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

PW's press archive address has changed a bit...

http://www.pw.utc.com/media_center/press_releases.asp

When I've talked of special coatings or other materials, I was typically talking 'external'; I know the USN likes to paint EVERYTHING for corrosion prevention and I know specific alloys used in gearbox and other large housings don't like salt-water. As for the actual guts of the motor: if they're designed that well to survive the required tolerances, and operating temperatures for the engine's overall design; it's likely each services requirements were build almost directly into the engine from the start as part of the 'commonization' demanded by the JSF mentality. The fact that there are separate sub-types (IE PW-100/400) indicates SOME level of difference, no matter how slight.

I remember stories of how the Sea Shadow stealth ship demonstrator built by Lockheed, had to include a 'paint locker' due to USN regulations.... among some other things that were almost silly on a stealthy modern prototype.


TEG

From my reading TEG the USN requirements put a lot of 'hardiness' into the F-35 - the new stealth coating being one example. I guess the engine received the benefit also from extra anti-corrosion requirement (gathered from Buus comments).

Aircraft carriers are required to have a 'spud locker' also with the 'Davy Jones Locker' in submerged long deep, deep trail.

P&W Delivers 50th F135 Engine for the F-35 JSF 03 May 2012

http://www.asdnews.com/news-42495/P&W_D ... 35_JSF.htm

"Pratt & Whitney has successfully delivered the 50th production F135 engine – powering Lockheed Martin's fifth-generation F-35 Lightning II – to the U.S. Department of Defense. Pratt & Whitney is a United Technologies Corp. (NYSE: UTX) company.

The 50th engine is scheduled to be installed in a F-35C Carrier Variant (CV) for the United States Navy. The F-35C aircraft will be delivered to Eglin Air Force Base this summer for Navy pilot training.

"Delivery of the 50th production F135 engine is a significant milestone for the program," said Chris Flynn, vice president, F135/F119 Engine Programs, Pratt & Whitney. "We are proud of the progress made on the most advanced fifth-generation fighter engine in the world. We will continue to work diligently toward production and testing benchmarks while meeting our cost objectives."

Pratt & Whitney remains committed to increasing production levels while decreasing costs. To date, Pratt & Whitney and its suppliers have been able to reduce the cost by more than 25 percent on the CV/Conventional Takeoff and Landing (CTOL) engine, compared to the original test engines. Engine production output in 2012 is expected to double from 2011, as was demonstrated from 2010 to 2011.

The F-35 program includes three variants to meet the unique needs of the U.S. armed forces and the international participants in the program: the CV, the CTOL and the Short Takeoff and Vertical Landing (STOVL). To date, the F135 propulsion system has powered more than 330 vertical landings, 2,000 test flights producing more than 3,000 flight hours. Pratt & Whitney has delivered 30 CTOL/CV and 20 STOVL engines and related propulsion system hardware. The success of the F135 engine program validates the reliability, safety and performance of the engine.

Included in the 50 deliveries was the last deliverable hardware required for the third lot of Low Rate Initial Production (LRIP) engines. Pratt & Whitney is now delivering to the fourth lot of LRIP contract requirements which are scheduled to be completed by the end of 2012."

Is it any truth to what Sharkey Ward claim about the B model's performance over at his website:

"DSTL analysis has also demonstrated that the F-35B would not be able to launch at all from a flat deck in the extremely hot climates that will be experienced East of Suez. And, critically, it may well not be able to recover on board at all to a flat deck or a ramp-fitted deck in such climates without ditching ordnance and expensive stores"

And WTF is a DSTL analysis?

http://www.sharkeysworld.com/

DSTL is who, not what.

https://www.dstl.gov.uk/

Sharkey did not supply a specific reference or source to the report so details are missing.

SharkeyWard has a habit of making things up. Sad indeed. He should be better than that or at least give a specific reference. Only 'Mad Dogs and Englishmen go out into to the mid day sun' it is said. Perhaps he is referring to that 'East of Suez' condition where the air is made of concrete. However the USMC KPP is for WOD 10 knots on a tropical day at sea level (one could argue what that means) but I take it that will encompass anything East of Suez (what a pretenious claim - as if the US has not been there for many years now).

Anyway all that aside the KPP for STO & Vertical Landing with full internal stores and enough fuel for 450 combat radius and VL with reserve fuel etc is being met.

Search the F-35 forum here for 'Scorecard' to see many references to this KPP:
ONE example amongst many - UK MOD in a MUDDLE over F-35C
http://www.f-16.net/index.php?name=PNph ... ard#221433

&/OR whatever: F-35B an Analysts viewpoint of Marine Corp Tactical Aviation
http://www.f-16.net/index.php?name=PNph ... ard#211727

spazsinbad wrote:...the USMC KPP is for WOD 10 knots on a tropical day at sea level (one could argue what that means)

There are four specific "non-standard" atmospheric models that are defined in MIL-STD-210A. They each have their own temperature vs altitude profiles, but at sea-level:

Standard (US, 1962) : 59 deg F
"Cold" : -60.0 def F
"Polar" : -15.7 deg F
"Tropical": 89.8 deg F
"Hot" : 103.0 deg F

Also, I read somewhere that after Pearl Harbor the USN started hand-scraping all the paint from the interiors of all their ships, due to the fact that it had burned so badly.

Thanks 'Raptor_claw'. Yep the interiors of USN ships are now painted 'rust'.

Not sure if 'East of Suez' is in this pub probably in same place as 'Beyond the Black Stump' but anyway:

GLOBAL CLIMATIC DATA FOR DEVELOPING MILITARY PRODUCTS

http://www.google.com.au/url?sa=t&rct=j ... 2B-%2B0499)%2Fdownload.php%3Fspec%3DMIL_HDBK310.1851.pdf&ei=VSCjT6LqNNCViAehi620Dw&usg=AFQjCNGzqxBoX3I8r4NhKAcmbLFU_p9blg (0.5Mb)
________________

ENVIRONMENTAL ENGINEERING CONSIDERATIONS AND LABORATORY TESTS

www.dtc.army.mil/pdf/810.pdf (5Mb)
_________________

The US Defense Department Non-Standard Atmospheres

http://www.pdas.com/milstd210.html

"In the document MIL-STD-210A, variations of the standard atmosphere are defined. These variants are the hot atmosphere, the cold atmosphere, the polar atmosphere and the tropical atmosphere. These may be used in place of the standard atmosphere to study the effects of extreme temperature.

The four atmospheres have different profiles that are shown in the following table. The atmospheres are defined to 100000 feet with temperature in degrees Rankine."

spazsinbad wrote:SharkeyWard has a habit of making things up. Sad indeed. He should be better than that or at least give a specific reference. Only 'Mad Dogs and Englishmen go out into to the mid day sun' it is said. Perhaps he is referring to that 'East of Suez' condition where the air is made of concrete. However the USMC KPP is for WOD 10 knots on a tropical day at sea level (one could argue what that means) but I take it that will encompass anything East of Suez (what a pretenious claim - as if the US has not been there for many years now).

Anyway all that aside the KPP for STO & Vertical Landing with full internal stores and enough fuel for 450 combat radius and VL with reserve fuel etc is being met.

Search the F-35 forum here for 'Scorecard' to see many references to this KPP:
ONE example amongst many - UK MOD in a MUDDLE over F-35C
http://www.f-16.net/index.php?name=PNph ... ard#221433

&/OR whatever: F-35B an Analysts viewpoint of Marine Corp Tactical Aviation
http://www.f-16.net/index.php?name=PNph ... ard#211727

...but a tropical day is quite tame compared to a hot day, right?

Tame? What a funny choice of words. How about 'tropical day 90 degrees F' and 'hot day 103 degrees F'? And we are still guessing what it is 'East of Suez'. Also we have only a 'Scoreboard' assessment of what the KPP conditions are. We have no inkling what 'the powers that be' consider the conditions for KPP to be. The 'Scoreboard' is the only reference I have seen (apart from East of Suez malarkey). If you consider a 13 degree F difference a show stopper then be my guest.

It is possible to use aircraft takeoff distance charts to figure out what that F difference might make on it; but let us not forget our runway can make more speed into wind, which is likely to cater for such matters.

As far as hot vs hot/humid; humidity plays a huge factor in power for a motor.

The more 'water' in a square foot of 'air' the less oxygen or 'air' in that square foot. The humidity displaces the oxygen (air) you need for the given fuel/air ratio.

TEG

That_Engine_Guy wrote:As far as hot vs hot/humid; humidity plays a huge factor in power for a motor.

The more 'water' in a square foot of 'air' the less oxygen or 'air' in that square foot. The humidity displaces the oxygen (air) you need for the given fuel/air ratio.

TEG

It also makes the air less dense, which reduces lift.

It would be nice to have all the facts and figures for the F-35. Perhaps we will see a NATOPS online one day (similar to what is now available for the Super Hornet). As for the 'humidity factor' I don't recall it being one.

From BOEING:
http://www.smartcockpit.com/data/pdfs/f ... Basics.pdf (3.3Mb)

Propulsion (1): Jet Engine Basics

Factors Affecting Thrust
page 29: “Air density, a function of temperature and pressure altitude, is a very significant component affecting thrust.”

Other Factors Affecting Thrust
page 30: “Humidity has a negligible effect on thrust.”

Okay. Put in another way, do the B model with it's current weight and power (witch I understand is difficult to upgrade/increase because of the lift fan/clutch) has to small a margin for operating with sufficient take off/bring back capability in "unfavorable" conditions?

According to the current KPP (elaborated on threads many times now) the F-35B can operate as required regarding STO and VL. What we do not know are the conditions of WX for these conditions - hence discussion.

The 'unfavourable condition' needs to be quantified but is meaningless when we also don't know the 'power available margin' but it is known to be within KPP for the KPP condition - so it goes. Maybe some online hackers know?