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Joint Strike Fighter

posted by Jiri Wagner

The Joint Strike Fighter, the JSF, is being developed for the US Air Force, Navy and Marine Corps and the UK Royal Navy. It is estimated that approximately 3,000 aircraft are planned for the US Air Force, Navy and Marine Corps and the UK Royal Navy with a further requirement for 2,000 export aircraft over the life of the JSF programme.

Program

The Concept Demonstration Phase of the programme began in November 1996 with the award of contracts to two consortia, one led by Boeing Aerospace and the other by Lockheed Martin. The contracts involve each of the consortia building demonstrator aircraft and refining the concepts for three different configurations of next generation fighter aircraft. Flight evaluation of the demonstrator aircraft is to take place in 2000. One of the two consortia will then be selected in 2001 for the development and manufacture of all three variants of Joint Strike Fighter. The Joint Strike Fighter is expected to enter service in 2008. The JSF program will demonstrate two competing weapon system concepts for a tri-service family of aircraft to affordably meet these service needs: USAF-Multi-role aircraft (primarily air-to-ground) to replace F-16 and A-10 and to complement F-22. The Air Force JSF variant poses the smallest relative engineering challenge. The aircraft has no hover criteria to satisfy, and the characteristics and handling qualities associated with carrier operations do not come into play. As the biggest customer for the JSF, the service will not accept a multirole F-16 fighter replacement that doesn't significantly improve on the original. USN-Multi-role, stealthy strike fighter to complement F/A-18E/F. Carrier operations account for most of the differences between the Navy version and the other JSF variants. The aircraft has larger wing and tail control surfaces to better manage low-speed approaches. The internal structure of the Navy variant is strengthened up to handle the loads associated with catapult launches and arrested landings. The aircraft has a carrier-suitable tailhook. Its landing gear has a longer stroke and higher load capacity. The aircraft has almost twice the range of an F-18C on internal fuel. The design is also optimized for survivability. USMC-Multi-role Short Take-Off & Vertical Landing (STOVL) strike fighter to replace AV-8B and F/A-18A/C/D. The Marine variant distinguishes itself from the other variants with its short takeoff/vertical landing capability. UK-STOVL (supersonic) aircraft to replace the Sea Harrier. Britain's Royal Navy JSF will be very similar to the U.S. Marine variant.

LOCKHEED MARTIN JSF

The Lockheed Martin JSF team includes Northrop Grumman, Pratt and Whitney, Rolls-Royce, Allison, and BAE Systems. The demonstrator aircraft is under construction at Lockheed Martin Skunk Works. The first flight engine was installed in the X-35A demonstrator in December 1999.

Construction

The three variant models of the Lockheed Martin JSF (designated X-35) are of similar appearance and have common structural geometries. In order to minimise the structural weight and complexity of assembly, the wingbox section integrates the wing and fuselage section into one piece. The major sections of the fuselage contain common parts or closely related parts determined by the operational requirements of the three aircraft. The canopy, radar, ejection system and most of the avionics are common to the three variants. The advanced electronically scanned array radar is by Northrop Grumman. Sanders and Litton Amecon are to supply the electronic countermeasures equipment. The electro-optical targeting system will be supplied by Lockheed Martin Missiles and Fire Control. The DAIRS (Distributed Aperture Infrared Sensor) thermal imaging system is being developed by Northrop Grumman for JSF. DAIRS consists of multiple infrared cameras which provide 360 degree coverage for situational awareness, missile warning, infrared search and track and navigation. Vision Systems International (a partnership between Kaiser Electronics and Elbit of Israel) are to provide the advanced helmet-mounted display.

Stealth

The aircraft structure incorporates proven stealth features. The sweep angles are identical for the leading and trailing edges of the wing and tail, known as planform alignment. The fuselage and canopy have sloping sides to deflect hostile radar emissions. The seam of the canopy and the weapon bay doors are sawtoothed and the vertical tails are canted at an angle. The serpentine path of the inlet duct covers the forward section of the engine from surveillance radar signals and reduces the radar cross section of the front of the aircraft.

Cockpit

The cockpit will be equipped with colour flat panel displays and helmet mounted displays. Symbols for targeting and navigation are displayed on the pilot's visor and not on a head up display. Stereo speakers are built into the helmet and information such as missile warning are audibly presented with directional discrimination.

Propulsion

All three aircraft variants are powered by the Pratt and Whitney JSF119-611 engine, a derivative of the Pratt and Whitney F119.

Air Force variant

The performance level of the air force version aircraft matches or exceeds that of the F-16 aircraft, and greatly exceeds it in terms of the level of stealth, range on internal fuel and installation of advanced avionics.

The air force variant has an internally mounted gun and is equipped with internally mounted infrared sensors and a laser designator.

STOVL aircraft for US Marien Corps and UK Royal Navy

The STOVL propulsion system is designed to minimise noise and heat on the deck of the carrier and on the aircraft. During short takeoff and vertical landings a large proportion of the downward thrust is provided with cool air from the lift fan mounted in the forward fuselage and driven by a drive shaft connected to the main engine. The lift fan arrangement increases the total thrust of the engine and has been developed by Rolls Royce Defence North America (formerly Allison). 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 VSTOL capability.

The STOVL variant has completed environmental testing at BAE Systems facilities in the UK.

The Marine variant of JSF is similar to the Air Force variant but with shorter range. The Marine variant has no internal gun but an external gun can be fitted as a mission option.

Carrier based naval JSF

The internal structure of the naval version is very strong to withstand the high loading of catapult assisted launches and tailhook arrested landings. The landing gear has a higher load capacity and a longer stroke. The aircraft has larger wing and tail control surfaces for improved control on low speed approaches for carrier landing and larger range and payload. Larger leading edge flaps and foldable wingtip sections provide a larger wing area.

The aircraft has an internally mounted laser designator and internal gun.

 

BOEING JSF

Boeing's team includes: Raytheon Systems Co, Pratt &Whitney, Rolls Royce, Messier-Dowty, BAE Systems and Flight Refuelling Ltd. Boeing are to build and flight test two aircraft - X32A the USAF variant and the US Navy carrier variant, and X32B the STOVL variant for USMC, UK RN and RAF. Final assembly of the X-32A began in March 1999 and has successfully completed structural proof testing.

X32B is based on the established Rolls Royce direct lift concept currently used in the Harrier aircraft of the USMC and UK Royal Navy.

Boeing completed the final design review of the X-32 demonstrators and made some design alterations to the basic flight qualities including: a refined empennage with horizontal tails for additional control power; a modification to the wing's trailing edge while retaining the same high leading edge sweep of the delta wing, and an aft-swept chin inlet.Both demonstrators were shown by Boeing for the first time in December 1999.

The primary propulsion system for all three JSF variants will be the Pratt and Whitney JSF119-PW-614 engine with a thrust-vectoring nozzle, a derivative of the Pratt and Whitney F119 engine being used for the US Air Force F-22 fighter aircraft.

The gun system for the Boeing JSF will be the Advanced 27 mm Cannon being developed by a team led by Boeing, with Mauser-Werke of Germany and Primex Technologies and Western Design of USA. The cannon is a single barrel, gas-operated lightweight revolver gun that fires electrically-primed ammunition at 1800 shots per minute.

F-35B first flight (vertical takeoff and landing)

From: Air Force Technology