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Posted: 3/23/2020 9:24:56 PM EDT
[#1]
Quote HistoryQuoted: There was an interview with a career F-15C driver (20yrs) who flew F-22s his last 4 years. He said the maintenance was less on the F-22 compared even with the F-16.....if you didn't include the RAM. Is that your perspective too? Quote HistoryQuoted: Quoted: Quoted: Quoted: Quoted: Most fun was de-pickling a motor after an engine change. They put some kind of preservative in them when they're overhauled, and it gets burned off the first time you crank it up on the aircraft. Fire department comes out, and the poor dope-on-a-rope (crew chief on ground cord) gets as far from the jet as possible. It produces a cloud that can completely envelope the aircraft. Seemed kind of cool at the time. Only jet-related activity that ever really kind of scared me was the man-on-a-stand run on the AC-130s. They wrapped the casters on the stand in chains to keep the stand from being dragged in that big-ass swinging prop, and adjusted the pitch to as close to neutral as possible. You're literally two or three feet from the world's biggest mix-master, and it's hypnotic in a bad way. Never enjoyed that, ever. Pickled engines were awesome! Just make sure you tell the fire department guys in advance.  I don't think I would like being that close to a 130 prop either. My biggest pucker moment running engines was my first burner run after finishing engine run class. I was running an F-15E in a hush house troubleshooting an engine stall in the #2 engine. I ran it slowly from idle to max AB a couple times and nothing happened, then I slammed the throttle from idle to max AB. That caused a nice compressor stall that sent a huge fire ball out the intake, over the canopy, and down the #1 engine. Turned out the nozzle control was binding and not allowing the nozzle to open up fast enough when you advanced the throttle quickly.I worked F15C/D/Es for 10 years and 6 years on F-22s. I would take working 15s over 22s every day of the week and twice on Sundays! And every Crew Chief I know who as worked both will say the same thing. There was an interview with a career F-15C driver (20yrs) who flew F-22s his last 4 years. He said the maintenance was less on the F-22 compared even with the F-16.....if you didn't include the RAM. Is that your perspective too? I'm sure he saw some BS figures saying that. 
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Posted: 3/23/2020 9:26:16 PM EDT
[#2]
Quote HistoryQuoted: Most fun was de-pickling a motor after an engine change. They put some kind of preservative in them when they're overhauled, and it gets burned off the first time you crank it up on the aircraft. Fire department comes out, and the poor dope-on-a-rope (crew chief on ground cord) gets as far from the jet as possible. It produces a cloud that can completely envelope the aircraft. Seemed kind of cool at the time. Quote HistoryQuoted: Most fun was de-pickling a motor after an engine change. They put some kind of preservative in them when they're overhauled, and it gets burned off the first time you crank it up on the aircraft. Fire department comes out, and the poor dope-on-a-rope (crew chief on ground cord) gets as far from the jet as possible. It produces a cloud that can completely envelope the aircraft. Seemed kind of cool at the time. 1010 Oil, MIL-6081. Quoted: Only jet-related activity that ever really kind of scared me was the man-on-a-stand run on the AC-130s. They wrapped the casters on the stand in chains to keep the stand from being dragged in that big-ass swinging prop, and adjusted the pitch to as close to neutral as possible. You're literally two or three feet from the world's biggest mix-master, and it's hypnotic in a bad way. Never enjoyed that, ever. You hot refuel the C-2 / E-2 behind the stbd prop in the wheel well. Scary as fuck the first time you do it, especially when it's in high ground idle. |
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Posted: 3/23/2020 9:29:52 PM EDT
[#3]
Quote HistoryQuoted: MD88/90? Or the B717? I'm just throwing shit at the wall to see what sticks at this point Quote HistoryQuoted: Quoted: @M82Assault Nope, though a “Boeing” does have this engine hung off of it, and it is in current airline use today. MD88/90? Or the B717? I'm just throwing shit at the wall to see what sticks at this point B717/MD95 has the BMW/Rolls Royce BR715, which the core plant was designed for industrial power. It als explains all the craptastic half measures that were used to make it an “aircraft engine.” When the engine works, it’s beautiful, when it decides it’s that time of the month, well I’d almost rather go lav diving. |
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Posted: 3/23/2020 9:46:55 PM EDT
[#4]
Quote HistoryQuoted: 1010 Oil, MIL-6081. You hot refuel the C-2 / E-2 behind the stbd prop in the wheel well. Scary as fuck the first time you do it, especially when it's in high ground idle. You get into another 'hole level of craziness with naval aviation. Worked with an AF SNCO who was former carrier mx. He told me about thinking he was going to die the first time they had him installing tail fin pitot static covers with a ten foot metal rod in the middle of a lightning storm. He used to laugh at our "lightning within 10" warnings. Ever seen the pictures of the Italian FE that got out to look at a battery problem they were having on their C-160? Ital AF said he lost his "situational awareness". They put a little orange cone everywhere they found a piece of that guy. There must have been 300 cones on that ramp... |
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Posted: 3/23/2020 10:52:38 PM EDT
[#5]
Quote HistoryQuoted: @2A373 One thing I've wondered about is how did the actual connections from the throttles in the F-15 link to the motors? Was it cables and pulleys before DEEC? How would you even service that system and the lines? There is no difference in how throttle inputs are transmitted to the engine between the old -100s with EECs and -220/229 with DEECs. It is just pulleys and cables to a junction box in the engine bay where throttle movement is converted to a rotation motion that is transferred to the engine by a shaft. I've forgotten what all does what from that point on as to how the engine is controlled. I'm curious if the new 15s coming off the line still use the same throttle system since they are fly by wire now. |
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Posted: 3/23/2020 11:32:10 PM EDT
[#6]
Quote HistoryQuoted: Small jet engines get started with an electric starter. That only works for things like business jets or the auxiliary power unit on airliners. Once the APU is started they pull bleed air off the compressor section and use that to spin an air powered starter on the main engine. In flight the air moving across the blades is enough to windmill the motor to get an air start. What's really cool is that you can make your own jet engine out of a car's turbocharger if you like living dangerously. I like living dangerously. Tell me how it's done. |
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Posted: 3/23/2020 11:34:20 PM EDT
[#7]
Quote HistoryQuoted: I like living dangerously. Tell me how it's done. Quote HistoryQuoted: Quoted: Small jet engines get started with an electric starter. That only works for things like business jets or the auxiliary power unit on airliners. Once the APU is started they pull bleed air off the compressor section and use that to spin an air powered starter on the main engine. In flight the air moving across the blades is enough to windmill the motor to get an air start. What's really cool is that you can make your own jet engine out of a car's turbocharger if you like living dangerously. I like living dangerously. Tell me how it's done. https://www.instructables.com/id/How-to-build-your-own-Jet-Engine/ |
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Posted: 3/23/2020 11:37:59 PM EDT
[#8]
Quote HistoryQuoted: What actually happens from a mechanical standpoint when you advance or retract the throttles? Throttles forward, cable connected to a lever on the motor that does what? Do they open up the fuel flow and nozzle position simultaneously and how is that done? I've never seen schematics for any of that. There are two cables connected to each throttle, one to advance and one to retract. They go out to the engine through a series of pulleys. The cables connect to the main engine control, which is a hydromechanical thing that had to be designed by a madman. It takes input from a bunch of sensors and uses pressurized fuel to move the variable stator vanes, variable bleed valves, and the fuel schedule to the rings. The reduction in fuel flow slows the motor down and the VSVs and VBVs keep it running smoothly and efficiently. |
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Posted: 3/23/2020 11:58:22 PM EDT
[#9]
Quote HistoryQuoted: Small jet engines get started with an electric starter. That only works for things like business jets or the auxiliary power unit on airliners. Once the APU is started they pull bleed air off the compressor section and use that to spin an air powered starter on the main engine. In flight the air moving across the blades is enough to windmill the motor to get an air start. What's really cool is that you can make your own jet engine out of a car's turbocharger if you like living dangerously. F-15s & 16s use a small turbine engine called a Jet Fuel Starter (JFS) that is mechanical connected to the engine(s) during startup. F-22s use bleed air from the APU. |
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Posted: 3/24/2020 8:02:28 AM EDT
[#10]
Quote HistoryQuoted: It's amazing that they can blow exhaust hot enough to melt the canopy of an F16.  |
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Posted: 3/24/2020 9:29:13 AM EDT
[#11]
Quote HistoryQuoted: F-15s & 16s use a small turbine engine called a Jet Fuel Starter (JFS) that is mechanical connected to the engine(s) during startup. F-22s use bleed air from the APU. Quote HistoryQuoted: Quoted: Small jet engines get started with an electric starter. That only works for things like business jets or the auxiliary power unit on airliners. Once the APU is started they pull bleed air off the compressor section and use that to spin an air powered starter on the main engine. In flight the air moving across the blades is enough to windmill the motor to get an air start. What's really cool is that you can make your own jet engine out of a car's turbocharger if you like living dangerously. F-15s & 16s use a small turbine engine called a Jet Fuel Starter (JFS) that is mechanical connected to the engine(s) during startup. F-22s use bleed air from the APU. There's enough little one-offs that I was just trying to hit the major means. Heck, a T-38 doesn't even have an onboard way to start the motors and has to use a huffer. A B-52 can use cans of black powder to spin up. |
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Posted: 3/24/2020 9:41:37 AM EDT
[#12]
Speaking of APU’s, there was always this bastard of an afterthought. Even though I’d rather change these over a MD-11 APU any day.
 
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Posted: 3/24/2020 10:55:25 AM EDT
[#13]
Quote HistoryQuoted: Speaking of APU’s, there was always this bastard of an afterthought. Even though I’d rather change these over a MD-11 APU any day. https://www.AR15.Com/media/mediaFiles/31717/5195E05A-3BA1-4E68-BE01-361CA5AC815F-1330869.jpg https://www.AR15.Com/media/mediaFiles/31717/56A96540-1BDB-442E-B29C-97D82F198695-1330870.jpg They're really easy to get to if you just put them on the main deck.  Attached File |
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Posted: 3/24/2020 12:24:30 PM EDT
[#14]
Quote HistoryQuoted: They're really easy to get to if you just put them on the main deck. https://www.AR15.Com/media/mediaFiles/66085/2764666218_698299b566_c_jpg-1330967.JPG That’s cheating right there! |
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Posted: 3/24/2020 12:37:36 PM EDT
[#15]
Quote HistoryQuoted: That’s cheating right there! Kind of! 135 engine mechanic here. Theres 2 APUs in that box, with a wall dividing them. So what is easy to fix on one APU is a giant pain in the ass on the other one. Essentially doing it blind. Im sure its better than most, though. |
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Posted: 3/24/2020 12:42:01 PM EDT
[#16]
Quote HistoryQuoted: That’s cheating right there! And great fun for the PAX if you didn't just happen to have ear defenders or headsets handy and had to make do with the spongies the loadmaster hands out. |
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Posted: 3/24/2020 4:08:13 PM EDT
[#17]
Quote HistoryQuoted: Kind of! 135 engine mechanic here. Theres 2 APUs in that box, with a wall dividing them. So what is easy to fix on one APU is a giant pain in the ass on the other one. Essentially doing it blind. Im sure its better than most, though. Quote HistoryQuoted: Quoted: That’s cheating right there! Kind of! 135 engine mechanic here. Theres 2 APUs in that box, with a wall dividing them. So what is easy to fix on one APU is a giant pain in the ass on the other one. Essentially doing it blind. Im sure its better than most, though. That's why the generator is always on number 2.
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Posted: 3/24/2020 5:32:27 PM EDT
[#18]
Quote HistoryQuoted: That's why the generator is always on number 2. Sounds like E&Es problem!  |
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Posted: 3/24/2020 7:01:33 PM EDT
[#19]
Quote HistoryQuoted: Jet engines are based on the Brayton Cycle, a deriviative of the Otto Cycle. Steam Turbines and power generation is based on the Carnot Cycle. Turbo Fans were invented to reduce noise and improve fuel efficiency. Jet engines provide better thrust in a smaller profile but are noisy as hell. Imagine a jet engine strapped to the wing of a 737...no one would sit behind the wings...lol Steam Turbines are based on the the Rankine cycle. The Carnot cycle is an ideal cycle where the maximum efficiency of a thermal engine is achieved. Otto cycles are internal combustion engine cycles. |
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Posted: 3/24/2020 7:16:13 PM EDT
[#20]
Quote HistoryQuoted: Sounds like E&Es problem! Quote HistoryQuoted: Quoted: That's why the generator is always on number 2. Sounds like E&Es problem! We have a kit to swap the generator in the road. It would be a bad day if it came to that. Have all system red X, will travel.
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Posted: 3/24/2020 7:40:46 PM EDT
[#21]
I liked the old ATM and GTC's of the old old Hercs...(NONONONO)
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Posted: 3/24/2020 10:54:19 PM EDT
[#22]
Quote HistoryQuoted: Speaking of APU’s, there was always this bastard of an afterthought. Even though I’d rather change these over a MD-11 APU any day. https://www.AR15.Com/media/mediaFiles/31717/5195E05A-3BA1-4E68-BE01-361CA5AC815F-1330869.jpg https://www.AR15.Com/media/mediaFiles/31717/56A96540-1BDB-442E-B29C-97D82F198695-1330870.jpg Thats a 727 APU aint it? First time I saw where that thing was my first thought was "whoa, right NEXT to the damn fuel tanks????!" |
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Posted: 3/24/2020 11:47:08 PM EDT
[#23]
Variable Stator Vanes don't look so simple to me....
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Posted: 3/25/2020 12:20:30 AM EDT
[#24]
If you think that's cool look up 2 other things.
First if its still available. Variable Ultra High Bypass Turbofan. Second Pulse Detonation Wave Engine. Hint Follow "Flux Liner". |
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Posted: 3/25/2020 5:45:40 AM EDT
[#25]
Quote HistoryQuoted: Thats a 727 APU aint it? First time I saw where that thing was my first thought was "whoa, right NEXT to the damn fuel tanks????!" Quote HistoryQuoted: Quoted: Speaking of APU’s, there was always this bastard of an afterthought. Even though I’d rather change these over a MD-11 APU any day. https://www.AR15.Com/media/mediaFiles/31717/5195E05A-3BA1-4E68-BE01-361CA5AC815F-1330869.jpg https://www.AR15.Com/media/mediaFiles/31717/56A96540-1BDB-442E-B29C-97D82F198695-1330870.jpg Thats a 727 APU aint it? First time I saw where that thing was my first thought was "whoa, right NEXT to the damn fuel tanks????!" Yep 727. Don't worry, it lives inside a fireproof bathtub! |
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Posted: 3/25/2020 6:50:00 AM EDT
[#26]
Quote HistoryQuoted: A ramjet needs no moving parts (although there may be to control the air flow) but needs a lot of speed before it works. Quote HistoryQuoted: Quoted: I remember reading about ramjets in popular mechanics a few decades ago. No moving parts are there? A ramjet needs no moving parts (although there may be to control the air flow) but needs a lot of speed before it works. Typically, yes, a ramjet needs to be traveling about Mach 3 to be lit off, a scramjet more like Mach 6. I know the guy that has a patent to configure a ramjet to light off standing still. L-M has been trying to steal his work for years. |
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Posted: 3/25/2020 8:24:38 AM EDT
[#27]
Quote HistoryQuoted: Efficiency makes em maintenance heavy. F machines are pretty reliable, but the new stuff has 2000 degree firing temperatures. Think about that for a minute. F Technology is old Technology. We installed the First 501F's in Lauderdale in 1993. G-GAC is the proven class now but, H&J Technology is where it is at. M501JAC Specs Fire Temps at 1600 C = 2912 F  60 Hz Simple Cycle 370 MW = 496,178 hp @ 42.6% efficiency Combined Cycle 540 MW = 724,152 hp @ >63% efficiency (1 on 1) 50 Hz Simple Cycle 493 MW = 661,124 hp @ 42.9% efficiency Combined Cycle 717 MW = 961,513 hp @ >63% efficiency (1 on 1) All off of Suck, Squeeze, Boom, Blow
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Posted: 3/25/2020 5:14:01 PM EDT
[#28]
Quote HistoryQuoted: F Technology is old Technology. We installed the First 501F's in Lauderdale in 1993. G-GAC is the proven class now but, H&J Technology is where it is at. M501JAC Specs Fire Temps at 1600 C = 2912 F 60 Hz Simple Cycle 370 MW = 496,178 hp @ 42.6% efficiency Combined Cycle 540 MW = 724,152 hp @ >63% efficiency (1 on 1) 50 Hz Simple Cycle 493 MW = 661,124 hp @ 42.9% efficiency Combined Cycle 717 MW = 961,513 hp @ >63% efficiency (1 on 1) All off of Suck, Squeeze, Boom, Blow Not a fan of the H, finicky, ran a new construction with 2 of them for 2 years, single shaft has ....um...unique issues. Heat rate was pretty awesome though, 6500 btu/kw On another new one now (3x1) with the new "improved" 5000F, much more robust and proven tech. heat rate still good coming in at 6700-6800. Been doing this for 30 years now, I remember the first plant on a good day could do 8200, with nox and co in double digits. Now we are running low single digits. Amazing improvements in just a couple of decades. Metallurgy, coatings, controls, great stuff. |
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Posted: 3/25/2020 5:50:31 PM EDT
[#29]
Quote HistoryQuoted: There are two cables connected to each throttle, one to advance and one to retract. They go out to the engine through a series of pulleys. The cables connect to the main engine control, which is a hydromechanical thing that had to be designed by a madman. It takes input from a bunch of sensors and uses pressurized fuel to move the variable stator vanes, variable bleed valves, and the fuel schedule to the rings. The reduction in fuel flow slows the motor down and the VSVs and VBVs keep it running smoothly and efficiently. Fuel control units, by whatever name, are always complicated. This particular one sounds... ummmm... more complex than most. |
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Posted: 3/25/2020 5:54:11 PM EDT
[#30]
Quote HistoryThat’s a lot of damaged hearing right there! The Bone is definitely on the short list for loudest plane. |
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Posted: 3/25/2020 9:11:27 PM EDT
[#31]
Quote HistoryQuoted: Ram jets have NO moving parts. Just need a LOT of speed to compress the air enough to start the process (RAM of RamJet) & as long as you have fuel, you have thrust. Quote HistoryQuoted: Quoted: Quoted: I remember reading about ramjets in popular mechanics a few decades ago. No moving parts are there? You’re thinking pulse jet. Ram jets have NO moving parts. Just need a LOT of speed to compress the air enough to start the process (RAM of RamJet) & as long as you have fuel, you have thrust. Yes, every ramjet except one. Here is a link to a ramjet that can start from static and accelerate to Mach 3.  SPACE ACCESS Ejector Ramjet Engine Run |
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Posted: 3/26/2020 7:49:59 AM EDT
[#32]
Quote HistoryQuoted: Fuel control units, by whatever name, are always complicated. This particular one sounds... ummmm... more complex than most. Quote HistoryQuoted: Quoted: There are two cables connected to each throttle, one to advance and one to retract. They go out to the engine through a series of pulleys. The cables connect to the main engine control, which is a hydromechanical thing that had to be designed by a madman. It takes input from a bunch of sensors and uses pressurized fuel to move the variable stator vanes, variable bleed valves, and the fuel schedule to the rings. The reduction in fuel flow slows the motor down and the VSVs and VBVs keep it running smoothly and efficiently. Fuel control units, by whatever name, are always complicated. This particular one sounds... ummmm... more complex than most. Ours is a hydro mechanical beast that was either designed by a genius or a madman. |
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Posted: 3/26/2020 11:19:09 AM EDT
[#33]
Quote HistoryQuoted: Ours is a hydro mechanical beast that was either designed by a genius or a madman. Quote HistoryQuoted: Quoted: Quoted: There are two cables connected to each throttle, one to advance and one to retract. They go out to the engine through a series of pulleys. The cables connect to the main engine control, which is a hydromechanical thing that had to be designed by a madman. It takes input from a bunch of sensors and uses pressurized fuel to move the variable stator vanes, variable bleed valves, and the fuel schedule to the rings. The reduction in fuel flow slows the motor down and the VSVs and VBVs keep it running smoothly and efficiently. Fuel control units, by whatever name, are always complicated. This particular one sounds... ummmm... more complex than most. Ours is a hydro mechanical beast that was either designed by a genius or a madman. Ahh, brings back memories. Trimming a fuel control for a J-52 in an EA-6B at military power will make your teeth hurt. My ears are still ringing 48 years later. God, I wish I could do it again. |
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Posted: 4/1/2020 9:34:00 PM EDT
[#34]
 World's simplest gas turbine |
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Posted: 4/1/2020 10:29:25 PM EDT
[#35]
Quote HistoryQuoted: Typically, yes, a ramjet needs to be traveling about Mach 3 to be lit off, a scramjet more like Mach 6. I know the guy that has a patent to configure a ramjet to light off standing still. L-M has been trying to steal his work for years. Quote HistoryQuoted: Quoted: Quoted: I remember reading about ramjets in popular mechanics a few decades ago. No moving parts are there? A ramjet needs no moving parts (although there may be to control the air flow) but needs a lot of speed before it works. Typically, yes, a ramjet needs to be traveling about Mach 3 to be lit off, a scramjet more like Mach 6. I know the guy that has a patent to configure a ramjet to light off standing still. L-M has been trying to steal his work for years. Though, why do I remember reading somewhere that the difference between a ramjet and a scramjet is the airflow INSIDE the ramjet is subsonic, but inside the scramjet is supersonic? I know I'm getting old (over a half century on this mudball), but that just sticking in the brain cells for some reason. |
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