11/127 manned flight engine.

[wannabebuilderuk]

Shame about the turbine, rip your wallet... At least you can still probably use it for a freepower?

Ben

[racket]

Hi Ben

Yep , It could be ground down , but theres some nasty cracks in the exducer , by the time it was cleaned up it mightn't be very big :-(

Probably best to stick it on the wall as a reminder not to be so "adventurous" with the fueling .

Cheers
John

[racket]

Hi Guys

Replacement turbine wheel's exducer given a "mild" clipping , back from 25 degrees to 30 degrees rather than the previous 40 degrees , the extra deflection should help with turb power production and less fuel/temps.

Exducer throat area increase with the mild clip is only about half that of the 40 degree one , but with more deflection , things will hopefully still workout OK .





I'll get the NGV opened up tomorrow :-)

Cheers
John

[racket]

Hi Guys

Well , the NGV has been split ,,,,,,,,,,bugger of a job :-(

But its cleaned up and ready to have the slots for the vanes ground out to remove the remnants of the old vanes .

The exducer shroud and exhaust stub assembly had "sprayed Inco" inside it , some thankfully flaked off when heated with the oxy torch , but enough remained to be a problem , so popped it in the lathe to cleanup ..............duh, didn't work , the bits of molten turbine wheel are kinda hard compared to the shroud material , looks like I'm gunna have to grind them , the clearance between shroud and wheel will hopefully be able to be fudged a bit to resore it to something near what it was before .

Maybe start milling NGV vanes tomorrow ...............one of my favourite jobs :-(

I've ordered some new K type thermocouples , I need to replace the broken off one , but may as well replace both while I'm at it as the remaining one looks a tad "cooked", and a matched pair is a safer option anyway .

Cheers
John

[racket]

Hi Guys

Bit of an update ...............the NGV vanes have been made and welded in place , time to "precision grind" them all to the design 23.5mm height , so mounted the NGV front wall with its vanes into "the grinder" and trimmed back the ~1-1.5mm of excess .


With "cuts" of 0.25 mm it didn't take long to get to size



The new vanes are fitted into the same positions as the old ones , I simply ground out half of the old vane left in its slot and fitted the new one into it , the new vane has a "kink" in it at mid length with an ~5-6 degree bend to reduce the throat width by ~15-20% , I'll measure it up more accurately once things are cleaned up .

.

All I need to do is join the two sides back together in precisely the same posion as before and everything should fit .....fingers crossed :-)

New thermocouples have arrived and a new stainless pitot tube fitted to the jetpipe to replace the melted off one .

Things are progressing OK , hopefully back together in a couple of weeks

Cheers
John

[racket]

Hi Guys

That "simple job" of joining the two NGV sides back together has taken all day just to get 4 tack welds in place .

No matter which way I went, things would align in one plane but not the other :-(

After checking the "rear wall" for trueness, I found its bore and wall had warped , so when it was remounted in the lathe with its shallow rebate for the vanes to seat into, troubles started , rebate and vanes both turned to 205mm dia so it should have just clipped together and been concentric , but because that warped bore couldn't be mounted up in the lathe correctly ..............frustration and more frustration .

Finally , with the help of some packing on the chuck jaws I was able to get a reasonable , nope , not even reasonable positioning , but resigned to my fate I was able to clamp the two sides of the NGV together and get a fairly OK trueness at the NGV mounting surface .

Then the fun started , trying to "clock" the two halves so that the rear wall, which has the flametube mounted onto it , was in the original orientation to the NGV to shaft tunnel mounting so that the ignitor will hopefully be able to be inserted , as soon as I made a minor correction to clocking , the concentricity changed , this went on for another hour until eventually I got a lucky break and alignment suddenly appeared :-)

With 4 tack welds holding things together I'll do a quick reassembly of the engine to check alignments and clearances , I might need to run slightly larger turbine clearances if things are off centre by any more than ~0.2 mm .

LOL ....theres not a true running piece in the NGV , probably all of the early development problems with their associated thermal excursions have done some damage , but I'm quietly confident the engine will live again .

Cheers
John

[racket]

Hi Guys

A rough assembly completed.

Miracles do happen :-)

The ignitor was able to be slipped back into the flametube, not quite as good as before , but OK alignment , thats a load off my mind .

The turbine exducer is sitting a tad to one side in its shroud , it was possible to hear a light scrapping sound when the wheel was forced to that side, so I've "excentrically" machined the shroud for more clearance , it was a bit neat before anyway , so another 15 thou won't be a problem on a 129 mm hole.

Because of the need to cleanup the damaged surfaces , the exducer shroud is now sitting a bit further forward and decreasing the axial clearance , so more grinding needed , much easier than trying to make a 20 thou shim spacer to fit under the shroud mounting flange .

Things are progressing :-)

Cheers
John

[pitciblackscotland]

Hi John,
Good to hear the rebuild is working out for you

Cheers,
Mark.

[racket]

Hi Mark

Yep slowly getting there .

Thankfully you sent enough Inco for two sets of vanes , theres a coupla hundred mms left :-)

I've spent the arvo massaging the exducer shroud into shape , but something doesn't seem quite right with clearance between the back wall of the wheel and the NGV wall , it only appears to be ~0.5 mm whereas I'm pretty certain I left more , guess I'd better check my "notes??" .

The thrust bearing doesn't appear to have suffered , or the shaft bushes , so thats a plus .

Cheers
John

[racket]

Hi Mark

Bit of an update on that "missing" clearance .

There should have been 1mm clearance between wheel wall and NGV , same as the original TF15M CHRA had , but because I was only able to source 1/2" stainless plate locally, rather than 5/8" , I skimped on the clearance so as to prevent the piston ring protruding from the front side of the NGV plate during assembly and creating all sorts of potential problems .

But I turned another half millimeter anyway , so I've now got the right clearance , and the piston ring is half exposed when the wheel touches the wall , the thrust bearing when installed pushes the shaft rearwards ~1mm and has the piston ring seal "just" seating OK .

The rotor has been assembled and packed ready to go off to be balanced tomorrow .

The 1.1mm dia comp inlet static pressure port has been redrilled in a more convenient position .

And the surface where the surge slot exhausts has been widened as I need to be able to seal the exhaust , either permanently or post spoolup .

Theres not much more to be done , might have time to go fishing this week , high tide is at crack of dawn , just right for some tailor fishing :-)

Cheers
John

[racket]

Hi Guys

Rotor is back from being balanced :-)

Also picked up some new silicone O'rings for sealing the NGV/shaft tunnel joint , reassembly begins in the morning.

Cheers
John

[racket]

Hi Guys

Engine back on the test stand .

Had an alignment problem with the ignitor when I tried to fit it to the engine , don't know why as it fitted OK when I tried it after modifying the NGV , maybe a compounding up of a few variables .

Anyway , outer can off and the ignitor sealing arrangement ground off the flametube , outer can replaced and position of ignitor marked on flametube , can removed and hole modified and sealing arrangement tack welded back on , outer can back on to check , and ignitor slipped into place , so can off , fully welded arrangement and can replaced permanently :-)

Weather isn't looking good for a testrun until next week , so plenty of time to test everything is working properly before loading onto the trailer ..

Cheers
John

[racket]

Hi Guys

Test stand back on the trailer , so time to check everything is working .

Oilpump OK , fuel pump interlock OK , fuel pump "screaming" OK , ignitor working OK ..............starter motor solenoid OK , starter motor nope , just some "magic smoke" :-(

Pulled the starter apart and found two brushes jammed , the couple servicing the field coils .

Unjammed them and gave the armature commutator a skim , she works fine now , spooling the rotor to 10,000 rpm under 70 psi of cold oil pressure , about 0.1 Bar of P2 produced by the comp, gave it two spoolups just to be sure , the starter gets a bit hot after two tests , so plenty of power going through her .

I'll make up a fuel brew and wait for the weather to improve , can't wait to see what the mods produce :-)

Cheers
John

[madpatty]

Hi Racket.
I also want to develop the mental control where everything is loaded and ready and I am just waiting on weather for the test run.
How are you able to do that?

Test run it already 😂
All the best for your test run!

Cheers.

[racket]

Hi Guys

Its "different" , some surprises ;-)

youtu.be/516eoEGjuTc

youtu.be/qqUDY7hcyRw

Cheers
John