although I won't garanty I won't try it ... He he he .... stuborn me lolllllllllll.

As for the engine, I would like to use six (6) Garrett GT6041 with a potential 270 lbs. thrust each, but the 6041 has journal bearing and I would rather use roller bearings, so, I might settle for GTX5533R and a 206 lbs. thrust potential per turbos for a 1236 lbs. pound of thrust @ 100%, but I do want to put an afterburner on this thing too and over that 1236 lbs. of thrust.

The overall idea is to have a vehicle having a 3:1 thrust to weigth ratio @ 110% (AB On) power.

As for building a new thread on another board ... I don't know ... You know me the "Not to crasy guys about spreading my self all over the Web" ... One guys did that for me years ago and it was more then enough ... He he he ... Joke ... Lollllllll

But I will take your above writing with true considerations, although I REALLY have a big problem using 6 leaf blower to start that big bitch ... Lolllllllll

Cherrs buddy,
Luc
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racketmotorman
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Re: Jet Snowmobile Project/Team

Post by racketmotorman » Thu Mar 06, 2014 5:03 am

Hi Luc

Theres a build Thread on JATO for my GT6041 kart that might be of interest to you ...............http://jetandturbineowners.proboards.co ... wered-kart .

One potential "problem" with GT55 range is the turbine flow , even the GT6041 has to have the larger 1.47 A/R turb scroll rather than the standard 1.25 A/R for the compressor to flow its optimum rate , you'll need to do the "corrected flow" calcs for the various GT55 turbos and their various turb scroll A/Rs to see if they're large enough.

Is there any reason why you want to use roller bearings rather than brass bushes , the lube system will still need to be fairly generously sized whichever bearing system you use .

Where did you get your potential thrust levels from ??

Using fairly normal efficiency levels as well as turbine inlet temperatures of ~900 deg C the GT6041 will only produce ~140 lbs "dry" and ~170 lbs of thrust with afterburner , so ~1,000 lbs of thrust max with six , and six GT60's will weigh nearly 500 lbs ......... with mounts , combustor , afterburner, pumps etc that'll probably go out to ~600 lbs ...................she'll be a weighty engine :-(

No need for leafblowers , my mate Smithy fitted an electric start to the GT6041 .

The guys in the UK are using high pressure air impingement from SCUBA tanks on their large turbos to spool them up ...................Andy M has fitted similar to my 9/94 engine thats in his drag bike thats under construction http://jetandturbineowners.proboards.co ... ike?page=4

Cheers
John

luc
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Re: Jet Snowmobile Project/Team

Post by luc » Thu Mar 06, 2014 1:49 pm

Hi Luc

Nice kart I have to admit ...

Roger that for the correction ...

The reasonS why I want to use roller bearings rather than journal bearing brass bushing is because; 1) They are more tolerant to vibrations, especially when you're 300 kl/h on a "Bumpy" frozen lake, and 2) I have developped a clutch system to general good level of linear tthrust on the bearings ... Rollers are tuffer.

I got the potential thrust levels estimation from a document I have here, but its size does not allow me to attach it here ... Look on thre Internet for the PDF document titled : Constructing A Turbocharger Turbojet Engine
By Edwin H. Springer ... There is a chart in that document.

I got an electric start system capable of running 12 VDC ... But it will take ALOT of power to simulataniously start 6 turbos.

I will have to put my head in "Starting" that big baby ...

Cheers
Luc
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racketmotorman
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Re: Jet Snowmobile Project/Team

Post by racketmotorman » Fri Mar 07, 2014 12:22 am

Hi Luc

I'll have to disagree about roller bearings being better , the GT6041 is used on a lot of BIG CAT diesel engines of >2,000 hp that vibrate like hell for thousands of hours on end ................the oil damping effects increase life of a turbo , all the huge ABB ship turbos run brass bushes for 30,000 hour TBOs.

Springer ..........bloody Springer , he's been the bane of my life, I've spent countless hours helping guys who've read Springer and constructed engines that won't work .......Springer knows "shit all" about turbine engines .

Lets take an example ..... a 4" inducer ............ yes his area is correct at 12.57 sq ins and 0.087 sq ft , but thats where it stops being correct ....................with an average turbo inlet velocity of ~475 ft/sec for good efficiency , the static pressure has dropped from 14.7psia to ~12.7 psia , that 475 ft/sec is worth ~2psi of dynamic pressure which when added onto the 12.7psia restores us to the 14.7 psia total pressure we had in the ambiant air before it was accelerated thru the nozzle ( bellmouth) into the compressor wheel, the compressr wheel doesn't suck the air in , ambiant air " forces" its way in by changing some static for dynamic pressure .

Now air at 12.7 psi has a density of ~0.066 lbs/cu ft, and with say 475 ft/sec through an area of 0.087sq ft , thats ~41.3 cubic ft /sec , multiplied by our 0.066 lbs/cu ft gives us a mass flow of 2.72 lbs/sec , nowhere near Springers 6.67 lbs/sec figure , a Garrett GT6041 has a mass flow of ~2.75 lbs/sec thru its 4.16" dia inducer ..................there is some inlet choking of a GT6041 at high rpm due to the relative air speed at the inducer tips going supersonic because of the wheels 56 Trim , most high pressure wheels are <50 Trim , preferably low 40s Trim .

So we can now say Springers figure from here on will all be incorrect .

A well built DIY engine will produce a jetpipe total pressure of ~24.7 psia or ~10 psi on a the gauge supplied from a pitot tube in the jetpipe. ....................10psi indicates a potential Pressure Ratio across the jet nozzle of ~1.68 :1 and will produce a jet velocity of ~1650 ft/sec , thrust = mass flow times velocity , 2.75 X 1650 div by 32.2 =140.9 lbs of thrust for a GT6041 nowhere near Springers 269 lbs for a 4 incher.

If we were to use Springers mass flow of 6.67 lbs/sec that would produce a thrust of 341.8 lbs .......................he knows bugger all about the maths .

As for his flametube design, it doesn't work , far too small a cross section resulting in too high an airspeed for the combustion of kero , also the hole areas are all wrong , and the fact that he uses an annular dilution ring at the bottom of the flametube , an area which will change due to both axial and radial expansions of the metal parts resulting in a change in dilution area percentages ..........I could go on and on and on :-((

DO NOT USE SPRINGER'S PAPER, ITS CRAP .

Cheers
John

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Re: Jet Snowmobile Project/Team

Post by luc » Wed Mar 19, 2014 2:01 pm

Hi John,

Sorry for not answering sooner, for I'm all over my shoulders here ....

As for Springer, I will take your words for it because I've learned to trust you and I know YOU know your stuff. But sadly, I think about ALL THE peoples that will fall for it and maybe it is time for you buddy to publish a book about the topic.

As for the choice of "Roller bearings" over "Bushing", I will have to stand against your opinion, and for as I will NEVER argue against you over "Turbines", I will also do the same for my "Turbo Expert" guy here http://www.turboexperts.com/ and for he is TRUELY a turbo expert having the firm position that "Bushing Turbos" will NEVER last as long as a "Roller Bearing" turbo. In fact, what ever you can post in "Working Hours" for bushing turbos, make it even MORE for "Roller", and this, not discussing "Starter motor induced axial thust" ... ;-)

Suggestion; Why don't you correct Springer's chart and posted here on Pulse-Jets.com by the way ... I'm certain much will appréciate the data ... ;-)

Always nice to chat with you budy ... ;-)

Regards,
Luc
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racketmotorman
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Re: Jet Snowmobile Project/Team

Post by racketmotorman » Wed Mar 19, 2014 9:14 pm

Hi Luc

LOL., ...........I must have written "the book" a hundred times with the thousands of replies I've contributed to http://groups.yahoo.com/group/DIYGasTurbines/ .......and the http://jetandturbineowners.proboards.com/

I think the "brass vs roller" preference is like Ford vs GM preference , its in the eye of the beholder , ball bearing turbos for putting on autos where rotor acceleration is important vs steady state long life use with brass bushes , " horses for courses" ,...... when I see ABB , MAN and other heavy industry turbo manufacturers using balls , I'll believe they're better for our DIY gas turbines ,

checkout the latest from ABB http://www05.abb.com/global/scot/scot26 ... arging.pdf

............heh heh , your mates at http://www.turboexperts.com/ have been listening to the turbo company reps trying to sell their "over priced" ball bearing products ;-)

I guess you'll need to reappraise the build in light of the lowered thrust levels , I hope you do make a multi turbo unit , it'll be unique .

Cheers
John

luc
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Re: Jet Snowmobile Project/Team

Post by luc » Fri Mar 28, 2014 3:22 pm

Hi John,

Replying to your message using your own text ...
LOL., ...........I must have written "the book" a hundred times with the thousands of replies I've contributed to http://groups.yahoo.com/group/DIYGasTurbines/ .......and the http://jetandturbineowners.proboards.com
I will keep an eye ont these, but I still think your should put all this together and write the "John Wallis DIY Turbine" novel ... I would shure buy it in an instant ... ;-)
I think the "brass vs roller" preference is like Ford vs GM preference
I would agree to that no problem ... :wink:
checkout the latest from ABB http://www05.abb.com/global/scot/scot26 ... arging.pdf
NICEEEEEeeeeee .... What's the price rage from size to size comparisson with Garrett? Are they cheaper or more expensive?
............heh heh , your mates at http://www.turboexperts.com/ have been listening to the turbo company reps trying to sell their "over priced" ball bearing products ;-)
Bla bla bla ... Don't be a "Rep" your self ... It suits you not ... Lollllllllll ... :wink:
I hope you do make a multi turbo unit , it'll be unique .
Welll ... I want to ... And more peoples are aware of my projet, more either ppushes me doing it or want to join. As fopr "Multi turbo", I do not consider any other avenue, but with you kinda "Blew" my bubble telling me the other guy's writing was bullshit ... I need to rethink my position and "Thrust" requirement, for "Multi Turbo" yes ... But not using 20 turbos to acheive 1000 lbs of thrust ... Hooo welllll ... Back to the calculations sheet ... (Taugh; Why are they allowing idiots to publish on Internet ... Geeeeeeeeeeeee).

Cheers mate ... :wink:
Luc
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Re: Jet Snowmobile Project/Team

Post by racketmotorman » Fri Mar 28, 2014 10:50 pm

Hi Luc

The ABB turbos are very expensive :-(

Yeh , Springer should be sued for false advertising , it really is all crap , just another poorly attempted money grab from unsuspecting guys wanting to build a turbine engine , thats why the DIY Gas Turbines Site was able to help out .

Our thrust outputs depend almost entirely on the size of "hole in the front" , its mass flow that we need as its only possible to produce ~50 - 55 lbs of thrust per pound/sec of mass flow from the average large turbo , this might be pushed to 60 lbs/lb/sec with a good quality turbo running at its limits , these figures can be increased by ~40 % by afterburning ........so lets consider a max of ~80 lbs/lb/sec .

Your 1,000 lbs of thrust requirement would need at least 12 lbs/sec , say 5 X GT6041 turbos with afterburning to be on the safe side ...............but they're going to weigh a lot :-(

There are some other "large" Chinese turbos that might be worth looking at , you may not be able to push them as hard as the GT6041 but its mass flow we're after not high pressures , have a look at the J160 Model which presumably can flow 2kgs- 4.4 lbssec , this is probably well into the choke region but even if we come back a bit to 4 lbs/sec for better efficiency , you'd be needing less turbo's :-)

http://www.turbochargers.cn/Products/Tu ... eries.aspx

Cheers
John

luc
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Re: Jet Snowmobile Project/Team

Post by luc » Wed Apr 02, 2014 9:11 pm

HI John,

Indeed, ABB are very expensive ...

As for the GT6041, I was planing to use 6 turbos originally and weigth is not a concern since this would be an ice racing jet sled.

Now, and since we are at destroying Springer, I got a few "Rules of Thumbs" for dimensioning the flame tube and chamber, such as 3 time the compressor inducer for the flame tube diameter and 6 time for the lenght ...ect ect ect.

Now if I would ask, what would be YOUR "Rules of Thumbs" for the flame tube diameter and lenght and chamber diameter and lenght???

As for "Holes area", I'm using your spread and guest what ???? I done building two jet engine using GT4708R and I get 450°C (842°F) EGT and 187°C (370°F) ejected inducing fresh air to cool that exhaust gas for the industrial application I working on ... I will soon have a movie for you by the way ... ;-)

Hooooo ... And my baby(s) starts 12 VDC with a nice electric motor I found and the clutch I've designed ... You will LOVE this .. ;-)

Cheers,
Luc
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racketmotorman
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Re: Jet Snowmobile Project/Team

Post by racketmotorman » Wed Apr 02, 2014 10:55 pm

Hi Luc

LOL.........I helped design Jetspecs , Jesse took my Rule of Thumb numbers from the Yahoo DIY Gas Turbines Site and put them into a workable Program , we spent months getting it "sorta right" , its not perfect but it does produce a working engine , so I'd still recommend a large combustor :-)

6 X GT6041 turbos have ~82 square inches of inducer area , X 3 = 246 sq ins for the flametube crossection , mmmmmmmmmmm,.......... 17.7 inch diameter , BIG , but then theres a lotta air being processed .

Length can be varied depending on your fueling , a single spray nozzle feeding diesel will need a long flametube of probably 40 inches overall , whereas multipoint injection of propane could cut the length to half that and reduce the diameter a bit , multiple spray nozzle of diesel could be a similar length to propane but at "full" diameter , a considerable portion of the overall length will be taken up with "splitting" the flow into the 6 ducts feeding the individual turbine scrolls .

Outer can diameter , 21 inches, to give a reasonable flow clearance between flametube and can.

Cheers
John

luc
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Re: Jet Snowmobile Project/Team

Post by luc » Thu Apr 03, 2014 1:12 pm

Hi John,

Lollll ... You obviously did not understand my question or did I formulated it wrong ... Lollll

My question was more toward providing the audience with your "Rules of Thumbs" since I know they work great, and not for my big jet project, but more for someone wanting to build a single DIY turbine using a car (Truck) turbo ... Lolllllll
Example (Yours) ;
- Flame tube diameter should be ......(This).......in reference of ....(This)
- Flame tube lenght should be ............(This).......in reference of ....(This) ......
- Combustion chamner diameter should be ......(This).......in reference of ....(This) ......
- Combustion chamber lenght should be ............(This).......in reference of ....(This) ......
Mine are ;
- Flame tube diameter should be the resulting diameter of 3X the selected turbo inducer's inlet area (Inducer area X 3 converted into a diameter).
- Flame tube lenght should be 4X the selectec turbo inducer's diameter converted into a length (Diameter X 4 = Length) ... For propane (Don't know the reference for kerosene).
- Combustion chamber diameter should be 50% bigger then your flame tube diameter (Flame tube diameter X 50% + Flametube diameter = Chamber diameter) ...... For propane (Don't know if this would work for kerosene).
- Combustion chamber lenght should be equal to flame tune length PLUS a little gap to allow flame tube thermal expansion.

The above (Mine) make a great running turbine using liquid propane ...

This way, with can have this thread "Sticky" so NO ONE else will fall in Springer damn delusion ... Lollllllll ... ;-)

Cheers,
Luc
Designer & Inventor

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