F-35 Lightning II
The British government signed on early to the JSF effort, but its officials were previously frustrated by U.S. refusal to hand over sensitive technology that would allow Britain to maintain and upgrade its fighters without U.S. involvement. An agreement made in May 2006 was hoped to resolve this dispute.
For five years, British officials sought an
ITAR waiver to secure greater technology transfer. This request, which has the blessing of the Bush administration, has been repeatedly blocked by U.S. Representative
Henry Hyde, who says the technology may find its way to other countries.
[Spiegel, Peter, MSNBC UK denied waiver on US arms technology. Financial Times (MSNBC reprint). Retrieved 8 February 2006.] (Which is particularly ironic considering Britain's openness with such technology as the
jet engine during the powerplant's formative years.) BAE Systems
CEO Mike Turner complained that the U.S. had denied access to the aircraft's
source code. On
21 December 2005, an article in the
Glasgow Herald quoted the chairman of the
House of Commons Defence Select Committee as saying "the UK might have to consider whether to continue in the program" if no access were granted.
[UK Defence Committee Statement MoD 'slippage' set to leave forces with reduced capability, says committee UK Parliament. Retrieved 8 February 2006.] Lord Drayson,
Minister for Defence Procurement, took a firmer stance during a March 2006 visit to Washington: "We do expect the
software technology transfer to take place. But if it does not take place we will not be able to purchase these aircraft," and he said there was a Plan B if the deal fell through.
[Matt Chapman Britain warns US over jet software codes vunet.com Retrieved 16 March 2006.] This may have been the development of a navalized
Typhoon.
[Evidence to UK Defence Select Committee. Retrieved 1 April 2006.]On
May 27,
2006, President
George W. Bush and Prime Minister
Tony Blair announced that "Both governments agree that the UK will have the ability to successfully operate, upgrade, employ, and maintain the Joint Strike Fighter such that the U.K. retains operational sovereignty over the aircraft."
[Financial Times Bush gives way over stealth fighter. Retrieved 27 May 2006]Australian participation
In May 2005, the Australian government announced that it would delay its planned 2006 decision on buying the JSF to 2008, and thus past the term of the present government. Australia, like the U.K., has insisted it must have access to all software needed to modify and repair aircraft, citing American firms' profiteering on F/A-18 maintenance.
Royal Australian Air Force opinion remains strongly in favor of the JSF, but media, lobby groups and politicians have raised doubts that the aircraft will be ready in time to replace the aging Australian air force fleet of
General Dynamics F-111 strike aircraft and
F/A-18 Hornet fighters. Some critics say the
F-22 Raptor may be a better choice, offering better range,
dogfighting capability, and
supercruise at a cost that may not be much more than the F-35
[Related discussions and analyzes on Air Power Australia web site.] — claims that as of July 2006 are being examined in a parliamentary inquiry.
[Inquiry into Australian Defence Force Regional Air Superiority, Joint Standing Committee on Foreign Affairs, Defence, and Trade, Australian Parliament]In a statement released in early August, 2006, Australian defense minister
Dr. Brendan Nelson revealed that whilst the F-35 still had governmental support, Australia is starting to investigate other possible aircraft should the F-35 prove to be infeasable. Whilst not revealing which aircraft the Australian government were considering, he did rule out the F-22 from Australian considerations.
 |
Boeing X-32 (left) and Lockheed Martin X-35 prior to down-select in 2001, where the X-35 was chosen. DoD photo |
The Joint Advanced Strike Technology (JAST) program was created in 1993, implementing one of the recommendations of a
United States Department of Defense (DoD) "Bottom-Up Review." (The review also led the
Pentagon to continue the
F-22 and F/A-18E/F programs, cancel the Multi-Role Fighter (MRF) and the A/F-X programs, and curtail
F-16 and F/A-18C/D procurement.)
The JAST program office was established on
27 January 1994, to develop
aircraft,
weapons, and
sensor technology with the aim of replacing several disparate U.S. and U.K. aircraft with a single family of aircraft.
Two contracts to develop prototypes were awarded on
16 November 1996, one each to Lockheed Martin and
Boeing. Each firm would produce two aircraft to demonstrate conventional takeoff and landing (CTOL), carrier takeoff and landing (CV version), and short takeoff and vertical landing (
STOVL).
Also in 1996, the U.K.
Ministry of Defence launched the
Future Carrier Borne Aircraft project. This program sought a replacement for the
Sea Harrier (and later the
Harrier GR7); the Joint Strike Fighter was selected in January 2001.
The contract for System Development and Demonstration (SDD) was awarded on
26 October 2001 to Lockheed Martin, whose X-35 beat the
Boeing X-32. DoD officials and the U.K.
Minister of Defence Procurement said the X-35 consistently outperformed the X-32, although both met or exceeded requirements.
On
19 February 2006, the first F-35 (USAF version) was rolled out in
Fort Worth, Texas. The aircraft will undergo extensive ground testing and then flight tests at
Edwards Air Force Base in fall 2006.
Naming
On
7 July 2006, the U.S. Air Force officially announced the name of the F-35: Lightning II,
["Lockheed Martin Joint Strike Fighter Officially Named 'Lightning II.'" Official Joint Strike Fighter program office press release. 7 July 2006.] in honor of Lockheed's
World War II-era twin-prop
P-38 Lightning and the
Cold War-era jet
English Electric Lightning. English Electric's aircraft division was incorporated into
BAC, a predecessor of F-35 partner
BAE Systems. Other names previously listed as contenders were
Kestrel,
Phoenix,
Piasa,
Black Mamba, and
Spitfire II. Lightning II was also an early name for the aircraft that became the
F-22 Raptor. Lightning II can be used in both the U.S. and U.K., which have previous aircraft named "Lightning."
F-35A
 |
The Harrier, which the F-35 is set to replace |
The F-35A is the smallest, lightest version, intended primarily to replace the U.S. Air Force's aging
F-16 Fighting Falcons and
A-10 Thunderbolts. It is the only version with an internal 25mm gun, an upgrade from the 20mm weapon carried by USAF fighters since the
F-4E Phantom.
F-35B
|
An X-35 demonstrating its VTOL capabilities |
The F-35B
STOVL aircraft is intended to replace the vertical flight Harrier with the world's first operational supersonic short-takeoff / vertical-landing fighter. The U.S. Marine Corps will use this to replace both the Harrier and
F/A-18 Hornet fighters with a design similar in size to the Air Force F-35A, trading fuel volume for vertical flight systems. Like the Harrier, guns will be carried in a pod. Vertical flight is by far the riskiest, and in the end, a decisive factor in design.
Lockheed had previously been a pioneer in the V/STOL race. The
XV-4 Hummingbird was built for the U.S. Army. It sought to "augment" available thrust by injecting air into a central chamber, first flying vertically in 1963, but suffering a fatal crash in 1964. It was converted into the XV-4A Hummingbird II as a testbed for separate vertically mounted lift engines, similar to those used in the
Yak-38 Forger. That plane flew and later crashed in 1969
[X-Planes and prototypes by Jim Winchester, Barnes and Noble Books]. Another plane which experimented with a technology used in the F-35 was the
Ryan XV-5, which was also built for the U.S. Army. That plane used fans in the nose, and each wing, covered by doors which resembled half garbage can lids when raised. However, it crashed twice, and proved to generate a disappointing amount of lift, and was difficult to transition to horizontal flight. Of dozens of
VTOL and
V/STOL designs tried from the 1950s to 1980s, only the subsonic Harrier and
Yak-38 Forger reached operational status, with the Forger being withdrawn after the fall of the Soviet Union.
No previous supersonic fighter was ever made into a practical V/STOL aircraft. Boeing had studied another odd-looking supersonic fighter in the 1960s which never made it beyond photos in
Aviation Week. Rockwell built, and then abandoned, the
XFV-12 supersonic fighter which had an unusual wing which opened up like
Window blinds when deployed for vertical flight. It never generated enough lift to get off the ground despite 30,000 lb of thrust. The French had a nominally Mach 2
Dassault Mirage IIIV fitted with no less than 8 lift engines that flew (and crashed), but did not have enough space for fuel or payload for combat missions. The German
EWR VJ 101 used swiveling engines mounted on the wingtips with fuselage mounted lift engines, but never transitioned to supersonic flight.
The experimental Mach 1.7 (not much slower than the F-35)
Yakovlev Yak-141 did not find an operational customer, but it was the first to use a rotating rear main nozzle like the F-35B. Instead of lift engines, or front fan nozzles, the F-35B uses a complex, never before tried
Remote Shaft-Driven Lift Fan. Somewhat like a
turboprop embedded into the fuselage, the main shaft power is diverted forward via a clutch-and-bevel gearbox to a vertically mounted,
contra-rotating lift fan located forward of the main engine in the center of the aircraft. Bypass air from the turbofan exhausts through a pair of roll-post nozzles on either side of the fuselage, while the lift fan balances the rotating tail nozzle. In effect, the F-35B power plant acts as a flow multiplier, much as a
turbofan achieves efficiencies by moving unburned air at a lower velocity, and getting the same effect as the Harrier's huge, but supersonically impractical main fan. Like lift engines, this added machinery is dead weight during flight, but increased lifting power increases takeoff payload by even more. The cool fan also reduces the harmful effects of hot, high-velocity air which can harm runway pavement or an aircraft carrier deck. Though risky and complicated, it was made to work to the satisfaction of DOD officials. Unlike Boeing's entry, the prototype was able to demonstrate a historic flight starting with a vertical takeoff, transitioning to supersonic flight, and ending with a vertical landing.
During concept definition, two Lockheed airframes were flight-tested: the Lockheed X-35A (which was later converted into the X-35B), and the larger-winged X-35C.
[Joint Strike Fighter official site - History page] Both the
Boeing X-32 and X-35 power plants were derived from Pratt & Whitney's
F119, with the STOVL variant of the latter incorporating a
Rolls Royce Lift Fan module.
|
The X-35 fighter in National Air & Space Museum |
Boeing's X-32 STOVL variant redirected engine exhaust gases to thrust-vectoring nozzles to provide lift during a STOVL landing, similar to the Harrier. But the unaugmented lift was deemed inferior compared to the Lockheed design. In addition, some of Boeing's hover-tests were marred with engine surge and fade problems determined to be caused by the engine's hot exhaust being ingested in the large forward inlet. While some fixes were intended for developmental aircraft, the short distance from the inlet to the hot exhaust virtually ensured that this problem could not be permanently resolved in the Boeing design. Unlike Lockheed's plane, the Boeing prototype could not transition from vertical to conventional flight, and had to be fitted with different intakes. The Boeing prototype, which had a delta wing, also differed from the final design, which had a conventional tail for added agility, though it was judged close enough for evaluating the crucial vertical flight capability.
Finally, the large front air intake was widely regarded as both ugly and inefficient. Critics said Boeing designed an aircraft "only its mother would love", violating the
maxim "if it looks good, it flies good" (which probably refers to the
aesthetic qualities of highly
streamlined designs). It should be noted that one of the most successful U.S. fighter designs of all time, the
F-4 Phantom, was also dubbed the "Double Ugly".
Arguably the most persuasive demonstration of the X-35's capability was the final qualifying Joint Strike Fighter flight trials, in which the X-35B STOVL aircraft took off in less than 500 feet, went supersonic, and landed vertically.
[PBS: Nova transcript "X-planes"]Elements of the F-35 design were pioneered by the
F-22 Raptor. If anything, by contrast with Boeing's challenged aesthetics, the F-35 appears to be a trimmer and sleeker one-engine sibling of the two-engine F-22. The exhaust duct design was inspired by the
Yak-141 prototype.
[AIAA article] Lockheed had a teaming relationship with the
Yakovlev Design Bureau on their bid for the Joint Advanced Strike Technology competition.
[John Hayles. Yakovlev Yak-41 'Freestyle'. Aeroflight. March 28, 2005. Accessed August 6, 2006.] This has fueled speculation that the overall design of the F-35 was heavily influenced by the
Yak-141.
Stealth technology makes the aircraft hard to detect as it approaches short-range tracking
X-band radar, although its rear is much more easily spotted by X-band, and the aircraft is not stealthy to long-range
L-band radar.
Some specific improvements over current aircraft are:
* Durable, low-maintenance
stealth technology* Integrated avionics and sensor fusion that combine information from off- and onboard sensors to increase the
pilot's situational awareness and improve identification and weapon delivery, and to relay information quickly to other C2 nodes.
* Low life-cycle costs
The F-35, which will have helmet-mounted displays, will be the first combat aircraft in modern times without a
heads-up-display. (Although Swedish manufactured 4th generation multi-role jet
JAS 39 Gripen already incorporates a helmet mounted display system)
F-35C
The Naval F-35C variant will replace the
F/A-18A, -B, -C, and -D Hornets, which replaced subsonic but long-ranged attack types such as the
A-7 Corsair and
A-6 Intruder. It will also serve as a stealthy complement to the
F-15 Eagle-sized
F/A-18E/F Super Hornet. It will have a larger, folding wing and larger control surfaces for improved low-speed control, and stronger landing gear for the stresses of carrier landings. The larger wing area provides increased range and payload, with twice the range on internal fuel compared with the F-18C, achieving much the same goal as the much heavier Super Hornet. The U.S. Navy plans to purchase 480 JSF.
[http://www.fas.org/man/dod-101/sys/ac/f-35.htm FAS F-35]Directed-energy weapons
Directed-energy weapons may be installed in conventional takeoff F-35 Lightning IIs, whose lack of a direct lift fan frees up about 100 ft³ (2.8 m³) of space and whose engine provides more than 27,000
hp (20
MW) for electrical power.
[Fulghum, David A. (8 July 2002). Lasers Being Developed for F-35 and AC-130. Aviation Week and Space Technology Retrieved 8 February 2006.] Some concepts, including
solid state lasers and high-power
microwave beams, may be nearing operational status.
[Fulghum, David A. (22 July 2002). Lasers, HPM Weapons Near Operational Status. Aviation Week and Space Technology Retrieved 8 February 2006.]The JSF program was designed to replace the F-16, A-10, F/A-18 and AV-8B fleet of tactical fighter aircraft. Joint Strike Fighter critics say that like the aircraft it is replacing, it has insufficient range to replace dedicated bombers; and as primarily a strike platform, its inability to
supercruise limits it as an air defense platform, and as a new aircraft, that it is almost certain to suffer cost overruns and lengthy development delays. Indeed, through 2004, the JSF's total projected cost had risen 23% to US$244 billion, and as of April 2006 the Pentagon is projecting the budget to rise to US$276.4 billion. They say some militaries may need to buy other kinds of aircraft to fill the gap between the retirement of older aircraft and the arrival of the JSF.
The JSF brings up the ghost of "commonality". A
Reuters report in 2005 said that the Pentagon was seeking to cancel the Air Force version and adopt the larger Navy version because a larger winged JSF made more more sense for the USAF needs than an aircraft with the smaller wings of the STOVL variant.
*
Robert McNamara was best remembered among fighter circles for the original
F-111 "commonality" debacle of the 1960s. The money-saving vision of the most advanced and versatile fighter in history was marred by the total failure of the Naval
F-111B while the Air Force version was limited to the narrow all-weather strike role. However, one of
Robert McNamara's better calls was to direct the USAF to adopt the Navy's
F-4 Phantom II in the 1960s. The Phantom would be the only fighter to serve equally well in all roles and with all flying services, clearly the preferred "commonality" outcome for the F-35. Navy fighters tend to be heavier and more expensive compared to land-based fighters, as is the case for the
Hornet vs. the
F-16, but there would be cost savings in building only one CTOL version. Other stories have been published that Boeing is preparing a stealthier version of the Super Hornet should the F-35 be delayed or fail.
Close air support theorists, especially those with experience flying the
A-10 on those missions, are vocally skeptical about the F-35's capacity to carry out that role. They point to the claim during procurement of the
F-16 that it would replace the A-10, which it did not, and to the F-35's similar shortcomings for the close air support mission, specifically its small gun and ammunition capacity, and the tight constraints on the number and variety of bombs and missiles it can carry in its stealth configuration -- not an issue when carrying external stores in a non-stealthy A-10-like configuration.
[Grange, David, Brig Gen, USA (Ret.) et al. (12 June 2006). Return of the Air Commandos: USAF Close Air Support for the 21st Century. Combat Reform Retrieved 19 July 2006.]Its defenders say the JSF was never intended to replace bombers or be an air defense platform, and they say a thorough requirements definition process with years of analysis and international participation has mitigated cost and schedule concerns. The potential solid state laser is also offered as an advantage for the close air support role, since
aerial refueling would essentially also rearm the laser, which could be used even with enemy ground forces located too close to friendly ground forces for employment of explosive armaments.
Proponents say the multi-role design philosophy has been proven in combat by the F-16 Fighting Falcon and the F/A-18 Hornet, and point to several nations, mainly F-16 and F/A-18 users, that have committed substantial sums to become minority partners in the JSF manufacturing team. They say that even without substantial performance advances over existing aircraft, the F-35's stealthiness and information warfare technology make it an enticing product.
The program's advocates see the JSF's joint-development concept as an opportunity to break out of the decades-old pattern of U.S. military aircraft procurement, allowing commonality and saving development and operating costs. This follows the philosophy behind the
SEPECAT Jaguar and
Panavia Tornado international development programs. Accordingly, JSF is the first U.S. aircraft program to consider
cost as an independent variable. Unlike earlier programs in which extra features always boosted the cost, such changes are not permitted in JSF development.
JSFs will feed diagnostic information into the ground-based Autonomic Logistic Information System, built by Lockheed Martin Simulation Training and Support, to make the aircraft less expensive to operate and maintain.
Cost-to-weight ratio
The major technical problem was the F-35B variant's
mass, which was reported to be one metric ton (2,200
pounds) or 8%, over the target, threatening performance requirements.
Lockheed Martin solved the weight problem by adding engine thrust and shedding more than a ton by: thinning the aircraft's skin; shrinking the weapons bay and vertical tails; redesigning the wing-mate joint, portions of the electrical system, and the portion of the aircraft immediately behind the
cockpit; and rerouting some thrust from the roll-post outlets to the main nozzle.
[Fulghum, David A.; Wall, Robert (19 September 2004). USAF Plans for Fighters Change. Aviation Week and Space Technology Retrieved 8 February 2006.]The smaller weapons bay will return the F-35B to its original 2 × 1000 lb (450 kg) internal-weapons carriage. This is not expected to hinder
close air support missions, which are likely to take place after enemy air defenses are down, but may make the "B" variant different from the other two, boosting costs.
The internal weapons are stored offline to the external air flow, which will complicate weapons certification testing — no demonstrations of weapons delivery capability were done prior to contract award.
Speculated USAF STOVL Purchase
As costs grow, there have been rumors about canceling the F-35B variant. However, U.S. operations in
Afghanistan have highlighted a need for jump jets in unimproved battlespaces, leading to a hazy USAF "commitment" to buy F-35B and preserve the economic rationale to produce the STOVL jets needed by the USMC, RN, and RAF.
The USAF has reportedly investigated buying up to 216 STOVL F-35s, enough to outfit three
wings. One option discussed and discarded was a fourth, F-35D, variant that would have a different propulsion system to increase emphasis on
STOL capability over that of
VTOL, a larger wing to allow more fuel, an interior cannon (as opposed to the USMC external gun pod), and changes to in-flight refueling (sacrificing compatibility with Air Force
KC-135 Stratotankers, which only use the flying boom in-flight refueling system, but not the
KC-10 Extender). Should USAF's new tanker program include substantial hose-and-drogue refueling capability, the feasibility of the Air Force operating the F-35B will increase.
Future of the JSF
In the view of some analysts, the future will be dominated by
pilotless aircraft, which has led to speculation that the F-35 might be "the last manned combat aircraft".
["UK's defense industrial strategy envisages end of manned combat aircraft" Aviation, Defense & Space article, December 26, 2005] ["JSF - The last manned fighter?" BBC Article, 26 October, 2001] |
X-35 |
Some information is estimated.
* Spick, Mike (2002),
The Illustrated Directory of Fighters. Salamander ISBN 1-84065-384-1
* Kopp, Carlo; Goon, Peter,
Australian Aviation,
JSF related articles.
*
Official homepage*
Official Industrial Team homepage*
F-35 Web Page at the Royal Air Force Website*
Data on the F-35 Joint Strike Fighter (JSF) by the Federation of American Scientists*
Global Security on the F-35 JSF Program*
JSF advanced military gas turbine engine Test Stand C-14 (West Palm Beach, Florida)*
PBS NOVA: Battle of the X-Planes (JSF selection)**
Inside the first ever approved filming of an U.S. weapons competition*
F-35 JSF news articles*
F-35 photo gallery*
British threats of disassociation with the program*
Air Power Australia JSF Page*
Britain in clash over US fighter secrets The Times, March 15, 2006
*
Smiths Aerospace JSF Project Page*
Carriage of weapons on pylons and bays on F-35
