Thanks Jay for the video, that was, i think, your longest and most in-depth. You put a lot into this with the info and the editing and i for one am very thankful for your effort. Wish i could put a thousand more thumbs up and views for you.
I am a former U.S. Air Force Jet Engine Mechanic 2A651A, I Worked on GE CFM 56-2 / F-108 on KC-135 R at Fairchild AFB WA, GE CF 6 / F103 on KC-10 extenders, DC-10, B-747 / VC-25 ( air force one ) and is also the core engine of GE LM-2500 ship and powerstation engine, GE F-110 of F-16D block 40`s at Kunsan AB ROK, P&W F-100-200 of F-15C at Langley AFB, VA 1st Fighter Wing etc etc. Got experience on P&W TF-33 / JT3D ( the core engine is J-57 ) of Lockheed C-141 and GE TF-39 of lockheed C-5 A and B Galaxy ( the spawn of GE YJ-93 turbojet for the six pack XB-70 Valkyrie bomber which is the core engine with a 1 1/2 stage front compressor ) Its also the bead rock of GE 90 and GenX engines. I know what i am talking about. The main reason those GE J-79 smoked so much was because of that era`s " Can " and " Can annular " designed combustion section liners and un efficient swirl cups where the fuel nozzles spray to mix with air coming off compressor / diffuser air. Modern Turbojet and Turbo Fan engines use a Annular combustor design ( one big open burner with lining on the outer casing inner surface and inner center body liner surface ) with more efficient swirl cups with Fuel spray nozzles. That's why today's jet engines don`t smoke so much. Just helping you out AgentJayZ
Leon Swan. I have a question for you. Do you know where the water was injected into the Engine of the F105 Thunderchief? Was it Aft of the Spray Bar of the Afterburner? ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-KvevElwHe1k.html The F105 had the Powerplant: 1 × Pratt & Whitney J75-P-19W afterburning turbojet engine, 14,300 lbf (64 kN) thrust 26,500 lbf (117.88 kN) with afterburning and water injection[108]
As a grad of AMOC/test pilot course and having dealt with turbine eng. for years I find your videos of highest caliber and very informative.. Thumbs up!
Jay , great video and technical explaining! If only someone could explain women the way you explain jets ! many thanks for all your detailed work and great editing !
Thanks for the videos JZ, I know it's a lot of work to produce them and they are appreciated and enjoyed. Seeing all the control inputs for the jet nozzle positioning it occurred to me that all the control inputs were, of course, analog. Amazing engineering from the designers; it would be so much simpler with todays digital technology. It reminds me a bit of the Cosworth F1 fuel injection control from BITD. Again, thanks for the interesting and informative videos.
I just watched your video titled *Afterburners, reheat, and post combustion...* and I was wondering why the nozzle was open both when it was at low power and while the after burner was going. This video answered a lot of my questions. Thank you. I'd love to see the way those leaves of the nozzle fit together. I suspect the leaves of the nozzle might be more complicated than the leaves of my vegetable steamer. Thanks for the fun and interesting videos.
AgentJayZ thank you for your help as always, I will research your jet cars video's to understand why, It is nearly 800 video's you have made, thanks for all the time you must put in, You say it's always good to study more than one source to better understand, There is only one Jet Technician with a complete knowledge of the turbo-jet, In a way that helps me to really comprehend what's being taught, There are not 3 or 4 different jet-tech's, like you from Jet City Canada, I have learned my Patron membership hasn't been paid, I will restart these payments from 9/6/2023, Sorry this happened, I will check this gets done in the future, Best wishes. Mic stone I will never work again, through disability, but it's great to learn anyway,
EXCELLENT video (as are all of your videos) Thanks for all the time you put into this particular video as well... I think the word complicated is a BIT of an understatement! :-D (I just realized I wasn't subscribed to your channel for some stupid reason, lol)
Back in the'70s and '80s, when I worked on RF-4Cs, the engine personnel called the variable exhaust nozzle parts the "turkey feathers" or "turkey tail feathers." The assembly, as attached to the engine, was simply the "nozzle." Still think the F-4 is an incredible machine...
thanks jay another really in depth and informative video all though i had to watch it a couple of times to get my head around some of it haha keep up the good work mate
Hi Jay. When you were talking about the F-16 torch igniters, you were correct about them always being "on". The main igniters always have power going to them, but they don't spark while the engine is self sustaining because they are designed to stop sparking once the combustor pressure and temperature is up to a certain amount. This is for the P&W F100-PW-220 and -229 engines. I'm sure that a lot of other engines are set up this way as well.
from now on I'm just gonna assume that everything in a jet engine is more complicated than I originally thought. Even a bearing has so much engineering around it...
I just watched your 11 year old video of this engine on the test rig, when I saw the nose open and close so close up. I wondered how it worked, I could see the rods, I guessed wrongly that they would all be attached to a ring /collar that was hydraulically actuated, thus no worries with trying to synchronize them, I can't believe I was wrong, it very fast really quite amazing !
The nose, or the nozzle? I have a J47 video where the inlet screens open and close. I have a few vids where the variable exhaust nozzle operates on the J79.
RD says; Fantastic editing ! You could be a producer . All the engineered parts were made why back when bids and contracts were farmed out around the country , from Ma&Pa machine shops to mega corporations . None of which are in existence today for these old engines , Reproducing any one of these parts would cost a fortune ! This is a great video , really opens the mind to all the engineering and thinking into a functional Omni thrust producer component .
AgentJayZ I once see a J 79 in your test cell running without AB But the spark generator on and glowing, You said it was a fault somehow which was fascinating to see As it would normally never be seen, This video on the variable jet nozzle dated 6 years ago, It is likely to be a more recent video, And must be very rare to see, might it overheat with fuel ? Wish you well, thank you for being there at exactly the right moment mic stone
Both the afterburner, and the torch igniter, are designed for continuous operation. If that's what you are asking about when you say "overheat with fuel".
Hello @AgentJayZ, where would I be able to get a hard copy of this reading material? Very interested in the function of and movement of variable jet exhaust nozzles.
Wow, the afterburner fuel pump alone uses more than 100 HP. The scales of these things is amazing. I'm an engineer, and find your work very interesting.
you teach alot my guy. I am working on my masters thesis project on a robust controller for a micro gas turbine. my only problem is that I don't have access to a gas turbine 24/7, although my school has one
You should do a guest lecture at a university. It is great to learn the theory from professors, but to hear from someone who actually works on these engines and knows what all our variables are actually useful for is awesome! Also the video of you and that other guy standing just feet away from the exhaust stream is awesome. I'd be afraid to go within 10 feet of that
Thanks, dude. I've been to university, and the quality of instruction there spoils you for anything else. We have fun on my channel, but I could not meet the standard required for an engineering course, even at the introductory level.
Well you say that, but I think your videos helped me more than my professor did last semester... He just wouldn't stop ranting about how the Jumo-004B was the most important jet engine ever, and then would go into unintelligible ravings about the compressors and turbines and the GE-NX turbofan...
The Jumo was among the first... like an iron plow... but jeez, the dirt really stuck to that pos, until somebody made a better one. It's a;ways been that way.
The Junkers 109-004B has been described as "the world's first successful axial flow jet engine", which is probably why your prof raves about it. However, it was difficult to start, tricky to handle, unreliable and had a very short life 25 to 50hrs (if the pilot was careful). Yes, the engine manufacturers in wartime Germany produced engines with axial flow compressors and annular combustion chambers, which were, in terms of their architecture, in advance of their time. At the same time, there were engines in the UK with compressors that were effectively oversized supercharger impellers, which (after some development) started easily, handled well and lasted reliably for 150hrs between overhauls, having been tested to 500hrs. They were followed on closely in the UK by bigger and more reliable axial flow engines and, if Frank Whittle had been allowed to develop it, he would have produced a by-pass engine with a BPR of 2.3 soon after the WWII.
So you (and others) might wonder why Frank Whittle went for a centrifugal compressor and was initially followed in that direction by other UK manufacturers. The answer to this is that Whittle started his jet engine work on a shoestring budget: in terms of both cost and facilities, he could never have afforded to develop and manufacture an axial flow compressor. Similarly, he didn't have the resources to develop an annular combustor. Getting a even single small combustor, which could be multiplied by eight, ten (or more) in the engine, took quite a lot of experimental work in those days.
Synchronizing the nozzle actuators... It's intuitive that you'd want the nozzle to remain symmetrical, but what forces would be acting asymmetrically on the nozzle components in the first place?
Hey Jay, in all the video's (or most) that have a variable nozzle on the engine - you mention that they are restricted to military aircraft or more precisely they are illegal for civilian use. I can't seem to remember if you ever mentioned why. Can you share this little tidbit? On another topic, GE has been manufacturing some of the "90" parts with their Titanium 3D printer. What's the chance they might let you in for a tour and show you these very cool machines? They'd be way more apt to let you in versus me. Anyways, it would be a really cool field trip. Thanks for all the great years. I have learned a lot from you and really appreciate you doing the video's. As a kid I would sometimes get to watch the F16's at McClellan AFB do touch and go's. When he crossed the near end of the runway he would be in a vertical climb in full afterburner. That was awesome to watch. I've been hooked on planes ever since.
As for the variable nozzle, I think the government would rather not have those things in the public domain, because of the (admittedly very long-shot) possibility of anyone getting a plane flying that could outrun an F-15 or an F-22. But I don't know the exact details of the legalities, because vintage Starfighters are flown by commercial companies in the US. As for a tour of a modern factory, I doubt there is any chance of that. In the world of big manufacturers, my little shop/business/channel counts for nothing. I even went back to my jet training school, BCIT for a visit, and they would not even allow me to speak to the chief instructor. I was sent away by the receptionist. I could hardly believe it. One of the main reasons I make my vids is because if I worked at a large company, I would never be allowed to. The stuff I show at the test cell, and on my patreon vids, can almost be considered classified and completely forbidden. I've worked in a large overhaul facility. They had shop cameras that were not allowed to leave the building, and copies of the images were not allowed. Too many managers, lawyers, and compliance officers interfering with everything. None of those even allowed into the Jet City building!
im loving all your videos! i was hoping you could explain why the vanes of a lot of the compressor wheels are kind of loose in their "tree" mounts. im sure theres a good reason i just havent been able to find an answer.
Hello AgentJayZ: I have a question about the Orenda Iroquois. In the video Turboprop Core - Turbine Engines: A closer look ( Published on Aug 05, 2012), At the beginning of the video you walked around the Iroquois and there is a green compressed gas cylinder mounted on the front end. In my experience that would be an oxygen tank, if the color coding is the same now as it was when it was produced. What would this tank be used for? Thank you for all of the great videos and the information they contain. One other question. On the J47 engines, you (company) have had the turbine blades ceramic coated, also looked line the turbine guide veins were also ceramic coated ( from the video about locking in the turbine blades ). I was wondering if the turbine blades and / or their guide veins on the IA-25, could those be ceramic coated for more protection from overheating due to a hot start or excessively high temps from the combustion section. Thank you again! Please keep the great videos coming. Jeff Thompson .. from western Wisconsin
AgentJayZ I have heard you explain that it is possible to own a GE J79 or others, But for an unknown reason to me that is illegal to own the variable jet nozzle, In England some owns a Rolls Royce/Snecma Olympus 593 from a Concorde, fitted to a cab - over truck, and air show test runs, Concorde's engine is a large Turbo-Jet no bypass at all, but capable of super-cruise, a 2 spool type first made in 1950, This also has no variable jet nozzle, but do think it's possible for a compatible metal shop to rebuild, However might the accessories paired with the engine for this task also being removed, I scatch my head and just wonder why, I do hope I didn't miss your explanation in another video, I so appreciate your help to understand this mighty Turbo-Jet, Thanks always. Mic stone
Good video, but I was wondering how the nozzle links together. Do you ever have to take the nozzle a part and service it? The reason I am asking is I wonder if RC Ducted fan jets can put this knowledge to use. I hope my crazy question makes sense. Thank you for your videos!
An RC ducted fan does not need a variable nozzle. It does not need any nozzle. A jet nozzle is used to accelerate pressurized gases by efficiently converting their pressure to velocity. The RC fan likely does all the acceleration of the air, and produces zero pressure rise in the duct.
Does modern thrust vectoring have anything in common with this? Is thrust vectoring similar to using the actuators without the interconnecting shafts, so that the nozzle can be pushed into asymmetric configurations?
Thrust vectoring is a separate nozzle movement, in addition to the variable nozzle needed for afterburning. So the thrust vectoring nozzles of an afterburning low bypass turbofan engine are quite complicated and very impressive.
No. Thrust vectoring is adding two rotation axis' of control, which gives the pilot more authority of the jet. (The engine physically moves, instead of the air over the control surfaces driving the movement) Variable nozzle control is there so the nozzle is at maximum efficiency no matter the altitude or throttle (for more info on that, look up "Thrust Separation")
I tell you, the video segment shot at 29:03 from the top of the engine looking aft along the exhaust nozzle is excellent. Some great video editing effort went into this product. Much thanks for that! I've been somewhat perplexed about the physical principal(s) that allow the exhaust thrust to keep moving rearward instead of finding another exit such as the large inlets at the foreward end of the variable nozzle (i.e. 29:03; 36:07, etc). Is this the effect of our friend Bernoulli at work with a low pressure, high velocity exhaust stream inside the variable exhaust nozzle acting as a venturi? (But doesn't Bernoulli only describe pressure and velocity of incompressible fluids?...) Fasincating stuff, but there's a reason I didn't become a jet engine designer.
Thank you for these videos. You obviously put a lot of effort in them. At the risk of sounding lazy, are there any books you would recommend for an absolute newcomer in the world of jet propulsion?
An article in Aviation History Magazine mentioned that S&S Turbines rebuilt a J79 for a Norwegian F-104 that has recently been restored. Were you a part of that rebuild? That's the first time I've seen S&S mentioned outside of your videos. Keep up the great work!
Thanks for theAwesome informative videos. I just joined your channel and I was wondering what limits the rpm of an engine, is it aerodynamic or is it controlled by some kind of mechanical or electronic system? I'm not sure if you already explained in one of your videos.
The rpm of the engine is controlled by how much fuel is fed to the combustors. That is controlled by the fuel control, which is digital electronic on newer engines, and increasingly hydromechanical as you look at older and older designs.
Hi AgentJayZ, have you ever disarmed a GE TF39? To see it more in detail, would be great. The sound of that engine is spectacular, it would be nice to know more about your particular style of making videos. I send you a hug from Argentina
@@AgentJayZ Flight GA-421 found enough. I do not know how much power the 777-300 engines produce at "flight idle" but there was enough rain and hail to cause both to flame out.
i have a question - the nozzle dampers which close down look relatively flimsy - would they not have to redirect a good deal of the thrust being produced just to achieve the effect? I mean - newton's third law and all that... wouldn't they need to be just as robust as the engine itself just to work?
How to fire extinguisher systems work with engines in commercial aircraft and do the engines you work with have feature like this in cases of uncontrolled fire in the engine?
Liam, Most of the aircraft that I have worked on have had fire extinguisher bottles mounted in the engine pylons. Those bottles would be discharged by pulling the T handle inside the cockpit, which would activate an explosive squib, discharging the bottle into various stainless steel hard lines with holes in them causing the fire extinguisher agent to be dispersed all around the engine area.
hi Jey. just a wish. will ther be any more videos from them jetboats with helicopter engines? it were amasing to see that speed on the water. and keep up with all them amasing videos you make. thanks to you i been understanding alot more about how jet engines work. / Jan from Sweden.
Some newer jet fighters with afterburners have turbo fan engines (1970's??). Is the pressure of the air coming out of the fan greater than the pressure in the exhaust pipe with afterburners on? What do they do with the nozzle while in cruise? I know this isn't what you work on but any theories?
An afterburning (I'm a Brit, but I'll avoid the term 'reheated') military turbofan is designed so that the by-pass pressure is higher than the jetpipe pressure: it has to be. Are you thinking that afterburning would increase the jetpipe pressure ? Well it doesn't, unless the control system fails and the variable nozzle doesn't open, in which case there could be a monumental engine surge. When an engine goes into afterburner and it's all operating correctly, then the jetpipe pressure doesn't change. If the aircraft is cruising or loitering at subsonic speed without afterburner, then the nozzle will normally be closed. However, if the aircraft can 'supercruise', that is cruise at supersonic speeds without afterburner, then the variable nozzle will be open, to produce a rearward exhaust velocity that is faster than the aircraft forward speed. When Concorde was in supercuise at 58,000ft without reheat (sorry, but Concorde's engines didn't have afterburners, they had reheat systems) its variable nozzles were open.
Car engine coolant thermostats use a similar system but they have a wax in them that is thick enough to stay inside the seals. As it expands with increasing temperature, it opens the valve that allows coolant to flow to the radiator.
I'm very impressed with the toolboxes sold by the guys in the trucks... but I doubt if I'll ever own a toolbox that costs as much as a car. Pants? I get them in the mail from a company in Duluth, but I'm not going into any more detail unless they want to sponsor me... :)
okay thanks even with my discount Snap on wants 2000 dollars. I have one for my own use already(Husky) but I think I'm going to go with US General for the one I use at my job after I get my A&P
The toolboxes our local truck guy wants to sell me are real nice, but they start at 8 thousand dollars, and go to over 20.... Nice, but I'd rather buy another motorcycle.
The only thing classified as pertaining to military aircraft, would be maximums and performance data in the flight envelope, radar systems, reconnaissance systems, and possibly weapons capabilities. Maybe when the engines 1st came out some of this was possibly classified. But not any longer. You can look up any data you want about the SR71 blackbird, and possibly the only thing still classified would be Vne.
to it´s very fascinating that on these older engine all the stuff is controlled mechanically or by fuel / oil pressure... it must be very time consuming to develop this stuff.. lot of try and error... how do you define how large a specific hole / valve inside a fuel control must be ?
I absolutely love your videos! I'd love to do what you do for a job! One question? In the test shed/cell you guys use, it looks like anyone at the controls are right in the "line of fire" if the engine throws a blade. Is this something that's in the back of your mind when first testing an engine, or is it so rare that you probably have a better chance of being killed by a piece of space junk? Lol!
This question is common, so the answer is in the form of a video. It's in the playlist called Your Questions Answered. There's an index which will help you find it.
Oh! Cool! I interpreted it the wrong way thinking heat conduction from the blades was part of intended design. Great video but. Must tell you that your reference is there in almost all the jet engines related discussions on internet.
Say there aren't any of these engines left in working order (which will entirely happen) how hard would it be to build a new one from scratch with current tech?
Difficulty in terms of tech and understanding of how they work? Trivial... Difficulty in terms of price? Very high! It'd be extremely, incredibly expensive.
+BERBEC 5a5gf. Doesn't work like that. The pilot is in control of the aircraft, but only gets a vote with the engine. The fuel control is in control and can't be overridden.
Many current military engines have a back-up fuel system (BUFS), for use in the event that the electronic engine control system fails. BUFS is essentially a tap (OK, faucet for N American readers), which the pilot operates ..... very carefully.
under rigth angle of the tooth in the worm gear it want jam,its no more "selflocking?", see the oldstyle speedometer worm gear in the car...almost the same.
Sir. I am working for an engine manufacturing company . We are building a variant . Similar to GE F414 . With low by pass ratio and 6 stage core compressor . The only problem there is that it is making high noise at high throttle . Any suggestions? Please help!
We are looking for the solution to reduce the sound !! It can't be accepted by the company if it makes this much noise . How to reduce the sound ant suggestion
Solution: completely redesign the engine. You are not being taken seriously, based on your questions, which clearly indicate you are not designing or building anything. Please do not post any further questions. Thank you in advance!
in the UK they would put reheat versions of the RR Spey into the F4 Phantoms instead of the J-79, I wonder which worked the best, or was the UK just being patriotic . the J-79 is a Monster engine. the RR Spey was put on the trident airliner where it was underpowered, not what the designers wanted. the RR Conways would have been better, but BEA Airlines wanted it there way, making the B727 superior.
at war time the J79 could be fit with different fuel nozzels to reduce the smoke by increasing combustion temperature.... but greatly reducing time between overhauls
No, this is incorrect. The low smoke fuel nozzle and combustor liner combination were introduced to help eliminate the smokey trail in the sky left by the "standard" cans (liners) and fuel nozzles as a part of the program of continuous improvement of the engine. The lo-smoke cans are also referred to as the long-life versions, because they actually last longer in service. They reduce smoke in the exhaust by promoting more complete combustion of the fuel, but not at increased temperatures. The low smoke upgrade includes fuel nozzles and combustor liners, but no change to the materials used in the turbine blades, nozzles, disks, etc. All of those parts are already running at their temperature limit, so an increased running temp would shorten their service life significantly. As stated above, the lo-smoke upgrade increases the service life, and is the only configuration used for industrial engines, which may run at full power for many months continuously.
Nope. Usually a form of higher boilingpoint alcohol is used, even for the older less environmetal friendly engines, to be able to cope with the quite extreme temerature range. Mercury freeze at -38 °C, when subsonic and at say around 30-35k ft up in the air the inlet temperature (dependant on the intake type and thus how much pressure increase and temp. rise) the CIT might still be down in the -50-55 °C range where Mercury would already be frozen. Some cases are more extreme, like the J58 from the SR-7 (even tho Jay don't like it mentioned), where intake temp goes from -60 to +180 °C. In such cases thermocouples are used and for most modern engines that or some other form of electrical sensor is used.
i'm guessing it's just temperature conductive fluid (oil?) that is attached to a bimetal strip somewhere that functions like a thermostat for the CIT ... the coils are obviously so that the fluid inside can acclimatize to the temp in the chamber (maxiumum surface area etc)
Just a few days ago the Technikum museum in Germany got one of the 6 remaining Brayton engines running...the engine dates from about 1875. As far as I'm aware this is the first time an original Brayton engine has run since the 1920's ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-g7h3Hd40GfY.html Very cool!
