11/127 manned flight engine.

[racket]

Hi Guys

I did a pressure test yesterday on the bent tip injector and found the maximum pressure I could create was ~35 psi , with very fine atomisation at that pressure .

The 30ml syringe has a piston of 24 mm diameter , so I must have been exerting a force of ~25 lbs with my thumb , just to double check , I did a force check on the bathroom scales and it came in at roughly the 25 lbs , give or take a coupla pounds .

So even with 45 psi of P2 "backpressure" , I'll only need a max of 80 psi fuel pressure from the pump ............Looking good :-)

Made more NGV vanes today , only 3 to go , what a slow tedious job .

The comp cover has also had a bit more work done on it , the shroud curve is getting closer to whats required, might make up a template to save using the wheel for checking .

Cheers
John

[racket]

Hi Guys

The last of the NGV vanes finally machined


And welded in place





The turb wheel looks like it approves



Next job is to machine the vane heights down by ~1mm so that they are all parallel with the shaft tunnel mounting face , and to machine a very small step ( ~0.5mm) on their outer edge that will fit into a rebate in the rear wall of the NGV to produce a concentric unit .

Cheers
John

[racket]

Hi guys

NGV now finished .............finally .

Tacked it together yesterday but when spun on the lathe mounted at the shaft tunnel face, there was too much wobble , a compounding of machining inaccuracies

Thanfully there were only 3 small tack welds so apart it came and a steel jig made so as to align off both the exducer shroud mounting face and the piston ring seal shroud , this seemed to fix the problem and wobble was reduced to plus/minus 0.002" ..............the whole part will "relax" more than that the first time I spoolup .

Its a weighty piece at 3.625 kg - 8 lbs , but hard to make it lighter whilst still maintaining some rigidity


And a couple more pics





NGV throats are 23.5mm X 15.2 mm( avg) by 18 of for a total of 6430 sq mms , 9.966 sq ins , 0.0692 sq ft , vanes set at 26 degrees above tangent

Onto the "easy" aluminium tomorrow after cleaning up from the NGV construction

Cheers
John

[pitciblackscotland]

Hi John, All good Now i see why you don't fully weld the NGVs

Cheers,
Mark.

[racket]

Hi Guys

Front cover machined up for wheel , I was a tad over generous with the casting material so lots to remove .

Theres a 2 mm "pinch" outboard of the wheel reducing the 12.5 mm exducer tip height down to 10.5 mm for the diffuser vane height .

Weighs in at 2.7 kgs - 6 lbs , plenty of containment










On to the diffuser now .

Cheers
John

[pitciblackscotland]

Hi John,
looks like you put a lot of hours in this part. That first pic i see a boss sticking out there, is that for air impingement start

Cheers,
Mark.

[racket]

Hi Mark

Yep , air start boss :-)

Quite a few hours getting the shroud profile just right .

Started on the diffuser this arvo , got the rear boss machined and now chucked up and machining the vanes , though theres a fair bit of warpage in the casting , I'll need to fiddle things a bit .

Cheers
John

[wannabebuilderuk]

Aug 1, 2021 23:30:30 GMT -5 racket said:

Hi Guys

Front cover machined up for wheel , I was a tad over generous with the casting material so lots to remove .

Theres a 2 mm "pinch" outboard of the wheel reducing the 12.5 mm exducer tip height down to 10.5 mm for the diffuser vane height .

Weighs in at 2.7 kgs - 6 lbs , plenty of containment










On to the diffuser now .

Cheers
John

Another work of art john!

[racket]

Thanks Ben

Its coming together , but as always, I'm my worst critic , I'd like perfection but know its impossible to achieve, so gotta settle for just OK , LOL....such is life :-)

Cheers
John

[racket]

Hi Mark

The diffuser is coming along, I think I can live with the warpage .

With the main surfaces taken care of I need to figure out the the comp piston ring shroud mounting and axial distances before removing the diffuser from the chuck .

A work in progress pic


Cheers
John

[pitciblackscotland]

Hi John,
Did you have warpage in the castings you had done When i had a chat to Andrew he got this casting done at a different place this time.

Cheers,
Mark.

[racket]

Hi Mark

The diffusers generally have a bit of warpage due to their "flat plate" profile , whereas the front covers with their extra depth don't seem to suffer , it might actually pay to have a sacrifical ring at the outer edge of the diffuser that can be machined off .

Some of the diffuser vanes are 11mm high rather than 10.5 mm , but close enough not to be a problem .

I'll do a detailed drawing tomorrow of the piston ring holder through to the thrust bearing arrangement with respect to where the comp is positioned in the diffuser before cutting more metal .

Cheers
John

[racket]

Hi Guys

A tad more done today .

Got the stainless steel piston ring shroud finished and installed , the reason for 4 screws is so that none interfere with the lube ports at top and bottom of shaft tunnel/diffuser rear.

It appears to be "buried" rather deeply , but thats because I'm fitting a 10mm thick spacer behind the comp to provide a tad more space for "plumbing"


The comp sits happily in its diffuser , tomorrow I machine up the mounting jig so that I can machine the rear of the diffuser , spent the afternoon trying to get my head around all the various axial spacings ............I hope I've got them right .



Cheers
John

[racket]

Hi Guys

The castings are just about machined up , the front cover needs the airstart port, and the diffuser some lube ports which I really don't know how I'm going to fit , but I'll work something out




Diffuser weighs in at 1.75 kgs- 3.85 lbs , reasonably lightweight

Cheers
John

[pitciblackscotland]

Hi John,
Looking good For the air start do you have any idea what you will use scuba air tank I have a 3,000 psi manual valve or a 24 volt 3,000 psi valve like the one i use for the JFS engine and i have 3,000 psi hoses that i can send up to you.

Cheers,
Mark.