Since I've subbed to your channel I (IT guy at large aero company here in CH) have regularly spent my 15min breaks in the engine shop at one of our sites, roaming around J85s and F404s, asking holes into our mechanics. It's amazing how much detail you show in these videos and point them out in a clearly understandable fashion even to the most casual of observers.
love your video, so few of us left that remember them and the feeling of your body in tune with the sound, smell and adrenaline rush. thanks for the memories
One of the greatest smells and sounds for that matter, is that of a pair of J79's installed in an F-4E, started up and ready to roll on a cold, damp, semi-foggy morning in W. Germany; with coffee in hand of course.
Congrats! I was not surprised to hear about fuel on the floor. The US Air Force used to station airmen with fire extinguishers behind B-47s when their engines started, as they tended to spit out sometimes-burning fuel while being started.
Congrats on a successful test, when you pull the valve and diagnose what or why it not sealing, it would be awesome to be drug along. I love diagnostic side also, seeing why and how things fail.
Agent JayZ I love your videos. Thank you for all the time you invest. I’m hoping you might be able to help me. My wife has been on the Chem trail kick and I have tried and tried to explain to her every way I can that we are not having chemicals dumped on us by airplanes. I’m hoping you might be able to help me explain this to her. Btw I liked the Agent CrayZ video, I was dying from laughter. Thanks again for all your videos.
The people who take "chemtrails" seriously are not taken seriously by normal people. Nor should they. It's not a debate, nor a discussion. It is a lack of knowledge, and oddly, a resistance to it. I lump the flat earthers, the fuel hoaxters, and the chemtrailers in to the same group. Ignorant people who wish to remain that way... claiming to be seeking the truth, yet vehemently refusing to recognize it.
The engines of airliners and every other gas turbine powered aircraft up there are burning aviation grade kerosene: they are not dumping chemicals. The condensation trails that they produce are just that: they are not "chemtrails". Burning kerosene produces carbon dioxide and water, plus oxides of nitrogen. The water in the engine exhausts condenses and freezes, to form the trails of ice crystals that you see.
@@AgentJayZ Thank you for your respect. However, I gave the answer I did because I gained the impression that the misguided lady was a victim of the chemtrail and "jet fuel is a hoax" brigade's propaganda, rather than being an active proponent.
The KB-50J's and KC-97L's had 2 J47s that were modified to run on aviation gasoline. How were they modified to do this and how well did they run on aviation gasoline?
With the J79, there is a small adjuster on the fuel control for specific gravity of the fuel. Click click, bing bang. The fuel pumps wear faster in gasoline, so there is an accelerated replacement interval if gasoline is used for extended periods. The whole hydromechanical fuel system is designed to use jet fuel. History has shown it to be a false economy to run gasoline in jet engines.
Ajent J great work always interesting. Just wondering in a future video if you could discuss the important role of the bell mouth to a turbine ie clean acceleration of air mass to first compressor cheers.
Agent Jay Z, question for you if I may good sir (and another excellent video! ): How does the by-pass air cool the turbine blades if it "leaks" out from the seals that are BEHIND the turbine and being rapidly blown away, out the back? I watched again just to check and it looks like the disk the turbine blades are mounted on is solid, so I didn't see a path for the air to get in front of the turbine blades so I'm assuming all of the air comes out of the seal you pointed to in the video, which makes it look like it's entering the exhaust steam after the turbine blades and therefore had no way of coming into contact with the 1000 degree blades to cool them down. Did I miss something? Otherwise it appears that all that the by-pass air will do is cool the overall exhaust gases, but not the actual turbine blades. Can you please elaborate?
The term bypass air does not apply to the J47. There is none. The cooling air is taken from the back of the compressor, and is directed to the back of the turbine disc, through the pipe shown in the video. The front of the disc is not cooled. The blades are cooled by conduction through their mounting roots to the disc... so not very well. This is a very old engine, and it was awesome in its time, but it does not feature all the new modern technology. It was designed in the late 1940s, and it's important to remember that.
@@AgentJayZ got it, thanks. So what cooling that does happen is simply thermal conductive cooling resulting from the cool air blowing on the turbine disk and then drawing heat away from the blades. As always, thanks for all you do. Love your stuff. Oh, and by no means was it meant to be a criticism of that engine. Amazing tech for the time and something far beyond anything I could hope to repair today...! :)
How many amps does the starter pull and does it also assist the engine to gain speed like the air turbine? How long does the run? That engine is looking and sounding real nice. I knew about combustor drains from your combustor videos but I learned today there is a valve that closes? The pacing and the exuberance of this video was excellent.
1000 to start, down to 150 at cutoff. Yes, ignition occurs at 600 rpm, starter cutout at 1800 It's a reed valve that closes when subjected to about 5 psi.. normally. This one seems to close at about 20 or 30..
I did not think it would be so visible. and going between those two times I had to check a lot of things to convince myself that the camera did not move.
wow thanks for this comment. truly amazing how much it lengthened! that must have been something like 2-3 inches? so all the fatigue this brings on the engine itself but also the mount (because the structure of the airplane stays relatively low-temp I'm figuring) really gets to you. heatcycles > hours maybe? press 6 and 7 for direct comparison..
I clicked between 8:30 and 9:30 on the video several times. It seems the end of the nozzle changes position slightly. It seems that the test stand remains fixed. Between those two times, there is an addition of power/heat in the engine. Do you know if the movement is from the test rig measuring thrust or from heat expansion in the engine? I am just curious. Thanks for another neat video.
I saw Whittle's first engine running up and noted that due to it's centrifugal design, accidental bird ingestion wasn't an issue. But at some other costs. His original unrestored engines still start and run. Largely due to his working within the metallurgical limits of the day. Whereas the Jumo engines, in modern axial format, were perhaps less reliable than a 1932 BSA single. The German engine was a superior design, that lacked the modern alloys.😂😂🙌👍🚲
It all depends on what you mean by "superior design". Compared to the Power Jets/Whittle W.2B and the R-R Welland (which was really a development of the W.2B), the German engines were heavier with lower thrust/weight ratios, less efficient with lower pressure ratios, had poor handling characteristics and were notoriously unreliable. Better materials in the turbines might have improved their reliability somewhat, but would not have improved any of their other shortcomings. It took a few years before the "superior design" of axial flow engines surpassed the performance of the centrifugals. The J47 in the F-86 gave just under 6,000lb thrust for a weight of around 2,600lb. The Klimov VK-1 (a reverse-engineered development of the R-R Nene) in the MiG 15 gave only slightly less thrust, for a weight of less than 2,000lb, and was a few percent down on sfc as compared to the J47.
@@stevenhoman2253 So where have you seen a W.2B engine run? At Sir James' place at Malmesbury? I've seen the video clip and, as a gas turbine designer (retired), I really would like to see it run: I'll put it on on my bucket list. However, if someone offered me the chance to watch a restored Jumo 004B being run up, I would stand back a very, very long way. Yes, Whittle benefited from heat-resistant alloy development by Henry Wiggin, in producing a far more reliable engine than those in Germany. And yes, the first-generation British turbojets with centrifugal compressors were lighter, simpler and more reliable than the early axial compressor engines. Nevertheless, were you aware that, before the end of the war, Whittle was working on an axial flow turbofan with a bypass ratio of between 2:1 and 3:1?
@@stevenhoman2253 I'd agree with you that the double-sided compressor impellers of the Whittle/Power Jets engines and the early R-R centrifugal engines were probably less prone to bird and FOD ingestion, as the engine intake was surrounded by what amounted to a plenum chamber - and the engines typically had intake screens. This fact perhaps saved the life of one person, who was sucked into the intake of a Meteor engine. The same cannot, of course, be said about the early DeHavilland centrifugal engines, where the eye of the impeller was clearly visible from the front of the engine.
I am sure there are quite a few surplus J58s out there. I do not know if they are available to the public. My guess would be that they would be kept in storage for quite a few years, and maybe a few made available to museums. How about you start your search, and let us know how it goes? A regular person needs to be motivated, patient, and resourceful to obtain a military surplus jet engine, but it is possible.
@@AgentJayZ thank you.. I once inquired this with Craig breedlove . He said they would be hard to find. But looking and searching is allied could do. Lol
I saw a presentation by someone who used to work with them and he mentioned that the surplus compressor blades had been intentionally scrapped so that they wouldn't end up overseas. He didn't say anything about the other parts of it though but it might make it harder to find spare parts to assemble a working engine. But, by all means, go for it! And if you succeed, be sure to let AgentJayZ put it in the test cell :-)
@@zapfanzapfan thank you for that information. 6 yrs ago I saw the SR-71 at Boeing museum . My wife lived 10 minutes from the museum and dropped me off there for 9 plus hrs. I was in heaven. I took tons of pictures that day. But what I saw was the MD-21 VARIANT of the SR-71. This was the one that didnt get destroyed in that drone accident that they had been working on.. back in the day. My fascination with the j58 is due to my land speed record idea... you see alot of people using other engines from a variety of different planes... I think a single j58 would just demolish the record. I have sat down and tried to draw a vehicle for the land speed record but my drawing skills are less then perfect. I figure also a vehicle with the likeness of the SR-71 WOULD CRUSH THE RECORD. But finding the engines would be the big chase of a lifetime....
I found a presentation on the destruction of the spare parts for SR-71 by someone who was working with it. Really sad that warehouses full of spares were shredded. They had 14 engines... th-cam.com/video/hWJMHO00s8Q/w-d-xo.html
Rotor blades followed by stator vanes equals one stage. The blades do work on the air, increasing its velocity: the vanes convert velocity into pressure.
@@grahamj9101 thx for the answer! i have another one:is the noise of a jet engine depending on the distance between rotors and stators? i think the rotors and stators produce noise like air raid sirenes
@@tombmaster972 Yes, you are quite correct: that’s how a compressor produces its high-pitched whine, just like an old-fashioned air raid siren, or a wailing US police car siren in the movies. And yes, I recall that, years ago, the noise boffins at R-R were looking the relationship between blade and vane numbers (and possibly spacing) for noise reduction,. However, in my experience, the spacing between compressor blades and stator vanes has been dominated by quite another issue. Minimum spacing has been dictated primarily by the need to avoid blade/vane 'clashes' during surge events and this was what we designed for. Any greater spacing than this, even if it had some influence on noise, would have resulted in greater length and weight, probably with some slight reduction in efficiency, performance and surge margin. In any case, with increasing bypass ratio, fan noise has become more dominant than core compressor noise, while the real culprit, jet noise, has been substantially reduced with the lower efflux velocity.
Can you show a video of the damage that can be caused when a jet engine ingest a bird such as a duck or geese inflight. If you ever have a engine come in with that type of damage thank you
No, that's a self-contained portable electric power plant of 3MW capacity. It uses an Allison 501 as it's engine. There is an electrical generator in there, and a control room. There's a large fuel tank under the floor, which probably holds a few hours worth of fuel. Enough to get connected, started, and running, while the fuel trucks have some time to get there. The 501 is the original name of the T-56 turboprop, and the name has been retained for the industrial engine.
Best Saturday early afternoon ever! You said you didn't fully overhaul it and are therefore using the mineral-based non-synthetic turbine oil the J47 was built to run with. Why would a full overhaul change the oil you would be able to use in this particular gas turbine engine?
Because Mil-L-26399 is rather nasty to stuff like rubber, so changing the seals to synthetic rubber (Buna N ?) means that you can use 26399 instead of (if I heard it right, 1010 ?). My experience is only with turbines using 26399...
Have you seen the latest test of Reaction Engines first supersonic precooler test of the J79? Could you talk about how this new precooler helps it fly at Mach 5?
You brought it up, you fucking talk about it. Could you talk about something recent, only tenuously connected to the video’s subject, that I saw. Somewhere???
Lets not get too far ahead of reality. OK? There is no engine yet. A pre-cooler sounds great and all, but it does not fly. Maybe Reaction Engines has a design for a complete engine, but they have not built it yet. The pre-cooler was tested in the exhaust of a running turbojet engine. Nothing has flown anywhere, but I hear the research and development is going well.
Great video again. I love all that great flame coming out the back once in a while. Do you have an ETA on the Iroquois engine at all? Thanks again super video.
The mineral oil interests me. Sure, adequate or even superior synthetic oils hadn't been developed for the engine; however would a benefit not exist now with the introduction of 10W-10 now? Potential advantages being temperature stability, longer life etc, as is apparent for modern engines. I'm aware that no function is served by running a synthetic oil in an old 70's car engine and its cost would be a negative. However the J47 while not being the current star is still a high performance bit of kit, compared to a low revving pushrod V8. I've seen rotary engines ( reproduction ) in WWI aircraft, and I don't believe their running caster oil, but some modern suitable oil. The mineral oil does look extremely clear low viscous stuff. Almost water like. 👍👍👍👍👍🚲
The 1010 is a specification name, not a viscosity grade. The manufacturer's Name for it is 481. If it was graded like automotive oils, turbine engine oil looks like about a -5W - 0. The synthetic oil we use is called 2380, but it's specification name is 23699. We run the oil in the engine that the owner prefers.
Enjoying your videos as usual. Can you tell me what kind of throttle actuator you are using on the J47? We don't see many hydromechanical fuel controls anymore, but do see one occasionally. Our current motor-driven cable system isn't working. We are looking for something to replace it with. Any help would be appreciated. Thanks for all the great vids!
It's a digitally controlled linear actuator. For each engine, it is programmed for min and max position, and it matches the position of the operators T-handle.
Am I correct in assuming that all the thrust is a product of the tail cone on this particular engine, and that the jet pipe is just the path out of the plane? It would be fantastic if you would be able to attend and record the first flight of this engine's home fighter jet. Another great day, congrats on the successful test!
No. The thrust is created by the jet propelling nozzle, which is always at the exit of the aircraft. The very end of the jet pipe, where there is a slight narrowing - that is the nozzle. That is the location of the small tuning strips, by which the area of the nozzle can be adjusted to achieve maximum exit velocity of the gases.
Thanks Jay. 65 and still learning. So, is the outlet area of the tail cone equal to, or about equal to, the area of the turbine outlet? I hope I framed that right.
Gordon Richardson Thanks for that. I was asking more about the tail cone, directly behind the turbine. The steep taper of it had me thinking that it imparted velocity to the air stream, but then I realized that the actual area of the annular turbine discharge and the circular area of the cone outlet were probably about the same, resulting in little if any, change in velocity. Disclaimer: My terminology may well be wrong. :)
Gordon... you should look up the turbojet thrust equation. There's a nice page on it at the NASA website. You are incorrect in thinking that the thrust is produced by pressure. The nozzle at the jet pipe produces almost all of the thrust, by accelerating the exhaust gases. The tail cone does not produce thrust. The gases moving through it are also controlled by the inner cone, so the area remains the same. The tail cone has one job: to convert the annular, ring shape of the exhaust gases into a circular one. Then they can be efficiently fed into an accelerating nozzle. Residual pressure across the nozzle exit is a minor contributor to thrust, and in an ideal engine, would exactly match ambient. Don't take my word for it, read what the rocket scientists say. PS, the jet pipe is more than physically strong enough to hold the 20 psi of pressure or so that the nozzle converts to velocity to create thrust. 20 psi?... yeah, we measure that. In our test cell. When we test jet engines. Cheers!
@@steveegbert7429 The cone in the exhaust annulus of an engine is basically performing an aerodynamic function, by acting as a fairing behind the turbine. The exit area of the exhaust annulus is typically larger than that of the turbine, which means that it is acting as a diffuser. I recall that AgentJayZ has run an industrial gas generator that didn't have an exhaust annulus with a 'slave' jet pipe, so that the rear face of the turbine disc clearly visible, when looking up the jet pipe. The absence of an exhaust cone would have resulted in some additional pressure loss in the exhaust, but this would have a second-order effect on performance and thrust.
Hi Jay, love your work. I have what is probably a dumb question. Would there be any value, putting design and maintenance costs aside but not ignoring fuel costs, to having another set of combusted between the HP and LP turbines. Given the oxygen content, and possible additional energy delivery to the LP turbine? Thanks! More questions to come but I am trying to ponder them before asking.
@@gordonrichardson2972 There are. As I am familiar with the Brayton cycle, having spent a career lifetime designing gas turbines, industrial, marine and aero, I will attempt to explain, in my simplistic way ..... tomorrow, actually later today, here in the UK.
GR, the space between the HP and LP turbine is before, and hotter than, the space after the LP turbine... where the afterburner/reheat is. Also, if your engine needs interturbine combustion, then you need to light two fires for a start. Complication without advantage. An LP turbine/compressor rotor designed to use a combustor after the Hp system won't work without it. It'a not an option, like an afterburner is. Much simpler if you need a more powerful engine, is to just make it a bit larger in diameter and with higher compression.
So, further to my original and rather blunt answer to your question, AgentJayZ already has given you a good answer - and I don't think that it is a "ridiculous" question. Considering its potential application in an aero gas turbine, it would be possible (and an interesting design challenge), but would increase the complexity of the engine, adding weight and length. Secondary combustion between the turbines would certainly result in a lower thermal efficiency than burning the same amount of fuel in a single combustor before the HP turbine. Whether it would actually increase the power to weight ratio, I doubt very much. In addition, as AgentJayZ has already pointed out, both the primary and secondary combustors would have to be lit the whole time for the engine to operate efficiently, whereas lighting up an afterburner is optional. I question Mr Richardson's use of words (which are somewhat ambiguous), when he suggests that energy should be added to "the coolest part of the cycle". As I recall, the maximum efficiency for any of the simple heat engine cycles is achieved when energy is added at the point of highest compression of the working fluid, with efficiency also being increased by raising the maximum pressure of the cycle. In the Otto and Diesel cycles, stoichometric combustion achieves the maximum practicable combustion temperature, from which expansion take place, and there is little or no Oxygen present in the combustion products - in contrast to the gas turbine engine. In a practicable gas turbine engine, while the combustion process is locally stoichiometric, cooling and dilution flows reduce the effective peak temperature of the cycle, which is the HP turbine entry temperature. That is why, in addition to the progressive increases in the pressure (not compression) ratio of gas turbines, turbine entry temperatures have been increased substantially, in order to increase the thermal efficiency. Finally, I will make brief mention of the fact that, as a young designer, I was involved in a conceptual design study for an industrial gas turbine, with secondary combustion (aka 'reheat') between the gas generator and the power turbine. The power output could be increased substantially for a relatively modest increase in complexity, (and weight) as compared to, say, a combined cycle machine. However, costs absolutely spiralled, because of the need to have a second and larger combustor and the need start cooling the large power turbine blades and vanes.
@@gordonrichardson2972 Yeah, I was thinking that after I posted. Who knows though. He may get one through there one day for a private cargo plane or and after market sale?
APUs are too small. They are roughly 100 Hp. The jet boats use medium lift helicopter engines in the 1200 Hp range. I would enjoy running an APU shop, but no one has asked.
These never get boring. Congrats on another runner.
Since I've subbed to your channel I (IT guy at large aero company here in CH) have regularly spent my 15min breaks in the engine shop at one of our sites, roaming around J85s and F404s, asking holes into our mechanics.
It's amazing how much detail you show in these videos and point them out in a clearly understandable fashion even to the most casual of observers.
love your video, so few of us left that remember them and the feeling of your body in tune with the sound, smell and adrenaline rush. thanks for the memories
One of the greatest smells and sounds for that matter, is that of a pair of J79's installed in an F-4E, started up and ready to roll on a cold, damp, semi-foggy morning in W. Germany; with coffee in hand of course.
Congrats! I was not surprised to hear about fuel on the floor. The US Air Force used to station airmen with fire extinguishers behind B-47s when their engines started, as they tended to spit out sometimes-burning fuel while being started.
Yes. There's videos of that on TH-cam...
Great to see her going again! Another one in the books for Jet City & the crew... thanks for sharing.
What is there not to like about this, certainly didn’t see anything myself. Great vid thanks for sharing.
Another awesome video, thanks for taking the time to share with us.
Super Cool.
You have an excellent way of explaining things at least for me I really appreciate. Excellent information thank you
I should be doing yard work. These vids are too good to pass up! Thanks.
Congrats on a successful test, when you pull the valve and diagnose what or why it not sealing, it would be awesome to be drug along. I love diagnostic side also, seeing why and how things fail.
The most coolest dyno run lol !
"Ooh ooh that smell, can't ya smell that smell...". Thanks for sharing.
Awesome work. 😎👌
Thank you for sharing that. Wonderful!
Congrats on the successful test run.
Found this enthralling I live near an old American airbase in Suffolk Uk where sabres where based ,sadly they plan to build houses on the old base ☹️
That low rumbling-to-howling sound is just...music
Aaaaaaaawwwwweeeeeeesssssssssooooooooommmmmmme!!!!! I have heard just one of these in person, and its a glorious noise!!!
Agent JayZ I love your videos. Thank you for all the time you invest. I’m hoping you might be able to help me. My wife has been on the Chem trail kick and I have tried and tried to explain to her every way I can that we are not having chemicals dumped on us by airplanes. I’m hoping you might be able to help me explain this to her. Btw I liked the Agent CrayZ video, I was dying from laughter. Thanks again for all your videos.
The people who take "chemtrails" seriously are not taken seriously by normal people. Nor should they.
It's not a debate, nor a discussion. It is a lack of knowledge, and oddly, a resistance to it.
I lump the flat earthers, the fuel hoaxters, and the chemtrailers in to the same group.
Ignorant people who wish to remain that way... claiming to be seeking the truth, yet vehemently refusing to recognize it.
The engines of airliners and every other gas turbine powered aircraft up there are burning aviation grade kerosene: they are not dumping chemicals. The condensation trails that they produce are just that: they are not "chemtrails". Burning kerosene produces carbon dioxide and water, plus oxides of nitrogen. The water in the engine exhausts condenses and freezes, to form the trails of ice crystals that you see.
Graham, your response was very diplomatic and informative. Mine was condescending and abusive.
I like mine better, but I respect your point of view.
Thanks for both of your responses, I shared them both. Hopefully it sinks in. :)
@@AgentJayZ Thank you for your respect. However, I gave the answer I did because I gained the impression that the misguided lady was a victim of the chemtrail and "jet fuel is a hoax" brigade's propaganda, rather than being an active proponent.
just beautiful
I have a jet engine design. Watching your videos makes me want to make some adjustments to it.
I always thumbs up first, then I watch the movie.
Yay! more video!
What makes the "hooting noise" when they start up? Blades resonate until up to speed?
I think it's an airflow, aerodynamic thing.
@@gordonrichardson2972 yea thats what I think, similar to the "barking dog" experiment in chemistry
The KB-50J's and KC-97L's had 2 J47s that were modified to run on aviation gasoline. How were they modified to do this and how well did they run on aviation gasoline?
With the J79, there is a small adjuster on the fuel control for specific gravity of the fuel. Click click, bing bang. The fuel pumps wear faster in gasoline, so there is an accelerated replacement interval if gasoline is used for extended periods.
The whole hydromechanical fuel system is designed to use jet fuel. History has shown it to be a false economy to run gasoline in jet engines.
Good job!!!
So the J-47 only have one single stage turbine wheel?
Eres demaslado cool teaching maestro. Thanks
What kind of a nut job just sits around watching the last four minutes of this video? Er, that would be me ()
3:54 "make sure it goes the right way" ... I have to ask now.. how many times has that actually been a problem, if ever lol?
The recent Orenda 14 test revealed a fuel pump that wasn't working right.
Cold crank? Yet another example of "two nations divided by a common language": I would call it a dry motor.
I will accept your answer.
Translated from English to English.
@@AgentJayZ So what about a wet motor? Which, of course, has to be followed by a dry motor before attempting a start.
I think the USAF should give you a ride in an SR71 for your dedication to the J47 !
Ajent J great work always interesting. Just wondering in a future video if you could discuss the important role of the bell mouth to a turbine ie clean acceleration of air mass to first compressor cheers.
Must be one of the relatively few centrifugal jets still around maybe? An engine that retains a bit of Whittle flavor.
Good to see it running. :)
The J47 was one of the first American turbojets to feature an axial flow compressor.
Ahh - my bad - I was going by the combustion chambers appearance. .. so "whittle-like"! Thanks.
Agent Jay Z, question for you if I may good sir (and another excellent video! ):
How does the by-pass air cool the turbine blades if it "leaks" out from the seals that are BEHIND the turbine and being rapidly blown away, out the back? I watched again just to check and it looks like the disk the turbine blades are mounted on is solid, so I didn't see a path for the air to get in front of the turbine blades so I'm assuming all of the air comes out of the seal you pointed to in the video, which makes it look like it's entering the exhaust steam after the turbine blades and therefore had no way of coming into contact with the 1000 degree blades to cool them down.
Did I miss something? Otherwise it appears that all that the by-pass air will do is cool the overall exhaust gases, but not the actual turbine blades.
Can you please elaborate?
The term bypass air does not apply to the J47. There is none.
The cooling air is taken from the back of the compressor, and is directed to the back of the turbine disc, through the pipe shown in the video. The front of the disc is not cooled.
The blades are cooled by conduction through their mounting roots to the disc... so not very well.
This is a very old engine, and it was awesome in its time, but it does not feature all the new modern technology.
It was designed in the late 1940s, and it's important to remember that.
@@AgentJayZ got it, thanks.
So what cooling that does happen is simply thermal conductive cooling resulting from the cool air blowing on the turbine disk and then drawing heat away from the blades.
As always, thanks for all you do. Love your stuff.
Oh, and by no means was it meant to be a criticism of that engine. Amazing tech for the time and something far beyond anything I could hope to repair today...! :)
How many amps does the starter pull and does it also assist the engine to gain speed like the air turbine? How long does the run? That engine is looking and sounding real nice. I knew about combustor drains from your combustor videos but I learned today there is a valve that closes? The pacing and the exuberance of this video was excellent.
1000 to start, down to 150 at cutoff.
Yes, ignition occurs at 600 rpm, starter cutout at 1800
It's a reed valve that closes when subjected to about 5 psi.. normally. This one seems to close at about 20 or 30..
thermal expansion at 8:48-10:17
I did not think it would be so visible. and going between those two times I had to check a lot of things to convince myself that the camera did not move.
@@gagiotter4114 the camera didn't move. Compare it to the lines on the bunker in the background. A ~500 C ΔT makes for a pretty noticeable difference
wow thanks for this comment. truly amazing how much it lengthened! that must have been something like 2-3 inches?
so all the fatigue this brings on the engine itself but also the mount (because the structure of the airplane stays relatively low-temp I'm figuring) really gets to you.
heatcycles > hours maybe?
press 6 and 7 for direct comparison..
@@jodelboy Nowhere near 2-3 inches but there is a little movement.
@@MrBen527 you put a tape measure to it or also just a guesstimate?
I clicked between 8:30 and 9:30 on the video several times. It seems the end of the nozzle changes position slightly. It seems that the test stand remains fixed. Between those two times, there is an addition of power/heat in the engine. Do you know if the movement is from the test rig measuring thrust or from heat expansion in the engine? I am just curious. Thanks for another neat video.
Thermal expansion of the jetpipe
@@AgentJayZ Wow!
Lucky you get snow!
I saw Whittle's first engine running up and noted that due to it's centrifugal design, accidental bird ingestion wasn't an issue. But at some other costs. His original unrestored engines still start and run. Largely due to his working within the metallurgical limits of the day. Whereas the Jumo engines, in modern axial format, were perhaps less reliable than a 1932 BSA single. The German engine was a superior design, that lacked the modern alloys.😂😂🙌👍🚲
It all depends on what you mean by "superior design". Compared to the Power Jets/Whittle W.2B and the R-R Welland (which was really a development of the W.2B), the German engines were heavier with lower thrust/weight ratios, less efficient with lower pressure ratios, had poor handling characteristics and were notoriously unreliable. Better materials in the turbines might have improved their reliability somewhat, but would not have improved any of their other shortcomings.
It took a few years before the "superior design" of axial flow engines surpassed the performance of the centrifugals. The J47 in the F-86 gave just under 6,000lb thrust for a weight of around 2,600lb. The Klimov VK-1 (a reverse-engineered development of the R-R Nene) in the MiG 15 gave only slightly less thrust, for a weight of less than 2,000lb, and was a few percent down on sfc as compared to the J47.
@@grahamj9101 So you understood the point I was making? Or not?
@@stevenhoman2253 So where have you seen a W.2B engine run? At Sir James' place at Malmesbury? I've seen the video clip and, as a gas turbine designer (retired), I really would like to see it run: I'll put it on on my bucket list. However, if someone offered me the chance to watch a restored Jumo 004B being run up, I would stand back a very, very long way.
Yes, Whittle benefited from heat-resistant alloy development by Henry Wiggin, in producing a far more reliable engine than those in Germany. And yes, the first-generation British turbojets with centrifugal compressors were lighter, simpler and more reliable than the early axial compressor engines. Nevertheless, were you aware that, before the end of the war, Whittle was working on an axial flow turbofan with a bypass ratio of between 2:1 and 3:1?
@@stevenhoman2253 I'd agree with you that the double-sided compressor impellers of the Whittle/Power Jets engines and the early R-R centrifugal engines were probably less prone to bird and FOD ingestion, as the engine intake was surrounded by what amounted to a plenum chamber - and the engines typically had intake screens. This fact perhaps saved the life of one person, who was sucked into the intake of a Meteor engine.
The same cannot, of course, be said about the early DeHavilland centrifugal engines, where the eye of the impeller was clearly visible from the front of the engine.
I have a question concerning a specific engine.... pratt and whitney j58.. are there any around? OR are there any that can be fixed to work....
I am sure there are quite a few surplus J58s out there. I do not know if they are available to the public.
My guess would be that they would be kept in storage for quite a few years, and maybe a few made available to museums.
How about you start your search, and let us know how it goes?
A regular person needs to be motivated, patient, and resourceful to obtain a military surplus jet engine, but it is possible.
@@AgentJayZ thank you.. I once inquired this with Craig breedlove . He said they would be hard to find. But looking and searching is allied could do. Lol
I saw a presentation by someone who used to work with them and he mentioned that the surplus compressor blades had been intentionally scrapped so that they wouldn't end up overseas. He didn't say anything about the other parts of it though but it might make it harder to find spare parts to assemble a working engine. But, by all means, go for it! And if you succeed, be sure to let AgentJayZ put it in the test cell :-)
@@zapfanzapfan thank you for that information. 6 yrs ago I saw the SR-71 at Boeing museum . My wife lived 10 minutes from the museum and dropped me off there for 9 plus hrs. I was in heaven. I took tons of pictures that day. But what I saw was the MD-21 VARIANT of the SR-71. This was the one that didnt get destroyed in that drone accident that they had been working on.. back in the day. My fascination with the j58 is due to my land speed record idea... you see alot of people using other engines from a variety of different planes... I think a single j58 would just demolish the record. I have sat down and tried to draw a vehicle for the land speed record but my drawing skills are less then perfect. I figure also a vehicle with the likeness of the SR-71 WOULD CRUSH THE RECORD. But finding the engines would be the big chase of a lifetime....
I found a presentation on the destruction of the spare parts for SR-71 by someone who was working with it. Really sad that warehouses full of spares were shredded. They had 14 engines...
th-cam.com/video/hWJMHO00s8Q/w-d-xo.html
one stage includes rotor blades and stator vanes but which of them is at the front? or is this not important?
Rotor blades followed by stator vanes equals one stage. The blades do work on the air, increasing its velocity: the vanes convert velocity into pressure.
@@grahamj9101 thx for the answer! i have another one:is the noise of a jet engine depending on the distance between rotors and stators? i think the rotors and stators produce noise like air raid sirenes
@@tombmaster972 Yes, you are quite correct: that’s how a compressor produces its high-pitched whine, just like an old-fashioned air raid siren, or a wailing US police car siren in the movies.
And yes, I recall that, years ago, the noise boffins at R-R were looking the relationship between blade and vane numbers (and possibly spacing) for noise reduction,. However, in my experience, the spacing between compressor blades and stator vanes has been dominated by quite another issue. Minimum spacing has been dictated primarily by the need to avoid blade/vane 'clashes' during surge events and this was what we designed for. Any greater spacing than this, even if it had some influence on noise, would have resulted in greater length and weight, probably with some slight reduction in efficiency, performance and surge margin.
In any case, with increasing bypass ratio, fan noise has become more dominant than core compressor noise, while the real culprit, jet noise, has been substantially reduced with the lower efflux velocity.
Awesome work. I'm curious what was smoking throughout the entire test. It was blue, so I assume it was oil from somewhere.
What kind of generating plant is out there? A Capstone?
A four cylinder Mitsubishi, burning propane. 20 kW
nice accomplishment, this explains why large planes require 100 tons of fuel when flying from London to Delhi. Is it going into a jetplane?
Can you show a video of the damage that can be caused when a jet engine ingest a bird such as a duck or geese inflight. If you ever have a engine come in with that type of damage thank you
Only if one shows up in the shop.
I keep looking, is that test stand bolted down to the floor?
In my playlist called Our Engine Test Cell, you will see this th-cam.com/video/i_MTVAT6PrA/w-d-xo.html
@@AgentJayZ Has the building been moving farther south little by little?
Is that the portable trailer that engine came out of, behind you, at the end?
No, that's a self-contained portable electric power plant of 3MW capacity. It uses an Allison 501 as it's engine. There is an electrical generator in there, and a control room. There's a large fuel tank under the floor, which probably holds a few hours worth of fuel. Enough to get connected, started, and running, while the fuel trucks have some time to get there.
The 501 is the original name of the T-56 turboprop, and the name has been retained for the industrial engine.
What do I think? I think it's a bit of all right.
Best Saturday early afternoon ever! You said you didn't fully overhaul it and are therefore using the mineral-based non-synthetic turbine oil the J47 was built to run with. Why would a full overhaul change the oil you would be able to use in this particular gas turbine engine?
Because Mil-L-26399 is rather nasty to stuff like rubber, so changing the seals to synthetic rubber (Buna N ?) means that you can use 26399 instead of (if I heard it right, 1010 ?). My experience is only with turbines using 26399...
Synthetic oil is better at tolerating heat. We use the oil that the engine was built with.
After a full overhaul I would recommend synthetic.
Awesome! Is this the one that is gojng in the F-86?
Someone accidentally hit the thumbs down. They should fix that.
He thinks is boring because you don't see anything moving. Or he's a conspiracy therorist that thinks its running on air.
Have you seen the latest test of Reaction Engines first supersonic precooler test of the J79? Could you talk about how this new precooler helps it fly at Mach 5?
You brought it up, you fucking talk about it. Could you talk about something recent, only tenuously connected to the video’s subject, that I saw. Somewhere???
Lets not get too far ahead of reality. OK?
There is no engine yet. A pre-cooler sounds great and all, but it does not fly.
Maybe Reaction Engines has a design for a complete engine, but they have not built it yet.
The pre-cooler was tested in the exhaust of a running turbojet engine.
Nothing has flown anywhere, but I hear the research and development is going well.
Great video again. I love all that great flame coming out the back once in a while.
Do you have an ETA on the Iroquois engine at all?
Thanks again super video.
Wow...didn’t realize they used mineral in any turbine engines. I guess the synthetic allowed to ramp up the temperatures on later engines.
The mineral oil interests me. Sure, adequate or even superior synthetic oils hadn't been developed for the engine; however would a benefit not exist now with the introduction of 10W-10 now? Potential advantages being temperature stability, longer life etc, as is apparent for modern engines. I'm aware that no function is served by running a synthetic oil in an old 70's car engine and its cost would be a negative. However the J47 while not being the current star is still a high performance bit of kit, compared to a low revving pushrod V8.
I've seen rotary engines ( reproduction ) in WWI aircraft, and I don't believe their running caster oil, but some modern suitable oil. The mineral oil does look extremely clear low viscous stuff. Almost water like. 👍👍👍👍👍🚲
The 1010 is a specification name, not a viscosity grade. The manufacturer's Name for it is 481. If it was graded like automotive oils, turbine engine oil looks like about a -5W - 0. The synthetic oil we use is called 2380, but it's specification name is 23699.
We run the oil in the engine that the owner prefers.
@@AgentJayZ got it, my mistake. Thanks for advising.👍🚲
Enjoying your videos as usual. Can you tell me what kind of throttle actuator you are using on the J47? We don't see many hydromechanical fuel controls anymore, but do see one occasionally. Our current motor-driven cable system isn't working. We are looking for something to replace it with. Any help would be appreciated. Thanks for all the great vids!
It's a digitally controlled linear actuator. For each engine, it is programmed for min and max position, and it matches the position of the operators T-handle.
@@AgentJayZ thanks. I'll have to see if I can find one for a decent price. I should be able to fabricate a mount for it.
Heck YA!
as you have no oil cooler, is oil temperature an issue when running engines in the test cell ?
The engine has an on board fuel cooled oil cooler.
Am I correct in assuming that all the thrust is a product of the tail cone on this particular engine, and that the jet pipe is just the path out of the plane?
It would be fantastic if you would be able to attend and record the first flight of this engine's home fighter jet.
Another great day, congrats on the successful test!
No. The thrust is created by the jet propelling nozzle, which is always at the exit of the aircraft. The very end of the jet pipe, where there is a slight narrowing - that is the nozzle. That is the location of the small tuning strips, by which the area of the nozzle can be adjusted to achieve maximum exit velocity of the gases.
Thanks Jay. 65 and still learning. So, is the outlet area of the tail cone equal to, or about equal to, the area of the turbine outlet? I hope I framed that right.
Gordon Richardson Thanks for that. I was asking more about the tail cone, directly behind the turbine. The steep taper of it had me thinking that it imparted velocity to the air stream, but then I realized that the actual area of the annular turbine discharge and the circular area of the cone outlet were probably about the same, resulting in little if any, change in velocity. Disclaimer: My terminology may well be wrong. :)
Gordon... you should look up the turbojet thrust equation. There's a nice page on it at the NASA website.
You are incorrect in thinking that the thrust is produced by pressure.
The nozzle at the jet pipe produces almost all of the thrust, by accelerating the exhaust gases.
The tail cone does not produce thrust.
The gases moving through it are also controlled by the inner cone, so the area remains the same. The tail cone has one job: to convert the annular, ring shape of the exhaust gases into a circular one. Then they can be efficiently fed into an accelerating nozzle.
Residual pressure across the nozzle exit is a minor contributor to thrust, and in an ideal engine, would exactly match ambient.
Don't take my word for it, read what the rocket scientists say.
PS, the jet pipe is more than physically strong enough to hold the 20 psi of pressure or so that the nozzle converts to velocity to create thrust.
20 psi?... yeah, we measure that. In our test cell.
When we test jet engines.
Cheers!
@@steveegbert7429 The cone in the exhaust annulus of an engine is basically performing an aerodynamic function, by acting as a fairing behind the turbine. The exit area of the exhaust annulus is typically larger than that of the turbine, which means that it is acting as a diffuser. I recall that AgentJayZ has run an industrial gas generator that didn't have an exhaust annulus with a 'slave' jet pipe, so that the rear face of the turbine disc clearly visible, when looking up the jet pipe. The absence of an exhaust cone would have resulted in some additional pressure loss in the exhaust, but this would have a second-order effect on performance and thrust.
Hi Jay, love your work. I have what is probably a dumb question. Would there be any value, putting design and maintenance costs aside but not ignoring fuel costs, to having another set of combusted between the HP and LP turbines. Given the oxygen content, and possible additional energy delivery to the LP turbine? Thanks! More questions to come but I am trying to ponder them before asking.
No - and that is an answer from someone who had a lifetime career in gas turbine design. I'll give you a more detailed explanation in due course.
@@gordonrichardson2972 There are. As I am familiar with the Brayton cycle, having spent a career lifetime designing gas turbines, industrial, marine and aero, I will attempt to explain, in my simplistic way ..... tomorrow, actually later today, here in the UK.
GR, the space between the HP and LP turbine is before, and hotter than, the space after the LP turbine... where the afterburner/reheat is.
Also, if your engine needs interturbine combustion, then you need to light two fires for a start. Complication without advantage.
An LP turbine/compressor rotor designed to use a combustor after the Hp system won't work without it.
It'a not an option, like an afterburner is.
Much simpler if you need a more powerful engine, is to just make it a bit larger in diameter and with higher compression.
You did a good job!
So, further to my original and rather blunt answer to your question, AgentJayZ already has given you a good answer - and I don't think that it is a "ridiculous" question. Considering its potential application in an aero gas turbine, it would be possible (and an interesting design challenge), but would increase the complexity of the engine, adding weight and length. Secondary combustion between the turbines would certainly result in a lower thermal efficiency than burning the same amount of fuel in a single combustor before the HP turbine. Whether it would actually increase the power to weight ratio, I doubt very much. In addition, as AgentJayZ has already pointed out, both the primary and secondary combustors would have to be lit the whole time for the engine to operate efficiently, whereas lighting up an afterburner is optional.
I question Mr Richardson's use of words (which are somewhat ambiguous), when he suggests that energy should be added to "the coolest part of the cycle". As I recall, the maximum efficiency for any of the simple heat engine cycles is achieved when energy is added at the point of highest compression of the working fluid, with efficiency also being increased by raising the maximum pressure of the cycle. In the Otto and Diesel cycles, stoichometric combustion achieves the maximum practicable combustion temperature, from which expansion take place, and there is little or no Oxygen present in the combustion products - in contrast to the gas turbine engine.
In a practicable gas turbine engine, while the combustion process is locally stoichiometric, cooling and dilution flows reduce the effective peak temperature of the cycle, which is the HP turbine entry temperature. That is why, in addition to the progressive increases in the pressure (not compression) ratio of gas turbines, turbine entry temperatures have been increased substantially, in order to increase the thermal efficiency.
Finally, I will make brief mention of the fact that, as a young designer, I was involved in a conceptual design study for an industrial gas turbine, with secondary combustion (aka 'reheat') between the gas generator and the power turbine. The power output could be increased substantially for a relatively modest increase in complexity, (and weight) as compared to, say, a combined cycle machine. However, costs absolutely spiralled, because of the need to have a second and larger combustor and the need start cooling the large power turbine blades and vanes.
While I've seen many of your videos, I haven't come across any where you're working on an aircraft APU. Have you worked on any?
@@gordonrichardson2972 Yeah, I was thinking that after I posted. Who knows though. He may get one through there one day for a private cargo plane or and after market sale?
APUs are too small. They are roughly 100 Hp.
The jet boats use medium lift helicopter engines in the 1200 Hp range.
I would enjoy running an APU shop, but no one has asked.
@@AgentJayZ Give it time. APU's need love too.
Cool.
Pretty 👍. Should show your flag collection in a video.
Good job.
No skyhooks in the test cell, so you make do with the bolt-on actuator. =)
no matter how expensive some staff is we still use zip ties
like.
Hi!
Pretty wierd how they call it mineral oil and you can buy the same to use as a laxative at the pharmacy.
Don't be stupid.
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