SKULD 666

[nersut]

Wow that's a big compressor wheel!
Makes mine look like a toy, hehe!

Nice work John.


Cheers
Erik

[racket]

Hi Erik

It is kinda big, a bit too big for easy construction , but I'll get there eventually :-)

Cheers
John

[jettoymaker]

Hi John,

Finally got into the 666 build thread as I'm having to have an enforced break (who says a migraine isn't a good thing). Great work as usual. The guys at the foundry say your patterns are as good as any professional pieces that they use every day. Have sent a link to the guys down at the turbine re-builders at Moorabbin Airport and they tell me it looks scary awesome. 

Looking forward to finishing B1 up so Mark and I can get started on his 666...just as well he has a huge supply of fuel handy LOL

Regards, Andrew

[racket]

Hi Guys

Some recent developments ........

Been having a bit of a think about the flametube size and what to make and decided on a scaled up version of the 10/98 engines , same 18 evaporators though size increased from ~10mm to 16mm OD , with the same "Jackson D tube" design to increase turbulence within the evaporator for optimum evaporation and mixing of fuel vapour and air .

When I finally decided on the air split ratio between inner and outer walls of the flametube , 50% outer , 35% inner and 15% at the rear which includes ~10% to the evaporators and the remaining 5% to some intermediary holes between evaps, there appeared to be a restriction at the entry to the annulus between shaft tunnel and inner flametube wall , so inner wall diameter is needing to be increased which then reduces flametube crossection which then means I've got to crib a bit of space by increasing the OD of the flametube , but that started reducing flow area between the outer can wall and flametube and increasing losses .......bugger .

So I've decided I'd better mock up a section of shaft tunnel out of wood to see if I can decrease its diameter a tad from the 115mm of its current size, its not looking good as the shaft size is ~1.75" dia , brass bushes will be ~2.25" OD ( standard off the shelf bushing size), then theres a need for a thrust surface , so diameter now out to ~2.8" , there'll need to be room for an oil gallery around that for collection of the used oil , so diameters now up to ~3.25" , then we come to securing fasteners to hold diffuser onto the shaft tunnel , probably 6 X 12mm screws , diameter now out to~4.4" , and maybe a 1/16th dia O'ring around the outer edge for sealing ............bugger , we're out at 115mm :-(

Slightly smaller fasteners might help , but then I'd need a lot more of them which will make it more complicated finding space for scavenge cavities etc. between them ..........mmmmm, more contemplation required , I knew this was going to be a complicated build when the engine's envelope was restricted to the 14 inch diameter swing of my lathe, I really need another inch because of this large diameter shaft tunnel .............I found a similar problem when I started designing the 10/98 engine and was the reason I went to a 10 inch case after having made the 9/94 engine in a 9 incher .

Cheers
John

[gidge348]

I think if JATO had a coat of arms, the inscription should read...... Bugger...

[racket]

LOL....whats "bugger" in Latin..............Google translation ... Pedicabo ..............inscribed over a smoking turbo dripping oil into pool underneath.

[Johansson]

[Deleted]

Oct 11, 2013 21:09:10 GMT -5 gidge348 said:

I think if JATO had a coat of arms, the inscription should read...... Bugger...

only bugger..... your work shop mus be a very polite work shop

as they say things come in threes :-) bugger **it duck, yes duck because either a spanner or what i am working on is about to fly across the work shop

[racket]

Hi Guys

A bit of an update on whats happening .

Mark sent me a second stage turbine wheel and NGV to experiment with ...................thanks Mark :-)

Inlet side............



Outlet side ...........



Some "precision grinding" required to remove unwanted bits of the turbine wheel



Finished article ............bloody tough material in that turbine wheel , anything less than a sharp tungsten carbine tool was useless, even then the tungsten was working hard to scrape off small flakes at a time , ............. the cut off disc in the side grinder failed to cut it , OK on the labyrinth seal fixture though as it was probably a different material , possibly a stainless steel ring shrunk onto the wheel .



One last pic........... the NGV , unfortunately its flow area is too small for my use so will need to construct one , note the honeycomb shroud for the inter turb wheel labyrinth seal to run in




This morning I purchased some 5/8" -16mm stainless tubing ( bathroom towel rail) for the evaporators as I'll need to construct the flaring jig and another jig for the "D'ing" of the side walls of the evaporators as I do with my smaller engines where a 3/8" tube is used .

Things are moving slowly , but they are moving :-)

Cheers
John

[pitciblackscotland]

Hi John,
No worries glad to help out. Did you remove metal from both sides of the turbine wheel? Mmmmm maybe i need to try using a grinding disc to remove most of the metal from the turbine wheel and then finish off with a tungsten carbine tool??

Cheers,
Mark. -

[racket]

Hi Mark

Just the inlet side so that I could move the wheel closer to the bearing so there'd be less overhang which should help with the rotor dynamics , as well as making construction simpler and neater .

The large diameter labyrinth seal had to go , along with the curvic coupling and the metal behind it so that I can sandwich a disc with its labyrinth seal between turb wheel and shaft step at the end of the turb "quill" , one side of the disc will be the thrust surface .

The cutting disc ( Inox type for stainless) I used was "too hard" , its cutting surface "glazed over" , it was OK when cutting off the curvic teeth as the interruption between teeth meant the disc encountered a sharp edge when it hit the next tooth and this kept on "dressing" the wheel bring sharp abrasive to the surface , but on solid turb material it was a failure , we need a "soft" cutting disc same as we use soft grinding wheels for sharpening our tungsten tooling.

Thanks again for the wheel , much appreciated :-)

Cheers
Johnn

[Johansson]

Good job John, this thread is becoming more and more interesting!

[stoffe64]

mmmm, very interesting Reading and watching!

[racket]

A bit of an update ...........

Slowly getting a dummy shaft turned up to get a feel for whats required , rotor with comp and turb wheels currently weighs in at ~12.5 Kgs - 27.5 lbs , when the labyrinth seal discs are installed along with nuts and spacers etc, the weight will probably be closer to 15 kgs - 33 lbs







Cheers
John

[pitciblackscotland]

Hi John,
Aha now i can see how that shaft will turn out. Did you machine a tapered end for the comp wheel?
15 kgs nice and heavy duty just how i like it :-))))

Cheers,
Mark..