Powering the Fifth Generation: Inside the F-35’s Engines

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

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Unread post28 Apr 2012, 03:19

Why would B's engine not have the same corrosion resistance requirement as C's?
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Unread post28 Apr 2012, 03:59

More questions do not provide answers. If you have info then please refer to it. Thanks. As indicated earlier it seems to be 'common sense' but I'm looking for documentation about the state of any sea going corrosion proofing for the F-35B STOVL engine. I can guess also.
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Unread post28 Apr 2012, 08:02

spazsinbad wrote:I'm looking for documentation about the state of any sea going corrosion proofing for the F-35B STOVL engine. I can guess also.

delvo wrote:Why would B's engine not have the same corrosion resistance requirement as C's?

@ Delvo/Spaz - According to MIL-HDBK-516B both engines have the same materials requirements.

@ Spaz in his comprehensive pursuance of reference data :cheers:

REF: MIL-HDBK-516B "DEPARTMENT OF DEFENSE - HANDBOOK - AIRWORTHINESS CERTIFICATION CRITERIA"

http://www.theiplgroup.com/MIL-HNBK-516B.pdf

MIL-HDBK-516B Section 19 'Materials' wrote:(This section is applicable for Navy and Marine Corps aircraft only. This section is not required for Air Force or Army aircraft. Materials criteria are addressed throughout the MIL-HDBK-516B. If section 19 is used, the using aircraft or rotorcraft system office should tailor out the materials related criteria throughout the rest of the document as nonapplicable since these criteria may be in conflict with section 19.)

Materials comprise the entire flight vehicle including air vehicle structure, air vehicle subsystems, propulsion systems, electrical power systems, mission systems, crew systems, and armament/stores systems.

TYPICAL CERTIFICATION SOURCE DATA
1. Design criteria
2. Materials properties data and analysis
3. Environmental effects data and analysis
4. Galvanic compatibility data and analysis
5. Effects of defects data and analysis
6. Hazardous materials data
7. Material trade study results
8. Design of experiments results
9. Statistical process control data
10. Nondestructive inspection (NDI) criteria
11. NDI plan and records
12. NDI probability of detection data
13. Preproduction verification test data
14. First article destructive test data
15. Wear and erosion data
16. Material specifications
17. Process specifications
18. Finish specifications
19. Metallic materials properties development and standardization (MMPDS)
20. MIL-HDBK-17, Polymer Matrix Composites
21. Material safety data sheets
22. Contractor policies and procedures
23. Quality records
24. Defect/failure data
25. Fracture control plan
26. Fracture critical parts list


Now a little @ Otter

river_otter wrote:The corrosion-resistant materials have been previously cited as why the A is the only model with any thrust growth potential. The C's engine materials are less heat-resistant. It literally can't produce more thrust without failing durability specs.

Not that the materials are less heat-resistant, it's that the additional heat MAY pass USAF/USA spec (to which we have no evidence) but MAY not USN/USMC at that temperature. (also to which we have no evidence) With their increased tolerance of corrosion due to salt environments, additional heat would only accelerate deterioration. So not that the -400/-600 are 'less heat-resistant', but that given the more stringent requirements of the USN/USMC, the -400/-600 MAY not be able to operate at the increased temperatures above the original contract specification without failing to meet the specified tolerances for corrosion. (to which we have no evidence)

IE - Running the engine hotter than you asked for when you purchased it will cause undue wear/tear in the more unforgiving environment, which dictates more constrained limits.

What I'm getting at is this; the -100/-400/-600 can all make the thrust when asked more of them, but the -400/-600 MAY not make USN/USMC corrosion tolerance requirements at the 'increased' level. (according to River-Otter, to which we have no evidence) I'll cite the F100's 'V-MAX' option to increase thrust on demand. The switch would 'over-temp' the engine on purpose at the pilots request given specific operating parameters; after which an inspection was required of the engine(s), and after 5 minutes operating with V-MAX engaged, an engine hot section overhaul was required. (if memory serves this late on a bit of whiskey)

Remember the requirements have been met and exceeded for the engine. She makes more power than 'specified' and is lower weight than 'specified'. Beyond that, new power levels would require new 'specifications' for increased performance. With that, all new compliance with the applicable regulations would also be required (For any/all types of increased performance)

river_otter wrote:The B has no thrust growth potential even though the turbine engine is identical to the engine in the A. Re-design of the 3BSM and lift-fan drive to handle it would be prohibitive.

The F135-PW-600 is limited to it's 'thrust growth potential' by the additional components of the 'propulsion system' as you stated; yes, but the basic engine CAN produce additional thrust that is unusable by the 'system' as a whole in STO/VL flight. In CTOL flight, the additional thrust COULD be available. (Given it could pass airworthiness requirements at the given levels) The -600s FADEC shifts engine's operating parameters during STO/VL flight to accommodate the additional power requirements while that mode is engaged. During STO/VL mode, the engine would be limited in thrust/power by the other components unless they were redesigned; true.

river_otter wrote:The A's engine has been tested to over 50,000 lbf while still meeting durability specs.

Who said that?

PW Press Release of Oct. 18, 2010 wrote:The high temperature margin test which took place at Arnold Engineering Development Center (AEDC) in Tennessee involves intentionally running the engine to turbine temperatures beyond design conditions while simultaneously operating the turbomachinery at or above 100 percent of design conditions.

“While these are conditions the F135 engine will not experience during normal field operations, the purpose of this test is to demonstrate design margin at the most extreme operating conditions that could possibly exist,” explained Tyler Evans, director of F135 engine programs. “This is without a doubt one of the most demanding tests for an F-35 engine and the F135 passed the test with flying colors.”

The test also demonstrated the F135 propulsion system’s ability to produce margin relative to thrust with this engine producing 28 percent more thrust than the specification requirement.


Passing with 'flying colors' does not equal meeting durability specifications for an engine's entire life cycle limit. What it likely means is that the engine didn't fail during that excursion or exhibit immediate or un-flyable damage. Needless to say if one operated an engine beyond temperature and RPM limits on a consistent and regular basis, it will NOT live as long as it's counterparts that conform to the specification limits.

river_otter wrote:While the current exhaust tunnel wouldn't handle much over 43,000 lbf, re-designing a fairly straight tube for a future block upgrade or F-35D wouldn't be that difficult.

Exhaust Tunnel? :shrug:
Augmentor Duct? Augmentor Duct and Nozzle Module? Three Bearing Swivel Nozzle? What we talking here?

So long as it's straight like the -100's arrangement, the -400 and -600 (in CTOL mode), have essentially the same exhaust path profile. All 3 engine sub-types are rated at 43K MAX in CTOL mode. If the -100 can hit 128% MIL power during test, why wouldn't the -400/-600 in CTOL?

And what is your F-35D here? A two seat F-35A? Increased performance F-35B or F-35C?

D@mn it...... whiskey bottle ran dry....... guess it's time for some sleep?
(Not to mention my spell check is screaming about my typing/spelling at this point)

Keep 'em flyin' :thumb:
TEG
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Unread post28 Apr 2012, 08:36

TEG said: "Spaz in his comprehensive pursuance of reference data". And 'Spaz' thanks 'TEG' but will need to reread the material several times - I suspect - to comprehend it. And many thanks. :D
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Unread post28 Apr 2012, 08:40

spazsinbad wrote:TEG said: "Spaz in his comprehensive pursuance of reference data". And 'Spaz' thanks 'TEG' but will need to reread the material several times - I suspect - to comprehend it. And many thanks. :D


TEG :cheers: Spaz
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Unread post28 Apr 2012, 13:51

I think one of the technology calls recently has been for high temperature corrosion resistant engine materials, so perhaps there is something in the works that would allow for thrust growth in the -B and -C.
Einstein got it backward: one cannot prevent a war without preparing for it.
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Unread post28 Apr 2012, 13:59

What is the different dry weight of those three F-135 engines?
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Unread post28 Apr 2012, 15:05

That_Engine_Guy wrote:Now a little @ Otter

river_otter wrote:The corrosion-resistant materials have been previously cited as why the A is the only model with any thrust growth potential. The C's engine materials are less heat-resistant. It literally can't produce more thrust without failing durability specs.


Not that the materials are less heat-resistant, it's that the additional heat MAY pass USAF/USA spec (to which we have no evidence) but MAY not USN/USMC at that temperature. (also to which we have no evidence) With their increased tolerance of corrosion due to salt environments, additional heat would only accelerate deterioration.


Unfortunately, P&W seems to have pulled all their press releases prior to 2011 off their website, but I'd cited it previously, as quoted by aviationweek (which also seems to have lost the article). So I'll cite my prior citation of it: http://www.f-16.net/index.php?name=PNph ... ht=#201913 If I manage to find a saved copy of the original somewhere, I'll post it later. (The aviationweek article is also quoted and referenced in Wikipedia, for what that's worth.)

It was specifically stated by P&W in August, 2010 that the -400 is made of different materials chosen for salt corrosion resistance. Wikipedia also quotes Jane's on the point that the -400 uses different, salt-corrosion-resistant materials. The August 2010 P&W press release stated specifically that the materials used in the -400 would not handle the operating cycle that the -100 had used to make over 50,000 lbf. My memory is that they stated the reason was reduced heat resistance relative to the -100 / -600 materials, but I could be wrong on that.

That_Engine_Guy wrote:What I'm getting at is this; the -100/-400/-600 can all make the thrust when asked more of them, but the -400/-600 MAY not make USN/USMC corrosion tolerance requirements at the 'increased' level.


That may well be why they felt that the materials of the -400 wouldn't tolerate the increased temperature. Their press release didn't say. I'm also quite certain you're right that any of the variants could put out 50,000 lbf. for a short time on overload. (It may also be that the -600 didn't need the -400's corrosion-resistant materials because the 3BSM meant that the engine could never be pushed to a permanent higher thrust margin where extra corrosion resistance was needed anyway.)

That_Engine_Guy wrote:
river_otter wrote:The B has no thrust growth potential even though the turbine engine is identical to the engine in the A. Re-design of the 3BSM and lift-fan drive to handle it would be prohibitive.


The F135-PW-600 is limited to it's 'thrust growth potential' by the additional components of the 'propulsion system' as you stated; yes, but the basic engine CAN produce additional thrust that is unusable by the 'system' as a whole in STO/VL flight. In CTOL flight, the additional thrust COULD be available.


P&W stated there was a further limit placed by the geometry of the exhaust. That is repeated in http://www.dodbuzz.com/2010/08/27/pratt ... ust-parry/ . The -600 engine is just a -100 engine, which can do it. But no variant of the aircraft as it exists now could handle over 43,000 lbf today even in CTOL. (That may not be true for short periods or if damage to the aircraft and/or engine were permitted due to circumstances.) They did not state what exactly what part of the exhaust path was the problem, or what the limit to it was (temperature, pressure, flow velocity, backpressure on the engine, etc.?), but the article above implies it's the nozzle.

That_Engine_Guy wrote:
river_otter wrote:The A's engine has been tested to over 50,000 lbf while still meeting durability specs.


Who said that?


P&W, press release of August, 2010. Different test than the October one you reference below. They specifically stated that at 20% thrust over specification, the engine still met durability requirements.

That_Engine_Guy wrote:Passing with 'flying colors' does not equal meeting durability specifications for an engine's entire life cycle limit. What it likely means is that the engine didn't fail during that excursion or exhibit immediate or un-flyable damage. Needless to say if one operated an engine beyond temperature and RPM limits on a consistent and regular basis, it will NOT live as long as it's counterparts that conform to the specification limits.


At 43,000 lbf, the F135-100 currently exceeds the specifications for minimum operating life. That's why they could run it 20% harder while still meeting the specified life. It would not last as long at 50,000 lbf as it would at 43,000 lbf, as you say. But it would last long enough to continue to meet specs. At 28% over rated thrust it would have an even shorter life. Maybe not long enough to meet specs at that much over thrust, as you say.

That_Engine_Guy wrote:Exhaust Tunnel? :shrug:
Augmentor Duct? Augmentor Duct and Nozzle Module? Three Bearing Swivel Nozzle? What we talking here?


P&W's press release didn't say. It's not the 3BSM, though, they were clear that whatever the geometry issue was, it applied to all three variants. http://www.dodbuzz.com/2010/08/27/pratt ... ust-parry/ seems to imply it's the nozzle. In any case, the F-35 has the engine much deeper inside than most other aircraft, similar to the YF-23, and the exhaust has to go through a longer path from the back of the afterburner to the nozzle than in most other aircraft. Something along that path isn't compatible with a 50,000 lbf engine.

That_Engine_Guy wrote:So long as it's straight like the -100's arrangement, the -400 and -600 (in CTOL mode), have essentially the same exhaust path profile. All 3 engine sub-types are rated at 43K MAX in CTOL mode. If the -100 can hit 128% MIL power during test, why wouldn't the -400/-600 in CTOL?


The engine can, but none of the aircraft currently can. The -600 will never be able to because increased thrust for any variant would require a redesign of the exhaust path, which for the -600 includes the 3BSM. That's a pretty straightforward and cheap redesign for a plane with the -100, where the exhaust is a fairly straight tube with no moving parts. The path may also be straight in the -600 while it's in CTOL mode, but it's still made up of several moveable parts which are much more expensive to re-design than a tube. Also, if the diameter had to change, it starts to impact the nozzle doors. There isn't a lot of extra space in there. And the bearings are wider than the tube itself, so that further impacts the doors and potentially the upper fuselage as well. There's less growth potential for the 3BSM's diameter than there is for a straight tube without rings of bearings around it. Then further, if the 3BSM's diameter were changed to allow proper engine operation at 50,000 lbf in CTOL mode, how does that affect available thrust in STOVL mode? If maximum dry thrust changes, that means expensive changes to the lift fan too. And if it's optimized for 50,000+ lbf, most likely that means less dry thrust available for STOVL, where there isn't all that much margin to begin with. The lift fan clutch would also have to tolerate the engine running hotter and potentially faster, and it has had heat problems even when not engaged to turn the fan.

And as previously stated, for whatever reason (heat resistance, corrosion specs, etc.) P&W said the -400 has no margin for thrust growth due to its materials not being able to handle the increase.

And what is your F-35D here? A two seat F-35A? Increased performance F-35B or F-35C?


It's just a notion. Increased performance A to gap-fill the lack of sufficient F-22s, maybe. Or maybe not, and the engines will just last longer at 43,000 lbf than they were originally intended to. That's not a bad outcome either. I don't think a steady-state increase in weight like a second seat would be likely; the thrust growth is likely to be mostly in afterburner so that would still leave a substantially poorer-performing aircraft through most of its envelope. For reasons stated above, I don't think there will ever be an increased performance B or C.
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Unread post28 Apr 2012, 17:17

bjr1028 is correct. Google is your friend Spaz.
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Unread post29 Apr 2012, 09:31

Preparing the F-35C for the Carrier Eric Tegler on October 3, 2011

http://www.defensemedianetwork.com/stor ... 9D-legs-2/

"...The same can be said for the F-35’s Pratt & Whitney F135 engine. Save for some attached accessories for the B model, there are no significant changes to the 43,000-pound thrust engine whether situated in an A, B, or C model. Buus added that the engine has the same thrust rating across all three variants and that no special anti-corrosion or FOD (foreign object damage) tolerance modifications have been made for the F-35C.

“I’d go so far as to say nothing at all. It’s the same engine.”
... QUE?
Last edited by spazsinbad on 29 Apr 2012, 22:31, edited 2 times in total.
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Unread post29 Apr 2012, 10:05

I'm a Fan of Lift! :D

AFRL Nanoscience Technologies - Applications, Transistions and Innovations 2010 Page 19 [numbered]

http://www.dtic.mil/cgi-bin/GetTRDoc?Lo ... =ADA523398 (PDF 2.6Mb)

Nano-Composite Coatings for F-35 LiftFan and RL-10 Rocket Engine Turbopump

Accomplishment: Composite coatings combining nanocrystalline particles with an amorphous metal matrix have been developed that give an order of magnitude decrease in component wear, good corrosion prevention in salt environments, and enable system operation under demanding lubricant starvation requirements.

Impact: This advancement satisfies operational requirements for endurance and reliability in liftfan gears and bearings of the short takeoff-vertical landing (STOVL) F-35 aircraft. Conventional coatings are unable to satisfy the full range of operation conditions, placing successful accomplishment of mission requirements at risk. This advanced coating is being certified for F-35 aircraft gears and is also being validated in component-level testing for gears in the RL-10 liquid rocket engine turbopump.

Motivation and Approach: Gears and bearings in jet engines and rocket turbopumps must perform under difficult conditions that include high contact stresses, high wear conditions and corrosive environments. The F-35 STOVL LiftFan adds the demanding requirement of continued engine operation after 60 seconds of unlubricated runtime, which could not be satisfied by any wear resistant nano-composite coatings has an unusual combination of high hardness that exceeds ceramic materials, and fracture strength similar to that of tough metal alloys. These properties result from the combination of 3-5 nanometer grains of very hard carbides or oxides embedded in an amorphous metal matrix. The material design was further enhanced by introducing coating interfaces with corrosion prevention layers and by using carbon in the composite matrix to reduce friction during unlubricated operation. Subsequent applied research and process development is establishing these nano-composite coatings for use in F-35 STOVL propulsion system components and RL-10 liquid rocket engine turbomachinery, where component-level testing is now underway.

Team: These coatings were conceived and developed under the leadership of Dr. Andrey Voevodin, with significant contributions from Dr. Jeff Zabinski, Dr. John Jones and Benjamin Phillips, (all at the Materials and Manufacturing Directorate), and from Dr. Chris Muratore (Universal Technologies, Corp.) and Dr. Jiaunjun Hu (University of Dayton Research Institute). Funding was provided by the Air Force Office of Scientific Research (Maj. Jennifer Gresham, Program Manager). Small Business Innovation Research programs with Arcomac Surface Engineering, Inc. and Tribologix, Inc. developed processes to apply these coatings, which are being validated by component testing by the Rolls-Royce Corporation (for the F-35 LiftFan) and Pratt and Whitney (for the RL-10 rocket engine)." PAGE 19
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Unread post29 Apr 2012, 15:35

'haavarla ' asked: "What is the different dry weight of those three F-135 engines?"

http://en.wikipedia.org/wiki/Pratt_%26_Whitney_F135

3,750 lbs basic / 1,701 kg
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Unread post01 May 2012, 14:49

madrat wrote:So if a customer was going to operate said -C model strictly over land then they should be able to use the -A engines after being uprated?


Yes, you'd be able to fit a -100 in the C. As for uprating, that depends on whether the uprated engine requires modifications to the airframe.

spazsinbad wrote:Preparing the F-35C for the Carrier Eric Tegler on October 3, 2011

http://www.defensemedianetwork.com/stor ... 9D-legs-2/

"...The same can be said for the F-35’s Pratt & Whitney F135 engine. Save for some attached accessories for the B model, there are no significant changes to the 43,000-pound thrust engine whether situated in an A, B, or C model. Buus added that the engine has the same thrust rating across all three variants and that no special anti-corrosion or FOD (foreign object damage) tolerance modifications have been made for the F-35C.

“I’d go so far as to say nothing at all. It’s the same engine.”
... QUE?


Unless the entire engine is made from corrosion resistant materials, this could end up being a maintenance nightmare for the Department of the Navy.
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Unread post01 May 2012, 17:43

Perhaps all the three engines are 'corrosion resistant' with the LiftFan having the special treatment described?
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Unread post01 May 2012, 18:13

Rolls-Royce awarded propulsion system order for F-35B

http://www.flightglobal.com/news/articl ... 5b-371306/

Rolls-Royce awarded propulsion system order for F-35B
By: Craig Hoyle London

Pratt & Whitney has awarded Rolls-Royce a $315 million contract to produce LiftSystem equipment for 17 F135-powered short take-off and vertical landing (STOVL) F-35B combat aircraft.

Announced on 1 May, the propulsion system order covers the delivery of LiftFans, roll posts and three-bearing swivel modules this year for 17 aircraft ("BEEs") included in Lockheed Martin's fourth low-rate initial production (LRIP) deal for the Joint Strike Fighter.

R-R says it has so far delivered 32 LiftSystems, plus spare parts. These have been installed on test aircraft and early production examples, including three US Marine Corps jets recently delivered to Eglin AFB, Florida, and the first of two STOVL test aircraft flown for the UK for the first time in April.

"We anticipate continuous cost improvements as production volumes ramp up to meet the needs of the F-35 programme," says Neil Mehta, R-R's LiftSystem programme director.

The company expects to receive its next order for LRIP 5 aircraft later this year.
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