In 1973 I was an fresh apprentice working on the installation of 250's or their successors. I never saw inside one other than a drawing! That was a nerdgasm of viewing 48 years late....
Thanks for the great video love the work ethics it's that detaile of not even marking the fasiners that makes it, even skipping through the tools to find that one that fits. The inside of that thing is amazing.
Cool stuff agent Jay. I've flown them but never drilled down to working with the nuts and bolts on them. I consider you a master technician. I'm learning about the Walter 601 turbines as well. Amazing how much horsepower is available when you can afford the fuel flow. The Walter 601 in the Long Nose Thunder which is an experimental reduced scale P-51 delivers 220 Kts true at a fuel flow of 43 GPH. In neutral wind components that calculates to 5.88 MPG. Not very economical to operate as a single place aircraft but lots of fun. In larger aircraft that carry more cargo/people. Pound per pound weight to horsepower the numbers related to fuel consumption economy become very competitive. The petrol air-cooled piston aviation propulsion units deliver about 10 HP per 1 GPH fuel burn. Dual volute turbo CI diesels deliver about 20 HP per 1 GPH. with a weight comparable to the air-cooled petrol cousins. Bellow 500 HP these 3~4 L aluminum CI diesel engines are proving reliability better than the petrol AC SI petrol engines with 20 years of data) with fuel flows of 25 GPH delivering 500 horsepower or 375 KW equivalents. It's all about application but I've always preferred Jet, turbine/turboprop propulsion with aircraft over piston. Thanks for sharing. Cheers
I'm througherly enjoying this C18 mini series. That's an engine I'd like to own. I can't wait to see and hear it run for the first time in decades. 😊🇬🇧
Happy Easter Agent Jay Z thanks so much for some Epic jet city action on my day off! Glad the engine is looking in good shape! Also nice talk on correctly loosening fasteners, most back yard mechanics are too careless and that causes problems.
Big points to you! 👍What a pleasure hearing someone with advanced mechanical skills say “ I agree the metric system makes much more sense”😁😋- if only the majority of the other North American inhabitants could understand this basic truth 🤔
The engineers are always tweaking the machine. It may have been to reduce resonance or turbulence when running. Such details are not mentioned in the overhaul manuals.
I suspect that the stage 3 and 6 blades suffered a high order harmonic resonance, which cracked the corners off the blades. Rather than trying to redesign the aerofoils to change their natural frequencies, the expedient solution was to crop the corners. It would have cost something, in terms of performance and surge margin.
I want an engine like that! Doesn't have to be even close to running condition, just complete enough to display. Heck even just the compressor section with the gearbox would be nice. I would totally put that up on a stand in a room!
There's just the gearbox for a C18 on EBay UK at the moment for £16 000 . There's another one for the MB250/C20 for £5 000 ! I could buy 6 Rolls Royce Viper engines in good shape from the Jet Provost for £16 000 !
In this video you explain that later models of the engine dispensed with the axial compressor altogether, and just relied upon centrifugal compression. If so, what does this axial compressor actually generate in terms of the overall pressure ratio for the engine? (2:1, 3:1, whatever.) Effectively, did the actual overall pressure ratio remain constant and this thing is so weedy it offers next to nothing, or was the centrifugal compressor on this unit actually just rubbish? I suspect the latter but it would interesting to emphasise this trade-off in subsequent episodes.
The centrifugal compressor design was improved to the point that the axial stages were no longer necessary. Any further details on actual numbers of individual stages is not included in the overhaul manuals.
there some numbers on page 29 of in this linked on the wikipage: web.archive.org/web/20161004205229/www.enginehistory.org/Convention/2009/Presentations/Model250Hx.pdf 3.2:1 axial and 2.2:1 centrifugal for the -C20, 7:1 centrifugal for the -C28
Yes! There's a song I bet you will like, by Corb Lund. It's called Hard on Equipment. His breakthrough song was called Truck Got Stuck. You'll like that one too!
Nice video. At 10:08 (and other places in the video), it's fascinating to see the illusion of the compressor stages moving on independent disks at different speeds and some even appearing to run backwards temporarily. Must be the effect of both the camera frame rate and the progressively smaller blades.
Would love to see the difference between the centrifugal compressors of the 250 you have and the c30. Seems crazy that they could get the same compression with just the one (centrifugal) stage.
No titanium. For nuts and bolts, titanium is more expensive , weaker, and a little bit lighter than steel. So they have to be bigger, which defeats some of the weight advantage. If I was trusting my life to a machine, I would always choose stainless steel fasteners over titanium.
@@AgentJayZ That makes a lot of sense. Someone once told me they were Titanium, and I had seen titanium hardware that looked similar to those T-bolts, so I just believed them without ever looking up the part numbers to verify. Thanks for the clarification.
A nut re-assembling tip from a recent Andrew Camarata video was to use a swatch of paper shop towel to press home and hold a nut in a ring spanner to prevent it falling through when access is awkward.
Off the top of my head 10-32 is used for the gas key to bolt carrier cap head screws in the AR15 rifle , and the mil spec torque for these is 56-58 in/lbs , so 60 is close enough . There are no metric equivalent for these sizes in Europe so raid the boot sales and tool markets and vintage car rallies . Allen keys are not really a problem , but most of my spanners were obtained this way and was lucky to find old 'Blue Point' branded double end ring spanners at a quid each . Nice looking compressor stage with no intrusions except an over zealous aerosol of aluminium paint . No reason why the turbine end should be any different if the history is as good as described . I must admit those ugly mild steel stubs are beginning to annoy me , but I supposed we'll just have to wait until the engine is inverted and well stuffed before lopping those off and repairing the V flanges . Googled Allison C18 Operation and Maintenance Manual and there are no shortages available including the 1971 Detroit Diesel one free to download online .
Hey Jay! Would love an explanation of the 'HP recoup system'. I found it while looking at airflow diagrams of Gas turbines used in the Snøhvit LNG powerplant. Keep up the awesome work :)
I've worked on more the a dozen aviation and aeroderivative industrial gas turbine engines. Nowhere, in any of the overhaul, operation or maintenance documentation, is the word recoup used. So I'm not your guy.
@@AgentJayZ Just found out that it was referring to a recuperator, a heat exchanger system in gas turbines that takes some heat from the turbine outlet and gives it to the compressor outlet air to increase efficiency. Here's a link if you were interested: www.turbomachinerymag.com/are-recuperators-always-great/#:~:text=The%20recuperator%20is%20a%20heat,pre-heat%20the%20combustion%20air.&text=This%20advanced%20cycle%20is%20often,with%20reciprocating%20engines%20on%20efficiency.
Hello and thanks for your videos. Compared to axial compressors with many more stages, it seems this one constantly tapers up to the centrifugal stage without having the straight area to reduce air velocity. Is this because here is not required? Or is the centrifugal stage architecture playing a role in this instead? Again thanks!
Is the inclination to do the other side of the compressor cleaning just out of a sense to be good and thorough? Or is it out of concern for some possible imbalance (of air flow, or something... I don't know, that's why I'm asking!), due to grimy stator fins on only one side of the compressor?
The compressor only needs a light cleaning, so the other half doesn't really need to be removed. This is a non-flying application. But might as well make it all shiny!
Hopefully there are fewer troublesome socket and wrench fits on the other side! Thanks for the reply, and for these not-only-informative-but-also-fun videos!
Nothing in the UK I'm afraid sometimes I get lucky with a little used manual here . Ebay UK has a C18 gearbox ONLY for £16 ,000 ( about Ca$30 000 ?) . To put this in perspective a Rolls Royce Viper from a Jet Provost in clean condition is £2500 ! Try the one month free download for the Dietroit Diesel manual . Picked up a couple of tips from guys who have worked on these . Tip 1 CSL 1176 starting procedure - open throttle at N1 =12-15% rather than 18% as recommended in the operation manual as it reduces wear and burnout . Compressor and turbine mounting stud torque is low at 80 in/lbs as this does not allow for 'drag torque' and these will come undone . Torque to 110 in/lbs to make sure they do not !
There are only two ways: 1 - Build your own fantastic creation. 2 - Pay a fortune to someone who has completed (1) and is willing to part with it. Each one of these things is a work of art and a labor of love.
I had a good look at the WWW trying to find the fuel system manifold for the A250-C18 type, I don't think my efforts would find anything you were unable to, but yours is the Allison 250 Rolls-Royce also do the C18 type and I hope you may be able to find the PDF there I had to watch this video with a few breaks while caring for my boy Damian, I don't think I missed your explanation of why the third row of axial blades had the leading edge cuts, I wonder if you might be able to explain why, I have seen your own from your learning days when these parts were being thrown out, blacers ? I think you called them, makes good shelf ornament, am waiting for my own RR RB-211 compressor mounted blade from 757-200. good luck with this race boat build, looking forward to more videos, thankyou AgentJayZ
Just a guess but I know corner crops are used to change the resonant frequency of the blade. If the operating frequency of the engine and the blade resonant frequency are too close all hell breaks loose
I'm guessing airworthy wouldn't be too hard to acheive with some time and skill and patience, even if it wasn't in that particular state to begin with. But sometimes pennies do cost $.
It might be because, as he mentions at 7:00, they've been "blended" - Had a small bit ground off of each blade to balance the mass of the compressor as it rotates.
@@Ropponmatsu2 He did, but as he spun it around, it sounded like he went back and said the whole stage is just like that. I don't think balancing would require the whole stage to be ground.
I know its probably silly, but I just don't care for 12 point sockets. I only like using high quality 6 point sockets. I have 12 point sockets, I just avoid using them.
Some NAS bolts and various commercial high tensile bolts and nuts are available in 12 point, they are a godsend in tight locations such as UNI joints, the spanner for them is almost the same diameter as the head. For hex heads 6 points usually can handle more torque. You can even get 12 point socket head bolts and they are less prone to slip than the 6 point ones when used with a 12 point driver.
In aircraft maintenance I rarely need 6 point sockets. Most things are torqued to specific specs and corrosion is strictly controlled, so rounding fasteners really isn't a concern most of the time. That said you occasionally run into a 6PT fastener made of soft metal with a high torque, and then you get out your 6pt socket.
In 1973 I was an fresh apprentice working on the installation of 250's or their successors. I never saw inside one other than a drawing! That was a nerdgasm of viewing 48 years late....
I've been watching you for years now Jay and you still make me laugh, i am no mechanic, i am a taxidriver but i love your channel.👍😊
He's a character, stay safe!
love the ambiance music in the back ground very soothing. appropriate for tedious operations.
I love seeing people who love what they do so much they do it on their free time!
You look so smug turning that compressor and who wouldn’t be. Great to see the blades & stators, thank you!
Thanks for the great video love the work ethics it's that detaile of not even marking the fasiners that makes it, even skipping through the tools to find that one that fits.
The inside of that thing is amazing.
Cool stuff agent Jay. I've flown them but never drilled down to working with the nuts and bolts on them. I consider you a master technician. I'm learning about the Walter 601 turbines as well. Amazing how much horsepower is available when you can afford the fuel flow. The Walter 601 in the Long Nose Thunder which is an experimental reduced scale P-51 delivers 220 Kts true at a fuel flow of 43 GPH. In neutral wind components that calculates to 5.88 MPG. Not very economical to operate as a single place aircraft but lots of fun. In larger aircraft that carry more cargo/people. Pound per pound weight to horsepower the numbers related to fuel consumption economy become very competitive.
The petrol air-cooled piston aviation propulsion units deliver about 10 HP per 1 GPH fuel burn. Dual volute turbo CI diesels deliver about 20 HP per 1 GPH. with a weight comparable to the air-cooled petrol cousins. Bellow 500 HP these 3~4 L aluminum CI diesel engines are proving reliability better than the petrol AC SI petrol engines with 20 years of data) with fuel flows of 25 GPH delivering 500 horsepower or 375 KW equivalents.
It's all about application but I've always preferred Jet, turbine/turboprop propulsion with aircraft over piston. Thanks for sharing. Cheers
I'm througherly enjoying this C18 mini series.
That's an engine I'd like to own. I can't wait to see and hear it run for the first time in decades. 😊🇬🇧
Currently my favorite series on youtube.
Happy Easter Agent Jay Z thanks so much for some Epic jet city action on my day off! Glad the engine is looking in good shape! Also nice talk on correctly loosening fasteners, most back yard mechanics are too careless and that causes problems.
Thanks letting us ride along with this initial assessment. I hope you are able to locate the books you seek. I'm excited to see this boat go together!
We have a couple of manuals now, thanks to helpful viewers!
"Every little guy doing every thing he can to be a part of the team."
"Put me in coach, I'm ready to play!"
I think that may be be my all time favorite AgentJayZ quote. That should be in some kind of museum for posterity.
@@greghelms4458 in a way only AgentJayZ can articulate, it elegantly captures the collective complexity of a turbine
@@jt8251 spot on. Couldn’t have said it better.
Thanks. We're all here to enjoy these fantastic machines aren't we? That's why I started doing these videos, back in 2006 (!)
all us viewers think your great, I love hearing how and why
Big points to you! 👍What a pleasure hearing someone with advanced mechanical skills say “ I agree the metric system makes much more sense”😁😋- if only the majority of the other North American inhabitants could understand this basic truth 🤔
I never cease to be amazed. Thanks!
Nice video. So looking forward to seeing this gem restored. What a great project.
She's so cute :-D
Man, can't wait to hear this beauty spool up to idle RPM.
Great video. I wonder why there was that chamfer on the edges of those blades on stage 3 and 6. The only service manual I have is for the JT3D engine
Why do the blades of stages 3 and 6 have a notch cut out of the tip of their leading edges (most visible at 8:20)?
The engineers are always tweaking the machine. It may have been to reduce resonance or turbulence when running. Such details are not mentioned in the overhaul manuals.
I suspect that the stage 3 and 6 blades suffered a high order harmonic resonance, which cracked the corners off the blades. Rather than trying to redesign the aerofoils to change their natural frequencies, the expedient solution was to crop the corners. It would have cost something, in terms of performance and surge margin.
I want an engine like that! Doesn't have to be even close to running condition, just complete enough to display. Heck even just the compressor section with the gearbox would be nice. I would totally put that up on a stand in a room!
There's just the gearbox for a C18 on EBay UK at the moment for £16 000 . There's another one for the MB250/C20 for £5 000 !
I could buy 6 Rolls Royce Viper engines in good shape from the Jet Provost for £16 000 !
In this video you explain that later models of the engine dispensed with the axial compressor altogether, and just relied upon centrifugal compression. If so, what does this axial compressor actually generate in terms of the overall pressure ratio for the engine? (2:1, 3:1, whatever.)
Effectively, did the actual overall pressure ratio remain constant and this thing is so weedy it offers next to nothing, or was the centrifugal compressor on this unit actually just rubbish? I suspect the latter but it would interesting to emphasise this trade-off in subsequent episodes.
The centrifugal compressor design was improved to the point that the axial stages were no longer necessary. Any further details on actual numbers of individual stages is not included in the overhaul manuals.
there some numbers on page 29 of in this linked on the wikipage: web.archive.org/web/20161004205229/www.enginehistory.org/Convention/2009/Presentations/Model250Hx.pdf
3.2:1 axial and 2.2:1 centrifugal for the -C20, 7:1 centrifugal for the -C28
bolts loosen if you go either direction just keep cranking and it will give up
Yes! There's a song I bet you will like, by Corb Lund. It's called Hard on Equipment.
His breakthrough song was called Truck Got Stuck. You'll like that one too!
Thank you!
Love all of your stuff! :)
The TurBoat's engine might be old and you sounded a bit worried while preparing to inspect the compressor, but so far so good.
Cheers
Great video as always Thank for sharing Yf.....
The old machinist term for a bolt used as a dowl, or close to a dowl, is "body bound" .
Yes. I prefer dowel bolt, but a lot of people I know use your term.
They used to be called "fitted bolts"
@@whitemonkey7932 or shoulder bolt/screw
@@whitemonkey7932 That's what I know them as.
Nice video. At 10:08 (and other places in the video), it's fascinating to see the illusion of the compressor stages moving on independent disks at different speeds and some even appearing to run backwards temporarily. Must be the effect of both the camera frame rate and the progressively smaller blades.
Yup, stroboscopic effect.
Frame per second.
Would love to see the difference between the centrifugal compressors of the 250 you have and the c30. Seems crazy that they could get the same compression with just the one (centrifugal) stage.
That outer casing looks so expensive!
Looking forward to the naming contest!
That outro...lol
Essential = Day old coffee :-)
Dumb question? Are the nuts and bolts titanium? Are any of the parts titanium and can you point some of them out?
No titanium. For nuts and bolts, titanium is more expensive , weaker, and a little bit lighter than steel. So they have to be bigger, which defeats some of the weight advantage.
If I was trusting my life to a machine, I would always choose stainless steel fasteners over titanium.
@@AgentJayZ I believe the bolts on the hot side (the turbine side) of the engine are titanium with inconel nuts on them.
No titanium. Especially on the hot end.
Titanium is weak, soft, and catches fire.
@@AgentJayZ That makes a lot of sense. Someone once told me they were Titanium, and I had seen titanium hardware that looked similar to those T-bolts, so I just believed them without ever looking up the part numbers to verify. Thanks for the clarification.
thanks
A nut re-assembling tip from a recent Andrew Camarata video was to use a swatch of paper shop towel to press home and hold a nut in a ring spanner to prevent it falling through when access is awkward.
Off the top of my head 10-32 is used for the gas key to bolt carrier cap head screws in the AR15 rifle , and the mil spec torque for these is 56-58 in/lbs , so 60 is close enough . There are no metric equivalent for these sizes in Europe so raid the boot sales and tool markets and vintage car rallies . Allen keys are not really a problem , but most of my spanners were obtained this way and was lucky to find old 'Blue Point' branded double end ring spanners at a quid each . Nice looking compressor stage with no intrusions except an over zealous aerosol of aluminium paint . No reason why the turbine end should be any different if the history is as good as described . I must admit those ugly mild steel stubs are beginning to annoy me , but I supposed we'll just have to wait until the engine is inverted and well stuffed before lopping those off and repairing the V flanges .
Googled Allison C18 Operation and Maintenance Manual and there are no shortages available including the 1971 Detroit Diesel one free to download online .
Hey Jay! Would love an explanation of the 'HP recoup system'. I found it while looking at airflow diagrams of Gas turbines used in the Snøhvit LNG powerplant. Keep up the awesome work :)
I've worked on more the a dozen aviation and aeroderivative industrial gas turbine engines.
Nowhere, in any of the overhaul, operation or maintenance documentation, is the word recoup used.
So I'm not your guy.
@@AgentJayZ Just found out that it was referring to a recuperator, a heat exchanger system in gas turbines that takes some heat from the turbine outlet and gives it to the compressor outlet air to increase efficiency.
Here's a link if you were interested: www.turbomachinerymag.com/are-recuperators-always-great/#:~:text=The%20recuperator%20is%20a%20heat,pre-heat%20the%20combustion%20air.&text=This%20advanced%20cycle%20is%20often,with%20reciprocating%20engines%20on%20efficiency.
Recoup is a term used in GE engine CF6. It steals some of the leaking air and used it for sealing in bearing chambers.
Hello and thanks for your videos. Compared to axial compressors with many more stages, it seems this one constantly tapers up to the centrifugal stage without having the straight area to reduce air velocity. Is this because here is not required? Or is the centrifugal stage architecture playing a role in this instead? Again thanks!
Is the inclination to do the other side of the compressor cleaning just out of a sense to be good and thorough? Or is it out of concern for some possible imbalance (of air flow, or something... I don't know, that's why I'm asking!), due to grimy stator fins on only one side of the compressor?
The compressor only needs a light cleaning, so the other half doesn't really need to be removed. This is a non-flying application. But might as well make it all shiny!
Hopefully there are fewer troublesome socket and wrench fits on the other side! Thanks for the reply, and for these not-only-informative-but-also-fun videos!
It's such a cute lil' engine :-)
Nothing in the UK I'm afraid sometimes I get lucky with a little used manual here . Ebay UK has a C18 gearbox ONLY for £16 ,000 ( about Ca$30 000 ?) . To put this in perspective a Rolls Royce Viper from a Jet Provost in clean condition is £2500 ! Try the one month free download for the Dietroit Diesel manual . Picked up a couple of tips from guys who have worked on these .
Tip 1 CSL 1176 starting procedure - open throttle at N1 =12-15% rather than 18% as recommended in the operation manual as it reduces wear and burnout .
Compressor and turbine mounting stud torque is low at 80 in/lbs as this does not allow for 'drag torque' and these will come undone . Torque to 110 in/lbs to make sure they do not !
Great video's. Thanks AgentJatZ
Is that resin filling around the stator blades used in other engines? Looks like a bit of a nightmare if you had to replace one of the stator stages.
My god I wish you had more views! I loved this
Yellow case-old style. The Blur ribbon update was black. I remember doing what you are doing. What was the issue?
Very cool !
I wish that I had a jet powered boat….😎
There are only two ways:
1 - Build your own fantastic creation.
2 - Pay a fortune to someone who has completed (1) and is willing to part with it.
Each one of these things is a work of art and a labor of love.
Dude, thanks for sharing.
Excellent!
I had a good look at the WWW trying to find the fuel system manifold for the A250-C18 type,
I don't think my efforts would find anything you were unable to, but yours is the Allison 250
Rolls-Royce also do the C18 type and I hope you may be able to find the PDF there
I had to watch this video with a few breaks while caring for my boy Damian, I don't think I missed your explanation of why the third row of axial blades had the leading edge cuts, I wonder if you might be able to explain why, I have seen your own from your learning days when these parts were being thrown out, blacers ? I think you called them, makes good shelf ornament,
am waiting for my own RR RB-211 compressor mounted blade from 757-200.
good luck with this race boat build, looking forward to more videos, thankyou AgentJayZ
Just a guess but I know corner crops are used to change the resonant frequency of the blade. If the operating frequency of the engine and the blade resonant frequency are too close all hell breaks loose
@@qcan8468 ok that makes sense thanks
How much do I have to pay for an apprenticeship under this man
As ou know, watch for cracks in the plastic. The C18 was a dog barley making 317 hp
I can do my coffee gets cold same day, and microwave it. But second day? Lol
What was/is the cost of one of these engines? non airworthy i guess.
If you look, you will find. Then the price is whatever you can negotiate.
I'm guessing airworthy wouldn't be too hard to acheive with some time and skill and patience, even if it wasn't in that particular state to begin with. But sometimes pennies do cost $.
Certainly, gbowne1, making a junker airworthy is only a matter of half a million dollars or so. Piece of cake!
Such is the value of guesses.
@@AgentJayZ making an engine airworthy would basically require replacing everything that needs but doesn't have the proper paper trail?
Happy Easter:)
As we say at my software shop:
We're in the process of making progress.
I have an Allison 250 Technician's training manual I can part with if you want it.
We've got a couple good PDFs now, so thanks, but no need to part with a hard copy.
I believe I found a copy of the maintenance manual in pdf. Do you still need it?
We have the C18. What I need is the C20 parts catalog.
@@AgentJayZ sent what I'm hoping you are looking for to you email located on your jet city turbine Facebook page.
Can you explain why the third and sixth rotor stages have clipped corners?
It might be because, as he mentions at 7:00, they've been "blended" - Had a small bit ground off of each blade to balance the mass of the compressor as it rotates.
@@Ropponmatsu2 He did, but as he spun it around, it sounded like he went back and said the whole stage is just like that. I don't think balancing would require the whole stage to be ground.
Answered yesterday in the comments.
@@AgentJayZ Thank you. I found it eventually. Reasonable explanation.
please show us inside a fuel pump
So how was that toy-size rotor and stator made? Casting? Machined? Some other way?
That toy compressor needs six hundred horsepower to do its job...
The method of manufacture is not specified.
Oh... Polish flag on wall
I know its probably silly, but I just don't care for 12 point sockets. I only like using high quality 6 point sockets. I have 12 point sockets, I just avoid using them.
Most of the bolt heads I see are 12 point, except on the really old engines, So I need to have both.
Some NAS bolts and various commercial high tensile bolts and nuts are available in 12 point, they are a godsend in tight locations such as UNI joints, the spanner for them is almost the same diameter as the head. For hex heads 6 points usually can handle more torque. You can even get 12 point socket head bolts and they are less prone to slip than the 6 point ones when used with a 12 point driver.
In aircraft maintenance I rarely need 6 point sockets. Most things are torqued to specific specs and corrosion is strictly controlled, so rounding fasteners really isn't a concern most of the time. That said you occasionally run into a 6PT fastener made of soft metal with a high torque, and then you get out your 6pt socket.
Is this going on that motorbike of yours JZ? 🤣🤣
Not needed. My 84 Hp V-four with loco-torque is enough to destroy any "real" bagger.
Oh just a weed seed lol.. seeds come on man we know better than that Haha
I sent an email to robin call me if you still need the books.