General Electric - GE F136

All about the Pratt & Whitney F135 and the (cancelled) General Electric/Rolls-Royce F136
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by aaam » 01 Jan 2016, 02:21

duplex wrote:Rolls Royce is already involved in F-135 Project, why on earth they tried to create a rival engine with GE ?
Why Pratt & Whitney didn't raise any objection to that ? I am a little hazy about the whole story .


The lift system itself consists of the Lift Fan, Clutch, Drive Shaft, Roll Posts and the Three Bearing Swivel Module . The Lift Fan was designed to be agnostic as to which of the two engines the program was originally supposed to have was supplying the power. It draws its power from the Drive Shaft coming from whichever engine. So, in this case it acts as a "subcontractor" to Pratt as part of the overall propulsion system. Had the F136 been allowed to continue into its planned role, Rolls Lift Fan probably would have for contract purposes also been a "subcontractor" to the GE/Rolls team.

In the case of the F136, GE and [another segment of] Rolls-Royce were partnered on developing the alternative engine envisioned as part of the F-35 program. Although initially conceived as a derivative of the YF120 in much the same manner as the F135 is a derivative of the F119, it was decided by the team early on to go for a fresh start which allowed them to utilize more advanced technology and optimize their engine more around the F-35 them. The F136 teaming also was part of the relationship between the US and its only Tier 1 Partner on the F-35, the UK.

Of course Pratt raised an objection... after all, every GE/Rolls F136 sold would mean less profit due to a lost sale of an F135. But that was only to be expected.


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by spazsinbad » 31 Mar 2021, 10:04

F136 the F-35's Alternative Engine [6 page PDF attached] [NOTE THE YEAR DATE 2011]
Jun 2011 Chris Kjelgaard

"Its future as an alternative engine for the F-35 Lightning II is not assured at the time of writing, but the F136 is, nevertheless, a major technological achievement. Chris Kjelgaard reports..."

Source: AIR International Magazine June 2011 Vol.80 No.6
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GE F136 Air International Jun 2011 pp6.pdf
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GE F136 GRAPHIC Air International Jun 2011.jpg


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by viperzerof-2 » 12 Dec 2022, 15:01

Was it true the F136 could reach up to 56000lbf of thrust?


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by steve2267 » 12 Dec 2022, 15:50

I hadn't heard that one. I did read that P&W had tested the F135 up to 52,000 or 53,000, so I suppose it might be within the realm of possibility... as long as you didn't care if it lasted very long.
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.


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by f119doctor » 12 Dec 2022, 18:50

viperzerof-2 wrote:Was it true the F136 could reach up to 56000lbf of thrust?


steve2267 wrote:I hadn't heard that one. I did read that P&W had tested the F135 up to 52,000 or 53,000, so I suppose it might be within the realm of possibility... as long as you didn't care if it lasted very long.


Jet engine performance is hugely affected by inlet air temperature. As the temperature goes down, rotor speeds and turbine temps decrease while maintaining the same airflow and thrust. Most of these “thrust demonstrations” are done on a cold January day with inlet temps below 40F. They can then crank up the rotor speeds to increase airflow and thrust without having exceeding the rotor speed and turbine temp limits. They never fly at these demonstration levels because they need to operate at the lower levels while at altitude to gain the durability necessary to make their advertised depot inspection interval.
P&W FSR (retired) - TF30 / F100 /F119 /F135


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by viperzerof-2 » 12 Dec 2022, 21:30

f119doctor wrote:
viperzerof-2 wrote:Was it true the F136 could reach up to 56000lbf of thrust?


steve2267 wrote:I hadn't heard that one. I did read that P&W had tested the F135 up to 52,000 or 53,000, so I suppose it might be within the realm of possibility... as long as you didn't care if it lasted very long.


Jet engine performance is hugely affected by inlet air temperature. As the temperature goes down, rotor speeds and turbine temps decrease while maintaining the same airflow and thrust. Most of these “thrust demonstrations” are done on a cold January day with inlet temps below 40F. They can then crank up the rotor speeds to increase airflow and thrust without having exceeding the rotor speed and turbine temp limits. They never fly at these demonstration levels because they need to operate at the lower levels while at altitude to gain the durability necessary to make their advertised depot inspection interval.

Ah ok that makes more sense. It seemed so off from even the two new engines I had to ask.


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by Corsair1963 » 12 Dec 2022, 23:53

The P&W F135 and GE F-135 could have easily made over 50,000 lbs. Yet, you would have to subtract substantial amounts of service life for the engines in the process. Which, would greatly increase the lifecycle costs for the engine and hence the F-35. Something the US was unwilling to do......


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by f119doctor » 13 Dec 2022, 02:16

spazsinbad wrote:
F136 the F-35's Alternative Engine [6 page PDF attached] [NOTE THE YEAR DATE 2011]
Jun 2011 Chris Kjelgaard

"Its future as an alternative engine for the F-35 Lightning II is not assured at the time of writing, but the F136 is, nevertheless, a major technological achievement. Chris Kjelgaard reports..."

Source: AIR International Magazine June 2011 Vol.80 No.6


I thought that it was interesting in the Air International article that GE made a big deal of eliminating the LPT inlet vanes. But they have a 3 stage LPT. So they have 3 rows of bladed rotors and two rows of stator vanes in the LPT, while the F135 has only 2 rows of bladed rotors and 2 rows of stator vanes while retaining the LPT inlet vanes. Puts a lie to the statement of reduced parts count in the F136 LPT.
P&W FSR (retired) - TF30 / F100 /F119 /F135


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by disconnectedradical » 13 Dec 2022, 21:39

The big thing about F136 apparently is it has higher airflow which lets it generate F135 thrust level while operating at lower temperatures, so it runs cooler and has more potential for thrust growth and also has longer parts life. This is because it has a bigger core because it was design for the F-35 inlet that was redesigned for higher mass flow of 380-400 lb/s in 2005. I don't know how much if at all the F135EEP will increase mass flow over base F135.

viewtopic.php?p=181099#p181099


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by f119doctor » 13 Dec 2022, 22:57

disconnectedradical wrote:The big thing about F136 apparently is it has higher airflow which lets it generate F135 thrust level while operating at lower temperatures, so it runs cooler and has more potential for thrust growth and also has longer parts life. This is because it has a bigger core because it was design for the F-35 inlet that was redesigned for higher mass flow of 380-400 lb/s in 2005. I don't know how much if at all the F135EEP will increase mass flow over base F135.

viewtopic.php?p=181099#p181099

Seems like that is the GE playbook - design a higher airflow engine than the original specification and then claim wonderous performance: F110, YF120, F136 all followed this path, with two of them resulting in larger inlets - F-16 big mouth and F-35.

To my knowledge, the F135 EEP only affects the power module, with a higher efficiency high compressor and increased temperature capability turbines. The fan module remains the same, so airflow capacity is unchanged. The increased performance of the power module may allow the fan to flow more air over a larger part of the envelope, as shown in the 50K+ thrust demonstration.
P&W FSR (retired) - TF30 / F100 /F119 /F135


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by disconnectedradical » 13 Dec 2022, 23:14

f119doctor wrote:
disconnectedradical wrote:The big thing about F136 apparently is it has higher airflow which lets it generate F135 thrust level while operating at lower temperatures, so it runs cooler and has more potential for thrust growth and also has longer parts life. This is because it has a bigger core because it was design for the F-35 inlet that was redesigned for higher mass flow of 380-400 lb/s in 2005. I don't know how much if at all the F135EEP will increase mass flow over base F135.

viewtopic.php?p=181099#p181099

Seems like that is the GE playbook - design a higher airflow engine than the original specification and then claim wonderous performance: F110, YF120, F136 all followed this path, with two of them resulting in larger inlets - F-16 big mouth and F-35.

To my knowledge, the F135 EEP only affects the power module, with a higher efficiency high compressor and increased temperature capability turbines. The fan module remains the same, so airflow capacity is unchanged. The increased performance of the power module may allow the fan to flow more air over a larger part of the envelope, as shown in the 50K+ thrust demonstration.


With the F119 and F120 they both had increased airflow over the original specs because the thrust target was revised, it’s just that the YF120 prototype had the larger fan while the YF119 didn’t and the bigger fan only made it on the production F119.

About the F-35 inlet being bigger, LM made that change in 2005 but not sure if it’s specifically meant to accommodate GE for their F136. Did P&W ever plan to increase airflow on F135 at some point? Apparently engine thrust requirement was increased from 40,000 lbs to 43,000 lbs at that time too, so maybe that was LM’s way in case P&W increased airflow? But it seems like P&W increased operating temperatures instead, which increased thrust but I think that also increased engine wear too.


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by f119doctor » 14 Dec 2022, 00:33

disconnectedradical wrote:About the F-35 inlet being bigger, LM made that change in 2005 but not sure if it’s specifically meant to accommodate GE for their F136. Did P&W ever plan to increase airflow on F135 at some point? Apparently engine thrust requirement was increased from 40,000 lbs to 43,000 lbs at that time too, so maybe that was LM’s way in case P&W increased airflow? But it seems like P&W increased operating temperatures instead, which increased thrust but I think that also increased engine wear too.


I am unaware of any major changes that P&W made to the F135 to increase thrust from 40K to 43K. It may have just been the change from the generic "40K thrust class" to quoting the actual thrust specification as time went by.

The increase in inlet size of the F-35 to the 380 - 400 lb/sec is significantly larger than the F135 needs, so today it is just additional drag and possibly a high mach number (>>1.6) inlet stability issue (purely speculation on my part). It might help on the F-35B during STOVL operations where any inlet restriction inpacts installed thrust.

The current F135 turbine durability issues are due to 2 issues as I have heard:

1. Extracting bleed air well beyond the original specification for avionics cooling, which drives up turbine temperature across the flight envelope to maintain spec thrust. Running the engine hotter eats into hot section life

2. Exposure to Saudi high calcium sand during Middle East operations. This sand has a low melting point and deposits as molten glass on the turbine airfoils. When power is reduced, the glass solidifies and flakes off, pulling the protective coatings from the airfoil surfaces, exposing the base metals to higher temperatures and reducing blade life. This is a well known issue, affecting F100-100, RB199, and F110 engines in Saudi service. P&W fixed this problem with the F100-220, so I am somewhat surprised that it resurfaced on the F135. I know that operation with this Saudi sand exposure was a qualification requirement for the F119 engine, and assume it was for the F135. But levels of exposure and actual operational usage can sometimes create conditions that were not tested. P&W has improved hot section blades and vanes that resolve this issue in production, and it is just a matter of cycling the earlier power modules thru HMC to incorporate this improved hardware, which was taking too long. Latest info is that HMC has caught up and F135 engine availability is no longer a driver of F-35 NMC rates.
P&W FSR (retired) - TF30 / F100 /F119 /F135


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by fbw » 14 Dec 2022, 00:54

f119doctor wrote:
I am unaware of any major changes that P&W made to the F135 to increase thrust from 40K to 43K. It may have just been the change from the generic "40K thrust class" to quoting the actual thrust specification as time went by.

The increase in inlet size of the F-35 to the 380 - 400 lb/sec is significantly larger than the F135 needs, so today it is just additional drag and possibly a high mach number (>>1.6) inlet stability issue (purely speculation on my part). It might help on the F-35B during STOVL operations where any inlet restriction inpacts installed thrust. .


I believe disconnected is referring to the jsf119-PW-611, at the time, it was widely quoted as 25k/40k lbs/thrust.


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by f119doctor » 14 Dec 2022, 01:30

The JSF119-PW-611 was the Dem-Val engine for XF-35. Yes, there was EMD development from this engine to the F135 production engine.
P&W FSR (retired) - TF30 / F100 /F119 /F135


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