"Fat Boy" 12/118 thrust engine

[racket]

Hi Ron

I'd like to see 80 foot pounds of stall torque , which should mean ~40 ft lbs at peak rpm of 32,000 which would hopefully mean ~240 HP potential.

The "numbers" will be interesting..............LOL, I have no idea what will happen, hopefully there won't be too much restriction to flow and the gas producer takes it without complaining .

Cheers
John

[racket]

Hi Guys

The inner mounting tube of the scroll made and fitted , I'm trying a slightly different approach with this one by going for a smaller diameter tube rather than one the same diameter as the wheels disc diameter ( blade root dia ) to reduce the overal dimensions of the scroll duct , hopefully it won't cause problems .

This is going to be a mild steel scroll rather than all stainless seeing as its very much just a test piece , the only bit of stainless is the mounting flange as I already had the disc of stainless to make it out of and stainless will slow down the heat transfer to the alloy shaft tunnel, there'll be a ceramic blanket between the tube and tunnel as theres ~5 mm clearance .






Cheers
John

[racket]

Hi Guys

Bleed air cooling for area between wheel and shaft tunnel installed , the air exits in such a way that it'll swirl around the cavity, hopefully cooling things, before exiting in the axial clearance gap between wheel and scroll.

Bugger of a job drilling the 110 mm long by 5 mm dia hole through the length of the shaft tunnel with only a couple of millimeters clearance between hole and OD of shaft tunnel , having to keep on "rotating" the shaft tunnel every 10 mm or so was tiresome, but it drilled through without wandering off , the hole will eventually be extended through the other side of the gearbox ending in a fitting to accept the bleed air line from the gas producer



Cheers
John

[pitciblackscotland]

Hi John,
I tried drilling a 3/16 hole down a 100mm work piece at the other end it was 10mm off. Nice curvic coupling shaft you made

Cheers,
Mark.

[racket]

Hi Mark

Yeh , it was a bit of a concern , but I remembered what a German fitter I once worked with told me , ........"turn zee piece 90 degrees every 10 millimeteres " ............LOL, that must have been neary 50 years ago :-)

Bloody , curvic , started using a 6mm endmill and found it was a tad too big so had to drop back to a 5mm one , which gave me nightmares looking like it'd break at any moment .

Cheers
John

[pitciblackscotland]

Hi John,



LOL i have snap a number of endmills in my time, some were 10mm. Maybe next time try making it the way i did

Cheers,
Mark.

[racket]

Hi Guys

Finally got the freepower wheel shroud turned up , a 10kg lump of hollow bar , 250mm OD X 200ID X 50 mm , made into a 1.7 kg piece that I can use :-)



Theres been a delay in delivery of some other material so it looks like the scroll construction will be on hold for a few weeks , this'll give me time to turn up the shafting for the main gearbox gear and maybe start to think about how to mount things on the test stand .

Cheers
John

[racket]

Hi Guys

Been busy with the main gearbox output shaft .

Decided leave the the shaft 35 mm dia for mounting the sprocket on , the main gear sits on a 40 mm dia with a 12mm keyway , bearings are 6007 35 X 62 X 14 , I'll do the sprocket keyway once I have the sprocket .................LOL, this was the test shaft to find out what needed doing , its only in bright steel rather than high tensile , but I might just use it rather than make another one, its pretty heavy duty at 35 mm so I don't think the shaft will bend .



Cheers
John

[turboron]

John, The suffix “2RS” signifies the bearing is sealed, with rubber, on both sides. The suffix “ZZ” signifies the bearing is shielded, with metal, on both sides per Google. Which type do you have?

Thanks, Ron

[monty]

Jul 9, 2019 23:22:13 GMT -5 racket said:

I'm satisfied with the outcome , thanks to Monty supplying the larger G Trim turbine wheel its been invaluable , ........ thanks Monty :-)

Cheers
John

John,

You are very welcome! It's great to see it worked out. Gives me hope that mine will too.

Monty

[racket]

Hi Monty

Yep , the G Trim turb wheel was what was required , I can't thank you enough :-)

I'll be looking forward to seeing how you get on with your build .

Cheers
John

[racket]

Hi Ron

I'm using "metal" at the turbine wheel , but "rubber" everywhere else

Cheers
John

[turboron]

John, are your "metal" bearings continuously lubricated and the "rubber" bearings grease packed?

Thanks, Ron

[racket]

Hi Ron

All sealed bearings , no lubrication supplied, its a short duty gearbox

Cheers
John

[racket]

Hi Guys

Got the curved section blending wheel disc dia to the inner tube section of the "scroll" fitted , the "spider" arms will be mounted into it, the piece was a press on fit





Now to cut some slots for the stainless spider legs that the wheel shroud ring can be welded to .

Cheers
John