A look inside an afterburner , and how it is attached to a J79 Jet engine. A surplus fighter aircraft engine is being converted to an industrial gas generator.
The VSV system allows the engine to operate without compressor stall. Back in the day, this was the first of a new generation of engines that used high performance compressors. To get from idle to making power, these compressors pass through a range of rpm where they stall without some form of airflow modulation. Bleed Valves and Variable Stators are two ways to prevent stall, and they are necessary on all modern turbine engines. A video on compressor stall is in the works.
The flame holder is there to make sure the flame does not get blown out. It is an obstruction to the high velocity flow of the exhaust gases, producing an area of turbulence, in which the mixture of fuel and air is certain to burn. Without the flame holder, the velocity of the mixture in the jet pipe is so high that the fire might get blown right out of the engine.
When I worked GE before they closed the facility in Ontario, Ca. I,worked on the J79 engine for many years, and then I worked on the LM 1500 which was a converted J79. Then they took a CF6 turbo commercial engine and made a LM 2500 gas,turbine power plant. A lot of the LM 2500 engines are used aboard the U.S. Navy as power plants for the ships. I worked for HE for 30 years before they closed the facility.
The mass of the exhaust is increased by about 5% when afterburner is used, and this does contribute to the increase in thrust. If the mass was the major factor, you could inject water into the exhaust and have the desired effect. You can't, and it's not water... it's fuel. The main reason afterburners increase thrust is because the fuel is burned, and this greatly increases the temperature of the exhaust. This causes it to have a much greater volume, and greater acceleration.
Awesome video, thanks for posting...I'm in a aviation tech school earning my A&P with 4.5 months left! Amazing piece of engineering! I appreciate your video, thanks again!
@102trafalgar Yes, the CF-6 has what GE calls a "core booster" - a smaller second stage to the LP compressor. The first stage of the LPC is what we call the "fan", because most of its output is passed around the core engine. The second stage is the size of the inlet of the "core" or fuel-burning part of the engine. The TF-39 was the engine developed for the C5 Galaxy, and it led to the civilian CF6. The TF-39 had a small 1st stage LP, and a large fan as its 2nd stage LP. Unusual arrangement.
Thank you very much for all these extremely insightful video uploads. You are inspiring future generations of "gear heads". I just can't get enough of this stuff ;P
Hi, As an ex aircraft engineer can I say thank you for taking your time to upload these video's, never had a chance to work on Jets but worked on Piston and Radial... One small correction though, I'm 99% positive the F-105 was called the "Thunderchief" and the "Starfighter" was the F-104,
@Helicopterpilot16 The JT9D was used to power some 747s, and others were powered by the GE CF-6, which is what you see in the background. The engine we have is part of a long-term project, and it will be the subject of a video or two as it is worked on. We will run it, but when is still not decided.
@TheArfdog The power is transmitted by hot air...to a separate piece of equipment called a power turbine, which turns a shaft, which drives the load. We only test the engines... technically they are called gas generators, because they generate a stream of high-velocity gas that the power turbine can use.
The variable stators enable the engine to transition from idle to medium power without stalling the compressor. From medium power to full power, the VSVs are in the full open position. An industrial engine only needs the VSVs when coming online. However, they perform such an important function, they are absolutley necessary. The VSVs don't really do anything for a fighter, except during startup. At all power settings in flight, they are fully open.
@MusicMan20061210 An aircraft carrier has many engines in spares for replacements. In the field, engines are swapped out whole and shipped back home. All overhauls of turbine engines for the US Military ( as far as I know...) are done at a giant, gigantic, huge facility at a Naval shipyard/base, the location of which I'm not sure of right now. Each engine model has its own specified time between overhauls, and I'm not familiar with the specs of the newer, current engines.
@silver760 Sometimes, with some engines, it's something like that. There are very few engines that are currently or recently used in aircraft, that are also the basis of an industrial engine. Very few. One example is the P&W JT8-D, used on DC-9s and 737-200s, which is the basis for the FT8 industrial powerplant. Most aircraft engines have no industrial application, and most industrial gas generators have no current aircraft counterpart.
@krbruner In the combustion chamber itself, there is a huge excess of available air due to the use of air as the coolant, so the fuel burns as if it was a big candle... it just takes what it needs. The afterburner was invented because after realizing that about 20% of the air ingested by the engine is actually used to combust the fuel, it was thought a good idea to try and burn the other 80% by burning it in the duct "after" the engine.
@jyatim We don't paint any colors on the lines. Most of them are stainless steel tubing. Sometimes an oil leak can be cooked on to the steel as a brown color. The engine was taken from an aircraft and so would be in an uncleaned state as we disassemble it.
Absolutely love your videos! Just wish I would have found out about your stuff earlier. Good stuff to know as I will be working on GE jet engines this summer. Thanks for putting these up!
@klusmanp Don't feel too bad. In a jet fighter, this engine has the shit beat out of it, and it has a service life of 400 hours between overhaul, which takes thousands of man-hours. In an industrial application, the engine is pampered, with gradual changes in throttle, and a service life of about 20,000 hours between overhaul. It will live a long and happy life.
@AgentJayZ Actually I was using the technical meaning of diffuser. The device which expands exhaust gas in order to extract more work from it. A shaft-turbine (or turboshaft) drives something directly with its own shaft. Like a turbo-prop plane. I believe it has a more extensive, diffusing turbine, which extracts more energy from the exhaust gas to turn the shaft. Without an extensive diffuser, the energy goes into shooting a jet of air backwards.
Kind of makes me sad. These beautiful engines once screaming through the wild blue now stuck in some industrial facility as GPUs. I am an aerospace engineer and I own an aerobatic biplane called a Pitts. I spend every day chained to a computer in some industrial facility working as an engineer but on the weekends I scream (well... buzz) through the wild blue in my Pitts. Awesome videos!!
@TheArfdog There are many different turboshaft engines. Typically the term turboshaft refers to what is used in a helicopter. The most popular turboshaft engine out there has 2 gas generator turbine stages and 2 power turbine stages. The CF6 large turbofan has a 6 stage turbine driving its fan, and the LM2500 which is almost the same engine, but with a shaft output also has a 6-stage free power turbine.
Blades refers to the airfoils on the compressor rotor. No. The linkages control the angle of the airfoils which are attached to the outer case, and they are called stator vanes.
@Mastermind2011 The compressor delivers 150 lbs per second of air at 125 psi to the combustors. 35 gallons per minute of fuel is burned in that air. The resulting heat causes the air to expand and rush through the turbine. The turbine, like a windmill, is designed to take energy out of that stream of hot gases, and convert that energy to torque. Torque on the shaft which turns the compressor. This is how the compressor gets the power to turn and compress all that air.
No worries! I think the engines are not the limiting factor, and the J58 would just add massively to the expense, because of it's rarity, lack of parts , use of exotic fuels, etc. A hundred mil is not a joke. Cheers!
It gives the exhaust gases more mass which makes a larger thrust output. It's like trying to paddle a boat with air vs paddling with water. Water is much more dense which you can propel off of way better. Same thing with dry thrust (non-afterburning) vs wet thrust (afterburning) in a jet engine.
I am also a huge fan of the SR-71, and I think it would be pretty cool to have a J58 running in my backyard. You would need a 600 HP engine to start it. Wide open, it uses more than two gallons per second of JP-7 fuel. If you could find JP-7, it would be at least $5 per gallon, making the cost of running th engine at full throttle $10 per second, or $600 per minute. So like AgentJayZ said, the obstacle would be money. Fun to think about though!
Whattya mean by feasible? Not if money is of any consequence. If you've ever been close to a working jet engine, you know the tremendous, frightening hugeness of their power... even a small one. The J79 we supply to the North American Eagle is not as powerful as the J58, but a three second burst of afterburner takes that car from 200 to 400 mph. The twin afterburning Speys took Thrust SSC easily to the speed of sound.
@For54Ever If you mean return lines, there are none. The fuel control "controls" how much fuel is supplied to the fuel nozzles, and all of it then gets fed to the combustors.
Michael, without going into great detail stator vanes essentially reduce airflow turbulence in the compressor. As Agent pointed out they are attached to the casing and not a part of the rotor assembly. Stator vanes are variable while blades are not.
I appreciate the enthusiasm and assistance. As will be covered in an upcoming video, the function of stators is to convert the velocity of the air imparted by the rotor blades into pressure by way of aerodynamic diffusion. Both rotor blades and stator vanes are equally vital to the process of compression. Without either one, the compressor would not be a compressor. The actual increase in pressure of the air going through a stage in the compressor happens in the stators. The rotor blades cause the air to move, but do not increase its pressure.
AgentJayZ Thanks.....I was writing from memory as I have not touched a jet turbine since leaving the Navy in 1982. HA! Long time ago when I was but a young buck. The J-79 was my main focus as I had been assigned to F4's in A.I.M.D..
AgentJayZ Interesting. In what respect? The J-79 is not anything I would call "small" in size or thrust capabilities. Perhaps, he mistook it for the PW J52? I don't know. In terms of "size" I never really thought of jet turbines in that aspect. I always thought in terms of it's application and its capabilities of doing the job intended. In other words, if it does the job then it's the correct "size". But, really in terms of sq. ft. area the J-79 takes up...well, "small" is not what I would categorize it. After all, when it's fully assembled it's nearly 18 feet long! It's quite the workhorse given the fact that it's 1950's technology and still in use. The one complaint I had "way back when" were the carbon seals. We had a problem with them cracking frequently and replacement delivery took an inordinate time as opposed to other parts. I don't know if that was a GE or a US Navy problem. To me, it didn't matter who was at fault it was a problem nonetheless that I complained about...to no avail, of course.
The afterburner adds and ignites fuel in the exhaust of the engine, which still contains a lot of oxygen. This extra fuel being burned raises the temperature of the exhaust gases, so they expand even more, and therefore have to go even faster to fit out the jet nozzle. To get going faster, they accelerate. This acceleration takes force, and for every force... ... So thrust is increased.
The simple explanation is this: exhaust in a turbojet engine provides the thrust to propel the aircraft. So an extra flame in the exhaust stream boosts exhaust temperature and thus, the thrust, quite a bit (thrust increase is roughly the square root of the temperature ratio). This is quite inefficient but the afterburner is used only in short bursts for quicker acceleration. Kind of like "turbo boost" in a fictional racing video game. It's basic physics really.
Our engines do not use the CSD, but the "#5" bolt you mention is actually at the rear of the gearbox mounting pad, so we do install that one all the time. Is that the one you mean? One of the crappiest things to lockwire ever!
@AgentJayZ Thanks. That makes sense, since i suppose a jet engine is designed to produce a "jet", which has a high amount of kinetic energy. The power turbine (I would guess) would further diffuse and slow down the jet of air, converting it to mechanical power. A dedicated shaft turbine engine probably has a more extensive diffuser (performing the power turbine role) than a jet engine. Am I right?
@andytaggart We buy some surplus aircraft engines, but our main business is in the overhaul and repair of industrial turbine engines owned by other businesses.
Very instructive videos, kudos for you and your team. I have a question though: Is there a color code for the hydraulic lines or the fuel lines? I did see some brownish lines under the engine that Walter was converting. Thank you for your response.
Sure. You'll need all of them, so it's going to take some scrounging and some patience. There are no extra, nonessential parts in a jet engine. Just like a car engine... you can't put "most" of the parts together and have it run...
Uhhh, you're new to this channel, aren't you? Have a look around, and you'll find something you might like. Based on your comment, I recommend the playlist called "My Afterburner Videos". Enjoy!
ok, just so i understand, adding fuel is how you spool up a turbine, and in theory it will spool up until its gobbling in more air than the fuel can keep up with which is why there's so much O2 in the exhaust stream? I'm so used to piston engines where it's all about getting the A/F ratio stoichiometric. in this application the engine is basically running almost constantly lean which is why afterburners don't choke themselves out? thanks!
@AgentJayZ Pretty impressive stuff mate. I take it you buy these beasts from airlines because they are past their sell-by date. How much to buy, to recondition and to sell on?
Are these aircraft engines converted into industrial power plants when the engines run out of flying hours? From what I understand all aircraft components have a set number of hours flight before they must be replaced with a new unit.So despite the engine running out of flying hours they still have a considerable amount of life in them before they are considered to be worn out,making them suitable for conversion to generators.
Hey, at the begining of this video I se what looks like a JT9D engine outside, Could you possibly make a video of the engine it self and is s&s going to run it? Thanks Tyler
@chazkez07 Long enough to not be scared to stand next to one, but not long enough to lose my excitement at just seeing them run! Yeeeeee Haaaa! Only thing close is to be live at the start of an indy car race... and that's only close!
Alot bigger than my single stage turbine for my RC plane lol. Are there 4 seperate holes on each spray bar?. I'm guessing each ring is pressurized buy a pump and controlling AB stages by a fuel solenoids?. I'm thinking of adding AB to my jet engine lol.
Thanks a lot for your reply, but problem is, that I'm from Germany and that could be very expensive with shipping, custom etc....What engine type do you have? Regards Andre
@1:00 Do the 7 'L' shape levers linked by a rod control variable pitch stators? If so, does an 'industrialised' J79, running for long periods at constant power, have much need for variable pitch stators?
When you convert a J-79 to a LM-1500 how many extra rows of turbines do you add? An aircraft only takes as much power from the exhaust to drive the compressors, pumps and aux power needs. The rest is used for thrust. I would imagine industrial use means electricity generation, so I would imagine you add extra rows of turbines. Or does the engine simply blow onto a external turbine/dynamo ensemble?
I am not familiar what is involved in fuel metering for jet turbines, but I know for internal combustion that an overly lean fuel/oxy ratio is a bad thing. My first question is, does a turbine even care about the stoichiometric ratio of fuel/air, followed by, does it try to keep that ratio on the rich side similar to an ICE and thirdly, if the engine is dumping fuel into the afterburner, is it possible that there is just not enough oxygen in the exhaust to keep the afterburner lit?
just a quick question. i have not worked on the j 79 since 1971 but i have to ask. have they figured out an easier way to r and r the csd generator relative to the top nut. as i rmember it was so tight a fit it was difficult to get a wrench on it. thanks
Just wondering how much goes into converting an engine designed to produce thrust to something that does shaft work? Just a much larger gearbox(AMAD or similar)? Any redesign of turbine section to extract more shaft power?
so, with afterburners, the original output thrust is compressed against the afterburner and gives it more forward thrust??? Just asking because I want to learn.
@TheArfdog No. you are getting caught in the gap between popular meanings of words and their technical meanings. Diffusion is one word that does not apply here. And what do you mean by a dedicated shaft turbine engine? An engine that includes a power turbine in its design? Such engines do exist; the GE LM6000 is one of them. They are no more or less efficient in turning fuel into power then the usual gas-generator and separate power turbine arrangement.
Walter is the man!
The VSV system allows the engine to operate without compressor stall.
Back in the day, this was the first of a new generation of engines that used
high performance compressors.
To get from idle to making power, these compressors pass through a range of rpm where they stall without some form of airflow modulation.
Bleed Valves and Variable Stators are two ways to prevent stall, and they are necessary on all modern turbine engines.
A video on compressor stall is in the works.
Nice video. Thanks for sharing. Walter deserves a raise. He's getting shit done on the weekend when everyone else is out playing around. Good man
The flame holder is there to make sure the flame does not get blown out. It is an obstruction to the high velocity flow of the exhaust gases, producing an area of turbulence, in which the mixture of fuel and air is certain to burn.
Without the flame holder, the velocity of the mixture in the jet pipe is so high that the fire might get blown right out of the engine.
When I worked GE before they closed the facility in Ontario, Ca. I,worked on the J79 engine for many years, and then I worked on the LM 1500 which was a converted J79. Then they took a CF6 turbo commercial engine and made a LM 2500 gas,turbine power plant. A lot of the LM 2500 engines are used aboard the U.S. Navy as power plants for the ships. I worked for HE for 30 years before they closed the facility.
its amazing that those four little lines are responsible for so much extra power.
Good video. This whole section on Jet Engines is fascinating.
The mass of the exhaust is increased by about 5% when afterburner is used, and this does contribute to the increase in thrust. If the mass was the major factor, you could inject water into the exhaust and have the desired effect. You can't, and it's not water... it's fuel.
The main reason afterburners increase thrust is because the fuel is burned, and this greatly increases the temperature of the exhaust. This causes it to have a much greater volume, and greater acceleration.
Really enjoy your videos. Good quality and no long-winded explanations. Thanks.
Awesome video, thanks for posting...I'm in a aviation tech school earning my A&P with 4.5 months left! Amazing piece of engineering! I appreciate your video, thanks again!
@102trafalgar Yes, the CF-6 has what GE calls a "core booster" - a smaller second stage to the LP compressor. The first stage of the LPC is what we call the "fan", because most of its output is passed around the core engine.
The second stage is the size of the inlet of the "core" or fuel-burning part of the engine.
The TF-39 was the engine developed for the C5 Galaxy, and it led to the civilian CF6.
The TF-39 had a small 1st stage LP, and a large fan as its 2nd stage LP.
Unusual arrangement.
Thank you for posting , fascinating as always ! This is the thing about TH-cam, you never know what you will find next !
Way to go Walter ,your the backbone of that place. heheheh Very cool to see up close all the tubes hoses and fuel lines.
Thank you very much for all these extremely insightful video uploads. You are inspiring future generations of "gear heads". I just can't get enough of this stuff ;P
Thanks for this video. Now I know a bit more on jet engines.
Hi,
As an ex aircraft engineer can I say thank you for taking your time to upload these video's, never had a chance to work on Jets but worked on Piston and Radial...
One small correction though, I'm 99% positive the F-105 was called the "Thunderchief" and the "Starfighter" was the F-104,
awesome video man ! these engines are just incredible
@Helicopterpilot16 The JT9D was used to power some 747s, and others were powered by the GE CF-6, which is what you see in the background.
The engine we have is part of a long-term project, and it will be the subject of a video or two as it is worked on.
We will run it, but when is still not decided.
@TheArfdog The power is transmitted by hot air...to a separate piece of equipment called a power turbine, which turns a shaft, which drives the load.
We only test the engines... technically they are called gas generators, because they generate a stream of high-velocity gas that the power turbine can use.
The variable stators enable the engine to transition from idle to medium power without stalling the compressor. From medium power to full power, the VSVs are in the full open position. An industrial engine only needs the VSVs when coming online. However, they perform such an important function, they are absolutley necessary.
The VSVs don't really do anything for a fighter, except during startup. At all power settings in flight, they are fully open.
@MusicMan20061210 An aircraft carrier has many engines in spares for replacements. In the field, engines are swapped out whole and shipped back home.
All overhauls of turbine engines for the US Military ( as far as I know...) are done at a giant, gigantic, huge facility at a Naval shipyard/base, the location of which I'm not sure of right now.
Each engine model has its own specified time between overhauls, and I'm not familiar with the specs of the newer, current engines.
@silver760 Sometimes, with some engines, it's something like that.
There are very few engines that are currently or recently used in aircraft, that are also the basis of an industrial engine.
Very few.
One example is the P&W JT8-D, used on DC-9s and 737-200s, which is the basis for the FT8 industrial powerplant.
Most aircraft engines have no industrial application, and most industrial gas generators have no current aircraft counterpart.
@krbruner In the combustion chamber itself, there is a huge excess of available air due to the use of air as the coolant, so the fuel burns as if it was a big candle... it just takes what it needs.
The afterburner was invented because after realizing that about 20% of the air ingested by the engine is actually used to combust the fuel, it was thought a good idea to try and burn the other 80% by burning it in the duct "after" the engine.
@jyatim We don't paint any colors on the lines. Most of them are stainless steel tubing. Sometimes an oil leak can be cooked on to the steel as a brown color.
The engine was taken from an aircraft and so would be in an uncleaned state as we disassemble it.
Absolutely love your videos! Just wish I would have found out about your stuff earlier. Good stuff to know as I will be working on GE jet engines this summer. Thanks for putting these up!
@klusmanp Don't feel too bad.
In a jet fighter, this engine has the shit beat out of it, and it has a service life of 400 hours between overhaul, which takes thousands of man-hours.
In an industrial application, the engine is pampered, with gradual changes in throttle, and a service life of about 20,000 hours between overhaul.
It will live a long and happy life.
@AgentJayZ Actually I was using the technical meaning of diffuser. The device which expands exhaust gas in order to extract more work from it. A shaft-turbine (or turboshaft) drives something directly with its own shaft. Like a turbo-prop plane. I believe it has a more extensive, diffusing turbine, which extracts more energy from the exhaust gas to turn the shaft. Without an extensive diffuser, the energy goes into shooting a jet of air backwards.
Very nice overall clarification, thank you!
Kind of makes me sad. These beautiful engines once screaming through the wild blue now stuck in some industrial facility as GPUs. I am an aerospace engineer and I own an aerobatic biplane called a Pitts. I spend every day chained to a computer in some industrial facility working as an engineer but on the weekends I scream (well... buzz) through the wild blue in my Pitts. Awesome videos!!
@TheArfdog There are many different turboshaft engines.
Typically the term turboshaft refers to what is used in a helicopter.
The most popular turboshaft engine out there has 2 gas generator turbine stages and 2 power turbine stages.
The CF6 large turbofan has a 6 stage turbine driving its fan, and the LM2500 which is almost the same engine, but with a shaft output also has a 6-stage free power turbine.
Blades refers to the airfoils on the compressor rotor. No. The linkages control the angle of the airfoils which are attached to the outer case, and they are called stator vanes.
@Mastermind2011 The compressor delivers 150 lbs per second of air at 125 psi to the combustors. 35 gallons per minute of fuel is burned in that air. The resulting heat causes the air to expand and rush through the turbine. The turbine, like a windmill, is designed to take energy out of that stream of hot gases, and convert that energy to torque. Torque on the shaft which turns the compressor. This is how the compressor gets the power to turn and compress all that air.
@TalksWithDirt We don't add any stages.
The power is extracted by a "power turbine" which is another piece of equipment.
@AgentJayZ Actually, I checked today, and it's a CF6-6. An earlier version of the CF6, with higher bypass ratio, and more suited to our plans...
Working on the weekends, HELL YEAH WALTER! Harvest the overtime!
No worries! I think the engines are not the limiting factor, and the J58 would just add massively to the expense, because of it's rarity, lack of parts , use of exotic fuels, etc. A hundred mil is not a joke.
Cheers!
this is awesome how did your new engine turn out.thanks for sharing
It gives the exhaust gases more mass which makes a larger thrust output. It's like trying to paddle a boat with air vs paddling with water. Water is much more dense which you can propel off of way better. Same thing with dry thrust (non-afterburning) vs wet thrust (afterburning) in a jet engine.
I am also a huge fan of the SR-71, and I think it would be pretty cool to have a J58 running in my backyard. You would need a 600 HP engine to start it. Wide open, it uses more than two gallons per second of JP-7 fuel. If you could find JP-7, it would be at least $5 per gallon, making the cost of running th engine at full throttle $10 per second, or $600 per minute. So like AgentJayZ said, the obstacle would be money. Fun to think about though!
..Walter is lucky to work there... you'll take this stuff with you at the end pf the trip... I, would love to work with these engines..
Very informative, thanks.
@MidShipCivic The afterburner fuel is supplied at up to 400 psi.
Whattya mean by feasible? Not if money is of any consequence. If you've ever been close to a working jet engine, you know the tremendous, frightening hugeness of their power... even a small one.
The J79 we supply to the North American Eagle is not as powerful as the J58, but a three second burst of afterburner takes that car from 200 to 400 mph.
The twin afterburning Speys took Thrust SSC easily to the speed of sound.
great video...very cool!!!
what an interesting job, love the video's
Great vid!! Awesome engine!
This particular engine came from a Starfighter, F105. It is very similar to the J79's that were used in the F4.
@For54Ever If you mean return lines, there are none. The fuel control "controls" how much fuel is supplied to the fuel nozzles, and all of it then gets fed to the combustors.
Michael, without going into great detail stator vanes essentially reduce airflow turbulence in the compressor. As Agent pointed out they are attached to the casing and not a part of the rotor assembly. Stator vanes are variable while blades are not.
I appreciate the enthusiasm and assistance. As will be covered in an upcoming video, the function of stators is to convert the velocity of the air imparted by the rotor blades into pressure by way of aerodynamic diffusion.
Both rotor blades and stator vanes are equally vital to the process of compression.
Without either one, the compressor would not be a compressor. The actual increase in pressure of the air going through a stage in the compressor happens in the stators. The rotor blades cause the air to move, but do not increase its pressure.
AgentJayZ Thanks.....I was writing from memory as I have not touched a jet turbine since leaving the Navy in 1982. HA! Long time ago when I was but a young buck. The J-79 was my main focus as I had been assigned to F4's in A.I.M.D..
Another viewer, a few days ago... called the J79 a small engine. I didn't know how to respond...
AgentJayZ Interesting. In what respect? The J-79 is not anything I would call "small" in size or thrust capabilities. Perhaps, he mistook it for the PW J52? I don't know. In terms of "size" I never really thought of jet turbines in that aspect. I always thought in terms of it's application and its capabilities of doing the job intended. In other words, if it does the job then it's the correct "size". But, really in terms of sq. ft. area the J-79 takes up...well, "small" is not what I would categorize it. After all, when it's fully assembled it's nearly 18 feet long! It's quite the workhorse given the fact that it's 1950's technology and still in use. The one complaint I had "way back when" were the carbon seals. We had a problem with them cracking frequently and replacement delivery took an inordinate time as opposed to other parts. I don't know if that was a GE or a US Navy problem. To me, it didn't matter who was at fault it was a problem nonetheless that I complained about...to no avail, of course.
The afterburner adds and ignites fuel in the exhaust of the engine, which still contains a lot of oxygen. This extra fuel being burned raises the temperature of the exhaust gases, so they expand even more, and therefore have to go even faster to fit out the jet nozzle. To get going faster, they accelerate. This acceleration takes force, and for every force... ... So thrust is increased.
you guys ... you have some skills downthere...i wish i could be in your team ...
The simple explanation is this: exhaust in a turbojet engine provides the thrust to propel the aircraft. So an extra flame in the exhaust stream boosts exhaust temperature and thus, the thrust, quite a bit (thrust increase is roughly the square root of the temperature ratio). This is quite inefficient but the afterburner is used only in short bursts for quicker acceleration. Kind of like "turbo boost" in a fictional racing video game. It's basic physics really.
let me do your physical and don't stop making these wonderful videos
...Nor does this.
@AugmentedB737
Good eye! That is indeed a CF-6-50. We are embarking on a long, strange project.
I will report on progress as it happens.
I try to explain the basics of this in my video about power turbines. Hopefully it will let you see how simple the idea is in concept. Let me know ...
New old stock bearings are readily available for these engines. I think you'll like my video on Jet Engine Lube Systems...
Our engines do not use the CSD, but the "#5" bolt you mention is actually at the rear of the gearbox mounting pad, so we do install that one all the time.
Is that the one you mean?
One of the crappiest things to lockwire ever!
@AgentJayZ Thanks. That makes sense, since i suppose a jet engine is designed to produce a "jet", which has a high amount of kinetic energy. The power turbine (I would guess) would further diffuse and slow down the jet of air, converting it to mechanical power. A dedicated shaft turbine engine probably has a more extensive diffuser (performing the power turbine role) than a jet engine. Am I right?
Very educational and useful shit right here
@basimpsn Have you seen my afterburner spraybar test video?
@andytaggart We buy some surplus aircraft engines, but our main business is in the overhaul and repair of industrial turbine engines owned by other businesses.
Very instructive videos, kudos for you and your team. I have a question though: Is there a color code for the hydraulic lines or the fuel lines? I did see some brownish lines under the engine that Walter was converting. Thank you for your response.
Sure. You'll need all of them, so it's going to take some scrounging and some patience.
There are no extra, nonessential parts in a jet engine.
Just like a car engine... you can't put "most" of the parts together and have it run...
Great video, we are in the early stages of attempting to design an afterburner for a model turbine engine. Any feed back would be helpful.
@AgentJayZ Found the video, thats some good information. Surprisingly thats how I test my fuel injector ring.
Awesome tour, what are the energy companies using these for?
Uhhh, you're new to this channel, aren't you?
Have a look around, and you'll find something you might like. Based on your comment, I recommend the playlist called "My Afterburner Videos".
Enjoy!
ok, just so i understand, adding fuel is how you spool up a turbine, and in theory it will spool up until its gobbling in more air than the fuel can keep up with which is why there's so much O2 in the exhaust stream? I'm so used to piston engines where it's all about getting the A/F ratio stoichiometric. in this application the engine is basically running almost constantly lean which is why afterburners don't choke themselves out? thanks!
very informative video. Thanks, mate.
On a different note, are you Canadian?
i would love your job
we do the same thing in our aviation high school :D we wear the coveralls has well
i love test cell
interesting. thanks mate
@AgentJayZ I suppose I'll want the same pampered treatment when I'm old...
walter wins best job
Did Walter finish the job?
Saved to favorites. . .
AWESOME! LOVE THE VIDEOS!
@AgentJayZ Pretty impressive stuff mate. I take it you buy these beasts from airlines because they are past their sell-by date. How much to buy, to recondition and to sell on?
Are these aircraft engines converted into industrial power plants when the engines run out of flying hours? From what I understand all aircraft components have a set number of hours flight before they must be replaced with a new unit.So despite the engine running out of flying hours they still have a considerable amount of life in them before they are considered to be worn out,making them suitable for conversion to generators.
walter is the man
You ask me a question, yet specifically request I do not answer it... I'll cooperate as best I can...
Hey, at the begining of this video I se what looks like a JT9D engine outside, Could you possibly make a video of the engine it self and is s&s going to run it?
Thanks Tyler
@chazkez07 Long enough to not be scared to stand next to one, but not long enough to lose my excitement at just seeing them run!
Yeeeeee Haaaa!
Only thing close is to be live at the start of an indy car race... and that's only close!
AgentJayZ, what do the variable stators do? when converting to industrial engine, do you still use the variable stators or lock them?
do the linkages on the front compressors adjust the angle of the blades?
Alot bigger than my single stage turbine for my RC plane lol. Are there 4 seperate holes on each spray bar?. I'm guessing each ring is pressurized buy a pump and controlling AB stages by a fuel solenoids?. I'm thinking of adding AB to my jet engine lol.
what's the physical explanation for afterburners having to be so big (compared to the 'front' parts) ?
What maintains the continuos torque of the turbine after the APU start the engine ? pressure of the fuel burning ?
Thanks a lot for your reply, but problem is, that I'm from Germany and that could be very expensive with shipping, custom etc....What engine type do you have?
Regards
Andre
@1:00 Do the 7 'L' shape levers linked by a rod control variable pitch stators? If so, does an 'industrialised' J79, running for long periods at constant power, have much need for variable pitch stators?
When you convert a J-79 to a LM-1500 how many extra rows of turbines do you add? An aircraft only takes as much power from the exhaust to drive the compressors, pumps and aux power needs. The rest is used for thrust. I would imagine industrial use means electricity generation, so I would imagine you add extra rows of turbines. Or does the engine simply blow onto a external turbine/dynamo ensemble?
The flag in the shop and the info in my info section kind of give it away.
I am not familiar what is involved in fuel metering for jet turbines, but I know for internal combustion that an overly lean fuel/oxy ratio is a bad thing. My first question is, does a turbine even care about the stoichiometric ratio of fuel/air, followed by, does it try to keep that ratio on the rich side similar to an ICE and thirdly, if the engine is dumping fuel into the afterburner, is it possible that there is just not enough oxygen in the exhaust to keep the afterburner lit?
just a quick question. i have not worked on the j 79 since 1971 but i have to ask. have they figured out an easier way to r and r the csd generator relative to the top nut. as i rmember it was so tight a fit it was difficult to get a wrench on it. thanks
Just wondering how much goes into converting an engine designed to produce thrust to something that does shaft work? Just a much larger gearbox(AMAD or similar)? Any redesign of turbine section to extract more shaft power?
so, with afterburners, the original output thrust is compressed against the afterburner and gives it more forward thrust??? Just asking because I want to learn.
@tranceaddict704 Send me one, and I'll be happy to do a whole series on it !
Any chance you could do a video on the P&W jt11d-20, better known as the J58?
@AgentJayZ
dang. how long you been workin on turbines?
@TheArfdog No. you are getting caught in the gap between popular meanings of words and their technical meanings.
Diffusion is one word that does not apply here.
And what do you mean by a dedicated shaft turbine engine?
An engine that includes a power turbine in its design?
Such engines do exist; the GE LM6000 is one of them.
They are no more or less efficient in turning fuel into power then the usual gas-generator and separate power turbine arrangement.