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Post by racket on Apr 11, 2022 17:18:19 GMT -5
Hi Andy
Nice "click bait" ;-)
With your tach , they can be a bit of a problem in bright sunlight , I've found I need the reflective tape stuck to the comp snout along with the usual half white/black , gloss white with matt black , reflective tape on the white side .
Yep , thats a much safer setup for the lube , lotsa variations in static pressures within our engines.
I think you can be pretty happy with these early spoolups , we all have our little "problems" working out whats required by our engines "personality" , a lovely build :-)
Cheers John
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Post by racket on Apr 11, 2022 16:32:37 GMT -5
Hi Andy
A beautifully made engine :-)
I'm a tad concerned about the bearing lubrication though , it appeared as though the only time any lube went to the engine was when it was switched off and the engine spooled down , there seems to be a "pressure differential" issue .
Cheers John
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Post by racket on Apr 10, 2022 0:06:19 GMT -5
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
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Post by racket on Apr 9, 2022 17:42:14 GMT -5
High speed gearing is a whole new world of problems , theres no point just having an oil bath as the gears will run "dry" at the speeds you're looking at , you need oiljet lubrication to penetrate the windage .
I'd use Joe's recommendation of the hp841 freepower unit , it'll save time and money in the long run
Cheers John
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Post by racket on Apr 8, 2022 23:20:41 GMT -5
Hi Joe
Yep , instead of feeding the bearing air at close to 200 deg C which doesn't do much for the lubricant , if its reduced to 30-50 degrees its gunna help , and if the air is filtered those fine bits of airbourne dust don't get a chance to grind the bearings away .
As you say , a 50 HP turboshaft engine would rarely be run at full throttle the same as a 50HP IC engined bike rarely sees max RPM , probably <5% of the time , at a guess I'd imagine ~60% N1 would be an "average" for a bike out on a ride .
Cheers John
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Post by racket on Apr 8, 2022 21:48:55 GMT -5
Hi Joe
Yep his biggest engine would work nicely , even with 25 hours between bearing changes thats a lotta rides .............LOL, and a lot of fuel to buy :-)
With very good balancing and a dedicated "filtered and cooled " air supply to the bearings, that TBO can be extended considerably as theres space on a bike for the extra bits required .
Cheers John
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Post by racket on Apr 8, 2022 16:53:25 GMT -5
I can relate to your 20 hp , I was thinking a similar number when I made my TV84 based bike, but had no idea what or how to produce it back in 1990 :-( This is what a turbine bike could be like jetandturbineowners.proboards.com/thread/34/motorcycle-project any bigger engine and we start to need a "special" frame geometry , this one is pretty lightweight and should produce the same power as Anders 304 kph landspeed bike as the engines are "cousins". 50 HP will only need a modest sized gas producer , a 50 lb thrust engine , roughly 1 lb/sec mass flow . A fun ride is much more that raw horsepower :-) Cheers John
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Post by racket on Apr 8, 2022 4:21:03 GMT -5
Yeh , the Y2K is an overpriced , overpowered, overlong , overhyped and overthirsty machine............other those few faults its an interesting bike ;-)
A good turbine roadbike needs no more than ~100 hp to keep fuel burn within reason and negate the need for the Y2Ks 34 ltr fuel tank and to extend its 20 mile around town range .
To have good handling we need a reasonable wheelbase , the Y2Ks rather stretched length is OK for straight lines but lets forget the corners .
A lightweight 100HP turbine engine would make for a 150 kg bike weight rather than the extra 100 kgs of the Y2K .
At 150 kgs and ~100 hp you end up with a civilised bike rather than a bike that would soon become "uncomfortable" to use ............excessive horsepower generally makes for a less than nice ride .
LOL..............just the thoughts of an old rider :-)
Cheers John
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Post by racket on Apr 7, 2022 1:03:28 GMT -5
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
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Post by racket on Apr 7, 2022 0:56:48 GMT -5
Hi Joe Have you considered a suction air preheat plug www.iskra-agv.cz/us/aet_products.htmYeh , its hard accepting what the years do to us , LOL, I'm not thinking 18 year old anymore , maybe 40'ish would do :-) Once you have all the bits it'll soon go together Cheers John
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Post by racket on Apr 6, 2022 22:10:06 GMT -5
Hi Joe
Take it easy, your health is number one, LOL ...........maybe I should listen to myself :-)
Some nice bits there , stick them in plastic bags so they don't get dirty , and come back to them when you get the all clear from the Doc .
Cheers John
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Post by racket on Apr 6, 2022 20:04:00 GMT -5
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
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Post by racket on Apr 6, 2022 1:21:07 GMT -5
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
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Post by racket on Apr 4, 2022 1:59:08 GMT -5
Hi Joe
Starters need some guts for our engines, especially with oil pressure added , better to have it overpowered than underpowered , a quick start is a good start :-)
Yep , those chinese CHRA units are well priced , they now do HX82 units with Ti comp wheels
Pics please ..............LOL, its nice to put the pressure on someone else for a change ;-)
Cheers John
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Post by racket on Apr 4, 2022 1:40:30 GMT -5
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
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