Low observability The reduced radar cross-section of the F-35 allows it to evade most enemy air defenses, both airborne and ground-based. Program officials note that stealth features on the aircraft have been traded against cost, so it is not as stealthy from all aspects as, for instance, the F/A-22 Raptor. But still, low observability (LO) on the F-35 comes at a price in payload: each of the two internal weapons bays can carry only a single air-to-air missile plus one air-to-ground weapon.
Unlike earlier stealth aircraft, the F-35’s LO features are more easily maintainable. But will anti-tamper features inserted to protect the stealth technology prevent international customers from repairing the integrated radar/radome, or the aircraft’s edges?
Integrated avionics The central computer on the F-35 is the most powerful yet fielded in a fighter aircraft, and enables the unprecedented integration and fusion of mission sensors in the aircraft. The integrated core processor also handles flight control data and has four types of modules. Overall, the JSF will need 19 million lines of software code, of which programmers have written only some six million so far (there will be five software blocks, released from 2006 through 2011).
The tight integration will discourage third parties from adapting the aircraft. “Putting in different sensors is a really expensive thing to do,” admitted Lockheed Martin program manager Tom Burbage. According to one report, Israel has already been told to forget about modifying the F-35 with indigenous avionics, as it has done with the F-15 and F-16.
Cockpit displays The huge Rockwell Collins multifunction display system (MFDS) is an active matrix liquid-crystal display measuring 20 by eight inches which can show six full-motion images at a time, thanks to 1 gigabyte data interfaces. There is no head-up display, since much of the MFDS data is also presented to the pilot via the helmet-mounted display system (HMDS) from Vision Systems International. Although this joint venture between Elbit and Kaiser has encountered delays, an alternate HMDS from BAE Systems was cancelled. Voice activation capability may be introduced later, but it is not seen as a priority.
Advanced electronic scan array radar The Northrop Grumman APG-81 has all the multirole advantages of an advanced electronic scan array (AESA) radar, including ground moving target indicator and synthetic aperture mapping of “near-precision” quality sufficient to target GPS-guided weapons. The APG-81 is acknowledged to have an electronic warfare capability, but to what extent this function will be practical, when it will be introduced and whether the U.S. will fully share it with international customers remains unclear.
Distributed aperture system The aircraft is equipped with a distributed aperture system (DAS), a technology from Northrop Grumman and Lockheed Martin that will take electro-optical/infrared imagery from six ports around the aircraft and combine it to provide the pilot with a 360-degree view day or night through the HMDS. The aircraft structure becomes “invisible” to the pilot wherever he looks. The DAS warns of incoming aircraft or missile threats and eliminates the need for night-vision goggles. The system has been flying on an F-16 since late 2004, but when will the algorithms be sufficiently mature?
Electro-optical targeting system Another Lockheed Martin/Northrop Grumman collaboration, the electro-optical targeting system (EOTS) has an advanced third-generation focal plane array to provide a passive but very high-fidelity imagery for navigation and long-range target detection. A BAE Systems laser provides designation and ranging.
Communications, navigation and identification avionics Another tightly integrated package, the F-35 is equipped with a Northrop Grumman communications, navigation and identification (CNI) avionics subsystem that uses modular, software-programmable radios that simultaneously carry out more than 35 functions, including high-broadband datalinks. The JSF has been dubbed “The Internet Jet” because its development has coincided with the growth of netcentric operational concepts.
Powerplant At 43,000 pounds thrust, the Pratt & Whitney F135 is the most powerful engine ever fitted to a fighter. The six-stage compressor and single-stage turbine have already been proven on the F119 for the F-22 Raptor. There’s a new low-pressure spool, and (in the F-35B short takeoff and vertical landing [STOVL] version) the unique shaft-driven lift fan, roll posts and three-bearing axisymmetric nozzle.
Development of the powerplant is costing nearly $6 billion. There are 40 percent fewer parts than in current engines, helping reduce F135 support infrastructure by 50 percent. But despite already spending $1.2 billion on the alternative GE/Rolls-Royce F136 engine, which incorporates even newer technology and may offer even higher thrust, the Pentagon now wants to cancel it to save money.
Weapons The F-35 will have four wing stations each side for extra weapons or fuel tanks. The theory is that this non-stealthy configuration can be flown once air dominance has been achieved. But as Operation Allied Force over Serbia and Kosovo proved, the air defenses of a sophisticated enemy may not be easily removed.
The inner wing pylon can take 5,000-pound-class weapons, with 2,500 pounds on the mid-wing stations, and lighter air-to-air missiles (AAMs) on the outer pylons, and the wingtips. The STOVL version has a reduced internal carriage capacity. In addition to the AAM, only a 1,000 pound-class air-to-ground weapon may be carried on each side, versus 2,000 pounds on the F-35A and F-35C carrier versions (CV). The STOVL version will cost about $14 million more per copy than the CTOL (the CV is the most expensive, at a currently predicted $61.7 million).
Performance In 2003-2004, it became apparent that the aircraft would not meet some of the STOVL requirements. This led to an 18-month delay in the system design and development (SDD) program as the fuselage structure was lightened and the inlets and nozzles were improved to increase thrust. No other “show-stoppers” have yet been reported.
The F-35 has significantly greater internal fuel than the aircraft that it will replace (for instance, 18,000 pounds in the CTOL version versus 7,000 pounds in an F-16). Combat radius could be as much as 550 nm for the STOVL, increasing to 690 nm for the CTOL. The notion that the F-35 is primarily an air-to-ground warplane with secondary air-to-air performance “is a misperception,” according to Burbage. The aircraft is designed to sustain 6g at 400 knots, and reach a maximum Mach 1.6.
Manufacturing The all-digital design process worked well on the first SDD airplanes, with easy mating of the subassemblies despite very tight tolerances. Some advanced composite fabrication technologies are involved. Even the bifurcated inlet ducts are plastic.
At the peak of the program, the schedule calls for one F-35 to be completed every working day, therefore, the manufacturer is introducing mass-production techniques derived from the automobile and other industries, such as automatic drilling. Italy and the UK are studying whether to bid for their own production line, but that will involve them in significant extra investment, and a whole new set of U.S. technology disclosure hurdles.
Industrial Participation The UK paid $2 billion to become the only “Level 1” partner in the SDD phase. Seven other nations paid smaller sums to be Level 2 or 3 partners. The partner industries were awarded subcontracts for the SDD airplanes on a “best value” rather than a “juste retour” basis.
The UK has gained more than $6 billion of work. BAE is providing the aft fuselage and tails. Martin-Baker and Smiths are also key suppliers. But the plan to cancel the alternative F136 engine would reduce future production work for Rolls-Royce. Other partner nations are unhappy about the amount of F-35 work they have gained.
Negotiations about the partners’ role in the production phase are scheduled to finish by December, so that the memorandum of understanding for the production sustainment and follow-on development (PSFD) can be signed. The SDD partner contracts could be extended into production and there are new opportunities to compete as second-source suppliers (Alenia is bidding for the wings). Further, the U.S. has conceded that the international partners have “strategic sourcing” objectives that could result in noncompetitive contract awards, but only if the partner pays for any increase over a “best value” solution.
Technology Transfer Export control issues have plagued the SDD phase, according to BAE Systems chairman Dick Olver. The U.S. bureaucracy is fearsome: nearly 300 technical assistance agreements (TAAs) have been crafted for the UK participation alone, in nine batches.
The UK government has pressed for assurances that, if it commits to F-35 production, it will be able to operate and upgrade the aircraft without a U.S. veto. The U.S. crafted a “roadmap” of technology disclosure that may be required in the future so that international customers can modify the aircraft, add new weapons and so forth, but would not give an unequivocal guarantee about future TAAs. At a recent meeting, U.S. President George W. Bush and British Prime Minister Tony Blair agreed that the UK would be able to exercise “sovereign control.” But they must still work out the details, and the other partners want a similar deal.
Earlier this year, the F-35 survived the U.S. Quadrennial Defense Review intact: the plan is still to buy 1,763 for the U.S. Air Force and 680 for the U.S. Navy and Marine Corps. But the Government Accountability Office (GAO)–an official U.S. watchdog with access to program documents–wants low-rate initial production (LRIP) to be curbed.
The first five LRIP aircraft are due to be ordered early next year. Yet the first of the 15 SDD aircraft may not fly until the fall of this year, and a 10,000-hour flight test program lies ahead. The GAO says that “a fully configured and integrated JSF” won’t be airborne until 2011. The Pentagon will already have bought 190 by then, unless Congress heeds the GAO’s criticism of this “highly concurrent approach.”
According to Lockheed Martin’s Burbage, the international partners could order another 600 to 700 airplanes. But before they sign that PFSD memorandum of understanding, they will want assurance that the huge promise of the F-35 program can be converted into reality, and is affordable.
The GAO has noted that early production aircraft will be bought by the U.S. on a cost-plus basis, with no fixed price commitment from the contractors. The unit flyaway costs quoted in this article are in 2002 dollars, and could yet rise substantially.
If this all sounds too good to be true, it probably is. The first aircraft will soon fly, but with seven years still to go, the cost of the development phase has soared from the $25 billion envisioned originally to a predicted $45 billion. Still, the idea of a stealthy warplane that will be mass-produced, comes in three versions to replace 13 previous types and is sold to international customers as well as to the U.S. services, is powerful. What, then, does the F-35 really offer? And what are the downsides? Here is a look at some of its features.