F-35 Multirole Joint Strike Fighter

[Aussie Digger]

It say that the F135 has 40% fewer parts. The totality of all F119 parts = 100%, so 100-40=60% Are parts technology or not?

Nowhere does it say that the "parts" on the F-135 are the same parts as used within the F-119. It says it has 40% fewer "parts". You are reaching a (baseless) assumption that these "parts" are therefore the same.

If you'd bother checking Pratt and Whitney's website, you'd see that the F-135 is a new engine that uses an evolved and enlarged variant of the F-119's compressor and and an evolved (and enlarged) variant of the F-119's single stage turbine unit.

It has evolved from the F-119, but it if you'd even bother researching these things before making ridiculous claims, you'd see that the F-135 engine is considerably LARGER than the F-119, hence why it makes more power and why it does NOT use the F-119's "parts".

It has a larger fan, a higher bypass ratio, better fuel efficiency and greater thrust.

It is also being manufactured in 3 different variants (F-135-PW-100, F-135-PW-400 and F-135-PW-600) and is substantially modified for the F-35B STOVL variant because it has to connect to a shaft driven lift fan.

Here is the link:

http://www.pw.utc.com/StaticFiles/P...ts/1 Static Files/Docs/military_2008_f135.pdf

Hence, we come back to my original request. If you are going to make ludicrous claims, at least get your facts right.

 

[F-15 Eagle]

The dutch released a new study on F-35 noise levels today:

"According to the National Aerospace Laboratory (NLR), there is almost no perceptible difference between the JSF and the Saab Gripen NG. This is evident from a report published Monday by the NLR on the assessment of noise data from the two candidates for the succession of the current F-16. The difference in maximum noise level of the JSF and the F-16 is small (5 dB).

With full power, the maximum expected noise 109 dB for the Saab Gripen NG and 110 dB for the JSF. With afterburner the values are respectively 114 dB and 115 dB. For the current Dutch F-16, the results are from 104 to 107 dB in full power and 111 to 114 dB with afterburner."

Orginal link: http://www.refdag.nl/artikel/1398197/JSF+en+Saab+Gripen+NG+maken+bijna+evenveel+herrie.html

Translated link:

http://translate.google.com/transla...+maken+bijna+evenveel+herrie.html&sl=nl&tl=en


B. Bolsøy
Oslo

Is that all there is to the study? I would like to know how they conducted this study especially when they do not even say how they did it and they don't even have an F-35 to use for testing. I herd there is already a lot on criticism of this NLR study.

The Eglin BRAC tests released officially and in several dozens of pages concluded that the F-35 would be far louder than F-15 for instance. And I have not read anything about the F-35 noise level's being differnet from BRAC study or from the U.S. Air Force so the F-35 is still much louder than the F-15 Eagle.

 

[FutureTank]

Nowhere does it say that the "parts" on the F-135 are the same parts as used within the F-119. It says it has 40% fewer "parts". You are reaching a (baseless) assumption that these "parts" are therefore the same.

If you'd bother checking Pratt and Whitney's website, you'd see that the F-135 is a new engine that uses an evolved and enlarged variant of the F-119's compressor and and an evolved (and enlarged) variant of the F-119's single stage turbine unit.

It has evolved from the F-119, but it if you'd even bother researching these things before making ridiculous claims, you'd see that the F-135 engine is considerably LARGER than the F-119, hence why it makes more power and why it does NOT use the F-119's "parts".

It has a larger fan, a higher bypass ratio, better fuel efficiency and greater thrust.

It is also being manufactured in 3 different variants (F-135-PW-100, F-135-PW-400 and F-135-PW-600) and is substantially modified for the F-35B STOVL variant because it has to connect to a shaft driven lift fan.

Here is the link:

http://www.pw.utc.com/StaticFiles/P...ts/1 Static Files/Docs/military_2008_f135.pdf

Hence, we come back to my original request. If you are going to make ludicrous claims, at least get your facts right.

You have me at a disadvantage since I am not an aviation engineer, and have not had the opportunity to familiarise myself with both engines.

However, how does one get a "new engine" that's "evolved and enlarged" from another engine?

As I understand it the objective of the F135 design was two-fold: to increase thrust and to decrease weight. Fuel efficiency was the by-product of the overall weight reduction of the F-35, and not just the engine redesign. This weight reduction was not (as I understand) possible from the design reserve F120 engine.

I'm also looking at the available cut-away images of the two engines, and they look remarkably similar in appearance even to a non-engineer like me.

Now what "ludicrous claims" are you accusing me of making for lack of "facts"? What I said was that the F119 engine was being designed/developed even before the 1994 program start, at least from 1991. This is a fact. The JSF website itself says that "What is commonly known today as the F-35 Joint Strike Fighter Program had its origination in several programs from the 1980s and early 1990s."

The contract to develop the F135 was signed in 2001, almost a year before the SDD date Abraham insists on. First flight was in August 2006 (after 5,500 hours of engine tests), and production started in the last few months.

So does it take 17 years to build an engine? Or, does it take 8 years to redesign an engine? Which of these is a "ludicrous claim"?

I'm sure this program is being watched with interest by a lot of people, because if these are the new engineering development parameters for combat aircraft engine production, then considerations of type replacement will have to be advanced significantly in fleet planning by air forces throughout the World. On the other hand, just maybe, the program was not conducted as efficiently as one might have hoped, or suggested by P&W. All the "facts" you quoted are coming from the manufacturer's website who is not even saying when the engine design begun and why it has taken so long.

Which engine is "new"? Are you maybe talking about the F-35B's engine? That was a product of research by no less than three national design teams, so its not like it was a from-scratch attempt either. The Yakovlev concept dates back from 1960s, and the combined British/US (GE and Rolls-Royce) use of STOVL aircraft engines is such by now that adopting the F136 for the B variant should not have taken years. The US Navy's own STOVL Strike Fighter (SSF) program ran from 1987 to 1994, the year it was merged with the JSF program. I think that's a fact also. Are you saying its ludicrous to suggest the Navy learned nothing about engine design for STOVL in seven years?

In fact no one describes the F136 as a "new engine". The time/cost equation for this single engine is a seven-year, $2.4 billion contract. However, this only resulted in a prototype shown in February 2009. But the knowledge that Harriers/AV-8s would have to be replaced by the JSF design was known in at least 1994! It was certainly known when "Under Secretary of Defense for Acquisition, Technology and Logistics Edward C. "Pete" Aldridge Jr. announced on the afternoon of 26 October 2001 the decision to proceed with the Joint Strike Fighter program. This approval advanced the program to the next phase, the System Development and Demonstration (SDD) phase." (JSF site) Allowing a January 2002 start, the F-35B should have been in production and flying now, seven years later! Or is that also a ludicrous suggestion?

The issue I raised is very simple. The F-35 was intended to produce a saving on designing replacements for four aircraft by designing one.

Moreover, it was intended to allow increased technology/design sharing with the F-22. Even without the F-22 factor one would think that there would be a four-fold saving in development and in the unit cost.

The F-35B version is not radically different from F-35A for this contractualreason.

What I can say in F-35's defence is that the F-16C/D (the type it will mostly replace) reported unit cost in 2000 was $34.3 million. Between 2000 and 2007 the inflation in US varied between 2 and 4%. Taking the 3% average, the cost of the F-16 in 2009 would be about $44.75 million. According to the USAF budget estimate for 2009, the F-35 unit cost will be anywhere from $45 to $50+ ($83 million fly away), depending on who one believes and which accounting methodology one uses. And, the saving on the logistic support for what is a single type will be considerable over that of providing support for four different types, which was the initial reason for the program.

So in fact the F-35 will be (according to reports) a significantly superior aircraft when compared to the F-16, at virtually same unit cost, but why such a protracted program? This is what I can't fathom.

By the way, does anyone know the estimated final production unit cost?

Someone else did this list for fly away estimates from different sources
The Norwegians think it's $52M.
The Israelis think it's +$100M.
The Dutch think it's €56M.
The Danes think it's $82M with spares and training.
[program office director MG Charles] Davis thinks it's $70M for an F-35A in 2014.
Davis thinks it's $70M for a F-35C without engine in 2014.
Davis thinks it's $80M for a F-35A in 2014.
The USAF budget says it's $91M flyaway in 2013.
The GAO thinks it's $104M.

 

[gf0012-aust]

By the way, does anyone know the estimated final production unit cost?

Someone else did this list for fly away estimates from different sources
The Norwegians think it's $52M.
The Israelis think it's +$100M.
The Dutch think it's €56M.
The Danes think it's $82M with spares and training.
[program office director MG Charles] Davis thinks it's $70M for an F-35A in 2014.
Davis thinks it's $70M for a F-35C without engine in 2014.
Davis thinks it's $80M for a F-35A in 2014.
The USAF budget says it's $91M flyaway in 2013.
The GAO thinks it's $104M.

yes, we do. it was explained at the briefing and even the dimmest of the defence mag journos (Janes IMO) seem to understand it )

I never took the press releases avail to the journo's so am unsure as to whether they were included. however, as I am inherently lazy, I am going to leave the response to a scribe like Abe as I have really impatient fingers.

it's not like buying a family car, platform purchase is based on time of purchase, the cost impost of buying early, late, the through life issues and what other "bits" are included.

it's not rocket science when explained - unfort every man and his dog seems to have their own interpretation of V&V and how major capital items are bought (and they also seem to think that every country buys under the same overall provisions when thats not the case). The bottom line is that within the platform constraint itself, we buy at the same price as the US Forces, and every platform between the 9 countries and 13 customers is series identical.

 

[FutureTank]

yes, we do. it was explained at the briefing and even the dimmest of the defence mag journos (Janes IMO) seem to understand it )

I never took the press releases avail to the journo's so am unsure as to whether they were included. however, as I am inherently lazy, I am going to leave the response to a scribe like Abe as I have really impatient fingers.

it's not like buying a family car, platform purchase is based on time of purchase, the cost impost of buying early, late, the through life issues and what other "bits" are included.

it's not rocket science when explained - unfort every man and his dog seems to have their own interpretation of V&V and how major capital items are bought (and they also seem to think that every country buys under the same overall provisions when thats not the case). The bottom line is that within the platform constraint itself, we buy at the same price as the US Forces, and every platform between the 9 countries and 13 customers is series identical.

I do have some understanding of production economics, but if you can't say, why tell me all that?

Its "jet science", and one figure quoted was "engine excluded" which I, as many others, found 'interesting'. At least in rocket science there is always, well, a rocket included.

If the final production unit price is known, the production saving can be estimated based on current estimate extrapolation, even if considering averages. Unfortunately no one really seems to know that "bottom line" for the US forces, hence the list above.

 

[Grand Danois]

If the final production unit price is known, the production saving can be estimated based on current estimate extrapolation, even if considering averages. Unfortunately no one really seems to know that "bottom line" for the US forces, hence the list above.

Excluding the marginal factual errors in that list, it is not inconsistent. They're estimates of UFC, UPC +/- engines at different times in the planned schedule to partners and export customers.

A fixed price is naturally dependent on fixed orders.

You've got your estimates: ~71-75 million USD UFC at 2008 levels for the F-35A if the current production schedule sticks.

 

[FutureTank]

Excluding the marginal factual errors in that list, it is not inconsistent. They're estimates of UFC, UPC +/- engines at different times in the planned schedule to partners and export customers.

A fixed price is naturally dependent on fixed orders.

You've got your estimates: ~71-75 million USD UFC at 2008 levels for the F-35A if the current production schedule sticks.

Ah, thank you. As I said, that list was obtained from elsewhere, and although I had seen some of the figures and know the sources, for reasons you stated, they are hard to 'digest'.
~71-75 million USD UFC at 2008 levels for the F-35A seems on the low side, so if true, then they are quite affordable (as the LH marketing says) compared to similar aircraft, if as you say all goes to plan.

 

[gf0012-aust]

I do have some understanding of production economics, but if you can't say, why tell me all that?

Make the effort to read what I said, not what you'd like to think that I said.

It was not privileged, it was spelled out to the journos a number of times (for the dim ones who couldn't grasp the concept of timeline specific lot purchases)

I said I was lazy and leaving it up to Abe (but kindly GD has offered up).

again. Read my previous. 8 non US partners will buy exactly the same aircraft as the US Forces do. They all come with engines (or anything else the US buys come with within the lot allocations)

try not to be deliberately contrarian when my position and comments were made abundantly clear.

It was spelled out by LM, by the USG SOD and by RAAF SPO (Harvey). Short of drawing pictures (which still won't be good enough for some) there's not much more that can be added.

If you're that keen ask LM or RAAF for the Press release.

My commentary indolence is also a mark of the degree of contumelious indifference generated when people skew my comments. They were pretty simple so seemed self evident.

 

[chris]

The GAO thinks it's $104M.

Actually, the latest GAO report puts the price at $122M. Interesting read overall, that report.

 

[Grand Danois]

Actually, the latest GAO report puts the price at $122M. Interesting read overall, that report.

We were talking average fly-away cost (AUFC) in 2008 dollars for the F-35A. That's 70-75 million usd.

GAO is talking about program unit acquisition cost (PAUC) for all variants in then-year dollars, which according to GAO is 122 million usd (2034?).

The recent GAO report is mild and can hardly be considered damming in any way.

 

[FutureTank]

gf0012-aust, I do read what you write, if only because I dread your rather sergeant-majorish replies sometimes, the sensitive soul that I am

...but, I asked a question, and

yes, we do. it was explained at the briefing and even the dimmest of the defence mag journos (Janes IMO) seem to understand it )

no answer here, though some journalists got it...

I never took the press releases avail to the journo's so am unsure as to whether they were included. however, as I am inherently lazy, I am going to leave the response to a scribe like Abe as I have really impatient fingers.

no answer here, though now I know you are lazy

it's not like buying a family car, platform purchase is based on time of purchase, the cost impost of buying early, late, the through life issues and what other "bits" are included.

no answer here, though if I am discussing production costs, you would think I know "its not like buying a family car".

it's not rocket science when explained - unfort every man and his dog seems to have their own interpretation of V&V and how major capital items are bought (and they also seem to think that every country buys under the same overall provisions when thats not the case). The bottom line is that within the platform constraint itself, we buy at the same price as the US Forces, and every platform between the 9 countries and 13 customers is series identical.

still no answer here, and I already knew that "every man and his dog" has an idea given the list.

I understand we buy at the same price as the US forces which is explicit in the Australian Government intention to buy and the participation in the program, but what is that price?

So please don't think I don't read what you wrote, but I just needed the price as you see it, since you were at the briefing.

 

[Aussie Digger]

You have me at a disadvantage since I am not an aviation engineer, and have not had the opportunity to familiarise myself with both engines.

Nor am I.

However, how does one get a "new engine" that's "evolved and enlarged" from another engine?

It's considered sufficiently different to warrant a completely new designation...

As I understand it the objective of the F135 design was two-fold: to increase thrust and to decrease weight. Fuel efficiency was the by-product of the overall weight reduction of the F-35, and not just the engine redesign. This weight reduction was not (as I understand) possible from the design reserve F120 engine.

Well perhaps you should dig a little deeper. The design philosophies of the 2 engines are considerably different. My earlier comment in relation to bypass ratio might be worth investigating if you wish to understand why they are so different.

I'm also looking at the available cut-away images of the two engines, and they look remarkably similar in appearance even to a non-engineer like me.

And? One is optimised for high altitude supersonic flight and the other is not. Yet the one that is not, produces significantly greater thrust.

I can't tell that from looking at them.

Fact is they ARE significantly different engines.

Now what "ludicrous claims" are you accusing me of making for lack of "facts"? What I said was that the F119 engine was being designed/developed even before the 1994 program start, at least from 1991. This is a fact. The JSF website itself says that "What is commonly known today as the F-35 Joint Strike Fighter Program had its origination in several programs from the 1980s and early 1990s."

I'm starting to think you're trolling here, but here goes for the last time.

You made a claim earlier, that claims that because P&W stated that the F-135 has 40% per fewer parts, this somehow translates to each engine sharing 60 identical "parts".

This is ludicrous and not even logical.

So does it take 17 years to build an engine? Or, does it take 8 years to redesign an engine? Which of these is a "ludicrous claim"?

For god sakes. I've already SHOWN you what Pratt and Whitney itself STATES about the engine. Are THEY wrong perhaps?

Stop being obtuse.

The F-135 operate a developed version of the F-119's compressor and turbine unit. EVERYTHING ELSE is new.

Your argument is akin to stating that your axe, the one that has had 2 different heads and 3 different handles is the same old axe you always had.

I'm sure this program is being watched with interest by a lot of people, because if these are the new engineering development parameters for combat aircraft engine production, then considerations of type replacement will have to be advanced significantly in fleet planning by air forces throughout the World. On the other hand, just maybe, the program was not conducted as efficiently as one might have hoped, or suggested by P&W. All the "facts" you quoted are coming from the manufacturer's website who is not even saying when the engine design begun and why it has taken so long.

Ever tried developing a fighter engine? Neither have I, but P&W have and they are probably the most successful jet engine manufacturer. Period.

They are building a fighter sized engine that produces 43,000lbs of thrust. No-one has EVER done this in a production version before. They are also trying to produce the cheapest engine, ever fitted to a fighter, that is the most efficient, oh and contributes to the LO characteristics of the airframe.

In short, P&W are attempting something that has never been done before. How long should it take?

Which engine is "new"?

Are you serious?

In fact no one describes the F136 as a "new engine".

Do you have the faintest idea of what you are talking about? The F-136 is the General Electric/Rolls Royce engine that is the "alternate" engine for the F-35 fighter program.

Unlike the F-135, it is an almost COMPLETELY "clean skin" design. The only "derivative" piece on the entire engine is the augmentor (afterburner) and even this has been enlarged for this engine. Otherwise it's an all new design.

Here is the background for this engine:

http://www.geae.com/engines/military/f136/background.html

The time/cost equation for this single engine is a seven-year, $2.4 billion contract. However, this only resulted in a prototype shown in February 2009. But the knowledge that Harriers/AV-8s would have to be replaced by the JSF design was known in at least 1994! It was certainly known when "Under Secretary of Defense for Acquisition, Technology and Logistics Edward C. "Pete" Aldridge Jr. announced on the afternoon of 26 October 2001 the decision to proceed with the Joint Strike Fighter program. This approval advanced the program to the next phase, the System Development and Demonstration (SDD) phase." (JSF site) Allowing a January 2002 start, the F-35B should have been in production and flying now, seven years later! Or is that also a ludicrous suggestion?

This is a ludicrous suggestion and what's more it's complete bulls*t.

Check the link to F-136, I just gave you and you'll find out what the schedule for this engine is.

The issue I raised is very simple. The F-35 was intended to produce a saving on designing replacements for four aircraft by designing one.

Bullsh*t. It was intended to design 3 aircraft, with a relatively common base. It is intended to replace, Harrier, F/A-18, F-16, some F-15 and some Tornado aircraft. It is being built in 3 quite distinct variants.

F-35A (CTOL - F-135-PW-100 engine or F-136)

F-35B (STOVL - F-135-PW-400 or F-136 variant)

F-35C (CV - F-135-PW-600 or F-136 variant) is not "one" aircraft.

The F-35B version is not radically different from F-35A for this contractualreason.

Okay... Let's list the differences, then shall we?

1. Different engine.

2. Different airframe.

3.Vertical lift fan.

4.Different cockpit.

5.Different internal weapons bay size, shape and configuration.

6. No internal gun on F-35B.

7. Much smaller fuel capacity on F-35B.

8. Hose and drogue refuelling on F-35B. Boom refuelling on F-35A

Is that enough to be "radically different"?

So in fact the F-35 will be (according to reports) a significantly superior aircraft when compared to the F-16, at virtually same unit cost, but why such a protracted program? This is what I can't fathom.

They are effectively building 3x different aircraft simultaneously.

Btw, I finally agree with something. The F-35 will most definitely be a significantly superior aircraft.

By the way, does anyone know the estimated final production unit cost?

Why bother? It's going to depend significantly on numbers built. Until firm numbers exists for orders, price is always going to be up in the air.

 

[Feanor]

Is that enough to be "radically different"?

No. It's not. They're aircraft of similar capabilities, similar class, and similar mission profiles. One is VTOL and the other is not. The difference is major but not radical. The F-16 and MiG-29 are radically different. The F-35A and F-35B are not. In fact I dare say they are no more radically different then a MiG-29S and a MiG-35. At least in my opinion.

 

[Aussie Digger]

No. It's not. They're aircraft of similar capabilities, similar class, and similar mission profiles. One is VTOL and the other is not. The difference is major but not radical. The F-16 and MiG-29 are radically different. The F-35A and F-35B are not. In fact I dare say they are no more radically different then a MiG-29S and a MiG-35. At least in my opinion.

Well, I disagree when you take a look at the actual airframe capabilities v cost.

Range? B sacrifices over 110nm in combat range and over 300nm maximum range.

Payload? B sacrifices over 12000lbs in payload (fuel and weapons).

Weight? B is 3700lbs heavier empty.

Firepower? B has had to sacrifice internal weapons carriage, it's bays are considerably smaller (limited to 1000lbs class weapons or smaller) and it has had to sacrifice an internal gun.

Cost? B is expected to cost between $20 and $30m more per airframe than the A model.

Radically different enough for me...

 

[Feanor]

In principle it's a different variant of the same aircraft. Just like the Su-34 is a part of the Su-27 family. While the Su-39 is not.

I think we're stuck arguing about semantics here though. By the way the cost difference between a MiG-29S, and a MiG-35 are also similarly far apart. Anyways... I don't meant to start an argument over such a trivial point, just throwing in my opinion in case anyone cares. :

 

[Aussie Digger]

In principle it's a different variant of the same aircraft. Just like the Su-34 is a part of the Su-27 family. While the Su-39 is not.

I think we're stuck arguing about semantics here though. By the way the cost difference between a MiG-29S, and a MiG-35 are also similarly far apart. Anyways... I don't meant to start an argument over such a trivial point, just throwing in my opinion in case anyone cares. :

Fair enough. Obviously, I think there is a massive disparity between the 2 variants in terms of capability and apart from the USA, I don't think too many will ever operate both variants. Israel might be the sole exception.

In my mind:

B models will be bought by those who need a Harrier replacement.

A models will be bought by those who want a genuine stealth fighter.

C models will only ever be bought by the USN.

 

[OPSSG]

In principle it's a different variant of the same aircraft. Just like the Su-34 is a part of the Su-27 family. While the Su-39 is not.

I think we're stuck arguing about semantics here though. By the way the cost difference between a MiG-29S, and a MiG-35 are also similarly far apart. Anyways... I don't meant to start an argument over such a trivial point, just throwing in my opinion in case anyone cares. :

Feanor, like AD, I also think of the JSF program as a developmental program to produce 3 aircraft variants with different capabilities, with certain parts commonalities (to replace the various types previously mentioned by AD), rather than share your point of view.

We have had a big debate in a Singapore forum on whether the RSAF should consider the F-35B (like the Israeli air force). I don't think it is worth repeating the points here but we'll see what happen when the Singapore FMS order appears in about 2 years. The main point I'm trying to make is that many Singaporeans think like AD.

I make no comment on the MiGs as I'm not very familiar with Russian stuff.

 

[Sea Toby]

Frankly, most of the criticisms of the JSF is that it won't be a great interceptor, nevermind its sensors and stealthiness will allow the aircraft to shoot first. A sharper front end could make it a better interceptor, but to do so reduces its sensors and its internal bomb bay. Talk about a dog chasing its tail.

The aircraft was designed to be a multi-role aircraft, with an emphasis on bombing. Its turning out to be great at what it does. There is a reason why the engineers chose its length, its internal bomb bay, and the bluntness of its nose. Live with it.

 

[Abraham Gubler]

No. It's not. They're aircraft of similar capabilities, similar class, and similar mission profiles. One is VTOL and the other is not. The difference is major but not radical. The F-16 and MiG-29 are radically different. The F-35A and F-35B are not. In fact I dare say they are no more radically different then a MiG-29S and a MiG-35. At least in my opinion.

Actually the F-35A and F-35B are much closer than the MiG-29 and MiG-35. Both aircraft (and the F-35C) are completely identical except for those components needed to allow for the differing takeoff and landing profiles of the various versions. For example all the F-35 versions share the same combat systems, the same tails, the same centre afts and so on. Most of their spare parts will be the same and it will be very simple to convert from one platform to the other. They are also produced side by side on the same production line.

This is far more alike than different block upgrades of the same aircraft, for example the MiG-29S and MiG-35. Where not only new systems are added but many are changed because subcomponents are no longer available. There is also a lot more standardisation on a computer controlled production line like the F-35s compared to the old 'bang em' together type production line used for the FULCRUMs.

 

[FutureTank]

Nor am I.
It's considered sufficiently different to warrant a completely new designation...

etc.

Aussie Digger, I don't like being taken for a simpleton.

A new designation? Do you think that the aircraft being an F-35 had something to do with the engine being designated F135? I'm not even assuming, but certain that that designation was created as a business decision by the marketing team However,

On 26 October 2001, upon DoD downselection of the Lockheed-Martin (L-M) design, the JSF119 Program was redesignated F135, consistent with the tentative nomenclature of the JSF aircraft, the F-35.

Final report, United Technologies Corporation, Lt Col Clyde M. Woltman, USMC, June 2002

There is no "design philosophies of the 2 engines". The F119 is the same engine selected way before the contract was even signed, with the F120 as the reserve engine. I said that I am not an engineer, but I do know how engineers think (worked with enough of them). Few are given to philosophy

Why can't you just say that the F135 has a larger fan! So what? That's not a different engine!

"One is optimised for high altitude supersonic flight and the other is not" Do you think that I have never flown in a commercial aircraft? High altitude is FL9600. That’s 31,500ft in pilot speak. The F-35B is "believed to be" capable of supersonic flight at 15,000m, and a "reported service ceiling of around 57,000 feet" (air-to-air combat site says 60,000 ft. / 18,288 m). This is extreme high altitude. So what, you are telling me is that an advanced strike fighter can't go supersonic at 31,000ft?! I will want evidence in support of this statement.
This is the reason Yakovlev was brought into the program early on. You see the Yak-141 was the first VSTOL design to go supersonic. The Yak-41M designation was adopted around 1991 to reflect a shift to a multi-role configuration, but it never went into production. In 1994 the Yak bureau was contracted to contribute to the F-35B concept design and other engineering issues related to the B vertical take off config. The F-35B will be the first VSTOL production supersonic aircraft thanks to that input.

They are different engines because you can't tell they are same, and that's a fact?? Please look again. It’s the same engine with a RR subassembly from Pegasus for directing vertical thrust.

Do you know, the first time someone gets defensive, they claim the other person is 'trolling'.

I note you left out my 100-60=40 arithmetic from the quote.

Ok, lets try a bit of logic.
How did the engineers know they are using less parts? I'll tell you how. They have a thing called a BOM, Bill of Materials. This lists all the parts used in the design. So they ran a report after the redesign, and compared the last number on the BOM in both engines and subtracted on from the other. That is how they know. So, you see 40% less parts is 40% less parts off the same BOM. They don't have a different engine, just one with fewer parts. If they had a different engine, they would have had a different BOM. So, you see it is very logical. Besides that, what happened is that the engine may have been over-engineered. This happens a lot in engineering practice. Given they had to save weight and alter the performance somewhat, all the engineers had to do is simplify the design, with the result of 40% less parts. Who knows, 20% of those may have been superfluous wiring During the Second World War it was done all the time. Liberty ships are the best and largest examples. P&W engines were in lots of different aircraft then also. They were modified for each and every one. Some had 23% less parts, some 17% more, depending on the performance needs. You should see how many aircraft had the R-2800 Pratt & Whitney Double Wasp.

Pratt and Whitney are not telling the truth. Before the F135 there was the JSF119 (or the JSF119-611 to be exact) as reported for example in Sea Power on the 1 July 2001 who said in the article titled P&W, GEAE, DOD sign pact on JSF119 engine

Pratt & Whitney (P&W) and General Electric Aircraft Engines (GEAE) have reached a formal agreement with the Department of Defense to ensure that both companies' engines "will be physically and functionally interchangeable across all three variants of the JSF [Joint Strike Fighter] program," DOD officials said.

See above to how it became F135. The only thing new was the name. For the most part it was the same engine. The reduction or increase in parts doesn't even describe how same they were. They share the vast majority of overall physical parameters in order to comply with logistics and maintenance commonality specifications of the F-22. Probably to 90% if not more.

I beg to differ, but P&W are not probably the most successful jet engine manufacturer, just the one selected for the JSF program.

P&W are attempting something that has never been done before? No, they designed an engine for a fighter. That's been done before. The cost, performance and other parameters are just the project engineering constraints. They were selected because they showed that they could achieve these constraints. It took them a long time though. Much longer than the aircraft they are replacing.

Before you turn this into some sort of miracle, the F-16 was powered initially by the Pratt & Whitney JTF22 (F100) but was later changed to the General Electric F110. This was the 1979 engine used to modify the F-14B/Ds. Its derivative was the F118. The F-15s have two of the F-16's F110s, so the F-22/F-35 program replicates the much earlier program conducted for the aircraft they will replace, using a similar engine. The P&W greatness I fear is somewhat exaggerated. The grand-daddy of them all was the F100-PW-100. If you care to know, and I quote from nothing more than Wikipedia

Using technology developed from the F119 and F135 engine programs for the F-22 Raptor and F-35 Lightning II, the current production F100-229 incorporates modern turbine materials, cooling management techniques, compressor aerodynamics, and electronic controls. The first -229 was flown in 1989 and has a thrust of 29,160 lbf. It currently powers the X-47B and F-15E Strike Eagle.

So how was it that innovations supposedly only available from 2002 were incorporated into a 1989 engine?
The F1XX series is therefore at least about two decades old in terms of general design (and used to be designated in a different way).

So when I ask what engine is "new", I am not kidding. To me "new" would have been from scratch. A new company model type, maybe PW7000. But, here we have same series engines that are prolific in the USAF across the several aircraft types. They are, in the eyes of the maintenance personnel quite old, and easier to service because over the three decades much has been learned about how to simplify the designs, particularly when the DoD starts to turn the screws on cost. In fact the real age of the design starts before I was born in 1962 (F119) Pratt & Whitney PW5000 Joint (1962+): (2)F-22, (2)YF-23A http://www.designation-systems.net/usmilav/engines.html#_MILSTD1812_AirBreathing Engine supportability for this model was discussed as early as 1986.

The F136 is an "almost completely "clean skin" design”? I don’t even know what that means in reference to an engine. However,

The F136 engine is a derivative of the F120 which lost the F-22's propulsion contract against the Pratt & Whitney F119 engine. The F136 STOVL will power the US Marine Corps Short Take-off Vertical Landing F-35 variant operating from scarcely prepared runaways close to the battlefield front line.

and

The engine is derived from the successful YF120-GE-100 engine developed in the Advanced Tactical Fighter Program

The YF120-GE-100 (GE model GE37) [X – Experimental, Y - Service Test] was a rival to F119, and...you will love this..."The YF120 has 40 percent fewer components than the F110." : Yes the same GE F110 that powers the F-16/F-15 aircraft, and the one that the F-135 is derived from The P&W marketing team are really earning their keep I think

You won't find that in the GE link you gave me

The schedule? AD, before I "swallow", I "chew".
The GE/RR even advertised their GE37 engine as 'proven technology'. It’s proven because they have been testing them for as long as the P&W PW5000 series, since 1962 So why did it take three years

Following successful core and fan rig testing in 2000, [before] the Fighter Engine Team ran the first full engine to test in July 2004. The first engine to test continues on schedule to deliver production F136 engines in 2011.

That's 11 years to start production of 'proven technology'! And, they had been trying and selling this engine for ears before hand. Neither the GE F136 nor the P&W F135 even have a manufacturer’s model number. By the way, the Rolls-Royce part in this is the integration of the F402 Rolls-Royce Pegasus engine technology. That had been under development since 1962 also.

F-35 "was intended to design 3 aircraft, with a relatively common base."!!! Secretary Cohen though it was one aircraft with three different configurations that would have 90% commonality. F-35A, B and C suggest same aircraft just like the UH-1A/B/C/D/E/F/H/N were same helicopter though the N configuration had two engines. In terms of overall design the VSTOL capability of the B version is negligible. I could not find one DoD document that said the Program was designing three different aircraft. “A key challenge in the design of the JSF is to meet different service requirements without building three different aircraft.” (Bill Sweetman, Lockheed stealth, 2001) Muellner (the first Program head mentioned in previous post) “wanted to build a ""universal fighter"" that would fulfil the needs of all the participants, and was able to get everyone pulling in more or less the same direction.” (http://www.airtoaircombat.com/detail.asp?id=19) Preceding JSF was the JAST concept, of which you may be thinking.

The final word is

There will be three design variations of the aircraft based on the different missions of the Navy, Marines and Air Force. One configuration, the STOVL variant, will hover and land straight down, like a helicopter, thanks to a massive lift fan built by Rolls-Royce and patented by Lockheed Martin Corporation, Bethesda, Md. Another configuration will be able to land on Navy aircraft carriers while the third "cousin" performs conventional take-off and landing. All variants perform the functions of traditional multi-role fighters.

(Defence Contract Management Agency) http://www.dcma.mil/communicator/archives/spring%20summer%202002/The%20Joint%20Strike%20Fighter.htm

What this means in MIL-STD-879 system:
F-35A (CTOL - F135-PW-100 engine or F136) [engines do not have a dash]
Turbofan-Air Force-Pratt & Whitney-Air Force model
F-35B (STOVL - F135-PW-400 or F136 variant)
Navy model
F-35C (CV - F135-PW-600 or F136 variant)
Navy model
The Army and Air Force use odd numbers from 1 up, while the Navy uses even numbers from 2 up. The F135 is therefore an Air Force engine despite there being two Navy models in the type.
It is same engine AD.

Okay... Let's list the differences, then shall we?

OK
1. Different engine. - no

2. Different airframe. - no, just look at them...Even if you are the 'half empty' thinker, surely three identical glasses 90%+ identically filled are identical.

3.Vertical lift fan. - that's not different, but a design specification for a role. Consider all the different ‘bits’ added to the C-130s over the years to satisfy role requirements. In horizontal flight its a dead weight.

4.Different cockpit. - yes, the Navy insisted on the coffee grinder Come on....different cockpit?! How different? Not different enough that an AF pilot can't get into a Navy or USMC configuration and fly. The F-16D has a different cockpit to the F-16A (much different), but same aircraft.

5.Different internal weapons bay size, shape and configuration. - yes, that's crazy I agree. But they are just weapons bays. The are different only because of the B role configuration

6. No internal gun on F-35B. - This is even crazier that the weapons bays. I don't understand which Marine pilot is going to fly what is essentially a CAS role aircraft without an internal gun. When was the last time there was a US fighter in any service without an internal gun? F-4? Being a Marine, he will probably bring the M-16 “This is my rifle. There are many like it, but this one is mine...”

7. Much smaller fuel capacity on F-35B. - Again, this is role/mission profile specific, not 'different'. See the USMC sortie rate requirement. Fuel capacity is a mission variable anyway.

8. Hose and drogue refuelling on F-35B. Boom refuelling on F-35A - This is service specific requirements that have to be accommodated (external project influence)

Is that enough to be "radically different"?

No. Radically different is when a Chinese pilot sees two aircraft, and he can tell that one is an F-35A and which is an F-35B, and I don't think that's going to be possible unless he is in position to see the STOVL fan duct. And even that’s not possible unless he is flying above and at visual.

AD, please don't be defensive. It makes you trigger happy Please don;t think that I am "against" something or someone. I am just asking questions. That's allowed in a democracy. I know the military is not a democracy, but I am not in the military, and the military is in a democracy, so it gets asked questions, a lot. Program accountability is as much a priority as its deliverables. Any time anything goes 'perfectly' in reference to a military development program, I for one become naturally suspicious, particularly in the USA.

The bottom line is that the JSF is an evolutionary, not revolutionary design that has been in development, in parts if not the whole, longer than I have been alive. As a whole it has been in development officially since 1991 when all its legacy programs for individual services were killed by the then Administration as a peace dividend from the end of the Cold War. The rationale for the JSF was as much in keeping jobs and retaining strategic manufacturing industry as the need for the next generation of aircraft.

Try to be a bit more objective and questioning of the manufacturer's 'spin'.

PLEASE give civilians some credence of having a brain. I am not trying to prove anything or foist my POV on anyone, but simply asking what are the implications for end-of-type replacement planning when it takes two decades to go from contract signing to production. No need to get defensive and call me names. Its a public forum after all.