SUPERSONIC STEALTH: F-35 TAKES TO THE SKIES

THE MOST POWERFUL SINGLE-ENGINE FIGHTER EVER BUILT IS NOW ON THE HORIZON, AND THE ARMED FORCES ARE EAGERLY AWAITING ITS ARRIVAL. WITH IMPROVED SURVIVABILITY, SUPERSONIC SPEED, ADVANCED STEALTH, INFORMATION FUSION AND FIGHTER AGILITY, TO NAME A FEW PERKS, THE F-35 LIGHTNING II JOINT STRIKE FIGHTER (JSF) JOINS THE F-22 AS THE ONLY OTHER 5TH GENERATION FIGHTER IN THE WORLD.

PROGRAM BACKGROUND

The JSF program was conceived at the Department of Defense level as a fighter that would meet the needs of the Air Force, the Navy, and the Marine Corps., but still be derived from a single basic design. The plan was to create a multirole stealth fighter to replace aging AV-8B Harriers, A-10s, older F-16s, F/A-18 Hornets and the UK's Harrier GR.7s and Sea Harriers. The program aspired to build an aircraft optimized for the air-to-ground role with secondary air-to-air capability.

"The idea was to have a family of three airplanes that are very closely related, but each one is specifically tailored to the needs of the individual service," says John Kent, F-35 Program Spokesman at Lockheed Martin. "That's been tried before, with not a whole lot of success. If they could do this and leverage a lot of the advanced technology off of the F-22, mainly stealth and sensor fusion, you would save tens of billions of dollars, versus developing a separate airplane for each individual service."

The Lockheed Martin JSF propulsion team installs the shaft-driven lift fan in the JSF X-35B at the company's Palmdale, CA plant. The installation took less than three hours and required no subsequent adjustments. The STOVL X-35B, designed to meet U.S. Marine Corps and Royal Navy/Royal Air Force requirements, will begin hover-pit testing in February 2008. Photo Credit: Lockheed Martin

With the advancements in computer aided design, the possibility of the F-35 working for all three arms of the military was much higher than in the past, and the program was set in motion.

The JSF Program began its 12-year development cycle on October 26, 2001, when the Lockheed Martin-led JSF team won a $19 billion contract to develop the F-35. Lockheed Martin beat out competitor Boeing reportedly because of the demonstrated performance of its LiftFan Short Takeoff/Vertical Landing (STOVL) design, which will be incorporated into one of the three F-35 variants.

"The manufacturing and test program, or SDD (System Development and Demonstration program), is scheduled right now to be over in 2012," explains Bob Fiorentini, Vice President of F-35 Global Production at Lockheed Martin. "At that point, we will have proven all of the capabilities of the three F-35 variants to our customers."

Flight testing began in December of 2006 and is ongoing now with the first variant. There are currently 14 F-35s in various stages of production.

Not only is the aircraft proving to have unsurpassed situational awareness, new standards of reliability and maintainability, and network- enabled operations, but it will be affordable as well.

"It is going to be the lowest-cost airplane to keep in the fleet out of any other airplane that's ever been produced because of the design concepts behind it," says Fiorentini. "The low cost of sustaining the stealthy finishes and all of the equipment on the board has been designed into it; once the airplane is delivered, it will be the least expensive airplane to maintain out in the field."

The F-35 uses many of the same technologies that were developed for the F-22, develops them further, and adds major advancements to the preceding generations' fighters as well.

"This is going to be a very, very low-observable airplane, which means that we can detect our targets before their radars can detect us, which is a huge advantage," says Fiorentini.

The difference in stealth between the best 4th Generation fighters and 5th Generation fighters is astronomical, agrees Kent. "The 4th Generations have some low-observable features, but they're not specifically designed to be stealth airplanes. The 5th Generations are very stealthy."

The forward fuselage and wings are produced by Lockheed Martin.

The pilots will notice a difference in the aircraft as well. All of the capabilities the F-35 has – which includes a sensor suite, combined together as a common display – assist the pilot by making it easier to make quick decisions on the battle field. The F-35 is equipped with in-depth data that is prioritized to the conditions at hand, allowing the pilot to focus on tactics.

DESIGNING AND BUILDING THE F-35

Imbedded antennas, aligned edges, internally carried weapons, special coatings and materials, stealth, flexibility and agility are only some of the advantages these aircraft offer. The F-35 will have the ability to choose engagements, while remaining virtually invisible by enemy surface-to-air and air-to-air defense systems. Targeting flexibility allows the F-35 to find, track, target, engage and assess targets in daylight, darkness and all weather. When designing the F-35 fighter jet, Lockheed Martin and its subcontractors relied on advanced programs and 3D solid modeling to make their vision a reality.

"We used CATIA V5 for the design of the aircraft, and we used solid modeling that is flowed out to all of our tool designs, our manufacturing planning and our assemblies on the floor," says Fiorentini.

The key subcontractors were chosen based on their ability to use the CATIA V5 solid modeling, he explains. As a result of that, firstpart lead times are reduced by half of what have been experienced on legacy programs, and part quality and manufacturing quality on the first aircraft and assembly are better than legacy aircraft, according to Fiorentini.

"It was flowed completely through the design and production and procurement process; it wasn't just selectively applied to certain parts of the airplane," he says. "And that includes all of our tooling and all three of the teammates."

During the design process, the team hit a snag that forced a change of course early on.

"We had one major challenge back a few years ago when the airplane was really in the early design process," says Kent. "We discovered that we were running over our target weight significantly, which is critical for the Short Takeoff/Vertical Landing version, to the extent that we needed to redesign much of the internal structure."

The team took action by shutting down the program for an entire day. They needed to determine how to shed 3,000 lbs. from the aircraft, or it wouldn't meet its performance requirements.

They formed a group called STOVL Weight Attack Team – nicknamed "SWAT" – that was made up of 500 engineers working together to bring the weight down. SWAT focused the redesign on the internal structure rather than the outward fuselage, and improved it enough to lose the necessary 3,000 lbs., while actually improving structural integrity.

As the design process came to an end, it was time to start building the aircraft. The JSF Program enlisted the support of suppliers from around the globe to manufacture the F-35. With major production taking place in the United States, an international supplier network includes the United Kingdom, Italy, The Netherlands, Turkey, Canada, Australia, Denmark, Norway, Israel and Singapore.

"We're doing 5-axis machining and some 6-axis work, using specialized spray booths and drilling machines for the skin placement," says Fiorentini. "Lockheed Martin does not see, as a whole, precision machining as a core competency that we would invest in – that's where we would depend on our key subcontractors and suppliers that we select to be on the program. Most of the airframe parts are all 5-axis machined."

The subcontractors are vital to create precision parts used to keep the aircraft producible and low-cost in the maintenance. The aircraft is made up of materials such as aluminum forgings, aluminum plate machined parts, titanium forgings and titanium plate parts. The outer skins are all carbon-fiber composite, which makes up roughly 40% of the airplane's weight - the highest composites percentage ever for a fighter jet.

"Right now, we are in the process of really ramping the production rates up in the factory to build the 21 aircraft that are going to be used for testing on SDD," notes Fiorentini.

"We are very focused on getting our supply chain of precision parts up and running to support our ramp-up rate and SDD, and then eventually be able to transition into our initial low-rate production."

During this critical time in the production of the aircraft, Lockheed Martin must pay close attention to the way they apply people to the job as they increase work in the factory. "If we do it too fast, we become inefficient because we're outpacing the work, and then if we do it too slow, then we go behind schedule," says Fiorentini.

To help keep the workforce organized, the company has very detailed manpower plans that they watch on a weekly basis. This makes it possible to make adjustments based on supplier deliveries, design maturity, etc., so that they're not overstaffing or understaffing.

Pratt & Whitney's F135 engine in the testing phase. Pratt & Whitney and GE Rolls-Royce Fighter Engine Team are developing propulsion systems to be physically and functionally interchangeable between the three F-35 variants.

On the positive side of manufacturing, as the team progresses through building the aircraft, the process maturity that they are exhibiting is that of airplanes in their second or third phase of their low-rate initial production.

"When I talk about the 3D models that we use to produce everything including the tooling, our production concept in the factory is one that's been learned many times over the hard way, where we do not have mechanics lying all over the aircraft to install systems or install fasteners or funny precarious positions because that leaves them prone to injuries," explains Fiorentini. "If you look at OSHA recordables and industries like ship yards and airplane factories, they are higher than in other kinds of factories."

One of the reasons why their quality actuals are currently better than legacy aircraft is because when the mechanics are in a comfortable position, they're able to do repeated work at a higher quality and more efficiently. All of this has come together to form the most capable multirole fighter to date. All is on target to meet the expectations of the project.

"We had service pilots fly the X-35 variants, which were demonstrator aircraft for what has now become the F-35," says Kent. "The handling qualities were as predicted, and each version of the airplane essentially met the baseline needs of the services."

LEAN, MEAN FIGHTING MACHINES

As mentioned before, the F-35 project was conceived as a means to create a family of aircraft that is very similar, but able to support the needs of the armed forces. The three variants include the Conventional Takeoff and Landing (CTOL) F-35A; the Short Takeoff/ Vertical Landing (STOVL) F-35B; and the Carrier Variant (CV) F-35C. The F-35A is the Air Force's ideal variant, with the Marine Corp preferring the F-35B. The Navy plans to purchase 340 F-35C aircraft with the larger wing and tail and control surfaces, enabling low-speed approaches to sea-faring aircraft carriers.

Pratt & Whitney and the GE Rolls-Royce Fighter Engine Team (FET) are currently cooperating in the development of common propulsion system components, which includes the STOVL LiftFan system, roll ducts and three-bearing swivel cut, and the conventional exhaust duct and exhaust nozzles of the other two F-35 variants.

Pratt & Whitney F135 and FET F136 engines are being developed to be completely interchangeable across all F-35 aircraft and their autonomic logistics systems. Flight tests have already begun for the F-35A, with the first one completed on December 15, 2006. First flights are planned for the F-35B in 2008, and the F-35C in 2009.

Delivery of the aircraft to the armed forces is planned for 2010, with the first F-35s entering operational service in 2012.

THE JSF TECH TEAM

Lockheed Martin Aeronautics Company is the prime contractor for the F-35 JSF program. The company is responsible for the design, supervision and support of all major subsystems of the aircraft. Lockheed Martin is also in charge of producing the forward fuselage and wings, and, along with the governmentoperated JSF Program Office, has the ultimate responsibility to deliver the F-35 and its support systems. Final assembly of the F-35 will take place at Lockheed Martin's factory in Fort Worth, TX.

Northrop Grumman is designing and integrating the center fuselage section of the F-35, including incorporation of the subsystems and development of a large fraction of the F-35 mission systems software, ground and flight test support, signature and low-observables development support, and modeling and simulation activities support. Northrop Grumman is also in charge of the fire control radar and the electrooptical distributed aperture system. The company is responsible for the integrated communications, navigation and identification avionics suite and the training courseware. BAE Systems' experience with military aircraft ensures fast and precise design and engineering of the F-35 airframe, mission systems, aft fuselage and empennage, while meeting the F-35's stringent stealth requirements.

BAE Systems' is also responsible for the fuel system, crew escape, lifesupport system, and Prognostics and Health management system integration. The company shares the work load in autonomic logistics and is involved in the Integrated Test Force, including vehicle and mission systems flight test. The F-35 electronic warfare systems suite is BAE's work, as is the vehicle management computer and the communications, navigation and identification modules. The company provides advanced affordable and lowobservable apertures (antennas), as well as the pilot's control stick and throttle.