F-35 JSF JOINT STRIKE FIGHTER, USA

The Joint Strike Fighter, the JSF, is being developed by Lockheed Martin Aeronautics Company for the US Air Force, Navy and Marine Corps and the UK Royal Navy. The stealthy, supersonic multi-role fighter is to be designated the F-35. The JSF is being built in three variants: a conventional take-off and landing aircraft (CTOL) for the US Air Force; a carrier based variant (CV) for the US Navy; and a short take-off and vertical landing (STOVL) aircraft for the US Marine Corps and the Royal Navy. A 70 – 90% commonality is required for all variants.

The requirement is for: USAF F-35A –air-to-ground strike aircraft, replacing F-16 and A-10, complementing F-22 (1763); USMC F-35B – STOVL strike fighter to replace F/A-18B/C and AV-8B (480); UK RN F-35C – STOVL strike fighter to replace Sea Harriers (60); US Navy F-35C – first-day-of-war strike fighter to replace F/A-18B/C and A-6, complementing the F/A-18E/F (480 aircraft). In January 2001, the UK MOD signed a memorandum of understanding to co-operate in the SDD (System Development and Demonstration) phase of JSF and, in September 2002, selected the STOVL variant to fulfil the Future Joint Combat Aircraft (FJCA) requirement. Following the contract award, other nations signed up to the SDD phase are: Australia, Canada, Denmark, Italy, Netherlands, Norway, Singapore and Turkey.

The Concept Demonstration Phase of the programme began in November 1996 with the award of contracts to two consortia, led by Boeing Aerospace and Lockheed Martin. The contracts involved the building of demonstrator aircraft for three different configurations of JSF, with one of the two consortia to be selected for the development and manufacture of all three variants.

In October 2001, an international team led by Lockheed Martin was awarded the contract to build JSF. An initial 22 aircraft (14 flying test aircraft and eight ground-test aircraft) will be built in the programs System Development and Demonstration (SDD) phase. Flight testing will be carried out at Edwards Air Force Base, California, and Naval Air Station, Patuxent River, Maryland. In April 2003, JSF completed a successful Preliminary Design Review (PDR). The Critical Design Review has been postponed from April 2004 to February 2006. The first CTOL F-35A began final assembly in May 2005 and is scheduled for its first flight in August 2006. The STOVL F-35B first flight is set for 2007. The F-35A fighter is expected to enter service in 2008, the F-35B in 2012.

In September 2004, Lockheed Martin announced that, following concerns over the weight of the STOVL F-35B, design changes had reduced the aircraft weight by 1,225kg while increasing propulsion efficiency and reducing drag. The weight requirements will also call for a smaller internal weapons bay than on the other variants.

The Lockheed Martin JSF team includes Northrop Grumman, BAE Systems, Pratt and Whitney and Rolls-Royce. Final assembly of the aircraft will take place at Lockheed Martin's Fort Worth plant in Texas. Major subassemblies will be produced by Northrop Grumman Integrated Systems at El Segundo, California and BAE Systems at Samlesbury, Lancashire, England. BAE Systems is responsible for the design and integration of the aft fuselage, horizontal and vertical tails and the wing-fold mechanism for the CV variant, using experience from the Harrier STOVL programme.

DESIGN

In order to minimise the structural weight and complexity of assembly, the wingbox section integrates the wing and fuselage section into one piece. To minimise radar signature, sweep angles are identical for the leading and trailing edges of the wing and tail (planform alignment). The fuselage and canopy have sloping sides. The seam of the canopy and the weapon bay doors are sawtoothed and the vertical tails are canted at an angle.

The Marine variant of JSF is very similar to the Air Force variant, but with a slightly shorter range because some of the space used for fuel is used for the lift fan of the STOVL propulsion system. The main differences between the naval variant and the other versions of JSF are associated with the carrier operations. The internal structure of the naval version is very strong to withstand the high loading of catapult assisted launches and tailhook arrested landings. The aircraft has larger wing and tail control surfaces for low speed approaches for carrier landing. Larger leading edge flaps and foldable wingtip sections provide a larger wing area, which provides an increased range and payload capacity.

The canopy (supplied by GKN Aerospace), radar and most of the avionics are common to the three variants.

COCKPIT

L-3 Display Systems is developing the Panoramic Cockpit Display System, which will include 20in x 8in active matrix liquid crystal displays and display management computer. The following will also supply F-35 avionics systems: BAE Systems Avionics - side stick and throttle controls; Vision Systems International (a partnership between Kaiser Electronics and Elbit of Israel) - advanced helmet-mounted display; BAE Systems Platform Solutions - alternative design helmet-mounted display, based on the binocular helmet being developed for the Eurofighter Typhoon; Ball Aerospace - Communications, Navigation and Integration (CNI) integrated body antenna suite (one S-band, two UHF, two radar altimeter, three L-band antennas per aircraft); Harris Corporation - advanced avionics systems, infrastructure, image processing, digital map software, fibre optics, high speed communications links and part of the Communications, Navigation and Information (CNI) system; Honeywell - radar altimeter, inertial navigation / global positioning system (INS/GPS) and air data transducers; Raytheon - 24-channel GPS with digital anti-jam receiver (DAR).

WEAPONS

Weapons are carried in two parallel bays located in front of the landing gear. Each weapons bay is fitted with two hardpoints for carrying a range of bombs and missiles. Weapons to be cleared for internal carriage include: JDAM (Joint Direct Attack Munition), CBU-105 WCMD (Wind-Corrected Munitions Dispenser) for the Sensor-Fuzed Weapon, JSOW (Joint StandOff Weapon), Paveway II guided bombs, AIM-120C AMRAAM air-to-air missile; for external carriage: JASSM (Joint Air-to-Surface Standoff Missile), AIM-9X Sidewinder and Storm Shadow cruise missile.

In September 2002, General Dynamics Armament and Technical Products was selected as the gun system integrator. The air force variant has an internally mounted gun. The Carrier and Marine variants can have an external gun pod fitted.

TARGETING

Lockheed Martin Missile & Fire Control and Northrop Grumman Electronic Sensors and Systems are jointly responsible for the JSF electro-optical system. A Lockheed Martin electro-optical targeting system (EOTS) will provide long-range detection and precision targeting, along with the Northrop Grumman DAS (Distributed Aperture System) thermal imaging system. EOTS will be based on the Sniper XL pod developed for the F-16, which incorporates a mid-wave third generation FLIR, dual mode laser, CCD TV, laser tracker and laser marker. BAE Systems Avionics in Edinburgh, Scotland will provide the laser systems. DAS consists of multiple infrared cameras (supplied by Indigo Systems of Goleta, California) providing 360º coverage using advanced signal conditioning algorithms. As well as situational awareness, DAS provides navigation, missile warning and infrared search and track (IRST). EOTS is embedded under the aircraft’s nose, and DAS sensors are fitted at multiple locations on the aircraft.

RADAR

Northrop Grumman Electronic Systems is developing the advanced electronically scanned array (AESA) AN/APG-81 multi-function radar. The AN/APG-81AESA will combine an integrated radio frequency subsystem with a multifunction array. The radar system will also incorporate the agile beam steering capabilities developed for the APG-77. Northrop Grumman delivered the first radar to Lockheed Martin in March 2005 for flight testing.

COUNTERMEASURES

BAE Systems Information & Electronic Warfare Systems (IEWS) will be responsible for the JSF integrated electronic warfare suite, which will be installed internally and have some subsystems from Northrop Grumman. BAE is developing a new digital radar warning receiver for the F-35.

SYSTEMS

The following will supply the F-35 avionics systems: BAE Systems Avionics - side stick and throttle controls; Vision Systems International (a partnership between Kaiser Electronics and Elbit of Israel) - advanced helmet-mounted display; BAE Systems Platform Solutions - alternate design helmet-mounted display, based on the binocular helmet being developed for the Eurofighter Typhoon; Ball Aerospace - Communications, Navigation and Information (CNI) integrated body antenna suite (one S-band, two UHF, two radar altimeter, three L-band antennas per aircraft); Harris Corporation - advanced avionics systems, infrastructure, image processing, digital map software, fibre optics, high-speed communications links and part of the Communications, Navigation and Information (CNI) system; Honeywell - radar altimeter, inertial navigation / global positioning system (INS/GPS) and air data transducers; Raytheon - 24-channel GPS (Global Positioning System) with digital anti-jam receiver (DAR).

Other suppliers will include: ATK Composites - upper wing skins; Vought Aircraft Industries - lower wing skins; Smiths Aerospace - electronic control systems, electrical power system (with Hamilton Sundstrand), integrated canopy frame; Honeywell - landing system wheels and brakes, Onboard Oxygen-Generating System (OBOGS), engine components, power and thermal management system driven by integrated Auxiliary Power Unit (APU); Parker Aerospace - fuel system, hydraulics for lift fan, engine controls and accessories; Moog Inc - primary flight control Electrohydrostatic Actuation System (EHAS), leading edge flap drive system and wing-fold system; EDO Corporation - pneumatic weapon delivery system; Goodrich - lift-fan anti-icing system; Stork Aerospace - electrical wiring.

PROPULSION

Early production lots of all three variants will be powered by the Pratt and Whitney afterburning turbofan F-135 engine, a derivative of the F119 fitted on the F-22. Following production aircraft will be powered by either the F135 or the F-136 turbofan being developed by General Electric and Rolls-Royce. The F136 engine began ground testing in July 2004. Delivery of the first production engine is scheduled for 2011. Each engine will be fitted with two BAE Systems Full Authority Digital Electronic Control (FADEC) systems. Hamilton Sundstrand is providing the gearbox.

On the F-35B, the engine is coupled with a shaft-driven lift fan system for STOVL propulsion. The counter-rotating lift fan, developed by Rolls-Royce Defence, can generate more than 20,000lb of thrust. Doors installed above and below the vertical fan open as the fin spins up to provide vertical lift. The main engine has a three bearing swivelling exhaust nozzle. The nozzle, which is supplemented by two roll control ducts on the inboard section of the wing, together with the vertical lift fan provide the required STOVL capability.