The Lockheed Martin F-35 Lightning II is a family of single-seat, single-engine, fifth generation multirole fighters under development to perform ground attack, reconnaissance, and air defense missions with stealth capability.

The F-35 has three main models; the F-35A is a conventional takeoff and landing variant, the F-35B is a short take off and vertical-landing variant, and the F-35C is a carrier-based variant.

The F-35 is descended from the X-35, the product of the Joint Strike Fighter (JSF) program. JSF development is being principally funded by the United States, with the United Kingdom and other partner governments providing additional funding.

The partner nations are either NATO members or close U.S. allies. It is being designed and built by an aerospace industry team led by Lockheed Martin. The F-35 carried out its first flight on 15 December 2006.

The United States plans to buy a total of 2,443 aircraft to provide the bulk of its tactical airpower for the U.S. Air Force, Marine Corps and Navy over the coming decades.

The United Kingdom, Italy, Netherlands, Australia, Canada, Norway, Denmark, Turkey, Israel and Japan are part of the development program and may equip their air services with the F-35.

The F-35′s sensor and communications suite is intended to facilitate situational awareness, command-and-control and network-centric warfare capability.

The main sensor on board the F-35 is its AN/APG-81 AESA-radar, designed by Northrop Grumman Electronic Systems.

It is augmented by the Electro-Optical Targeting System (EOTS) mounted under the nose of the aircraft, designed by Lockheed Martin. This gives the same capabilities as the Lockheed Martin Sniper XR while avoiding making the aircraft more easily detectable.

Six additional passive infrared sensors are distributed over the aircraft as part of Northrop Grumman’s AN/AAQ-37 distributed aperture system (DAS), which acts as a missile warning system, reports missile launch locations, detects and tracks approaching aircraft spherically around the F-35, and replaces traditional night vision goggles for night operations and navigation.

All DAS functions are performed simultaneously, in every direction, at all times. The F-35′s Electronic Warfare systems are designed by BAE Systems and include Northrop Grumman components.

Some functions such as the Electro-Optical Targeting System and the Electronic Warfare system are not usually found integrated on fighters.

The AN/ASQ-239 (Barracuda) system is an improved version of the AN/ALR-94 EW suite on the F-22. The AN/ASQ-239 provides sensor fusion of RF and IR tracking functions, basic radar warning, multispectral countermeasures for self-defense against threat missiles, situational awareness and electronic surveillance. It uses 10 RF antennae over the leading and trailing edges of the wing leading and trailing edges of the horizontal tail.

The F-35 does not need to be physically pointing at its target for weapons to be successful. This is possible because of sensors that can track and target a nearby aircraft from any orientation, provide the information to the pilot through his helmet (and therefore visible no matter which way they are looking), and provide the seeker-head of a missile with sufficient information. Recent missile types provide a much greater ability to pursue a target regardless of the launch orientation, called “High Off-Boresight” capability, although the speed and direction in which the munition is launched affect the effective range of the weapon. Sensors use combined radio frequency and infra red (SAIRST) to continually track nearby aircraft while the pilot’s helmet-mounted display system (HMDS) displays and selects targets. The helmet system replaces the display suite-mounted head-up display used in earlier fighters.

The F-35′s systems provide the edge in the “observe, orient, decide, and act” OODA loop; stealth and advanced sensors aid in observation (while being difficult to observe), automated target tracking helps in orientation, sensor fusion simplifies decision making, and the aircraft’s controls allow the pilot to keep their focus on the targets, rather than the controls of their aircraft.

The communications, navigation and identification (CNI) suite is designed by Northrop Grumman and includes the Multifunction Advanced Data Link (MADL). The F-35 will be the first jet fighter that has sensor fusion that combines both radio frequency and IR tracking for continuous target detection and identification in all directions which is shared via MADL to other platforms without compromising low observability. However the F-35 also includes the non-stealthy Link 16 for communications with legacy systems for missions including Close air support.

The F-35 has been designed with synergy between sensors as a specific requirement, with the “senses” of the aircraft expected to provide a more cohesive picture of the reality around it, and be available in principle for use in any possible way, and any possible combination with one another. All of the sensors feed directly into the main processors to support the entire mission of the aircraft. For example the AN/APG-81 functions not just as a multi-mode radar, but also as part of the aircraft’s electronic warfare system. Northrop Grumman is offering the APG-81 as an upgrade for legacy aircraft, but because the “back end processing” on the F-35 is done in software on the main processors, the upgrade version requires their Scalable Agile Beam Radar electronics to operate on other aircraft.

Unlike previous aircraft, such as the F-22, all software for the F-35 is written in C++ for faster code development. The Integrity DO-178B real-time operating system (RTOS) from Green Hills Software runs on COTS Freescale PowerPC processors.The final Block 3 software for the F-35 is planned to have 8.6 million lines of software code.

The scale of the program has led to a software crisis as officials continue to discover that additional software needs to be written, General Norton Schwartz has said that the software is the biggest factor that might delay the USAF’s initial operational capability which is now scheduled for April 2016. Michael Gilmore, Director of Operational Test & Evaluation, has written that, “the F-35 mission systems software development and test is tending towards familiar historical patterns of extended development, discovery in flight test, and deferrals to later increments.

The F-35′s electronic warfare systems are intended to detect hostile aircraft first, which can then be scanned with the electro-optical system and action taken to engage or evade the opponent before the F-35 is detected. The CATbird avionics testbed for the F-35 program has proved capable of detecting and jamming F-22 radars.

The F-35 was previously considered a platform for the Next Generation Jammer, but attention has shifted to the use of unmanned platforms. Source:Wikipediae