F86_SABRE

Thanks Gerald for the link. Google is my friend so there will be not much of an issue with translation. Thank you!
Reuben

athome

No problem Gerald, but let’s get back to turbines. I‘m on the way of recreating the whole 2nd stage! Will design a new turbinewheel and a new NGV during my summer holidays. Much larger than the 85mm wheel. Airflow is the main problem!
I have the same problem like most of us: Too many ideas and no time
regards Lukacs

Gerald Rutten

That's ambitious! Maybe try and contact Dieter from Jetmax and see if he would be interested? He has all the moulding and casting equipment available, worth a try?

Rgds,
Gerald

athome

Hi Gerald
As far as I know, he has no bigger wheels and NGVs. That was also the reason he sold me the 84mm NGV and wheel. But now I know because of different measurements and calculations it is too small. I've already some ideas for creating...

I would like to talk with you once more about your design of the diffusor. I have calculated the turbine on the basis of Thomas Kamps and there I get an angle of only 18.5° for the angle alpaha
Thomas Kamps also wrote in his book about “backward curved blades compressor“ and then to use an angle of 21° for angle alpha. For “vertical blades compressors” he recommends an angele of 18°. So the compressor I use is the same as you took.
Which amazes me is that you have even steeper angle of 22°? Or is it the angle bisector who counts?
Why do I ask? It's because I'm still fighting with rotating stall or surging when I make the compressor more effective by closing some holes and move the inlet closer to the compressor

Attached you find my drawing of your diffusor with additional angle information.

happy to hear from you
regards Lukacs

Halcyon66

These guys have wheels and NGV up to 200mm, they will also produce from drawings.

yilicasting.com

Regards,

athome

Thank you Halcyon66
I‘m already in contact with them ;-)
regards Lukacs

Gerald Rutten

You should use the average angle of 17 degrees instead, this makes the angle quite flat.

You are absolutely correct, again, I do have to point out this diffuser has never been tested by me and was a retro fit of the older JG100 double stage diffuser. This particular compressor has a different retro curve compared to most compressors and also compared to the one Thomas refers to in his calculations. So you're in a trial and error zone here. The original JG100 diffuser has different angles as well, see picture below. As the outflow angles of the T04B compressor wheel seems quite critical I tried to adopt the angles from the older diffuser but again, never tested these. I was asked to release the plans anyway to do some own testing.

Here the JG100 diffuser using same compressor;


Compared to my GR180 which is quite different;



These diffusers are a bit of a black art within gasturbine engines and sometimes it's difficult to find the sweet spot in all rpm region where all angles coincide with the best compromise. If I would have the time I would gladly make a few diffusers with different angles and try them out. I however would be tempted to go even 1 degree flatter using this compressor to let's say 16 degrees and give it a go. If you have cnc equipment maybe make two diffusers, one +1 and one -1 and see the difference.

I hope this information helps in deciding what direction to go, I would be glad in assisting you on any thought you have.

Kind regards,
Gerald

athome

Hi Gerald
I feel so honored! I‘m also so impressed by your fast answering time! Thank you very much! And your answer clarify a lot.

regards Lukacs

athome

Hi Gerald
Thank you for this photo. I don’t know if a blueprint for the JG100 diffusor exists. If one exists I’m very interested to get it.
So I did a little bit reverse engineering. I found a lot of interesting things…

The alpha angle is probably 15° or 7.5° that’s quit flat. Flatter than Thomas recommends for “perpendicular blades compressors”
Then there is a bigger “blade free zone” probably 75mm which makes the diffusor less aggressive. It looks that the JG100 diffusor is strongly oriented on Thomas Kamps



My quintessence: Maybe I should build this compressor

Regards Lukacs

Gerald Rutten

I have no drawings for this diffuser, if I had I probably used this as reference for this engine as well... This diffuser is based on the KJ66 diffuser so outer blades would probably be almost the same, you have KJ66 drawings? I think the US built RAM1000 and the Australian TJT3000 from Chris Mounkley are identical so if you can find some info on those....

athome

Yes I have all the Books. Thank you. Do you still have your developed GR130 Turbine in a model running?

athome

Not yet finished with the design. But on the way!



Regards Lukacs

Gerald Rutten

It's going to be installed in my new 1/6 Thunderstreak. I overhauled the engine two winters ago after removal from my Avonds F15.

This one uses the older 2 stage diffuser, as said, the new design never has been tested before. This is also the reason I'm not gonna release my "GR220" plans until I'm satisfied. The GR130 plans where just a theory developed design for experimentors but I found a lot of people complaining and not fully understand my philosophy of the drawings.
I expected the diffuser to run well but you never know until it's fully tested!

Here's my GR130 which flew a lot of flights on my Avonds F16 and F15. In all those years used 3 combustion chambers, the rest remains the same;

Gerald Rutten

Looking good!

Gerald Rutten

Sorry for the late reply. There are many way's of doing this, my way is making it from glass fiber. I first make a positive mould from wood or some kind of filler plastic available. Next step is to vacuum a "canopy" at my local hobby store. This way you have an easy made negative mould, quickly done for prototyping. I use the inside of the vacuum shape to put the hand lay up of normal glass fibre or carbon fibre as you suits.

The FOD screen is just a simple kitchen strainer which is epoxied to the fiberglass housing.

Hope the picture helps;

athome

Hey Gerald
I’m not complaining! Absolut amazing what you did. I mean it’s working! But for my purpose, there is optimization potential So I will try this diffusor redesigned by me.
I did not find any drawings!
Thanks for your support and this design!

Regards Lukacs

athome

Here we go



regards Lukacs

Gerald Rutten

Nice! I assume you can't actually use this? You're gonna cnc this somewhere?