F135 upgrades, reengining considered in new F-35 propulsion

All about the Pratt & Whitney F135 and the (cancelled) General Electric/Rolls-Royce F136
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spazsinbad

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Unread post28 Aug 2022, 02:57

https://en.wikipedia.org/wiki/Armstrong ... n-situ.JPG

https://www.iwm.org.uk/collections/item/object/70000035 "Two turboprop Mamba engines driving contra-rotating propellers through a combining gearbox. Each engine consists of a 10-stage axial compressor, 6 combustion chambers, 2-stage turbine. Main application the Fairey Gannet."

XT752 Fairey Gannet engine start https://www.youtube.com/watch?v=jdBrfiYYQ8U

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f119doctor

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Unread post28 Aug 2022, 03:10

I did say most were abandoned. Another example is the TU-95 bomber.

The Double Mamba didn’t drive the coaxial contra rotating props thru a combining gearbox, unless there was a disengagement clutch in the system to allow independent operation. Under loiter conditions, one of the engines could be shutdown and its prop was feathered. The other engine and prop ran at a high power setting where the SFC was lower, saving fuel. Both engines and props were active for high power operation such as takeoff and landing.
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Unread post28 Aug 2022, 04:06

In RAN FAA use the Gannet did shut down one engine for the ASW patrols. Also a cartridge start was used similar to the Sea Venom Jet aircraft and the RAAF Canberra Bomber. rather than the clumsy compressed air we see in the video. Onboard Wessex Helos started with a compressed air hose though. I'm not sure if the Gannet used that method in those days.

.MP3 Sound file attached is the Double Mamba Full Bore Flyby ROAR.
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Unread post29 Aug 2022, 11:02

f119doctor wrote:
allesmorobranna wrote:I did not see any true cutaway about the GE XA100 engine, except the fancy infographics, but there the shafts are rotating with the same direction. The P&W F135 family (like the F119) has a counter-rotating shafts, where the most important benefit is not just the lack of one stator between the last and first stages of the two spools, but the almost elliminated precession. Without the preciession, the airplane has a better high AoA maneuvering capability, because the control surfaces have less required work to compensate the high AoA departure.
The shafts precession is a valid issue - like the propeller driven airplanes have it at take off, high RPM differnece or high AoA situation - so a counter rotating shaft design could be helpful.
If the XA100 has a similar rotation shaft design, the FbW has more workload to keep the same high AoA controllability and handling characteristics.
From this standpoint the XA100 integration would not be a simple "plug and play" thing. At high AoA the whole attitude is goind to be different.


While it is true that both the F119 and F135 engines have counterrotating high and low spools, P&W was unable to eliminate the stator vanes between the high and low turbine rotors, although this was the original design concept. They found that with the high levels of expansion in these high work single stage turbines, the hot gas flow exiting the high turbine tended to streamline straight into the middle of the low turbine blades. The added low turbine vanes have very little flow turning camber, but are 3D shaped to spread the flow evenly across the LPT blades from root to tip. The F135, in addition to this low turbine inlet vane, has a more conventional turning vane between the blade stages to split the work between the two rows of LPT blades.

FYI - the Harrier engine also had counterrotating high and low rotors for low speed and VTOL handling. In addition to the gyroscopic precession concern that occur with pitch and yaw rates, the counterrotating rotors offset any torque reaction of the engine. While jet engines have no external torque at steady state conditions, they have a very large torque opposite the direction of rotation during fast throttle movement rotor acceleration. Under low airspeed / hover conditions this accel torque could easily overpower the available control authority and roll the aircraft into an uncontrollable position. Each spool of a counterrotating dual spool engine applies this accel torque in opposite directions, cancelling much of it out.


And this is the reason, why the Lift Fan in the F-35B is actually a counter-rotating fan. To elliminate the gyroscopic precession AND provides as large propulsion efficiency as it could.
Stay at the VTOL aircraft world, the soviet Yak-38 main engine was a Tumansky R-27V engine, the engine of the first generation single seat MiG-23S-MS fighters and all the two seater MiG-23UBs, but without the afterburner chamber and with a rotary, separated, fix profile nozzles. The point is the R-27 engine itself, where the desgners kept the normal, single rotation twin shaft design, so the torque from the gyroscopic precession was not elliminated by the way, ahst we can see at the Harrier or the F-35B.
But at the engine of the successor, the Yak-141, the Soyuz (formerly known as Tumansky) R-79V, the shafts are counter-rotating. The design is focused on the high hovering power output. It has a large, single stage fan and a counter rotating HP compressor. The pressure ratio was not as high, as the late-70's western standard was at that time, but by the large diameter fan, the air mass flow was quite large, 180kg/sec. This mass flow was enough for the high power output at hovering mode (without AB) and it was compensated by two small, lifting engine with the very high specific thrust, because of the supersonic compressor stages. Approximetely, a 1000lbs engine could generate 10000lbs static thrust (this was a lifting engine, so the static thrust was the in-built thrust either) so the specific thrust reached the number 10.
It has two lift engine, so the main engine had to provide the other equal amount of thrust to got the overal lift thrust.
There was another unique feature: for the STOL mode, at the 45 degrees position of the 3 Bearing Swivel Nozzle, the R-79V could operate with min reheate mode to gain the accelartion. Ok, back to the F-35 engines.

So if, the GE design is not a counter-rotating one, the precession issue is significant at the F-35B in hovering mode, but also appeares at the high alpha maneuvering in the A and C variants. Maybe the F-35B will never get the GE engine.
But for a better promised economy and possibly optmized thrust envelope, will the GE sacrificed the quite good maneuvering capabilies of the F-35A and C family?
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Unread post29 Aug 2022, 12:46

f119doctor wrote:For propeller aircraft, you need counter rotating props to offset torque, P-factor, and spiraling prop wash hitting the rudder, all trying to roll and side slip on the aircraft at low air speeds. Many of the WW2 fighters required a slow throttle advance during go-arounds to keep from rolling and crashing inverted. Lots of attempts at coaxial counter rotating props thru the war, but most were abandoned with the advent of the jet age.

Microsoft Flight Simulator taught me that in 1984. Don't spin up your Piper motor too fast or bad things happen.
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Unread post07 Sep 2022, 22:15

New adaptive engine or fewer F-35s? Kendall says it’s time to choose
08 Sep 2022 Stephen Losey

"WASHINGTON — Choosing to replace the F-35′s engine with a next-generation adaptive model could force the U.S. military to buy 70 fewer of the fighters. Air Force Secretary Frank Kendall warned of the tough decisions that could come with a change to F-35 propulsion at the Defense News Conference in Arlington, Virginia on Wednesday....

...“If you have several hundred F-35s in your inventory, how many more F-35s are you willing to forgo to get the new engine?” Kendall said in a panel at Wednesday’s conference. “It’s an expensive engine. It takes a lot just to do the development — several billion dollars. [That] is, in rough terms, 70 F-35s. So are you prepared to have 70 less F-35s in order to have that engine in the ones that you do have?”...

...The Defense Department needs to make a choice one way or the other, Kendall said. “I don’t want to continue to spend money on an engine that we’re not going to develop and take into production,” he said. “We just need to make a decision, decide what to do, and get on with it.”...

...Industrial base concern an ‘overstatement’
Kendall downplayed concerns about the health of the adaptive engine industrial base recently raised by the head of the Air Force’s Propulsion Directorate, John Sneden. In a briefing with reporters last month, Sneden said that industrial base was “very thin,” and a decision to not move forward with an adaptive engine in the F-35 could lead to its “collapse.” Kendall called warnings of potential collapse an “overstatement.”...

...The Air Force’s recent Next Generation Adaptive Propulsion contract awards to five companies to develop adaptive engine prototypes for its next-generation fighter jets also show the strength of that market’s industrial base, Kendall said. In addition to Pratt & Whitney and GE, the Air Force awarded contracts to Boeing, Lockheed Martin, and Northrop Grumman.

The number of engines that will be produced under the NGAP contract — each company’s deal was worth up to $975 million — will be “relatively modest” compared to the F-35′s needs, Kendall said...."

Source: https://www.defensenews.com/air/2022/09 ... to-choose/
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Unread post08 Sep 2022, 04:21

spazsinbad wrote:
New adaptive engine or fewer F-35s? Kendall says it’s time to choose
08 Sep 2022 Stephen Losey

"WASHINGTON — Choosing to replace the F-35′s engine with a next-generation adaptive model could force the U.S. military to buy 70 fewer of the fighters. Air Force Secretary Frank Kendall warned of the tough decisions that could come with a change to F-35 propulsion at the Defense News Conference in Arlington, Virginia on Wednesday....

...“If you have several hundred F-35s in your inventory, how many more F-35s are you willing to forgo to get the new engine?” Kendall said in a panel at Wednesday’s conference. “It’s an expensive engine. It takes a lot just to do the development — several billion dollars. [That] is, in rough terms, 70 F-35s. So are you prepared to have 70 less F-35s in order to have that engine in the ones that you do have?”...

...The Defense Department needs to make a choice one way or the other, Kendall said. “I don’t want to continue to spend money on an engine that we’re not going to develop and take into production,” he said. “We just need to make a decision, decide what to do, and get on with it.”...

...Industrial base concern an ‘overstatement’
Kendall downplayed concerns about the health of the adaptive engine industrial base recently raised by the head of the Air Force’s Propulsion Directorate, John Sneden. In a briefing with reporters last month, Sneden said that industrial base was “very thin,” and a decision to not move forward with an adaptive engine in the F-35 could lead to its “collapse.” Kendall called warnings of potential collapse an “overstatement.”...

...The Air Force’s recent Next Generation Adaptive Propulsion contract awards to five companies to develop adaptive engine prototypes for its next-generation fighter jets also show the strength of that market’s industrial base, Kendall said. In addition to Pratt & Whitney and GE, the Air Force awarded contracts to Boeing, Lockheed Martin, and Northrop Grumman.

The number of engines that will be produced under the NGAP contract — each company’s deal was worth up to $975 million — will be “relatively modest” compared to the F-35′s needs, Kendall said...."

Source: https://www.defensenews.com/air/2022/09 ... to-choose/


Sounds like Kendall is trying to secure some additional funding for the project from Congress. As last month he was all in favor of adapting the Adaptive Cycle Engine to the F-35!
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Unread post12 Sep 2022, 21:35

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Unread post14 Sep 2022, 22:45

GE PR on the RAMpage: https://www.airandspaceforces.com/ges-a ... 35-engine/ "...The Block 4 upgrades to the F-35A may draw too much power for the current engine, Pratt & Whitney’s F135, to handle...." 14 Sep 2022 Chris Gordon
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Unread post16 Sep 2022, 09:39

Some GE XA100 news:
https://www.prnewswire.com/news-releases/ge-completes-latest-adaptive-cycle-engine-tests-successfully-concludes-adaptive-engine-transition-program-efforts-301621723.html

TULLAHOMA, Tenn., Sept. 12, 2022 /PRNewswire/ -- The U.S. Air Force and GE have successfully concluded testing on GE's second XA100 adaptive cycle engine at the Air Force's Arnold Engineering Development Complex (AEDC). With testing at AEDC completed, GE has accomplished the final major contract milestone of the Air Force's Adaptive Engine Transition Program (AETP), which began in 2016.

"This is the culmination of more than a decade of methodical risk reduction and testing GE has completed with the Air Force across three different adaptive cycle engine programs," said David Tweedie, GE Edison Works' vice president and general manager for Advanced Products. "The engine performance data we gathered at AEDC continued to show the XA100's transformational capability, while also demonstrating a return on substantial Air Force and taxpayer investment. We now stand ready to transition to an Engineering and Manufacturing Development program and bring this engine to the field with the F-35 before the end of this decade."

GE's milestones during AETP include:

  • Following competition, awarded one of two AETP contracts, June 2016
  • Detailed design completed with U.S. Air Force, February 2019
  • Initiation of testing on the world's first flight-weight, three-stream adaptive cycle engine, most heavily instrumented engine test in GE and U.S. Air Force history in Evendale, Ohio, December 2020
  • Initiation of second engine testing in Evendale, Ohio, August 2021
  • Beginning of first tests of an AETP engine at AEDC, March 2022
  • Completion of AETP testing and data collection at AEDC, August 2022

"This engine isn't a concept, proposal, or research program. This is a flight-weight, highly product-relevant engine that would provide the F-35 with 30% more range, greater than 20% faster acceleration, and significant mission systems growth to harness the F-35's full capabilities for Block 4 upgrades, and beyond," Tweedie continued. "The XA100 is the only F-35 propulsion modernization option that has been built, fully tested, and evaluated against Air Force performance targets, and the only option that provides the Air Force the capability it needs to outpace its adversaries for decades to come."

The XA100 combines three key innovations to deliver a generational change in combat propulsion performance:

  • An adaptive engine cycle that provides both a high-thrust mode for maximum power and a high-efficiency mode for optimum fuel savings and loiter time
  • A third-stream architecture that provides a step-change in thermal management capability, enabling future mission systems for increased combat effectiveness
  • Extensive use of advanced component technologies, including ceramic matrix composites (CMC), polymer matrix composites (PMC), and additive manufacturing
These revolutionary innovations increase thrust more than 10%, improve fuel efficiency by 25%, and provide significantly more aircraft heat dissipation capacity, all within the same physical envelope as current propulsion systems. GE's engine is uniquely designed to fit in the F-35A, as well as the F-35C without modifications to the tailhook. The XA100's improved fuel efficiency provides a significant reduction in carbon emissions and will operate on any U.S. Air Force-approved Sustainable Aviation Fuel.
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Unread post16 Sep 2022, 17:28

I love that little mention at the end about the " reduced carbon emissions." As if the lower carbon emissions of an engine powering a military fighter is going to sway the tree huggers in its favor.
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Unread post21 Sep 2022, 23:05

OH the great engine wars of years gone by.... Reminds me of the Strolling Bones song "START ME UP' - "I'll never ever stop.
You make a grown man cry." OPINIONS OPINIONS OPINIONS (mine) ALL <sigh>

https://aviationweek.com/shows-events/a ... sting-f135
&
https://aviationweek.com/shows-events/a ... ution-f-35
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Unread post22 Sep 2022, 19:27

It looks like the F-35B will be supported with the new adaptive-cycle engine.

https://www.thedrive.com/the-war-zone/x ... -f-35b-too
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Unread post22 Sep 2022, 23:10

jessmo112 wrote:It looks like the F-35B will be supported with the new adaptive-cycle engine.

https://www.thedrive.com/the-war-zone/x ... -f-35b-too


Yes, all it takes $$$. - many $$$$

GE says they can integrate the A100 into the F-35B. All they have to do is figure out roll post airflow thru the 3rd stream architecture, do a 3 bearing swivel nozzle with two bypass flows, integrate the lift fan thrust with the exhaust thrust on an engine that weighs 1000 lbs more while balancing the aircraft around the CG front to back, and for only a few dollars more than the $7B needed for EMD for the CTOL version. It isn’t going to be easy or inexpensive.
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Unread post23 Sep 2022, 12:56

Voila! says GE.

Betcha the technical risk is substantial; TRL level…(not very high).
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