You were right! It says right in the overhaul manual, and the flight manual, to operate the engine for two minutes at lowest EGT (65%) before shutting down. I also talk about this in my recent video Warming Up and Cooling Down. Also in my video called Cool Your Jets.

Boons will be boons. Jay has nothing to do with that don't even bring that crap on this channel.

You might be someone who would enjoy the increased level of hands-on detail in series of videos on restoring a 1950s fighter jet engine. It's featured on my Patreon channel.

Even more impressive is these were all designed with pen, paper, sliderulers, and trial and error. No computer modeling.

@@CDhn455 The human brain is more powerful than a computer, but nobody uses them any more.

Agreed! It's really cool to see all those amazing parts. It's even more fun to start to understand what they do.

I know the index was destroyed by KZfaq, but my earlier educational playlist: Your Questions Answered has over 100 episodes. I think you may enjoy it.

If you can rebuild a piston engine, you have the skills to work on jets. They are not better or more complicated, just completely different. Same tool skills are required for both.

@@AgentJayZ Thank you for the vote of confidence. I should have added that I am 66. Maybe at 23 I could have done this, but still the thought of an engine failure while off the ground because of a human mistake, weighs heavily on me. I worked on school buses at 23 and felt very responsible for the safety of the children, however the worst that happened was that the bus pulled to the side of the road and a spare was sent out to pick up the kids.

For the work I do... 66 is a better age for an apprentice than 16 or 26. If I was working on cars, they would all be '49 Mercs, with the odd '57 Bel Air thrown in...

Your homework assignment is to look at my playlist called Your Questions Answered.

I don't know what YT premium charges, but the Patreon full access membership is 5 bucks.

First choice.

Wood... any kind of wood... would burn. And the ceramic line guide bearing? There is not enough dimensional precision to make a ball bearing race out of it, and it's the wrong shape anyway. If you are implying that it was a journal bearing, it would have a life of minutes at best. So I'm contradicting the idea right now.

@@AgentJayZ Well, I never made the pilgrimmage to Bundaberg to see it, but the bloke who told me the story reckoned that his brother (who lived in Bundaberg) did go and knock on the door... I used to help the tale-teller to Aerotow Hang Gliders behind his Ultralight, we drank together weekly, and his brother had an obsession with Turbojets for a while...., after he cobbled up something from 2 Truck Turbochargers bolted together on a Shopping-Trolley (to hold the, Fueltank, Pump, Electrial Igniter Circuits & etc {I never saw the setup}, and got it to run well enough to propel the Cart accross his Garage with a tongue of Fire, before pulling it's Leads off the Car-Battery on the Bench...; and before he mortgaged his house to send $11,000 to a US Internet Address and then never ever recieved his promised Mil-Surp Turbine APU - with which he planned to attempt to build the World's first Jet Ultralight.... According to the Lore, yes the Runtime was indeed measured in minutes..., but the story was that for a while there was a bit of a track worn in the footpath in Bundaberg from the steady stream of people who'd been to "Jet Engine University...", and heard about the little Turbojet that lived in a Cigar-Box... My mate reckoned his brother was quizzed on the doorstep, and only after explaining about his Fire-breathing Shopping-Trolley was he invited in for a Cup of Tea..., shown the tiny Turbojet ; and (supposedly) saw it connected to a Can of cigarette-lighter Butane, had it's Spool hand-spun started, the Gasflow turned on with a Thumb pressing the Spiggot ; and then ignited by flicking a Bic Lighter accross the Tailpipe. The Shaft was supposedly turned to a clearance fit (because he couldn't work the Ceramic) so as to duly allow for thermal expansion...; and Jim had told Frank the story so convincingly that Frank seemed to believe it all when he told me of it...; Jim was at the time trying to hum some money from Frank, to go towards his Turbojet Importing (Fantasy) Project {he went as far as advertising the venture in both the Ultralight Magazines then publishing in Oz..., and I think 3 other people lost their money, as well as Jim - when the APUs failed to arrive...}. So..., I don't think the little engine was ever said to have run for any extended sort of time, probably 10 or 15 seconds would have been enough to impress the bejesus out of all who saw it (?)... I haven't ever ventured so far North as that, and it was 25 years ago ; but I'm still wondering about it... It's possible that Jim was duped, and it's possible that Jim made it all up to try convince Frank into funding the Jet Importing Fantasy...; but I'd like there to have once upon a time been a little tiny Turbojet, running on Butane in Bundaberg, with a hand-carved Ironbark Turbine... Even if it needed rebuilding every 5 minutes of Runtime, accrued in 10 or 20 seconds at a time...; as a Party Trick. My scepticism stems from the bloody great Swag of Computers required to get a modern Model Turbojet to start and run reliably..., and also I can't quite see how sparking a Lighter accross the Tailpipe could light the internal Fire, upstream of the Turbine...(?). But I figured you might enjoy the story of the alleged "Sighting Report"... Such is Life, Have a good one... Stay safe. ;-p Ciao !

1 - it's an open tube to the surrounding air 2 - If the carbon seals are working normally, they leak far less air than the scavenge pump pulls out, so air goes in the vent. 3 - Those holes allow additional compressor discharge air to join what is called 17th stage seal leakage air. It's the highest pressure and temperature bleed air available, and it is used for anti-icing purposes. The chamber into which those holes lead is connected to the outside of the engine via struts in the midframe. 4 - Those are covers for the openings from the ends of the struts. There are many different air pathways inside the midframe, all shown in the J79 air flow diagram I referred to. 5 - Answered and shown in the video.

The afterburner is built much like a combustor can. There is a gap between the outer casing and the perforated liner, and into this gap flows some of the inlet gases. These are engine exhaust, but still are cool enough (800F) to act as cooling air to protect the liner and the case from the heat of the burning mixture of fuel and engine exhaust gases (2500+F). I have shown this gap in several videos. Try putting cooling air into my channel search bar.

Don't know what you mean. The word recoup does not appear anywhere in any of the documentation I've seen ever.

@@AgentJayZ Sorry for the inconvience. Just have a look at this: 7con.com/7con.com/gs/GE/doc/sbs/cf6-50-sb-75-0074-r00-exec.htm

A hush kit improves the mixing of the jet exhaust with air, so the noise is reduced. It causes minimal restriction to flow, but does add weight.

The dust would have to get by the carbon seal, which is not an easy thing to do.

@@AgentJayZ ah ok. I was thinking the vent was directly ported into the housing.

In my video "warming up and cooling down" I talk about how much more important it is to allow the hot parts to cool for a few minutes at reduced power, than it is to worry about any sort of warm up after starting before increasing to max power.

That occurs during the taxi...

@@AgentJayZ Ah thank you, that makes perfect sense.

Even when properly clamped, flexible lines move more, and are more susceptible to wear. When an operator makes a modification to the "stock" engine, they use flexible, teflon lined braided SS lines. It makes fitment easier, but would never be used for an aircraft engine.

One of the greatest things about modern life is the search bar. It makes everything a matter of milliseconds, instead of hours or days of investigation...

I don't do other peoples work for them. It's not generally a recipe for success.

The spline is coated with grease on assembly. There is no movement at the interface, so rarely is any wear observed.

Is there any video of yours explaining air/oil separator function ?

I might have included that in Jet engine lube system. Let me know!

Close enough for part marks. It was 4 metal walls. Did you watch?

The Flygmotor RM6-C is recognizable as related to the Avon, but it has many differences. The most obvious is that is equipped with only one compressor bleed valve.

@@AgentJayZ Thank you.

@Skyisnotalimit If you are ever near Gothenburg, visit Aeroseum, an aviation museum in an underground hangar built in the 1950s. You can sit in a Draken and you can touch the engine sitting next to the plane.

That's a good idea. Watch blancolirio for the best updates and analysis.

@@AgentJayZ thanks for the reply I thought I'd be nice to know from your perspective as an engineer

Have a look at my vid about compressor stall.

Fire inside the engine: shut off fuel and purge with air by motoring the starter. Fire outside the engine: fire extinguishing system, which industrial installations also have.

@@AgentJayZ Awesome, thank you sir. When you work on engines is the external fire system part of what you receive or is it left behind at the facility or on the airplane?

The fire extinguishing system is not part of the engine. There is an excellent training film out there on YT that talks about tail pipe fires on airliners. I don't know exactly the name, but I know you can find it...

The bearings do not have their service life shortened due to oil coking.

It's a drawing, not a photograph, x-ray, or even a diagram... everything upstream of the rear frame and bearing sump is "out of bounds/not included/edited for simplicity"...

@@AgentJayZ Roger that. I'll do more research on my own to see if I can get that area clear in my head and understand it. Hey, thanks for taking the time to reply, and also, thank you for all the time, effort, and money you put in to making your videos. I really appreciate the technical detail you go in to and your careful choice of words to avoid ambiguity in your discussion. I have learned so much in the last year or two of watching your videos. Keep it up!

Find the J79 air flow PDF out there. It is huge, and allows you to see a lot of detail.

@@AgentJayZ OK, will do. My searches for LM 1500 details or LM 1500 hot section details has not borne any fruit.

I don't know what to tell you, bud... If you were to maybe follow my instructions... and put "J79 air flow " into the Google search box... ... ... it's the first hit.

Turbochargers are crude, simple devices, built to be tough and cheap, by making huge sacrifices in performance. If a turbojet was a seagull, and modern turbofans were eagles, automotive turbochargers would be beetles. Yeah, they can fly, but....

@@AgentJayZ Harsh

@@AgentJayZ And the turbocharger on my latest car allows the engine to produce almost 300 BHP out of two litres. The only problem is that the fuel gauge moves almost as quickly as the speedo.

For a single shaft gas generator, which becomes a turbojet when you add an exhaust accelerating nozzle to the back... the compressor uses up about 2/3 of the total power produced by the burning of the fuel. If you remove the exhaust nozzle from a turbojet, and use the exhaust stream to drive a separate turbine, you have a turboshaft engine. A turboprop is a type of turboshaft engine. So whatever the power output rating of your PT6 is, the compressor is using about double that.

I've stated this numerous times before, but it's worth restating: the power absorbed by the compressor is 'recycled', it's not wasted. There are inefficiencies, of course, which are inherent in any heat engine, and these affect a gas turbine to a relatively greater extent when it is operating off-design.

I'd just like to suggest that you make a donation to the patron page... for using my videos... 100.00 seems appropriate for an institution... what do you think?

An engine can be run without a final nozzle, but no engine can run "normally" at any significant power level without a final nozzle. Check out Adrian Bennett's KZfaq channel to see an ex-Concorde Olympus 593 running - without a final nozzle. It's never run much above idle, because, without the final nozzle, the pressure drop across the LP turbine will upspeed it and mismatch the compressors.

@@grahamj9101 Thanks for the answer. So whats the implication of the mismatch between the LP turbine and compressors; engine damage or the engine simply wont respond to throttle increase?

@@Automotive_Mountaineering As I'm a designer (retired), to give you a comprehensive answer, I'd have to call in a performance engineer. Even then, as it's not something that should normally happen to an engine, we might get a generalised answer. It would also depend on the design of the engine. In respect of a two-spool engine, such as the 593, with no final nozzle in place, there will be a relatively greater pressure drop across the LP turbine, which will then run relatively faster than with a final nozzle in place. Open up the throttle and with the LP compressor being turned relatively faster than it should, then the mismatch might well result in a surge. In the limit, it just might be possible to overspeed the LP spool. IF Mr Adrian Bennett tried to open up the throttle of his 593, I wouldn't want to be anywhere near it.

If you, or anyone out there, wants to treat themselves to a big boy's toy, there is an Olympus 593 on eBay UK for GBP585,000 (say USD750,000). I've just been invited to make an offer on it. I don't think so.

Let's hope someone buys it and then sends it to AgentJayZ for maintenance :-)

That would be interesting, but it is not done in aviation. The only way to keep the oil circulating is to have the main rotor shaft turning. It could be done, but as far as I know, no operators do that.

I was thinking about that too, but I bet the carbon seals would leak oil if they don’t have the negative pressure from the scavenge pump pulling in the chamber

In those shadows, in that light... your imagination is working double overtime.

@@AgentJayZ haha possibly!

It's a cartoon drawing. Don't expect too much reality...

The direction of rotation is correct for an Avon and for most (but not all) UK-designed gas turbines. However, if the angled lines in the cartoon of the turbine are supposed to represent the stagger angle of the blade shrouds then, yes, the angle is wrong. But as AgentJayZ has already told you, it is a cartoon.

It was purchased at the Alberta aviation museum in Edmonton, where this plane is on display. Aaviationmuseum.com. Email them about the Sabre Mk 1 shirt, and tell them AgentJayZ sent you!

I've not read that book, but I have read in many others that Hooker was extremely talented.

@@AgentJayZ Depends on the Hooker. 🤣🤣

Bacon and steel have very different properties...

Some cars have cooling fans that stay running for some time after turning off the engine to prevent damage from heat soak.

@@listerdave1240 Indeed - and I understand that some manufacturers engineer them to run in reverse, in order to draw cool air from beneath the car and exhaust hot air out the grill.

I have no idea what you mean, so you deserve some kind of award, maybe.

@@AgentJayZ My guess:What is the smallest jet engine used for aviation?

@@peterferryskipper Take a look at the small turbojets used for model aircraft: they are not toys. However, if you really mean an engine that will carry one human being, then take a look at Richard Browning of Gravity Industries Ltd, UK. He flies with small turbojets strapped to his forearms.

They have not even come close to creating a running engine. Don't talk to me about coolers, unless you have a lot of beer on hand.

AgentJayZ haha