F-35 Program History – From JAST to IOC Copyright © 2018 by Lockheed Martin Corporation. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Arthur E. Sheridan1 Lockheed Martin Aeronautics Company, Fort Worth, Texas, 76101, USA AIAA AVIATION Forum June 25-29, 2018, Atlanta, Georgia June 25-29, 2018, Atlanta, Georgia and 10.2514/6.2018-3366 2018 Aviation Technology, Integration, and Operations Conference Robert Burnes2 F-35 Lightning II Joint Program Office, Arlington, Virginia, USA The Joint Strike Fighter program leading to the Lockheed Martin family of F•35 aircraft has been unprecedented in terms of scope and challenge. This paper reviews the background and need for the air system. It summarizes the environment, objectives, approach, and results of each of three distinct development phases, and highlights some of the most significant challenges encountered and solutions achieved. It also covers initial production and sustainment achievements in parallel. Despite the ambitious goals and numerous challenges, the development program is drawing to a close, and a system is now being produced and sustained that meets its customers’ warfighting requirements. I. Background HE origins of the Joint Strike Fighter (JSF) program can be traced to the longstanding commitment of the U.S. T Marine Corps (USMC) and United Kingdom (UK) Royal Air Force (RAF) and Royal Navy (RN) to develop a short takeoff and vertical landing (STOVL) strike fighter, and to the end of the Cold War. Drastic defense budget reductions after the Cold War, together with aging fleets of fighter aircraft in the United States and across the west, demanded a new level of cooperation in development and production. The U.S. Department of Defense (DoD) Bottom- Up Review in 1993 cancelled previously separate fighter/attack development plans of the U.S. Air Force (USAF), U.S. Navy (USN), and USMC that aimed at replenishing U.S. fleets but became viewed as unaffordable. The need for new aircraft procurement was compelling, however, due to the end of production of legacy fighters (Fig. 1). Fig. 1 Historical and projected U.S. fighter procurement profile (circa 2001). 1 Program Management Principal, F-35 Customer Programs, AIAA Associate Fellow. 2 Director, Program Operations and Director, Program Management. Approved for public release 5/16/18, JSF18-530 1 Furthermore, the large number of aircraft types in use by the United States and its allies could not be affordably maintained (Fig. 2). Trends toward joint operations and coalition warfare required significant improvements in interoperability. In this environment, service leaders in the United States and UK agreed to develop a single program to address the next generation of affordable strike platforms. Additional affordability strategies contributing to the environment were acquisition reform initiatives advocating performance-based specifications and concurrent development, as well as the desire to exploit the digital revolution with simulation-based acquisition, digital design, and paperless commerce. Existing U.S. service strike fighter requirements were widely disparate, ranging from the U.S./UK Advanced STOVL (ASTOVL) (a small supersonic STOVL airplane for the USMC and UK with a maximum empty weight of 24,000 pounds) to the Navy’s A-12 (a stealthy carrier-based, twin-engine, long-range medium bomber), to a low-cost fleet-structure fighter to succeed the USAF’s F-16. Reference [1] and Ref. [2] provide summaries of U.S. precursor programs and their sequence, as well as the early development of STOVL propulsion concepts that together form the genesis of what is now the F-35 program. At the time, the industry had great doubt that a single aircraft could be designed to satisfy the needs of all services. For this reason, and lacking common air-vehicle requirements, DoD did not approve the creation of an aircraft acquisition program. Rather, the initial program mandate was to invest jointly in technologies that could be applied irrespective of a specific aircraft configuration, and to perform configuration studies to determine whether a common family of aircraft could meet service needs. Fig. 2 Legacy fighter types expected to be replaced by JSFs. II. Joint Advanced Strike Technology The services formed a JSF Program Office (JSFPO) drawing from the Naval Air Systems Command (NAVAIR), USAF Aeronautical Systems Command (ASC), and U.K. Ministry of Defence (MoD), and created the Joint Advanced Strike Technology (JAST) program in 1994. The JSFPO was (and remains) located in Arlington, Virginia, where top personnel from each systems command are co-located. The leadership structure was established with roles of the senior acquisition executive (SAE), program executive officer (PEO), and deputy PEO positions alternating among the departments of the USN and USAF, and rotating at nominally two-year intervals. That is, a USAF SAE would be served by a Department of the Navy PEO (USN or USMC officer) and a USAF Deputy PEO. The pattern would then reverse upon the change of command on a nominally two-year basis. Approved for public release 5/16/18, JSF18-530 2 A. Technology Demonstrations The new program issued initial contracts to industry under the JAST banner, with separate contracts for individual technology maturation and demonstration efforts. Contracts were issued to all eventual JSF competitors, but they were to collaborate in planning the efforts and were required to share the results across the industry. JSF Integrated Subsystems Technology (J/IST) is a prime example of such an effort, and within that, the More-Electric Actuation program is an example that was led by Lockheed Martin and eventually incorporated into the F-35 configurations. Other proprietary technologies were pursued separately by competitors, a Lockheed Martin example being the diverter-less supersonic inlet that performs as a mixed-compression inlet that avoids boundary layer ingestion through the use of innovative shaping with no moving parts, providing a lightweight and smooth configuration with favorable signature integration. Both the J/IST electric power and actuation concept and the diverter-less inlet were demonstrated on separate F-16 platforms [3, 4]. B. Concept Demonstration and Design Research In parallel with these technology programs, the JAST program also issued concept demonstration and design research (CDDR) contracts. These efforts were begun to conceive of specific aircraft configurations and specific performance requirements. In general terms, the requirements were to provide configuration variants to serve the services’ differing basing needs: conventional takeoff and landing (CTOL) for USAF, STOVL for the USMC and RAF/RN, and a carrier variant (CV) for USN operations with catapults and arresting gear. The up-and-away performance requirements for range/payload and maneuverability were to be common among the variants and approximately equivalent to combat-equipped current F-16s and F/A-18s. Signature levels and mission- systems/weapons were to be studied over a wide trade space, and an affordability target was established for the CTOL variant equivalent to the cost of an F-16 Block 50 with targeting and electronic warfare pods and external fuel tanks, $28 million (1994). The different variants were to be as common as possible to take advantage of economies of scale and interoperability. In light of budget constraints, the U.S. services recognized the value of commonality and saw that overly specific requirements could negate those benefits. So, they re-examined basic assumptions embedded in their previous development projects and adopted some important changes. Most notably, for the first time since the A-7, the USN accepted the single-seat and single-engine requirement, which was essential to achieve a practical STOVL configuration for the USMC. The result of the CDDR phase was that the configuration concepts and corresponding requirements trade studies instilled sufficient confidence in the JSFPO and the participating services to proceed to the next phase to develop a family of air systems to be known as the JSF, designed to satisfy a joint operational requirements document (JORD) that would also be developed in the next phase: the Concept Demonstration Phase (CDP). C. Industry Competitors Three industry competitors participated in the program, each with configuration families based on different STOVL propulsion concepts. Reference [2] gives an overview of the evolution of STOVL concepts preceding JAST. The Lockheed Martin CDDR designs were all based on the shaft-driven lift fan (SDLF) described below. The Boeing concept was based on direct lift, which relied on diverting the majority of engine exhaust to Harrier- like swiveling nozzles at the center of gravity for hover. Exhaust flow was abruptly switched to and from an aft- mounted vectoring nozzle during wingborne/jetborne transitions. A series of remote nozzles provided attitude control and a jet screen near the main inlet to reduce hot-gas ingestion. At this stage in the program, the Boeing configuration was a delta-wing arrangement that was essentially common for all three variants. The McDonnell Douglas (later acquired by Boeing)/Northrop Grumman/British Aerospace (now BAE Systems) concept was a conventional wing-tail arrangement with conventional propulsion for the CTOL and CV variants. The STOVL variant employed the lift-plus-lift/cruise propulsion system similar in arrangement to the Russian YAK-38 and YAK-141 aircraft. It was to have a single lift engine mounted forward and a combination of swivel nozzles and aft conventional nozzle for main-engine exhaust similar to but much shorter than the Boeing exhaust system. D. The Lockheed Martin Air Vehicle Concept The Lockheed Martin air vehicle concept centered on the SDLF propulsion system [1, 4] illustrated in Fig. 3, which was key to both STOVL capability and family commonality among variants. Together with a vectoring lift-fan nozzle and a continuously vectoring three-bearing swivel nozzle (3BSD) for the engine exhaust, the system inherently addressed the major challenges and typical causes of failure for previous supersonic STOVL concepts.