F-35 Joint Strike Fighter
The F-35 Joint Strike Fighter (JSF) is the name for a family of multirole fighters being built in three versions:
- F-35A Lightning II: Conventional takeoff and landing, not carrier-capable, specifically for United States Air Force requirements. Will replace A-10 Warthog and F-16 Fighting Falcon; complements F-22 Raptor. In addition to the U.S., to be used by Australia, Canada, Denmark, the Netherlands (may be reconsidered), Norway and Turkey; possibly Israel. "International partner versions" may lack some capabilities of the U.S. production models.
- F-35B Lightning II: Short takeoff and vertical landing, meeting the environmental requirements of shipboard use, but not catapulted. To be used by the Italian Navy, U.K. Royal Air Force and Royal Navy, United States Marine Corps; will replace assorted versions of the Harrier aircraft.
- F-35C Lightning II: Conventional takeoff and landing, carrier-capable and catapult-launched, for United States Navy requirements. Will replace F-18 Hornet but not necessarily F-18 Super Hornet
Part of the JSF competitive propulsion system program, within the JSF program, had been for General Electric/Rolls Royce to develop an F136 engine, which is intended to provide JSF users a competitive choice between the existing United Technologies' Pratt & Whitney division's F135 engine and the F136 engine. Congress has supported this initiative since 1995, but the Department of Defense has not included funding for the competitive propulsion system program in its budget requests since 2006. Since then, Congress has provided annual increases to the budget request to continue this program. Over the long-term, the House Armed Services Committee expects that engine competition will not only reduce engine procurement costs, but will also provide better engine performance, improved contractor responsiveness, a more robust industrial base, increased engine reliability, and improved operational readiness.
Advanced programmable avionics are among the features that make the F-35 fifth-generation. They interconnect in a modular, upgradable manner. Much of the avionics will be common, with the most extensive fit in the Air Force model. Interconnection of avionics is not limited to MIL-STD-1553B, but also includes IEEE 1394 Firewire and Fibre Channel. There are triple-redundant computers and Firewire buses in the Vehicle Management Computers of the Vehicle Management System for flight control, which act as the master for each bus. The bus cables are cross-connected so a cable failure can be circumvented.
While 1553 handles some legacy functions, most processing is over 1394b 
Given the importance of software, if the U.S. desires export control, it may be more a matter of what programming is included in a model, rather than what hardware devices are included
As with the F-22, much of the system is built around an AESA radar. A difference, however, is that the electro-optical tracking system (EOTS) is mounted in parallel with it.
Computing and networking
The two interface modules, one per rack, link the CNI processors with the F-35 integrated core processor. Where signals leave the aircraft, they are encrypted. The aircraft uses a hybrid of MIL-STD-1553 bus for controlling existing weapons and systems, but COTS high-speed interfaces for such things as video over Fibre Channel.
Many of the components are reprogrammable before or during flight. Software defined radio, for example, is the standard.
|Processors||7 Power PC, 5 signal/data processing; 2 interface|
|Bus||MIL-STD-1553||Fibre channel for high-bandwidth sensors|
|UHF/VHF radio||SDR for testing 6/2006|
Components residing on the 1394b network serve the following systems, from a combination of computing and input/output devices supporting 10 remote units: Vehicle Systems Processing, VMC and RIO (10 remote input/output units);
- Flight Control Systems: rudders, flaperons, horizontal tails, ailerons, air data probes, inertial electronics, and crash-survivable memory units
- Utilities and Subsystems such as weapons bay door drives, power system controllers, brake controllers, and thermal management system controllers;
- Propulsion Systems such as Full Authority Digital Electronic Control (FADEC) over the main engine
- Mission Systems including display management, lighting controller, communications/navigation/identification, and GPS;
- Flight data acquisition and recording
There are five basic sensor systems:
- The AESA phased-array radar,
- The electro-optical targeting system (EOTS) with forward-looking infrared (FLIR) and infrared search and track (IRST) system,
- The electronic warfare suite, developed by BAE Systems,
- The electro-optical distributed aperture system (DAS), and
- The communication, navigation and identification (CNI) suite, providing identification friend or foe (IFF) and offboard data delivered via a high-speed data link.
Perhaps the most guarded capability on the F-35 is its automatic target recognition. Lockheed Martin would only say that the aircraft will be continuously processing sensor detections regardless of the orientation (air or ground track). "Some tracks can be easily and rapidly resolved and categorized, while others will require some extensive processing to resolve ambiguities," says a Lockheed official. For automatic target identification, he adds, the F-35 aircrew "will be able to choose target types during the preflight mission planning process."
As does the F-22, the F-35 will have a AESA phased-array radar, but a different one, the Northrop Grumman AN/APG-81 from the F-22's AN/APG-77. The two systems have significant commonality, but the F-35 probably has more ground targeting capability. The F-22 has more air combat and electronic warfare ability in its radar.
When physically looking at the F-35's avionics, the EOTS, at first, might seem to be missing. After all, other aircraft either put it into a pod attached to a pylon, or has a turret.
On closer examination, the EOTS is there, operating through a sapphire window in the F-35 nose, just below the AESA radar antenna. Coaxial EOTS and radar help cross-cueing between EOTS and radar, as opposed to the situation where the EOTS is shifted to a wing-mounted pod.
One unique feature of the F-35 is the distributed aperture system, a set of six infrared cameras on the top, side, rear, etc., of the aircraft, so the pilot will have no blind spots; every possible view can be displayed on the "glass cockpit' screen.
- Guy Norris and Graham Warwick (26 April 2011), "GE/Rolls To Fight Termination Of F136 Engine", Aviation Week and Space Technology
- "IEEE 1394b Playing Pivotal Role in F-35 Lightning II Joint Strike Fighter", Air Attack, 5 September 2007
- Jensen, David, "F-35 Integrated Sensor Suite: Lethal Combination", Avionics Magazine