F-35B will have the most complex single engine for a jet
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Another thing hcobb seems to miss is that the specially prepared hardened landing pads are designed for very long-term use supporting probably thousands of take-offs and landings at a fixed operating base. Landings at any austere base will total orders of magnitude less for any given spot.
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Harriers would damage surfaces if not kept moving or landing in different areas, unless that is they are landed on 'specially prepared hardened landing pads'
Ever notice at airshows, when a Harrier would perform, they would typically NOT perform a vertical take off or landing. They were almost always STOL? And when performing a hover, the Harrier would be high enough to not damage said airport's landing or taxi surfaces (or sling chunks of sod from the infields).
Yes the F135-PW-600 will be the most complicated single engine EVER! Much the engines used in military aircraft before it were often called 'the most complicated'.
We don't have the best fighters in the world because we're using outdated engines with lack-luster technology or performance, otherwise the tried-and-true J75-P-17 from 1955 (which still holds the air breathing single engine speed record in the F-106) would be the 'standard' engine for new US fighter programs!
Likewise, IF the F136-GE-600 had seen production it would have run neck-in-neck with the PW motor as they would have shared the -600 gear common to both types. Both motors would have been complicated enough in the -100/400 types, but the added components of the -600 would have doubled their complexities.
Yes there will be engineering challenges, PW has already had to address drive shaft, lift post and clutch issues not foreseen when the 'requirements' were provided and/or contracted initially. In-flight testing has proven that modeling and simulation will still not provide a 100% solution to flight testing.
Yes there will be concerns, with ANY new propulsion system there will be tension.
Yes there will be incidents (God willing nobody will be hurt) but we learn from these to make even MORE reliable engines. Nobody is perfect, these propulsion systems are the results of decades off data, years of engineering and planning, dozens if not hundreds of contractors, all working for a common goal. Keep our pilots safe, and give them the best propulsion system to fit their needs.
NO this does not mean you get everything you want in an engine, aviation is a huge compromise. Get this, take that. More power, more fuel, bigger tanks, more weight, bigger wings, more drag, more power, bigger engine, more fuel, bigger tanks.....
Complex is complex whatever company builds it, if that is what you were getting at...
You obviously have NO IDEA what modern military augmented gas turbine engine looks like inside, how they're manufactured, built, operated, maintained, modified, matured, studied, cataloged, tracked, funded, forecast, or designed. Computers (FADECs), sensors, resolvers, solenoids, electronics, lines of code, MIL specs, software and interfaces; built in redundancy and fail safes; 4 or more levels of fault accommodation built into the system to provide 'reliable' power even when things do go wrong.
All of this equipment not only has to work correctly, but it has to last! The engines today far out-live the the previous generation of military jet engines.
Early F100s (also the most complex motors of the late 60's) had 800 hour overhauls on hot section components; today the latest F100-PW-229 EEP (with a helping of F119/F135 tech built in) will last 6000 engine cycles (8-10-12 years! depending on use)
The Jumo 004 of the ME262 had a 50 hour TBO in the 1940s (Though they rarely lasted that long without failing)
If I was a MOD I'd be changing the 'vote' options or deleting the 'vote' portion of the tread all together.
Seems like this was a personal talking point, not even a good joke or valid debate.
Where is my bourbon?
TEG
Ever notice at airshows, when a Harrier would perform, they would typically NOT perform a vertical take off or landing. They were almost always STOL? And when performing a hover, the Harrier would be high enough to not damage said airport's landing or taxi surfaces (or sling chunks of sod from the infields).
Yes the F135-PW-600 will be the most complicated single engine EVER! Much the engines used in military aircraft before it were often called 'the most complicated'.
We don't have the best fighters in the world because we're using outdated engines with lack-luster technology or performance, otherwise the tried-and-true J75-P-17 from 1955 (which still holds the air breathing single engine speed record in the F-106) would be the 'standard' engine for new US fighter programs!
Likewise, IF the F136-GE-600 had seen production it would have run neck-in-neck with the PW motor as they would have shared the -600 gear common to both types. Both motors would have been complicated enough in the -100/400 types, but the added components of the -600 would have doubled their complexities.
Yes there will be engineering challenges, PW has already had to address drive shaft, lift post and clutch issues not foreseen when the 'requirements' were provided and/or contracted initially. In-flight testing has proven that modeling and simulation will still not provide a 100% solution to flight testing.
Yes there will be concerns, with ANY new propulsion system there will be tension.
Yes there will be incidents (God willing nobody will be hurt) but we learn from these to make even MORE reliable engines. Nobody is perfect, these propulsion systems are the results of decades off data, years of engineering and planning, dozens if not hundreds of contractors, all working for a common goal. Keep our pilots safe, and give them the best propulsion system to fit their needs.
NO this does not mean you get everything you want in an engine, aviation is a huge compromise. Get this, take that. More power, more fuel, bigger tanks, more weight, bigger wings, more drag, more power, bigger engine, more fuel, bigger tanks.....
Complex is complex whatever company builds it, if that is what you were getting at...
You obviously have NO IDEA what modern military augmented gas turbine engine looks like inside, how they're manufactured, built, operated, maintained, modified, matured, studied, cataloged, tracked, funded, forecast, or designed. Computers (FADECs), sensors, resolvers, solenoids, electronics, lines of code, MIL specs, software and interfaces; built in redundancy and fail safes; 4 or more levels of fault accommodation built into the system to provide 'reliable' power even when things do go wrong.
All of this equipment not only has to work correctly, but it has to last! The engines today far out-live the the previous generation of military jet engines.
Early F100s (also the most complex motors of the late 60's) had 800 hour overhauls on hot section components; today the latest F100-PW-229 EEP (with a helping of F119/F135 tech built in) will last 6000 engine cycles (8-10-12 years! depending on use)
The Jumo 004 of the ME262 had a 50 hour TBO in the 1940s (Though they rarely lasted that long without failing)
If I was a MOD I'd be changing the 'vote' options or deleting the 'vote' portion of the tread all together.
Seems like this was a personal talking point, not even a good joke or valid debate.
Where is my bourbon?
TEG
[Airplanes are] near perfect, all they lack is the ability to forgive.
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The Engine Guy..... your wrong about the F-135 engine, it's relatively simple compared other aviation engines. Just take a look at Rolls Royce Merlin or Pratt and Whittney Dual Wasp Engine.
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That_Engine_Guy wrote:
If I was a MOD I'd be changing the 'vote' options or deleting the 'vote' portion of the tread all together.
Seems like this was a personal talking point, not even a good joke or valid debate.
Where is my bourbon?
TEG
Yup, a loaded question.
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alloycowboy wrote:The Engine Guy..... your wrong about the F-135 engine, it's relatively simple compared other aviation engines. Just take a look at Rolls Royce Merlin or Pratt and Whittney Dual Wasp Engine.
If you only consider "Mechanical Complexity" you may have a point. Turbine engines are mechanically simpler in terms of basic operation.
The Brayton Cycle is very simple when compared to Otto Cycle.
Jet engines have almost no 'timing' to speak of, and few moving part compared to a piston engine, either V or Radial.
Visual beauty.... is a stretch; Personally I find almost ANY aviation engine visually striking.
But when it comes to overall complexity, the F135 should have everything to date beat!
Electronically speaking the F135 will be the most intelligent (complicated) engine ever produced. This thing will rival the engines of the space shuttle from some of the things I've read.
The F135 team has also issued a contract of its own to Diagnostic software maker Qualtech Systems Inc. of Wethersfield, CT to provide real-time on-board diagnostics for its jet engines. The contract calls for Qualtech Systems to provide fault isolation development software tools and an an on-engine "diagnostic reasoner" as part of Pratt & Whitney's Joint Strike Fighter Engine Prognostics & Health Management (PHM) Program.
PHM will make use of electrostatic and other sensors to monitor such parameters as debris generation, vibration, blade health and lubricating-oil quality. The suite of sensors will constantly monitor approximately 500 data streams, which will be integrated with the F-35's own systems. The complete PHM system has been developed in partnership with NASA Ames, which created vital data-fusion algorithms, NASA Dryden and NASA Glenn, with flight development to be carried out with a C-17. As noted previously, the aim is to predict the need for inspection or parts-replacement, so that, via a satellite link, the airbase or aircraft carrier knows the engine health before the aircraft returns from its mission.
http://www.f-16.net/index.php?name=PNph ... c&p=116344
I hate to say but the intelligence of this engine, coupled with the advanced manufacturing processes, advanced materials, and '-600 portion' of the propulsion system for STOVL; easily outstrips the mechanical complication of the Merlin, Wasp or even the mighty Wasp Major.
The later never had 500 data-streams performing life engine diagnostics to aid maintenance for not only it's self, but it's co-motors longevity/safety over the cycle-life of the engine's use. (If not future military engine programs)
IMO
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hcobb wrote:The Merlin never had to worry about tapping a small part of the prop thrust and vectoring that off the wing tip.
The Merlin wasn't designed for 3 different airframes, for 3 different operating parameters. Conventional, Naval/Ship-Born, STOVL
The F135 was tailor made specifically for this and given the extra stage of low-pressure turbine and engine control logic specifically for the extra power to drive the -600's LiftSystem.
The F135's low-pressure turbine was designed for minimum pressure loss, and given an extra stage to extract HP with the least amount of engine performance impact. In addition, engine's control system is programmed for the resulting loss of operating pressure ratio when the roll-posts bleed air from the N2 compressor. It also contends with the added load to the low pressure turbine and the restriction of the 3BSM/nozzle bent from the 0* position. Added engine inlets open to allow larger amounts of airflow to help compensate for the low airspeed and increased demand.
This is WHY the F135-PW-600 is THE most complex single engine propulsion system ever devised for a fighter aircraft. The F135-PW-600's LiftFan, drive shaft, clutch, Roll-Posts, and 3BSM make it even more complex that it's -100/400 sisters.
My answer to this question: "YES; the Pratt & Whitney F135-PW-600 (to include RR-USA's LiftSystem) that powers the F-35B is THE most complex single engine fighter engine to date*"
Even though this option was not given in the poll.
Keep 'em flyin'
TEG
*that we know about, or are authorized to know about!
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WickedPedia seems to give a good summary but I'm certain the TEG can add more details:
http://en.wikipedia.org/wiki/Pratt_%26_Whitney_F135
http://en.wikipedia.org/wiki/Pratt_%26_Whitney_F135
"The conventional and carrier aviation engines, the F135-PW-100 and F135-PW-400, have a maximum (wet) thrust of approximately 43,000 lbf (191 kN) and a dry thrust of approximately 28,000 lbf (125 kN). The major difference between the -100 and -400 models is the use of salt-corrosion resistant materials.[11]
The STOVL variant, F135-PW-600, delivers the same 43,000 lbf (191 kN) of wet thrust as the other types in its conventional configuration. In STOVL configuration, the engine produces 18,000 lbf (80.1 kN) of lift thrust. Combined with thrust from the LiftFan (20,000 lbf/89.0 kN) and two roll posts (1,950 lbf/8.67 kN each), the Rolls-Royce LiftSystem produces a total of 41,900 lbf (186 kN) of thrust, almost the same vertical lifting force for slow speed flight as the same engine produces at maximum afterburner, without the extreme fuel use or exhaust heat as wet thrust.[12]
The STOVL variant engages a clutch to extract around 35,000 shp (26,000 kW)[citation needed] from the LP turbine to turn the forward lift fans, while switching power cycle from mixed (turbofan) to unmixed (turboshaft). Power is transferred forward through shaft to a bevel gearbox, to drive two vertically mounted contra-rotating fans. The uppermost fan is fitted with variable inlet guide vanes and the fan discharges efflux (low-velocity unheated air) through a nozzle on the underside of the aircraft. This cool air from the lift fan has the added benefit of preventing hot exhaust gases from the core section from being reingested into the engine while hovering. Finally, bypass duct air is sent to a pair of roll post nozzles and the core stream discharges downwards via a thrust vectoring nozzle at the rear of the engine.[3] Measured by lift thrust in full vertical lift mode, the engine operates as 43% turbojet, 48% turboshaft, and 9% turbofan."
http://en.wikipedia.org/wiki/Pratt_%26_Whitney_F135
http://en.wikipedia.org/wiki/Pratt_%26_Whitney_F135
"The conventional and carrier aviation engines, the F135-PW-100 and F135-PW-400, have a maximum (wet) thrust of approximately 43,000 lbf (191 kN) and a dry thrust of approximately 28,000 lbf (125 kN). The major difference between the -100 and -400 models is the use of salt-corrosion resistant materials.[11]
The STOVL variant, F135-PW-600, delivers the same 43,000 lbf (191 kN) of wet thrust as the other types in its conventional configuration. In STOVL configuration, the engine produces 18,000 lbf (80.1 kN) of lift thrust. Combined with thrust from the LiftFan (20,000 lbf/89.0 kN) and two roll posts (1,950 lbf/8.67 kN each), the Rolls-Royce LiftSystem produces a total of 41,900 lbf (186 kN) of thrust, almost the same vertical lifting force for slow speed flight as the same engine produces at maximum afterburner, without the extreme fuel use or exhaust heat as wet thrust.[12]
The STOVL variant engages a clutch to extract around 35,000 shp (26,000 kW)[citation needed] from the LP turbine to turn the forward lift fans, while switching power cycle from mixed (turbofan) to unmixed (turboshaft). Power is transferred forward through shaft to a bevel gearbox, to drive two vertically mounted contra-rotating fans. The uppermost fan is fitted with variable inlet guide vanes and the fan discharges efflux (low-velocity unheated air) through a nozzle on the underside of the aircraft. This cool air from the lift fan has the added benefit of preventing hot exhaust gases from the core section from being reingested into the engine while hovering. Finally, bypass duct air is sent to a pair of roll post nozzles and the core stream discharges downwards via a thrust vectoring nozzle at the rear of the engine.[3] Measured by lift thrust in full vertical lift mode, the engine operates as 43% turbojet, 48% turboshaft, and 9% turbofan."
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The Shaft Driven Lift Fan Propulsion System for the Joint Strike Fighter
Paul M. Bevilaqua ASTOVL Program Manager
Lockheed Martin Skunk Works Palmdale, California
http://www.dtic.mil/dticasd/sbir/sbir032/n184.doc (5.5Mb)
"Abstract
Analysis and testing are used to show the feasibility of an innovative shaft driven lift fan propulsion system for supersonic STOVL aircraft. Dual cycle operation of the cruise engine makes it possible to convert some of the jet thrust to shaft horsepower for driving the lift fan. Operation of the propulsion system is described and it is analytically shown that the designs of the engine, drive shaft, and clutch are within the state of the art. A demonstrator engine and lift fan were assembled from available components and operated for almost 200 hours in a full size airframe model. Testing proved the feasibility of changing the engine cycle to drive the lift fan, and of rapidly transferring thrust back and forth between the engine and lift fan to provide pitch control. The durability of the mechanical drive system and flight weight gearbox were also demonstrated."
The .DOC file has a lot of text explanations and illustrations about how the STOVL engine works.
Paul M. Bevilaqua ASTOVL Program Manager
Lockheed Martin Skunk Works Palmdale, California
http://www.dtic.mil/dticasd/sbir/sbir032/n184.doc (5.5Mb)
"Abstract
Analysis and testing are used to show the feasibility of an innovative shaft driven lift fan propulsion system for supersonic STOVL aircraft. Dual cycle operation of the cruise engine makes it possible to convert some of the jet thrust to shaft horsepower for driving the lift fan. Operation of the propulsion system is described and it is analytically shown that the designs of the engine, drive shaft, and clutch are within the state of the art. A demonstrator engine and lift fan were assembled from available components and operated for almost 200 hours in a full size airframe model. Testing proved the feasibility of changing the engine cycle to drive the lift fan, and of rapidly transferring thrust back and forth between the engine and lift fan to provide pitch control. The durability of the mechanical drive system and flight weight gearbox were also demonstrated."
The .DOC file has a lot of text explanations and illustrations about how the STOVL engine works.
Last edited by spazsinbad on 31 Dec 2011, 17:34, edited 1 time in total.
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hcobb wrote:The absence is tongue in cheek, really.hcobb...is there a reason you won't let anybody vote "yes"?
I personally have grave doubts about how well the F-35B will work, once the Marines get it down in the mud and the gravel.
Surely the same service can not be proudly stating both of these things:
The Marines are planning to use the F-35B from "unimproved surfaces at austere bases" and are preparing landing spots with "special, high-temperature concrete designed to handle the heat from the JSF".
I have my doubts as well, but I'm hoping LM and the Marines can prove me wrong. I don't see why F-35Cs can't be used at austere bases and on unimproved surfaces.
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Hardly surprising, but one can hope that complex doesn't mean unreliable. @alloycowboy old reciprocating engines may *look* complex, but you're ignoring the electronics and software that make modern turbines tick.
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madrat wrote:What's the difference between the F135-PW-100 and F135-PW-400?
spazsinbad wrote:WickedPedia seems to give a good summary but I'm certain the TEG can add more details
Spaz got it; the -400 is "Navalized" per USN regulation to use specified materials or add special coatings where required for use at sea. (Just as one example, there may be other requirements)
Magnesium has one of the highest galvanic corrosion rates, but is used on jet engines due to it's light weight. The -400 may use another type of material in this case, or require some sort of 'MIL-SPEC' coating to protect it from long term corrosion at sea.
In other words, if a particular air force (land based) decided to purchase F-35C aircraft for a particular tactical reason, the user could opt for the cheaper/lighter F135-PW-100 to be installed. I would see no reason why a foreign military would want to pay for USN requirements for their engines if they didn't need too... esp considering life-cycle costs for the 'special' materials, coatings, and processes; it could be significantly cheaper to maintain over 20 years. (You're already paying for wing-folds, heavy gear, massive hook, etc...)
Keep 'em flyin'
TEG
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