Jay, I have watched every one of your jet-related videos (and the speaker ones too, among others. I'm not sure if I have actually seen ALL of your videos though, so I won't claim that), and the information presented here today was new to me. You know things that seem elementary and obvious to you, but the intricacies of gas generator components are a mystery to most of us. Thank you for taking the time to create entertaining and informative videos.
I’m new to your videos and can’t get enough. I’ve never worked on jet engines but I am amazed by everything about them. At an early age I worked for Nordskog Industry as an aircraft riveter then joined the US Navy tasked as a Aviation Jet Engine Mechanic. Regrettably within three months I had come down with diabetes and was discharged. Ive spent the rest of my life in the automotive industry. Watching your videos has rekindled my love for Jet Engines. Everything you show me I understand how and why it works the way it does and I once again can’t get enough. A Giant Thank You. Howard
If RU-vid gave out awards for best technical content, AgentJayZ would be in the running! Thanks for teaching us how jet engines work and how they are maintained.
Enjoy your videos! Went to school for, ( and actually received! ) my A&P licence in 1975; but never pursued it as a career. It did give me an understanding on how things worked that came in handy through the years, so time well spent! Still love aviation so thanks for " Keeping 'em flying " brother!
Thank you for the videos. Every time I watch a video I learn something new. I work with cars and I never touch a jet engine. Just interested how jet engines work. You are a good teacher and explain things easy to understand. Greetings from Holland
Great channel. You’ll no doubt have lots of new followers who will ask questions which you’ve already answered. Some of them will be young and inquisitive and will look up to you. What I’m trying to say is you seem inpatient when followers ask a question which you feel has already answered in a video umpteen videos ago. Sharing knowledge is great and sometimes you do have to repeat yourself.
AgentJayZ, Thank you for all the incredibly informative videos!! I have been binge watching since I discovered them! I have experience maintaining a C-54 , a C-97 and their radial R-200's and R-4360 engines. Because of this I am going for my A&P license , but I don't have much exposure to turbine engines. Your videos have been instrumental to a much better understanding of these amazing engines. thanks for explaining even the most mundane( if that's possible) parts of the engine. As a gearhead who has to know everything, this has been a gold mine of information. Thank you for taking the time with these videos. Keep up the great work!!
Another great video. Thank you so much for generously sharing your vast knowledge. The passion and enthusiasm you display for your profession is a wonderful example to others of “do what you love, love what you do”. Your videos helped inspire me to follow my dream of becoming a silversmith. I was incredibly lucky to find locally a London-trained master silversmith who is passionate about his trade and the obligation he feels to pass his knowledge on to others so my dream is starting to become reality. Many people helped me along the way but you stand out with your often repeated message of “follow your dreams.”
Well done that man.....excellent vid..couldn't have been more clear....tension ties putting the torque shafts under compression...what beautiful engineering...thanks Russell
I have really valued all I learned about the Turbo-Jet In all it's types, accessories and most important cooling Your video's have been over the years like a university Degree, I wish I could take what I've learnt into the workforce Thank you for sharing man's greatest engine. Mic stone
It impressive to see just how seemingly small some big jet engine parts are. I kept having trouble believing that such a seemingly thin thing could hold an engine together. But you explained fairly well that those bolts only deal with the tension force. And that the rotational force goes through the much more beefy parts. Cheers for the vids.
I love this fuckin channel, been watching you for almost 2 years now and it never gets old, i love videos like this where i get to learn about stuff i have no idea about, although through this channel i have learned ALLOT about these engines, excellent video as always bro, see ya in the next one !
I love the videos... nothing like an expert bringing it down to basics... I have flown jets. I have worked on jet air-frame structural certification as an engineer, but I really did not understand jet engines, as well as I do now thanks to your videos. Thanks
Cool, I didn’t know that there was anything separate holding it together, and just assumed the shaft was under tension with the compressor and turbine disc being held on by a big nut or similar. You learn something new every day.
AgentJayZ, I love your videos! Really interesting stuff and your way of "teaching" and explaining it for us is just right. Thanks for great educational videos
One comment more... mcycle fellow here too. Did a 3-day w/ Keith Code(California Superbike School). Pretty damned awesome. I recommend for fellow 2-wheel and turbine-while enthusiasts. Quite a good way to spend 3 days. :)
Great explanation, thank you! Have seen most if not all of your videos and still find this basic explanation very telling. Thank you, JayZ, you are a treasure!
Very lucid explanation. Thank you for answering that elementary question. So in effect, the shafts of the compressor and the turbine are joined by splines held together by a bolt which may be even a 'nut'.
AgentJayZ those things that you just explained are maybe taken for granted for you but you have to realise 99,9% your audience never saw jet engine or any kind airplane/helicopter/gas turbine engine opened in real life. In your audience it's literally like 10 people who knows those stuff and another 50 that kinda know the the drill but all others 100 000-200 000 people here in person only saw front fan on commercial airlines engine. So do not take anything for granted that we know already about those engines
What I mean when I say "you've already seen that" is that either it's been in a recent video, or it has been discussed at length in quite a few videos I have already made. I know everybody has not seen all of my videos, but I can't include everything in every video, or they would all be 30 hours long. Also, although viewers may not have watched all my videos in the chronological order, that is how my existence is experienced, by me anyway.
AgentJayZ I watched like 50-100 your videos and I can't remember this exact thing about shaft. I just recently subscribe to your channel and you nailed it. You are the best in actually explaining how those things work. 👍👍👍 Keep up good work
Always great videos! I really appreciate that you do not tolerate the online keyboard trolls. As well your in-depth explanations of how these engines work is awesome. I use to weld combuster casings for helicopters engines in military applications, so we were kept in the dark as to how any and everything worked together. Thanks for all your time! Cheers
Jay, a quick comment on Redbubble, because I gathered from what you said in the intro, that you might be moving away from them. You are the first RU-vid personality that I've encountered that sells their gear through Redbubble, and, in fact, picking up my spiffy Jet City Turbines shirt was the first time I'd ever even heard of the place. And they're brilliant! The thing that I really appreciated about them is, as a print-on-demand service, they have all colors and all sizes available all the time. Other channels that I want to support, if they offer shirts at all, they're typically available only in a limited number of colors (perhaps just one) and a limited number of sizes. With Redbubble, I can (apparently) always get what I want. Will you still be able to offer that kind of flexibility with a local supplier? As a purchaser, that was a really nice change from the usual.
I don't think we will actually close down the Redbubble option. They are very nice, and have great customer service. The local connection will have even more options, and I will be able to work with them a lot more on the creation of the designs. That's what we are working towards...
@AgentJayZ Thanks for a great video. Is there any net forward force from the compressor/compressor-turbine assembly? Or is there the same amount of force pulling forward from the compressor as pulling backwards from the compressor turbine?
The connections, shown here, are called tension members by some manufacturers. They are under large tension forces. In a turbojet, the net force on the thrust bearing is usually backward. Check out an image i.stack.imgur.com/47W9J.jpg. It shows the various components you are talking about.
I had that question when I was first getting into turbojets. What holds it together? Well now I understand that and I’m nearly ready to build my model turbofan I just still don’t understand the oil system. Why do model jets put it in the fuel instead of using the same spray and receive system in larger jets? Idk
@@nicholasdelrossi3996 because large jets have the space for sealed off bearing sumps (the return mechanism for the oil around the bearings) inside the air seal system with the carbon rings around the shaft. In a model engine it's just simpler to allow the fluid to lubricate the bearings and then get burned off.
The People that came up with these Ideas were Drinking/Smoking/Popping Something Very Special! LOL! Amazing Engineers and Amazing Machinists. The Machinist Must Bring The Parts Out of The Engineer's Mind and Form it into The Proper Materials. There Were No CAD/CAM Systems or Even Calculators Back in The Day. Only Pencils, Paper, and The Slide Rule. Both Groups Were Truly Geniuses. Great Video, Very Well Crafted! Thank You Very Much!
When starting a turbine, what critical temperatures are important to watch? Basically, if you want to get moving quickly, what are the limiting safety issues re. warming up? Thanks for your great videos. I learn much.
From cold and black to full maximum power in about one minute is just fine.The cooldown after a hard run is much more important than any warmup from cold. This is discussed in more detail several times in my playlist "your questions answered" YT deleted my index. Sorry!
Sorry, AgentJayZ, but I'm going to disagree with you on this - to a degree. If you want to get an aero-derivative gas turbine, or the (military) aero engine from which it was derived, from cold to full power in as little as a minute, yes you can, but at a price. The Industrial Olympus, which AgentJayZ has shown us (and which I worked on as a young designer) was derived from an engine that would take a fuelled-up Vulcan bomber, with a "bucket of instant sunshine" on board, from a cold engine start to take-off in 40 seconds. However ..... the price to be paid is a nasty thermal shock to the turbine NGVs and blades, plus severe thermal gradients and hence stresses in the turbine (and even the HP compressor) discs, which significantly reduces their lives, as compared to, say, warming up the engine at idle for a couple of minutes, then taking it up to power more gradually. But then, if you wanted to get your H-bomb into the air before you were obliterated by their H-bomb, what the **** OK, there are also potential problems if an engine is not cooled down adequately before shut-down. In aero engines, whether military or civil, there is rarely a problem: typically, they spend more than a few minutes at idle, trundling down the taxiway to wherever they are going to be parked. Nevertheless, I know of one engine that powered a certain SST, which, on occasions, needed a 'debow' procedure to straighten out a thermally distorted HP rotor, to avoid heavy vibration due to unbalance - and there's a military engine out there that has a similar pocedure. In contrast, industrial engines may need to be 'tripped' from high power and that can cause problems - as I discovered to my cost, back in 1974. I have described it before in some detail on this channel, but we had a 'temporary' seizure problem on the Industrial RB211: if it was not shut down after idling for a couple of minutes, or was not restarted from a high power 'trip' within a few minutes, then the HP spool would seize for three or four hours.
Kind of amazing how much engineering goes into these engines that still manage to be so different. Are there any whose design really stands out to you as beautiful/efficient/a cut above the rest? Are there engines you dread working with because of their design?
Just occurred to me, how's the thermal expansion (of engine/parts) is dealt with when using a tension rod? btw, where is the main/center thrust bearing is located in relation to the joint? I always assumed the splines would facilitate that movement but then we have a tension rod pulling the splines together, so... they can't slide.... *scratching head The stubby tensioner makes sense since it connects the close ends together. that way the far ends is free to move, but the long rods pull the far end to tie the parts together? (also more length of metal and more thermal expansion/contraction to deal with)
Have you done a video to explain how the compressor disks are attached to each other and/or held together as a single spinning unit. If so, I missed it; would you point me to it. If not, would you do one. Thanks. Just fascinated by this stuff.
Awesome video good sir. Quick question on the shirts you have for sale.. Have you ever thought about putting a 3D view of some of the jet engines you guy's work on the back side of the shirt? Possibly give specs on the engine's too.. I think those would sell really well. 👍👍
Super AgentJayz I spotted a lot of tension in your voice. Then spotted tension in your arms. I did not see tension in the bolts even though they work in tension! How ironic. Lol
Have you made a video or answered this question: Does the Compressor require less power when the aircraft is at a cruise speed rather than during take off due to air being rammed into the inlet? I would like to understand this better.
Cruise and takeoff are different power settings. Something like 100% and 93%... very roughly. Aside from that, aircraft speed does help compressor efficiency due to what is actually called the ram effect.
I was just wondering if less horsepower is required to compress the air when the ram effect occurs and if there is much difference? I was thinking along the lines of a ground based gas turbine vs a jet liner moving at high speed. Is it minimal or a big efficiency changer?
As I said, the ram effect does increase compressor efficiency. Stationary engines are not at much of a disadvantage, because they use a bell mouth inlet fairing, which greatly reduces inlet losses.
All of the 3D "models" I've seen are so simplified and inaccurate that they would not be useful for training purposes. To call them "exact' in any way is a joke.
@@AgentJayZ ah okay. Maybe if there ar so many blueprints out there maybe i can make a model myself. I am planning on using it for personal projects like 3d printing or machining a small scale "semi functional" display model. (functional as in its shaft and spins, the stators rotate etc). Thanks a lot for your replies! Your videos are amazing.
The tension member holds the coupling in tension. The splined shaft ends transmit the torque and power. Not sure which one of the couplings you are referring to, but they range from about 5 thousand to about 30 thousand Hp.
@@AgentJayZ Yep I am referring to the shaft, the splined shaft. I pull´d my tractor apart for a repair years ago, and the transmission shaft was almost as big as the one i the video, they must be high high quality. So the torque must be fairly low cause the high rpm, ore ?. Love seeing you work on those bad ass engines
The magic of alloys man. I picked up a helicopter engine to main gearbox driveshaft that transmits 2200hp and it weighed about 200g. I was shocked and I've been in the industry for 10 years now. The technology just keeps improving.
I listened closely and the answer is in the vid I think. The force that tries to rip the compressor and the turbine from the shaft in opposite directions is resulting from the two thirds of the gross power that are needed to run the gas generator. That is twice as much as the thrust , but it's no thrust.
I have my copy of 'The Jet Engine' open at page 208. I think you may not have appreciated that the respective forward and rearward loads that are quoted for the compressor and the turbine (in an Avon engine) are the total loads on both rotating and static components in those engine sections. As a rough first approximation, the loads on the compressor and turbine rotors could be around half of the values that you have assumed.
I've explained several times before on this channel that the power absorbed by the compressor is transferred to the air being compressed, less the inevitable aerodynamic, etc, losses, of course. That power is effectively 'recycled' in the turbine, which is there to extract power from the hot gases (less the inevitable losses). The turbine doesn't distinguish where the power in the gases originally comes from.
..... plus the power required to drive the accessories, if a mechanical (or electrical) drive is taken from that spool. I'm familiar with the aerodynamics and thermodynamics of the Brayton cycle, having spent a career lifetime in the design of gas turbine engines, industrial, marine and aero. However, I'm also aware that all too many of AgentJayZ's subscribers are not and I'm happy to share my knowledge and experience in improving their understanding and in the correction of any misconceptions. Specifically, there is the matter of the huge amount of power produced by the turbine(s) and absorbed by the compressor(s). Many seem to be under the impression that it's going to waste somehow, possibly because they don't appreciate that exactly the same process is going on in a piston engine, since the power absorption during the compression stroke is not usually expressed. For anyone who needs convincing of this, get a tyre (spell it 'tire', if you must) pump, preferably a stirrup-style pump like mine, and try pumping up a car tyre from flat: you will soon get tired (no alternative spelling offered). That is indicative of the energy required and the power absorption during the compression stroke in a piston engine, which isn't going to waste, of course. In offering my comments on AgentJayZ's channel, I do not reply solely to one individual but for the enlightenment of as many as may wish to read my words.
i'd like to go back in time and witness the design and development of these engines from the 1950s... to witness the brains behind the technology. it must have been a hugely exciting time to witness the creation of these beasts.
give me pizza or give me death - i was thinking the same thing. My mind was blown when he showed the cone "thing", and i wondered how in the heck someone's mind would conceive such a part, let alone give specs for its manufacture. Then i had to laugh. A piston engine basically is a bunch of hammers and nails turning the shaft, whereas the jet engine is a bunch of coarse and fine threaded rods and fans sucking, blowing, pushing, pulling, and heating each other....combusting 150000 cubic feet of air out it's butt😖 This guy's semi simplification makes me a little more curious to investigate how a jet turbine engine works, which up until now i was happy to leave it as JFM😄
Very new to channel, have you produced a video that dissects a helicopter turbine? Suppose a turbo prop would be similar, different transmission. Thanks
Love your videos. You have awesome teaching skills, in addition to superb technical knowledge. Wish I had more instructors like you in college. I have a question, and perhaps you've already answered it. Q: What keeps the high-pressure gasses in the combustion stage from coming out the front? Isn't the pressure in the combustion stage greater than the pressure in the compressor? Dave in Texas Peace
AgentJayZ I believe you, just wondering why not? Is there no back pressure from the turbine nozzles, turbine and turkey feathers when they constrict? Obviously the answer has to be “yes, but not equal to the pressure from the compressor.” So I guess my question really is, what does the pressure gradient look like from inlet to exhaust? Thanks for your time and response. Love the vids.
There is no pressure rise due to the heat of combustion. The exhaust nozzle does not constrict. It opens up from it's "normal" area as the afterburner raises the temp of the gases. In my series Jet Engine Diagrams we look at the pressure, temperature and velocity profile through a turbojet engine.
You seem very Tense making this video . ( get it ). Are these long bolts one time use only. Or can they re-used.? Do you use a guage to check the stretch on the bolts or is the torque measured to the fastner all that is needed. Love the video's .
These are more accurately described as engine parts that take the form of a modified bolt. i.e. they are very expensive and of course reusable. They are not really torqued, but spun down to contact and then locked in place with elaborate mechanisms.
Jay: just to indicate what I see as zero to poor understanding a lady who's vehicle I jump started (engine did not turn over but only a clicking sound was heard) thought the fuel pump could be bad. What the technical types we are take as understanding is based on principles of organization, design, and for an engine its' start sequence.
High-pressure turbine and compressor held together with a tension component. Maybe a tube with 2 opposite threads? Low-pressure turbine and compressor held together with a tension component. Maybe a rod down the middle? What keeps the high-pressure system from moving forwards or backwards with respect to the low-pressure system? How much force is needed to keep them together? Wonderful video, BTW.
Each shaft has several main bearings, and one of them is always a thrust bearing, which axially locates the shaft. Got videos on bearings in turbine engines you might like.
The Olympus 593 in Concorde was bigger than the ***** ( an engine we don't mention in AgentJayZ's presence), with 38,000lb in reheat and 32,000lb dry, as compared to 34,000lb in afterburner and 25,000lb dry - and AgentJayZ has a 593 somewhere out in the yard, but I don't think that it has its reheat system. I wouldn't like to make any claims for the 593, but four of them were as loud as ***** on take-off and would set off the car alarms on the car park at the end of runway 09R at LHR.
At the Illinois State Fair I visited the IL National Air Guard Reserve Unit based here in Springfield IL that had on display a GE-110 engine. The young man asked if I had any questions and I thought a few seconds and asked if this engine was a descendent of the GE J-79, and he said, "Oh, no, sir, the 110 is it's own design." I'm not sure he had any freaking idea what I was even talking about because he had the strangest look on his face when I asked.
Driven or driving (drive) shafts are typically hollow because something like 90% of the load is experienced in the outer circumference. Makes the shaft a whole lot lighter when you remove useless material. Of course, this only applies to torsion and not tension. Hollow bolts need to have a larger diameter to account for loss cross sectional area. Tubes are analogous to pipe, and are used to move fluid. Pipe is measured on the ID and tube on the OD. (I very possibly may have those two reversed)
Yes. Tube is the way modern things get done. And... pipe is 19th century crap at best. Pipe is caveman, and pipe wrenches are an abomination, the antithesis of technology... unless you are a caveman.
There is always some vibration in a jet engine: it's inescapable. It's in the whine of the fan and compressors and the roar of the jet exhaust: that's the acoustic evidence of vibration, which pervades the engine. It might be of low amplitude and high frequency, but it's there and it's one of the major causes of frettage and wear between components in the engine. I spent a significant amount of time during my career lifetime in gas turbine design introducing and incorporating anti-frettage and wear features into engines.
I balance CF6 compressor rotors and it's all about balance. The nodes that cause resonance/ high vibes are designed to occur outside of operating conditions, like a certain rpm the engine sweeps through during startup
Thanks for the incredible videos you provide for all the interested people who clearly couldn’t have hands on access to these infos. I’m so Sorry, but not surprised, to see the moderately low view counts, in an era where everyone only aspire to be entertained, or dreaming to become a business man (haha) and make money (Hahaha). Maybe you could spit roast a chicken with one of these tension couplings , slice carrots with a fan blade, make mashed potatoes with compressor parts, have cute kittens purr and play in the background, but that would defeat the purpose of your intents. Thank you .
For a jet engine, power is not measured. What is measured is the force it can exert against its mounts in a static test. This force is what it can apply to an air frame and push it forward, so we call it thrust.
I have an opportunity to purchase a basket case T53-L-13B, any idea on reasonable price? I know this question has a million variables, but do you have any advice?
If it runs, 20K. If it doesn't run, but has a starter, and ignition box, all other accessories, and has no apparent damage, 10K. Obvious damage, and no starter or ignition, 500 bucks for a parts donor. If you don't already have a "good" T53, they can pay you 100 bucks to drag it away.
The shipping containers support the engines with their main airframe mounting points. Typically you remove the lid from the container, attach a lifting device to specific lifting points on the engine, and then remove the fasteners from the main mounts. Using a crane to lift up on the lifting device, the engine floats magically into the air, where it can then be placed on another set of main mounts on a work stand or transport trailer.
Just saw a video claiming that Japanese air force F-15 is so fragile that they may have to change engines after each flight. Even if not true, question rises, what are parts that wear the most or require repair after just such short usage?
Why segregate the transmission of the torque and the tensioning member(s) that keeps them together? Why wouldn't one long splined shaft with a nut of some sort on either end get the job done?
There are numerous ways of attaching a compressor to a turbine, taking both the end load and the torque. There is a way of transmitting both through one device: a helical spline.
What keeps the object from backing off of the helical spline? From the pictures I'm seeing it looks like a trapezoidal thread (acme thread) kind of like a screw-jack?
This is a good question - and I wondered who might be smart enough to ask it! The tooth form of the spline is normally a standard involute, but it doesn't have to be. The clever bit of the design is the angle of the helix: the torque from the turbine tends to screw the the turbine shaft forwards, while the rearward load of the turbine tends to unscrew it. Balance the two opposing effects and all that's needed is a locking device between the two, taking minimal end load. R-R Derby have used this principle for years: it's known as a Lombard coupling and it doubles as an axial adjustment device for the turbine. I designed a helical spline with a Lombard coupling for the IP turbine shaft of the Industrial RB211 back in 1972. The locking sleeve had to be inserted from the rear of the engine on the end of a special tool, which extended the full length of the shaft. After the first field trials engine had been in service for a year or two at Burstall in Canada, we had a report back from TCPL, telling us that they had found the locking sleeve still fixed to the end of the tool. The engine had been running quite happily for over 1,000hrs and the axial position of the IP turbine had not changed. PS One of our service engineers told me that, "Burstall's not the end of the world, but on a clear day you can see it from there!"
