Welcome to the JATO Forum!!!

[racket]

Hi Thomas

Beautiful engine you guys are making there, nice machining work :-) ....................LOL , I can well understand why your Site has been neglected .

Yeh , can't mix the start gas and kero in the same manifold , I tried that with my FM-1 engine
www.youtube.com/watch?v=VX5U8DlBzzk , I then made a dedicated propane manifold which fed gas to every third evaporator , this was then changed again to stop "explosive" ignitions by only feeding to the "lower half of the engine , this system was used in the subsequent 9/94 engine www.youtube.com/watch?v=8Y8jpaDTkEY and 10/98 engine www.youtube.com/watch?v=NR0rsTbkOS4.

7:1 pressure ratio , that's certainly going to need some serious tip speeds , 670-680 m's ........110 mm comp ........65-70mm inducer for 115,000 rpm ??

You and Andreas have excelled with that creation ...............very professional bit of kit with pretty expensive R and D by the look of things,............... nice :-)

Hope to hear a bit more as development progresses .

Cheers
John

[turbotom]

Hi John

thanks for these kind words. You can be sure that a lot of money went into the project, yet we received some support by the government (ministry for education and research). As I told, the PDF is not quite accurate anymore, we lowered the PR a little, it's now 6.5 and the compressor tip speed at the design point is 650m/s (equals 100krpm at a compressor diameter of 125mm, inducer is 75mm but the hub is quite large,too). As soon as a gearbox is involved, things become complex. Clearances are of major concern and the lubrication also gets much more difficult. We end up with three engine-driven accessory devices, our fuel control unit (variable displacement sliding vane pump with manual/stepper motor control, mechanical 102% limiter with differential perssure valve to prevent flameout, injection pressure limiter valve), an oil feed pump (with integral filter, filter bypass with electrical actuation signalling, pressure limiter valve and electronic oil pressure transducer) and a dual element oil scavenge pump with bypass valves. Only these accessories were hell of a design job and required considerable (financial) effort. The high speed reduction gearbox is another major factor. It's hard to believe how few companies actually can internally grind the single-piece ring gear for our planetary gearbox. The turbine section itself just becomes "one problem" among others. We tried several ways to produce the prototype waxes to have our turbine wheels cast but finally found that the only really viable way is to have a proper mold made. And that's just what I lately got accomplished. It's a real work of art, consisting of 30 wedges that are pulled individually after the wax has been injected (15 blades and each wedge had to be separated in two to be able to pull it out). Later I may post a photo or two.
I see you have also been busy... great job! And you've got something in advantage -- your engines are running already!

James -

the radial turbine wheel is clearly the better choice in this size and also you can expand a much higher pressure ratio across a single stage. In case of an axial turbine, we would have needed at least two stages. And the clearance losses are also more of a problem in the axial design. Another advantage is that a two-stage axial setup would have been difficult to design with a hub without bores. The single radial turbine easily permits this configuration, making a hub burst virtually impossible (provided the casting is free of voids). We'll see how it works - if the casting company finishes our wheels in due time, we may get the first prototype running by the end of this year.

Cheers,
Thomas

[propellanttech]

Thomas,

Your explanation makes perfect sense. I hope it works as you designed. I'm sure all of us will be eagerly waiting to see the new design come to fruition.

James

[racket]

Hi Thomas

Yeh , gear reduction for us home builders is even more of a nightmare , if you're having problems in the heart of industrial Europe , its a hell of a lot worse down under here in Oz , even being able to source a set of ready made gears is difficult , bespoke gears are horrendously expensive even for spur gears , I can only guess what that internal gear costs to produce , lotsa Euros :-( ..............even the "off the shelf" set of 6.125:1 helical redux gears we used for our freepower stage groups.yahoo.com/group/DIYGasTurbines/photos/album/176970103/pic/500109250/view?picmode=&mode=tn&order=ordinal&start=41&count=20&dir=asc cost ~$400 , and they're only "rough" industrial gears from a "low speed" electric motor gearbox

What bits are you going to use for the freepower turbine stage ?? ..... I'm assuming the engine is only a gas producer from looking at the compressor/turbine relative sizes .

Is it having a separate unit or is it mounting directly onto the gas producer ??

Our bike's freepower stage/redux needed to be a separate unit because of installation requirements/limitations that a sports bike imposes, thankfully it ended up being reasonably compact despite the 212mm axial turbine wheel , and came in weighing <20 kgs for the complete unit , we were rather fortunate that the helical gears were cut in the right direction as the gear mesh axial loads oppose the gas loads on the turb wheel

Cheers
John

[ouchthathurt]

Hi all i live in the uk and have just bought a Hamilton Standard APU but know nothing about it so any advice on building a test rig would be great. Thanks

[turbotom]

Hi John,

I won't comment how much has been spent so far on the whole project - if I knew that six years ago and also how long it would take us, I might have decided to attempt something else...

Actually, it's a single shaft unit, regarding the relitive size of the wheels you are right, at full power we've actually got a slight mismatch of the gas velocities in the turbine.

But theoretical papers on radial turbines report that the losses aren't too high if there's a "positive" mismatch, i.e. the circumferential speed of the gas is higher than the impeller tips. Yet, this means at slightly reduced (cruise) power, we'll have very high efficiencies. Moreover, the strong backsweep of the compressor blades will result in less circumferential speed of the air than of the impeller.

I guess we'll just have to test it and improve on whe we'll find. Because like always with a project like that, the trouble only starts when the "baby does it's first cry"

Cheers,

Thomas

[racket]

Hi Thomas

Yeh , they always seem to cost a lot more than expected , I've given up keeping a tally of costs , its upsetting to see you've spent hundreds of dollars just on stainless nuts and bolts .

I was curious about your turbine wheel size because of the high pressure ratio you are expanding through it , the turbine wheels on APU type engines seem to be "oversized", with the turb wheel being larger in diameter than the compressor wheel and having a large exducer area to flow the fully expanded gases , whereas your turb wheel is sort of normal turbo proportions which generally only cater for relatively low pressure ratios .

Are you designing for supersonic gas velocities at the turb wheel inducer ??

Something I'm not understanding here :-(( .........................LOL.....I'm only use to dealing with pressure ratios of up to ~2.3 :1 across my turb wheels ...............your >6:1 is giving my head a hard time :-)

OH yeh !!! "first cries",....unfortunately I've heard those a few times .................generally followed in quick succession by my screams of despair as another rotative is wrecked ;-)

The more I look at those pics of your new engine, the more I'm impressed by the thought and workmanship you guys have put into it ...................something for me to aspire too .

Cheers
John

[Drastyk333]

Hello to all,
My name is John,I'm a newbee to this forum,glad to have something like it.
THANKS!!!!
A little bit about my interests,I have been collecting and "PLAYING WITH"
APU and turboprop turbines for many years now.Currently my collection includes
Garrett TPE331-25-AA turboprop,2ea GTCP85-90,GTP70-19,GTP30-51,and a
Tiernay TT10 all in various states of operation.I also have quite a bit of manuals and PDF files on many other APUs.Am always looking for more and am willing to share what info I can.
I havent done any thing on the DIY turbines side of things yet,but am entertaining the thought.I have a turbo off of a CAT 3306 engine that is in good
shape.
Again thank for this forum
John

[racket]

Hi John

Welcome to the Group :-)

Thats quite a collection of commercial engines .

Plenty of info here for your DIY experiments , more technical info on the sister site at Yahoo DIY
tech.groups.yahoo.com/group/DIYGasTurbines/

Cheers
John

[ernie wrenn]

You in Fairbanks Alaska!!! you need to get one started on biodiesel and use it to heat your shop. We did a GPU on bio and the shop smelled like Chinese chicken wing for months.

Gald to have you on board.

ernie

[Drastyk333]

I've thought of biodiesel now and then,but thats all I have done.Eielson AFB
down the road recently had up for sale thru Gov Liquidation Sales 33,000 gal
of cooking oil from their mess halls.It was first time the US gov has tried to sell their cooking oil I dont know if they got any bids.Thats about 6000 gal of oil.
I could make a lot boidiesel for my shop and "my hobby". Lord knows turbines eat fuel in massive quantities.Hell of a hobby but tremendously enjoyable.


John

[boniholmes]

Hi all,

I am new to the forum. I am the member of the sister forum, been away for a while. I am about to start again my project, to build a DIY jet engine based on a (possible KKK ) turbocharger.

Keep up the good work, turbine freaks of the world!

Happy turbinating,
Bon

[nikita]

Thanks for setting such site. It is now easy to get answers of queries which can make growth in knowledge...

[Richard OConnell]

I am very grateful for the knowledgeable members we have aboard. Without them, this place would be an empty shell I just hope that the information contained within can be a valuable resource for our patrons.

[joolsned]

Hi everyone, I joined the group today. I have been interested in gas turbines for many years and have built many home made engines from old turbchargers, I also built a jet bike (Yamaha TZR 125) a few years ago powered by a Lucas aerospace cr 201. My new project is a Palouste powered bike with around 400 lbs of thrust