Talk:Lockheed Martin X-35/Archive 1

Archive 1

Number Built

There were more than 2 were built, wasn't there? One for each variant? X360 11:06, 1 January 2007 (UTC)

From the text, under Variants/F-35A: The X-35A was converted into the X-35B for the VSTOL part of the competition. One X-32 was also converted, I believe the X-32A into X-32C (Naval). - BillCJ 16:10, 1 January 2007 (UTC)

Ah, ok. Thanks for that Bill. :) X360 21:50, 11 January 2007 (UTC)

JAST

According to FAS.org the X-35 was developed during the JAST project, not the JSF project? - Maarten 22:52, 21 February 2007 (UTC)

The JAST became the JSF in 1995. Check the Joint Strike Fighter Program page for more info on this. Btw, that's an old page on FAS, dated Updated Tuesday, February 10, 1998 5:16:45 AM at the bottom. The [JSF page] on that site also has good info, and was last updated in 2005. - BillCJ 00:04, 22 February 2007 (UTC)

Yes JAST became JSF but the X-35 was originally designed for JAST, the article seems to skip that project entirely. Unless I've overlooked something. Ah well maybe I'm too much of a nitpicker. Maarten 00:26, 22 February 2007 (UTC)

confusing

when it says "Status: retired (museum)", it's not supposed to be retired. it has just been developed. also, i heard numerous times on The Discovery channel, they say it WILL/IS active in service. someone that works with airplanes or has something to do with it, please dig out the right information and change it. XU-engineer 19:06, 13 June 2007 (UTC)

I think you are referring to the F-35 Lightning II follow-on, which is currently undergoing flight testing. The two original X-35s have been retired, are no longer in active testing, and are currently in museums, per the text.

Summary

Who ever wrote this knows little or nothing about this subject. i dont mean to use this in a harmful way, but just to make him/her/them "notice" that they have wrote the wrong things.

This article is either a stub or a start rating. XU-engineer 19:13, 13 June 2007 (UTC)

Please be more specific: What particlular points are you objecting to, as there is no section entitled "summary"? This article was written by many editors, and eventually became the F-35 Lightning II page. A few editors and I streamlined the F-35 page by removing the X-35 info, and put that information here. It may not be totally accurate, but if you aren't specific about wha you feel is wrong, I have no way of knowing what the problems are. - BillCJ 19:21, 13 June 2007 (UTC)

Ah, Yes. thank you. why do they name the airplanes X-35 and F-35? To confuse us? XU-engineer 18:29, 15 June 2007 (UTC)

X and F are two different series in the US DOD designation system (X-Experimental; F-Fighter). The last fighter in the "F" series was the YF-23, so the next number should have been F-24. However, the USAF decided to keep the number "35", so the X-35 became the F-35. THe X-35 and F-35 aren't exactly the same, as the F-35 features many improvements over the X-35. In addition, the X-35 and Boeing X-32 were primarily concept demonstrators, and not intended to be armed, while the F-35 will be combat-capable. Hope this helps. - BillCJ 18:40, 15 June 2007 (UTC)

Difference

Whats the difference between F-35 and the X-35? They both look the same.(76.247.222.101 19:41, 27 September 2007 (UTC))

One of the difference is the powerplant. Whereas the X-32 and X-35 are both powered by Pratt and Whitney's F119 turbofan, the F-35 uses the Pratt and Whitney F135. (The encyclopedia of world aircraft. 2002. Silverdale books, pp 305 & 921. Combat aircraft, Nov 2009, vol. 10, no. 6, p 46--Hschantang (talk) 18:18, 2 February 2011 (UTC)

Other differences: 1) looking at the nose of the X-35, there is a pitot (antenna-like structure) which if I am not mistaken is absent/different on the F-35 (or at least probably will be in the operational aircrafts). 2) From the rear, looking at the engine, the F-35 has "multiple triangular slats" on the exhaust, most probably to reduce radar signature. This feature is absent on the X-35, if I recall. 3)Along the jet intake, the current F-35s all have the flags of participating countries according to the amount they contributed to the pgm. To my knowledge, these flags are absent on the X-35, hence the reason why I am contesting "international participation" on the X-35. Of course these flags will be absent on operational planes. oops, forgot to sign in--156.34.237.235 (talk) 23:57, 2 February 2011 (UTC). The shape of the nose and cockpit is also different between the two aircrafts--156.34.32.219 (talk) 23:18, 6 February 2011 (UTC)

There are other visible differences, presence of weapons bay door, sensors etc, but the above mentionned details should be enough if you only have a quick look--Hschantang (talk) 00:11, 3 February 2011 (UTC) As BillCJ mentionned above, the X-35 is not combat capable, as such, all the expensive software, avionics, radar, etc are probably very basic or even absent--Hschantang (talk) 00:29, 3 February 2011 (UTC).

Fair use rationale for Image:F35LightIIlogo.jpg

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BetacommandBot (talk) 20:43, 13 February 2008 (UTC)

Fair use rationale for Image:Oldjsflogo.jpg

Image:Oldjsflogo.jpg is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.

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BetacommandBot (talk) 16:36, 8 March 2008 (UTC)

Yakovlev influence on the X-35

Per BillCJ's request, I have assembled some reference sources on the Yak influence on the X/F-35. I have to admit I've not found many, and the better part of that the editors here are already aware of, but I’ll include all the main references for convenience. I've included the relevant text from each source that addresses the Yak-LM "heritage". I've also dummied up some reference tags, but they need style cleanup.

FWIW, here’s what I remember about what led to and was involved with the LM-Yak teaming relationship. (Since I was not personally involved with this team, this comes from what I read or heard.) It will at least help editors understand the subject better.

DARPA kicked off the ASTOVL program in 1983 to look at the requirements and technologies needed to design a supersonic V/STOL replacement for the Harrier for the USMC and RN (and later the USAF). By 1987, it was clear that the state of the art was not “there” yet, so the program entered a second phase intended to mature the needed technologies. This was supplemented in 1993 by the joint Common Affordable Lightweight Fighter (CALF) program, also managed by ARPA (as DARPA was renamed in 1993-96) to begin the development of a STOVL strike fighter (which had its origins in a previously classified program).

As a result of the Bottom-Up Review (BUR), a number of fighter development programs were canceled and replaced by the Joint Advanced Strike Technology (JAST) program in late 1993; it would absorb CALF in November 1994. In October 1994, the U.S. Congress directed that ASTOVL also be merged into JAST. JAST was intended to lead to development of a technology demonstrator, and would become the Joint Strike Fighter (JSF) program in 1996.

Yakovlev was contracted by several companies – including BAe, Boeing and Lockheed – in the early 1990s with regard to V/STOL technology consulting and testing. Lockheed’s contract envisioned a possible development partnership as well, and if all options had been exercised, this could reportedly have reached a value of as much as roughly US$4 billion (which would indicate that it was envisioned that Yakovlev could have become a full development and possibly a production partner). This did not occur, though, and I recall hearing that the total work amounted to only some $80-100 million, all told, including concept and technical consulting as well as the purchase of a lot of design, wind tunnel and other test data from the Yak-141M program.

While similar engineering material from the Yak-43 program may have been included, I cannot recall having heard the Yak-43 referred to in relation to this teaming effort. (In fact, it’s possible that this project wasn’t yet known in the West since a lot of information on Soviet aviation programs only became available in the second half of the 1990s.) In any case, the Yak-43 was reportedly intended to be a stealthy design; as such, it is highly doubtful that the Russian government would have authorized release of information on such sensitive technology. The decision to bring the STOVL Strike Fighter (SSF) out of the “black world” may have been the impetus to eventually abruptly truncate the LM-Yak relationship with a purchase of the data package. As it was, LM didn’t announce its teaming arrangement with Yakovlev to assist in the former’s bid for the JAST teaming arrangement with Yakovlev for the JAST program until mid-1995, when it revealed an 86% subscale model originally developed for the CALF project; testing ended in the Spring of 1996, and it’s unclear whether Yakovlev’s services were retained beyond this point. (Interestingly, it’s the aft half of this model that most resembles the Yak-43, rather than anything on the X-35.)

The greatest interest was shown in Yakovlev’s insights into exhaust gas recirculation, engine nozzle design (the R-79) and flight control during take-off and landing (as Gordon Yefim notes). Rolls-Royce Allison’s 3 Bearing Swivel Nozzle (3BSN) was developed from the “lobsterback” design used on the Yak-141 V/STOL prototype and licensed from Yakovlev. (While Yakovlev didn’t invent the swiveling nozzle concept, it was the first to develop a flight-proven design.) Following its debut on the X-35, the 3BSN nozzle was further evolved by Rolls Royce into the variable-area vane box nozzle (VAVBN), which is integral to the aircraft’s structure, for the F-35B.

Lockheed Martin’s vertically-orientated, shaft-driven lift fan (SDLF) may or may not have used insights from Yakovlev, as it is a rather different STOVL lift system than the lift-plus-lift/cruise system used on Yakovlev’s V/STOL fighters. The shaft, clutch and drive-control systems are critical items designed specifically for each concept, and the F-35B’s clutch is a complex and major innovation – and a “critical path” element for the aircraft’s successful development. (The F-35B’s system was developed by TRW Lucas Aerospace).

Some of the value that Lockheed Martin may have benefitted from through Yakovlev’s assistance may have been what they felt did not work and their insights into possible improvements to the Yak-41M design (some of which may have been explored in the Yak-43’s design approach). This is merely my speculation, but is realistic based upon my own professional experience, because there is true value in not having to “re-learn” mistakes and dead-ends. One of these would likely have been increasing the range/payload capability of the aircraft (always a problem with V/STOL aircraft and one known to have been addressed with the Yak-43). In the end, LM went with its SDLF concept because it provided far more thrust over the straight lift-fan approach, but it’s unclear – and probably unlikely – that Yakovlev had any contribution toward this. Another might have been techniques for reducing the heat footprint of the lift fan in powered-lift flight modes. The Yak-41 required use of the afterburner for every vertical take-off and landing – which also reduced range due to the increased fuel consumption. (I’m not sure if this would have applied to the Yak-43 which, while it used the same twin-lift-fan and cruise engine concept, was to use the same core engine – the Samara [now Saturn] NK-321 three-shaft augmented turbofan – as the Tu-160 bomber). The F-35B’s lift fan extracts power from the engine, which lowers its exhaust temperatures; the Yak-43 was to use the same RD-41 lift fans as its predecessor.

In summary, the Yakovlev team was contracted to provide design consulting services, technological assistance, wind-tunnel and other testing support, and Yak-41/41M design and test data to Lockheed Martin. Yakovlev also sold a license to the LM/Rolls-Royce team for its unique swivel nozzle design, which was further evolved by RR into the 3BSN and later into the VAVBN design. It’s unclear that information on the Yak-43 was part of this deal, although certainly some “lessons learned” and other insights obtained by Yakovlev may have been contributed. It also appears highly unlikely that the overall layout design of the X-35 or F-35 was significantly influenced, much less based upon, the Yak-41M; however, it’s likely – though uncertain – that the CALF technology demonstrator did.

I hope this helps and I welcome questions. Askari Mark (Talk) 20:48, 30 May 2009 (UTC)

Yak influence references

1) Gordon, Yefim; Komissarov, Dmitriy & Komissarov, Sergey: OKB Yakovlev: A History of the Design Bureau and Its Aircraft – "Joint work with Lockheed Martin on a VTOL aircraft project"

In 1995 the Yakovlev OKB received permission from the Russian Ministry of Defence to conduct joint work with the Lockheed Martin Company (USA) on the development of a new-generation VTOL combat aircraft. The US partners estimated the cost of research and development work under this programme intended to last until 1998 at some US$ 4 billion. The Yakovlev OKB promptly rendered the necessary assistance to the Lockheed Martin Company in solving many basic design problems on a concept level, associated with the choice of the main parameters of a VTOL fighter as a whole and of its powerplant, as well as operational problems concerned with exhaust gas recirculation and flight control during take-off and landing.

Upon completion of this stage the US partner took a decision to conduct further work on the project entirely on its own, albeit the potential of co-operation had be no means been exhausted. In late 2001 Lockheed Martin rolled out its X-35B technology demonstrator which, in the opinion of some specialists, had much in common with the Yak-141. As is well-known, the Lockheed Martin project became the winner of the Joint Strike Fighter (JSF) contest and the company received an order for the development and production of the F-35 aircraft under this programme.

<ref>Gordon, Yefim; Komissarov, Dmitriy & Komissarov, Sergey. "Joint work with Lockheed Martin on a VTOL aircraft project" entry in ''OKB Yakovlev: A History of the Design Bureau and Its Aircraft''. Hinckley, England: Midland Publishing; 2005. pp. 346-7. ISBN 1 85780 203 9.</ref>

2) Jane's All the World's Aircraft 1995-1996: "Common Affordable Lightweight Fighter (CALF)/JAST"

US Department of Defense designation X-32 allocated for technology demonstrator phase of Advanced Research Projects Agency (ARPA) programme. CALF project initially launched as STOVL Strike Fighter (SSF; now envisaged as X-32B) to provide US Navy/Marine Corps with replacement for F/A-18 Hornet and AV-8B Harrier II; later expanded to include USAF F-16 replacement candidate (X-32A), in which vertical lift system eliminated in favour of additional fuel to produce longer-range, conventional take-off aircraft.

Lockheed Martin one of four teams in contention for X-32 contract; others headed by Boeing, McDonnell Douglas and Northrop Grumman; Lockheed Martin partnered by Allison, Pratt & Whitney and Rolls-Royce engine manufacturers. Congressional pressure in Autumn 1994 resulted in CALF project merging with Joint Advanced Strike Technology (JAST) programme (see US Navy entry).

On 27 April 1995, Lockheed unveiled 86 per cent scale model of JAST demonstrator for wind tunnel tests and in June revealed agreement with Yakovlev of Russia to purchase data on cancelled Yak-141 programme, which employed similar propulsion system.

<ref>''Jane's All the World's Aircraft 1995-1996''. "Common Affordable Lightweight Fighter (CALF)/JAST". Jane's Publishing; 15 July 1995.</ref>

3) Aerospace America: "JSF Rivals Face Off"

Lockheed Martin engineers, on the other hand, studied the existing technologies and became convinced that a completely new system would be necessary to meet the rigorous JSF requirements. After all, the plane not only must hover like the Harrier but also must fly supersonically, be stealthy, and carry more weight. "It's our opinion that we're about at the limit of what direct lift can provide. There's just a fundamental difference in philosophy," Burbage says.

Unlike a direct-lift plane, the Lockheed Martin STOVL variant will not rely exclusively on air traveling through the engine. Instead, the front of the aircraft will be kept aloft by a separate, downward-pointing adjustable-lift fan that is attached to the F119 engine via a shaft. The shaft will engage and turn the fan during STOVL flight only. "It's a little more complex than a clutch in a car, but it's the same principle," Burbage says.

At the rear of the plane is a three-bearing swivel duct that deflects exhaust from the F119 engine downward to support the tail of the aircraft. The design of this duct was inspired by the Russian YAK-141 STOVL plane, Burbage says. The Lockheed Martin STOVL variant will also direct thrust from the engine to two roll ducts on the wings to control side-to-side motion.

In November 1999, Lockheed Martin published a paper arguing that its "shaft-driven, lift-fan concept" would generate 60% more vertical thrust from the F119 than the existing direct-lift approach. Although their STOVL variant will weigh 4,000 lb more than their conventional variant, the extra weight is worth it, because the STOVL plane will carry more payload than the Harrier, contend Lockheed Martin officials.

<ref>Iannotta, Ben. [http://www.aiaa.org/aerospace/Article.cfm?issuetocid=47&ArchiveIssueID=9 "JSF Rivals Face Off"]. ''Aerospace America''; January 2001.</ref>

4) Design Engineer: "Two approaches to achieving short takeoff and vertical landing"

While the Harrier is probably the best know VTOL (vertical takeoff and landing) or STOVL (short takeoff and vertical landing) aircraft, there are others. The Yakovlev Yak-38 (known within NATO as the Forger) was the Soviet Naval Aviation's VTOL multi-role combat aircraft, entering service in 1976. Following that, the Yakovlev Yak-141 (known within NATO as the Freestyle) was a supersonic VTOL fighter aircraft. As with the Yak-38, the Yak-141 gained its VTOL capability through a combination of a lift and lift/cruise engines. Two lift jets were mounted behind the cockpit and contributed to takeoff only; once the aircraft was in horizontal flight, the lift engines were shut down. The main engine was installed in the rear of the fuselage, with a swivelling nozzle and an afterburner. For takeoff and hovering, the exhaust from the jet was vectored downwards through 90 degrees to work in conjunction with the forward lift jets. To obtain sufficient power for vertical takeoff, it was necessary to use the afterburner, which limited the types of runway surfaces that could be used. In August 1991 the programme was halted due to budgetary constraints.

Lockheed Martin developed the concept for a STOVL lift system that uses a vertically-orientated, shaft-driven lift fan (SDLF). A two-stage low-pressure turbine on the engine provides the power necessary to drive the lift fan. The lift fan generates a column of cool air that provides nearly 20000 pounds of vertical thrust using variable inlet guide vanes to modulate the airflow.

An equivalent amount of thrust is provided by the downward-vectored rear exhaust. Because the lift fan extracts power from the engine, exhaust temperatures are reduced.

In December 2008 Rolls-Royce delivered the first production variable-area vane box nozzle (VAVBN) to Pratt & Whitney for integration on the F-35B. The VAVBN is integral to the aircraft structure and is used to control the lift fan exit airflow when the F-35B operates in powered-lift mode.

<ref>''Design Engineer''. [http://www.engineerlive.com/Design-Engineer/Aerospace/Two_approaches_to_achieving_short_takeoff_and_vertical_landing/21553/ "Two approaches to achieving short takeoff and vertical landing"]. Undated [but 2009]. Accessed 27 May 2009.</ref>

5) Jane's Aero-Engines: "Saturn RD-1"

Despite being the ultimate USSR lift jet, its application was abandoned.

This third-generation lift jet was designed for the Yak-41 supersonic V/STOL naval fighter, and was also fitted to the Yak-41M. In the Yak-41 the normal (neutral) attitude was 77°30'. These aircraft (which became known erroneously as the 'Yak-141'), and the derived Yak-43, later underpinned the project stage of Lockheed Martin's F-35 (JSF) in a teaming agreement of June 1995. Ultimately the F-35B replaced the lift jets by a shaft-drive fan, as described in the JSF entry. The RD-41 engine was designed in 1982, first ran in 1984, and was first delivered to Yakovlev in 1988. A total of 30 were produced.

<ref>''Jane's Aero-Engines''. "Saturn RD-1". Jane's Publishing; 31 March 2009.</ref>

6) AeroWorldNet.com: "Russian Fighter Tales: The Yak-141 and the MiG-29SMT"

Although the development prototypes performed rather well, out of their flight test program emerged a more advanced design, the Yak-141M. Due to the lack of funding the design was shelved, though. In 1992/93 Lockheed contracted Yakovlev on some work pertaining to short take-off/vertical landing (STOVL) aircraft studies in reference to the JAST (JSF) project. Yakovlev shared its STOVL technologies with the US company for several dozen million dollars.

Former Yakovlev employees accuse Yakovlev heads of taking personal interest out of the deal with Lockheed, because the official sum of the contract did not correspond with the value of the information presented to the US company. The data was on the Yak-141 test program, aerodynamics and design features, including the design of the R-79 engine nozzles.

After a careful study of those materials, Lockheed – without much noise – changed its initial JSF proposal, including a design of the engine nozzles that is now very similar to those of the Yak-141.

<ref>Karnozov, Vovick. [http://www.aeroworldnet.com/1ra12087.htm "Russian Fighter Tales: The Yak-141 and the MiG-29SMT"]. AeroWorldNet.com; 8 December 1997.</ref>

7) Aeroflight: "Yakovlev Yak-41 'Freestyle'"

The Yak-41 is a supersonic V/STOL (Vertical/Short Take-Off and Landing) naval fighter. Although it never entered operational service, some of it's advanced technology will see application on Lockheed-Martin's F-35 fighter. … The production version was planned to feature uprated engines allowing take-off with more weapons or additional fuel. A prototype two-seat trainer was never completed. An advanced stealthy version designated Yak-43 remained only a project.

During the summer of 1995, Lockheed Martin announced a teaming arrangement with Yakovlev to assist in the former's bid for the JAST (Joint Advanced Strike Technology) competition. Yakovlev's knowledge of jet lift technology was to prove invaluable. Lockheed Martin was subsequently selected to build a demonstrator aircraft, the X-35, which went on to win the JSF (Joint Strike Fighter) competition and will soon become a production fighter as the F-35.

One of the key problems with the Yak-41M jet-lift system was the need to engage afterburner for vertical take-off or landing. At land bases this soon resulted in damage to the runway, while the Admiral Gorshkov was fitted with a special water-cooling system to absorb the heat from the jet blast. Hence, the Yak-41M was in no sense a Harrier-style go-anywhere aircraft.

<ref>Hayles, John. [http://www.aeroflight.co.uk/types/russia/yakovlev/yak-41/yak-41.htm "Yakovlev Yak-41 'Freestyle'"]. ''Aeroflight''; 12 March 2005 (Last Revised: 28 March 2005).</ref>

8) AHS International, The Vertical Flight Society: "Towards First Flight: A Look at the STOVL Joint Strike Fighters"

The Allison Lift Fan is located behind the cockpit in a bay with upper and lower clamshell doors. When operating at normal speeds, the Lift Fan is capable of supporting nearly half of the weight of the X-35. Another STOVL-unique feature on the X-35 is the auxiliary inlet for the main engine, located above the fuselage and behind the lift fan; this is used for the high air flow demands of hover.

The engine exhausts through a three-bearing swivel nozzle (3BSN) that can deflect the thrust from horizontal to just forward of vertical. Two roll ducts supplied by engine fan air provide roll control. Yaw control is through swivel nozzle yaw. Pitch control is effected via Lift Fan/engine thrust split. … Simple configuration changes enable the conversion of the SE611 from a CTOL/CV to a STOVL engine. Engine controls and software will differ among the various configurations. For the STOVL variant, the fan duct incorporates a bypass offtake system for aircraft roll control. A shaft is attached to the engine's low-pressure rotor. The axisymmetric nozzle is replaced with the 3BSN.

The 3BSN nozzle, developed by Rolls-Royce, was patterned along the lines of the exhaust system on the Yakovlev Yak-141 STOVL prototype that last flew at the 1992 Farnborough air show. A US Navy program also developed swivel nozzles in the late 1960s and was proposed for a supersonic STOVL design by Convair (one of the Lockheed Martin heritage companies) in the early 1970s.

<ref>Maddock, Ian A. [http://www.vtol.org/Lockheed.htm "Lockheed Propulsion System"] in [http://www.vtol.org/maddock-stovljsf.htm "Towards First Flight: A Look at the STOVL Joint Strike Fighters"]. ''AHS International, The Vertical Flight Society''. Spring 2000.</ref>

9) Jane’s Air Forces News: "Joint Strike Fighter (JSF)"

Origins of Joint Strike Fighter (JSF) programme vested in separate USAF/USN Joint Advanced Strike Technology (JAST) and Defense Advanced Research Project Agency (DARPA) Common Affordable Lightweight Fighter (CALF) projects of early 1990s; designation X-32 then assigned to planned CALF demonstrator (see US Navy entry in 1997-98 and previous editions of Jane's for more details of JAST and CALF programmes).

Projects merged in November 1994, as JAST, after Congressional directive in mid-1994; programme renamed JSF in latter half of 1995. Previously, formal request for proposals (RFP) for preliminary research contracts released on 2 September 1994, stipulating industry response by 4 November and issue of contract awards by 16 December. … Merger of JAST and CALF resulted in expanded flight test programme, involving two finalists; each to build two demonstrators, one with ASTOVL capability and the other to use conventional take-off and landing (CTOL). Both variants to be built on common assembly line, with production for US and UK military expected to total around 3,000, including just over 750 ASTOVL-configured aircraft. … Lockheed Martin's X-35 design has a trapezoidal wing planform which initially featured foreplanes, although these since deleted; STOVL version embodies a lift fan, shaft-driven by a modified F119 with a vectoring lift/cruise nozzle developed by Rolls-Royce; lift fan replaced by extra fuel in the CTOL version. Lockheed Martin also turned to Russia for technical expertise, purchasing design data from Yakovlev; and used an 86 per cent subscale model (originally developed for the CALF project and fitted with a Pratt & Whitney F100-PW-220 engine plus an Allison shaft-driven lift fan) for testing. This was initially hover tested on an outdoor stand at NASA's Ames Research Center during July and August 1995, before being installed in the 24 × 36 m wind tunnel at Mountain View, California, in September for aerodynamic hover and transition trials which began in December. Wind-tunnel testing concluded on 5 March 1996, marking end of three-year effort to design, build and test large-scale powered model of VTOL version of JSF; this included 196 hours of propulsion system testing in 1995-96, representative of about 2,400 vertical take-offs and landings.

<ref>[http://www.janes.com/defence/air_forces/news/jawa/jawa010103_1_n.shtml "Joint Strike Fighter (JSF)"]. ''Jane’s Air Forces News''; 3 January 2001.</ref>

10) Global Security.org: "F-35 Joint Strike Fighter (JSF) Propulsion"

The exhaust from the engine flows through the 3 Bearing Swivel Nozzle (3BSN). The 3BSN nozzle, developed by Rolls-Royce, was patterned along the lines of the exhaust system on the Yakovlev Yak-141 STOVL prototype that flew at the 1992 Farnborough air show. A US Navy program also developed swivel nozzles in the late 1960's and was proposed for a supersonic STOVL design by Convair (one of the Lockheed Martin heritage companies) in the early 1970's.

<ref>Global Security.org. [http://www.globalsecurity.org/military/systems/aircraft/f-35-prop.htm "F-35 Joint Strike Fighter (JSF) Propulsion"]. Page last modified: 12 July 2006.</ref>

11) Air Force Magazine: "A Strike Fighter for the Future"

The swiveling rear exhaust is a licensed design from the Yakovlev design bureau in Russia, which tried it out on the Yak-141 STOVL fighter.

<ref>Tirpak, John A. [http://www.airforce-magazine.com/MagazineArchive/Pages/2002/January%202002/0102jsf.aspx "A Strike Fighter for the Future"]. ''Air Force Magazine''; January 2002.</ref>

12) Spick, Mike: Brassey's Modern Fighters: The Ultimate Guide to In-Flight Tactics, Technology, Weapons, and Equipment

Externally the X-35 closely resembles a small F-22 which, given its provenance, is hardly surprising. Power is again a modified F119 with a larger fan section. For the CTOL and carrier fighters, this will end in a low observable, axisymmetric nozzle. But for STOVL, a three-piece vectoring nozzle will be used, similar to the “lobsterback” of the Yak-141. The other STOVL difference is a shaft-driven lift-fan just behind the cockpit.

<ref>Spick, Mike. ''Brassey's Modern Fighters: The Ultimate Guide to In-Flight Tactics, Technology, Weapons, and Equipment''. Brassey's; 2002. p. 139. ISBN 157488462X, 9781574884623.</ref>

13) Gunston, Bill & Gordon, Yefim: Yakovlev Aircraft since 1924 – "Yak-43"

Compared with the Yak-41M the Yak-43 would have had much greater internal capacity for fuel and weapons (in most missions none would have been carried externally), improved agility because of the bigger wing, increased mission radius, and very much reduced radar signature. Yakovlev has never stopped working on this and successor projects but, ironically, the only people likely to benefit are Lockheed Martin, which in June 1995 revealed that it was being assisted by a teaming agreement with Yakovlev on its proposal for the V/STOL version of JSF (Joint Strike Fighter) for the US forces and Royal Navy.

<ref>Gunston, Bill & Gordon, Yefim. "Yak-43" entry in ''Yakovlev Aircraft since 1924''. London: Putnam Aeronautical Books; 1997. p. 201. ISBN 0 85177 872 0.</ref>

International participation and specs for the X-35 and X-32

I would like dispute the section on international participation. A) There are no references concerning level 2 and level 3 partners. B) The numbers pertaining to the Canadian contribution do not match those in published sources (please refer to the references 181 and 182 listed in the F-35 webpage). C) I find it highly unlikely that the X-35 would have 9 international participants and that there are none for the X-32 (or that Boeing would stay on the sidelines and not complain). D)Along the jet intake, the current F-35s all have the flags of participating countries according to the amount they contributed to the pgm. To my knowledge, these flags are absent on the X-35.

The Section with the Specs for the X-35 are those of the F-35. My references state that the powerplant on the X-35 is not the PW F135. Both X-35 and X-32 have the PW F119, the F-35 uses the Pratt and Whitney F135. (The encyclopedia of world aircraft. 2002. Silverdale books, pp 305 & 921. Combat aircraft, Nov 2009, vol. 10, no. 6, p 46.--Hschantang (talk) 00:44, 3 February 2011 (UTC) Looking up PW F135 on wikipedia also confirms my claim that the PW F119 was on the demonstrator plane.--Hschantang (talk) 00:50, 3 February 2011 (UTC)

Please make appropriate corrections, but in some ways, this article is now superseded by the Lockheed Martin F-35 Lightning II article. FWiW Bzuk (talk) 14:55, 10 February 2011 (UTC)

The F-35 and X-35 are two different aircraft, as such having a section only for the X-35 is appropriate in my opinion. Correction would mean deletion of the section on international participation.--Hschantang (talk) 21:48, 11 February 2011 (UTC)

I meant a correction for the engine type; as to international participation that appears to be more closely related to that of the production variant. FWiW, the section could remain but more likely belongs in the F-35 article. Bzuk (talk) 23:41, 11 February 2011 (UTC).