APS/Ω Gas turbine bike build

[Mobacken Racing]

I fitted the T2 probe just now.



I drilled the 5mm hole through one of the diffuser wedges and threaded the compressor cover with 1/8"NPT.



Here you can see the end of the temp probe.



As far as I can tell the modifications to the engine core are done and I can start putting it back together, when it is back in the test rig I will fit all of the gauges along with a jet pipe pressure pitot tube.

Cheers!
/Anders

[grumm441]

I fitted the T2 probe just now.





Cheers!
/Anders

I like that  hands free drill
G

[Mobacken Racing]

I like that  hands free drill
G

Actually I drilled the pilot hole through the diffusor vane in the mill, then I bolted everything together and drilled the rest through by hand.

[grumm441]

It's just that i can't see your hand
G

[Mobacken Racing]

Aha! 

One step backwards and one forward. Last night when I was assembling the engine core I managed to turn the thrust bearing the wrong way and before I noticed it the thin cast alloy wall that holds the thrust washer cracked.....

Breaking the cast diffuser plate with countless of hours of work put into it was no fun feeling, I had to sit down and consider my options for a while before I came up with a solution. It never occurred to me to take any pics of the damage, I had other things on my mind.

Since that thin wall was the only thing acting against the axial thrust it might have failed sooner or later anyway, so I decided to remove the damaged wall and turn a recess into which a stainless wall can be fitted.



Here I have started making the stainless part, I have milled and threaded two M4 holes to secure it.



The thrust washer is dropped in place just for reference.



A pair of matching recesses were milled in the part for the M4 screws, now it can´t go anywhere. After the pic was taken I drilled the three 3mm holes for the thrust washer so everything could be screwed together.



I took .05mm cuts from the stainless wall until the end to end axial bearing clearance was 0.20mm, well within specs but on the sloppy side in case something tightens up when the engine heats up. Now I just have to mill the oil ports that lets oil in from the backside of the wall to the thrust washer, then I can continue assembling the engine.

The best thing about this is that the axial clearance is set by removable parts and not the diffuser plate itself, so any modifications in the future can be done to these small parts without risking any damage to the cast part.

Pheww.

[Mobacken Racing]

Hi Ralph,

I didn´t quite understand what you meant at first, but after watching the video it all came clear. That it a very clever way of smoothening down a surface that for some reason can´t be grinded! Thank you a lot for showing me, I will remember this method for later.

Last night I finished the stainless insert by milling the oil ports and flow enhance them a bit with a file, I also tested the clearance with my kids playing clay and I got a uniform clearance all the way around the axial bearing so everything seems ok.



After that I could start assemble the engine again, a very simple job since there is no internal fuel supply or preheat lines that I need to be careful with.



I have also adjusted the radial holes in the engine cover a bit so now all of the securing screws fit without fuzz.



The last thing to do is to fit the fuel manifold, I will leak test it with compressed air and some soap water later to see if the gaskets are still leak free and then I can start installing the engine in the test rig!



Cheers!
/Anders

[Mobacken Racing]

Last night I leak tested the fuel manifold with compressed air and soap water, no leaks at all up to 6 bar so we are good to go.



The engine is back in the test rig now, the impingement air hose is on the top waiting to be coupled to the scuba tank. Now I just have to move all of the temp and pressure gauges from the bike dashboard to the test stand so I can watch and video tape them during the test runs.



A hose company sponsored me with a length of steel spring reinforced hose suitable for oil up to 90°C, I will use it for the oil return from the engine and the regulator so I can see the oil flow going back to the tank.



I have also made a fan mount for a new and more compact 12V preheat fan for the engine, the old one was very bulky and made a noise like a fog horn when running so this will be a nice improvement. I will keep it running all the time so it will get a cold air flow going through the engine after shutdown.



Have a great midsummer eve folks!
/Anders

[grumm441]

I have also made a fan mount for a new and more compact 12V preheat fan for the engine, the old one was very bulky and made a noise like a fog horn when running so this will be a nice improvement.

Have a great midsummer eve folks!
/Anders

That could be handy
G

[Mobacken Racing]

It sure will!

I finished fitting the transparent oil return hoses and used the AN8 fuel pump feed hose as the oil pump hose so I could test the oil system.



A few small leaks here and there since I haven´t tightened everything up with thread sealant yet but the oil pressure is rock solid with no oil coming from the engine cover drain.



The regulator adjusts the pressure from nothing at all to bottoming out the pressure gauge with a smooth increase in pressure as I tighten down the setting screw on the regulator. No idea if it will keep the pressure setting when the oil starts to heat up but I´ll find that out when I start test running the engine.

Cheers!
/Anders

[Mobacken Racing]

Today I picked up a C20 4th stage turbine wheel at the post office, I bought it from an Israeli Ebayer who sells lots of turbine stuff and will keep it as a spare in case I meet Mr Murphy some fine day.

I expected a time expired turbine wheel but got one with the balancing pencil markings still intact so it is either newly overhauled or brand new!



I´ve also recieved the AN8 hose and fittings so this afternoon I could give the engine a spin with compressed air to see if the air starter works like planned.

https://youtu.be/GMKb8ppynz0

Cheers!
/Anders

[Mobacken Racing]

Today I modified the oil pressure regulator and test ran the JU-02 engine for the first time since the bearing failure!

https://youtu.be/ju-RTJTAALU

I removed the nylon plunger from the regulator and measured the bleed port seat so I could make a coned plunger instead of the flat one that apparently don´t work so well.



I started out with a piece of steel rod, the nylon plunger is next to it.



After some work on the lathe it looked like this, I also added a rubber O-ring to the coil spring guide to prevent oil from leaking past the setting screw threads.



The oil pressure adjustment was much smoother now with the tapered plunger, and it was 100% consistent when I turned the pump on and off a handful of times. Success!

During the startup I had some problems with the preheat flaming out when I started to spool it up with the impingement air, possibly because I was a bit conservative on the idle fuel setting.

Other than that the run went well, in the end of the video the engine flamed out when I backed off the throttle but I know from earlier runs that it can happen when I throttle back from high idle so no problems.

Cheers!
/Anders

[Mobacken Racing]

I ran the engine tonight with good results, I had some very hot start attempts first when using the leaf blower but when I tried the impingment air it started right up. Earlier the leaf blower worked fine but now when I run a higher oil pressure the bearing drag has increased beyond the leaf blower capability.

I held the throttle at 2bar P2 and that gave 0.5bar P4 (dynamic pressure in jet pipe), 560°C TOT and 159°C T2 initially which slowly rose toward 170°C in the end. The T2 probe is unshielded and might have been affected by radiant heat from the combustor.

https://youtu.be/uMNXF52sJUA

Cheers!
/Anders

[tauruck]

I read but it goes right over my head.
High tech stuff but all the work you do is impressive.
Thanks Anders.

[Mobacken Racing]

I read but it goes right over my head.
High tech stuff but all the work you do is impressive.
Thanks Anders.

I´ve been rebuilding the entire electric and oil systems the past year to beef it up a notch, so the plan now is to keep testing the engine at higher and higher power levels until I reach 4 bar boost pressure which is beyond what anyone has run in a DIY turbine before (with an engine living to tell the tale... )

I will try to have the engine tested and installed in the bike by the end of this winter, it all depends on the outcome of these test runs of course but it would be nice to throw a leg over the bike next summer and start the road testing. 

Cheers!
/Anders

[tauruck]

WHAT???, no hockey this season?.

Seriously, Anders I wish you all the best.