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Document created: 10 March 03
Air
& Space Power Journal - Spring 2003
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PIREP |
Editor’s Note: PIREP is aviation shorthand for pilot report. It’s a means for one pilot to pass on current, potentially useful information to other pilots. In the same fashion, we intend to use this department to let readers know about aerospace-power items of interest.
John Kent*
*Mr. Kent is a senior communications specialist with the Lockheed Martin Joint Strike Fighter Program.
In late 2005, the F-35 Joint Strike Fighter (JSF) will rocket down the runway near Lockheed Martin’s Fort Worth, Texas, plant and lift into the air for the first time. The event will signal the beginning of an ambitious flight-test program designed to validate the effectiveness of the world’s most advanced multirole fighter. Between now and then, engineers and program managers will continue to work tirelessly to ensure that schedules are met, costs are minimized, and a mature weapon system is delivered that meets or exceeds customer expectations.
For much of the free world’s military forces, the F-35 represents the future- a new family of affordable, stealthy combat aircraft designed to meet the twenty-first-century requirements of the US Air Force, Navy, and Marine Corps, as well as the United Kingdom’s Royal Air Force and Royal Navy. The program is truly international in its scope and participation: Italy, the Netherlands, Turkey, Canada, Denmark, Australia, and Norway recently joined the F-35’s system development and demonstration (SDD) phase. All SDD partners will be active in the F-35’s development process and stand to gain economically from the program.
The goals for the F-35 are lofty: to be a single-pilot, survivable, first-day-of-the-war combat fighter with a precision, all-weather strike capability that uses a wide variety of air-to-surface and air-to-air weapons- and that defends itself in a dogfight. The F-35 program emphasizes low unit-flyaway cost and radically reduced life-cycle costs, while meeting a wide range of operational requirements.
The F-35 family tree branches into three distinct variants. The conventional takeoff and landing (CTOL) F-35A will replace F-16s and A-10s in the US Air Force. It will complement the F/A-22 Raptor air-dominance fighter as a nine-G-rated aircraft with an internal 25 mm gun mounted on the left intake shoulder and a combat radius of more than 600 nautical miles (NM). This model- and all F-35 variants- will have two internal weapons bays, each capable of carrying a 2,000-pound precision-guided munition and a radar-guided AIM-120 air-to-air missile. Current requirements calling for 1,763 aircraft will make the F-35A the most-produced variant.
The short takeoff/vertical landing (STOVL) F-35B will replace the aging AV-8B Harrier STOVL attack jets (which have also proven increasingly difficult to support) of the US Marine Corps, as well as its F/A-18s. The F-35B will have a stealthy, belly-mounted 25 mm missionized gun pod and a combat radius of more than 450 NM- nearly two times that of legacy STOVL strike fighters. A shaft-driven lift fan, in combination with a vectoring rear exhaust nozzle, gives this fighter the ability to take off in short distances, accelerate to supersonic speeds in level flight, and land vertically. Thanks to the lift-fan system, the F-35B’s total vertical lifting thrust is about 39,700 pounds (the aircraft weighs about 30,000 pounds)- more than 14,000 pounds greater than the engine alone would produce without the lift fan. The F-35B will be the world’s first operational supersonic STOVL aircraft. The Marine Corps currently plans to deploy 609 F-35Bs.
The F-35C carrier-based (CV) variant will complement the US Navy’s F/A-18E/Fs and replace F-14s and earlier model F/A-18s. The wings (with folding tips) of the F-35C will span nine feet more than the wings of the F-35A and F-35B models. Like the F-35B, it also will have a stealthy, missionized 25 mm belly gun. The combat radius on internal fuel will be greater than 700 NM- again, more than twice the range of the aircraft it is designed to replace. The Navy’s current plans call for 480 aircraft. The United Kingdom’s Ministry of Defence has chosen the F-35B to replace its Harrier GR.7s and Sea Harriers for the Royal Air Force and Royal Navy. The United Kingdom’s current plans call for 150 aircraft.
Led by prime contractor Lockheed Martin, along with principal partners Northrop Grumman and BAE SYSTEMS, the F-35 team is crafting an exceptionally lethal, survivable, and supportable next-generation strike aircraft. Compared with the aircraft it will replace, the F-35 will provide significant improvements in range, payload, lethality, survivability, and mission effectiveness. Uniting stealth with advanced mission systems and high maneuverability, the F-35 will bring revolutionary twenty-first-century capabilities to the battle space.
Conflicts in recent years have clearly demonstrated the desirability of longer combat radius (or longer time on station). The F-35 will dramatically increase its user’s ability to support combat operations at longer ranges due to its tremendous internal fuel capacity and single-engine design. For example, the CTOL F-35A carries more than 18,000 pounds of internal fuel- more than two-and-one-half times the internal fuel capacity of the legacy multirole fighters it will replace. Likewise, the advantage in range more than doubles. The F-35 is not limited to internal fuel only; it can carry 600-gallon external drop tanks for ferry flights or for missions that do not require a stealthy signature. This further stretch in combat radius means that the pilot can operate with reduced dependence on air refueling and can have significantly greater time on station for close air support or combat air patrol missions.
Survivability, a cornerstone of F-35 design, is enhanced foremost by the aircraft’s radar-evading properties. Stealth capability, available for the first time in a multirole fighter, will minimize the threat to the pilot during operations in heavily defended areas. The aircraft also is configured with advanced countermeasures to reduce the effectiveness of enemy defenses.
Integral to the aircraft’s low-observable equation is the large internal-weapons bay. When stealth is not required, the F-35 also can carry wingtip air-to-air missiles and up to 15,000 pounds of external ordnance mounted on underwing pylons. A pneumatically powered ordnance-release system replaces the traditional cartridge-powered equipment. This new design greatly reduces maintenance requirements. The internal 25 mm cannon will enable pilots to engage targets from higher altitudes and longer range.
The F-35’s mission systems are designed to return the pilot to the role of tactician and to increase combat effectiveness dramatically. Next-generation sensors will provide the pilot coherent and fused information from a variety of onboard and off-board systems. Sophisticated data links will connect the aircraft to both ground-combat elements and airborne platforms. In addition to fighter-to-fighter data links, the F-35 will be equipped with satellite-communications capability for both transmitting and receiving.
The aircraft’s onboard sensor suite is optimized to locate, identify, and destroy movable or moving ground targets under adverse weather conditions. This all-weather capability is achieved with the aircraft’s advanced electronically scanned array (AESA) radar built by Northrop Grumman. The AESA enables simultaneous air-to-ground and air-to-air operations. It can track moving ground targets and display them on a radar-generated terrain image, enabling precise target location relative to terrain features. These instruments, coupled with off-board sensors, will make the F-35 capable of all-weather close air support under the most demanding conditions.
An internally mounted electro-optical targeting system (EOTS) is installed in the nose of the F-35, enhancing both air-to-ground and air-to-air capabilities. The EOTS will provide long-range, high-resolution targeting-infrared imagery; laser-target designation; and battle-damage-assessment capability. This system will provide pinpoint weapons-delivery accuracy for close air support and deep-strike missions.
A distributed-aperture-infrared sensor system will provide full spherical infrared coverage around the aircraft. In addition to providing warnings of missile launches, information from the system can be displayed on the pilot’s helmet visor, permitting the pilot to see “through” the airplane’s structure in all directions, and eliminating the need for night-vision goggles. This system will dramatically increase the ability of the F-35 to conduct any type of mission at night.
The cockpit features a large eight-inch by 20-inch color display, providing tactical information as well as aircraft system data. A next-generation voice-command system allows the pilot to manage systems without manual input. Tasks such as changing radio channels are accomplished simply by speaking a command. The pilot also has the option to manipulate the displays by touching the screen or by using a yoke-mounted cursor. Unlike the cockpit design of current-generation fighter aircraft, the F-35’s does not include a head-up display. Rather, the information normally visible on such a display is instead projected on the pilot’s helmet visor.
Most of the cutting-edge technologies scheduled for incorporation into the F-35 were independently demonstrated during the previous concept demonstration phase (CDP) and will now be integrated into a single platform. During the most visible part of the CDP, the JSF team validated the aircraft’s superb aerodynamic performance. From October 2000 through August 2001, the JSF X-35 demonstrator aircraft established a number of flight-test standards during 139 flights and 107 flight hours:
Despite the promise of awe-inspiring performance and capability, affordability has long been the F-35 program’s foundation, and it is a subject of intense focus. According to Jim Engelland, the F-35 JSF systems-integration director, “Every decision we make across the program has to address cost. We’ve always worked under a performance mantra- that is, get as much performance out of an aircraft as we can. Before JSF, nobody ever said, ‘If I can add five pounds here, this part will be easier to manufacture and will cost less.’ We have asked all of our integrated product teams to design and develop as though they were spending their own money.”*
*All quotations in this article are sourced internally at Lockheed Martin.
The F-35 is designed to reduce operational and support costs significantly by increasing reliability and reducing required maintenance. Such high reliability will enable rapid deployment with minimum support equipment. The cost to operate and maintain the F-35 is expected to be 50 percent less than that for the aircraft it is designed to replace. For decades, the concept of repairing new aircraft came only after the aircraft was built. Then, it had to conform to an existing logistics structure. But the F-35’s logistics system has to be up and running before the first aircraft is flown. Don Searles, deputy director of JSF autonomic logistics, notes that “the government directed [that] the logistics system be built concurrently with the air vehicle and that it perform with a level of information accuracy, best value, and total life cycle cost from the beginning.”
The autonomic logistics system, as the F-35 system is called, will monitor the health of the aircraft systems in flight; downlink that information to the ground; and trigger personnel, equipment, and parts to be pre-positioned for quick turnaround of the aircraft. Ultimately, this automated approach will result in higher sortie-generation rates. Autonomic logistics is also something of a mind reader. Through a system called prognostics and health management, computers use accumulated data to keep track of when a part is predicted to fail. With this aid, maintainers can fix or replace a part before it fails and keep the aircraft ready to fly. Like the rest of the program, the autonomic logistics system is on a fast track. It has to be available to support the air vehicle during operational test and evaluation.
The F-35 assembly line will be notable for its automation, reduced tooling, and virtual elimination of hammered rivets. The subassemblies will be loaded into simplified tooling capable of building any of the F-35 variants. The machine will do its work, and the entire assembly- tool and all- will move to the next position. Previous manufacturing technologies would require different tooling for each variant as well as require the subassembly to be unbolted from one tool and reinstalled in another before the next process could proceed- a time-consuming exercise. Because the three variants have more than 80 percent of their parts in common, all of which are located in the assembly tooling in a common manner, major components such as bulkheads can be manufactured from the same blanks, milled and drilled on the same fixture, and assembled using common tools. Again, using the bulkheads as an example, the only difference among the variants is their thickness.
Larry Mestad, leader of the F-35 JSF Airframe System Engineering Integration Team, comments that “the main task is to build the aircraft affordably. We want to eliminate as much tooling as possible, improve production flow, and reduce disruption and delays. By using precise fabrication and robust assembly methods, we can eliminate hand fitting and rework as the assemblies come together. We are not using technology for technology’s sake; we are using technology to reduce cost.”
The first 22 airframes- 14 flyable aircraft and eight nonflying ground-test articles- will be built on that assembly line during the current phase of the program. The test fleet will include five flyable CTOLs, four STOVLs, and five CVs. Static- and fatigue-test F-35s will be built for each variant, along with a CTOL radar-signature test article. A CV drop-test article will be used for live-fire testing later on. “The SDD aircraft will look a lot like the X-35,” says Paul Park, director for the JSF air vehicle. “Your grandma won’t be able to tell the difference, but the production models will be different from the X-35 demonstrators.”
Although the automotive industry was not a direct source of expertise for the F-35, it was a source of inspiration to the people who will build the aircraft. According to Mestad, “Automotive plants don’t keep inventory on an auto assembly line. They only have about two hours worth of inventory on the floor at any given time. Even the seats come off the delivery truck in sequence of installation. Our assembly line will resemble that line. It is called mixed-model production. We won’t have three assembly lines; we’ll have one line. We might build a CTOL version today, a STOVL version tomorrow.”
The F-35 team combines the manufacturing expertise of the program’s three principal partners- Lockheed Martin, Northrop Grumman, and BAE SYSTEMS- and builds on the lean-manufacturing legacy of the highly successful single-seat, single-engine F-16, as well as the F/A-18, B-2, and Eurofighter. Comparing the F-35 to current-generation fighters, engineers project that Lockheed Martin F-35 assembly will
The F-35 is designed to accommodate growth in both mission and technology. Possible future versions of the aircraft include an electronic-attack variant, an uninhabited version, and an F-35 that incorporates a laser weapon.
Because of designed-in flexibility, the F-35 will be able to accommodate a wide range of next-generation weapons, including the small-diameter bomb currently under development. This weapon’s smaller size will enable the F-35 to carry a far greater number of bombs internally, thus increasing the number of targets that can be specified per mission.
The Air Force is tentatively scheduled to receive its first F-35 in 2008, but initial operational capability (IOC) for the service is set for 2011. The US Navy, along with the Royal Navy and Royal Air Force, is scheduled for a 2012 IOC. The Marine Corps, with an IOC planned for 2010, will be the first of the military services to operate a fleet of F-35s.
On 27 June 2002, the F-35 program achieved its first major technical milestone, on schedule and under budget, when engineers finalized the external lines of the aircraft. The resulting “lines freeze” configuration is nearly indistinguishable from that of the X-35 JSF demonstrators that underwent flight testing in 2000 and 2001. Design changes, though small, will bring overall performance gains to the stealthy fighter. The design has been evolving incrementally since the configuration that flew as the X-35 demonstrator.
Finalized changes include the following:
Earlier in the design phase, engineers also reduced the length of the engine’s inlet ducts, thereby saving weight and improving performance.
“During the concept demonstration phase of this program, we believed the only way to validate the aerodynamic performance of our concept was to test-fly an aircraft that was representative of the one we intended to produce,” points out Tom Burbage, executive vice president of Lockheed Martin and general manager of the JSF program. “When you look at this final design and compare it to the one we flew during CDP, it’s clear that the two aircraft are essentially identical, save for some fine-tuning. That means the outstanding performance of our X-35 JSF concept demonstration aircraft can also be expected of our production model, the F-35.”
The F-35, designed to survive in a high-threat environment and provisioned for growth, will feature levels of supportability and maintainability that have never before been achieved. Jim Engelland effectively captures the excitement and anticipation surrounding the JSF: “We are really on our way. I told some new hires that we will have a first flight in less than 40 months. We will see some tears and a lot of goose bumps that day. If you don’t get either one, you are in the wrong business.”
Disclaimer
The conclusions and opinions expressed in this document are those of the author cultivated in the freedom of expression, academic environment of Air University. They do not reflect the official position of the U.S. Government, Department of Defense, the United States Air Force or the Air University.
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