<< Val Baganza,Italy, AUG-14-2024 >> F-35 : Origins Part II- The Joint Advanced Strike Technology Program (JAST) Goals of the JAST Program The Department of Defense (DoD) Joint Advanced Strike Technology (JAST) program was initiated in the early 1990s with the primary goal of developing a next-generation, multi role strike aircraft that would meet the needs of multiple branches of the U.S. military. It aimed to unify and streamline the development process of future fighter aircraft, reducing the cost and complexity traditionally associated with creating separate platforms for the Air Force, Navy, and Marine Corps. The program focused on leveraging emerging technologies in stealth, propulsion, avionics, and weapons systems to create a versatile, high-performance aircraft capable of operating in a variety of combat environments. Another key objective of the JAST program was to ensure interoperability and joint mission capability among U.S. forces and allied nations. The program placed strong emphasis on cost reduction, both in terms of production and long-term maintenance, by encouraging commonality of parts and systems. In 1996, JAST merged with the Common Affordable Lightweight Fighter (CALF) program to become what is now known as the Joint Strike Fighter (JSF) program. Drivers of Requirements for the Joint Advanced Strike Technology (JAST) Program The JAST program was initiated in response to a set of pressing operational and technological challenges that emerged prominently during the late 20th century. The primary drivers behind the program’s requirements were as follows: Escalating Threat of Advanced Air Defense Systems One of the foremost motivators for the JAST program was the rapid evolution of mobile, networked, and highly integrated air defense systems during the 1980s. These systems were advancing in sophistication and lethality at an unprecedented pace. Notably, radar systems, command and control networks, and surface-to-air missile (SAM) technologies were all experiencing major improvements. Missiles, in particular, were transitioning from semi-active radar guidance to fully active radar seekers, significantly increasing their effectiveness and lethality. In this increasingly hostile and technologically advanced threat environment, survivability became a top operational priority for future combat aircraft. Obsolete and Insecure Communication Capabilities At the time, the existing fleet of tactical aircraft was equipped with primarily analog, unsecured voice communication systems and lacked robust digital data-sharing capabilities. These aircraft had limited capacity to exchange critical information with other airborne platforms or ground-based command and control centers. Furthermore, the communications systems in use were highly susceptible to detection, jamming, and interception, posing significant operational security risks. The need for secure, resilient, and high-bandwidth data links was clear and urgent. Aging Fleet and Need for Streamlined Production The legacy aircraft inventory was experiencing widespread block obsolescence, with many platforms nearing or exceeding their operational service lives. The escalating cost and complexity of sustaining these aging fleets highlighted the urgent need for a new generation of aircraft. This new platform would need to be modern, adaptable to multiple mission profiles, and capable of being produced efficiently and economically in large numbers. A key design objective was to reduce the diversity of aircraft types across services in favor of a common solution wherever possible. Safety Concerns with STOVL Aircraft For the Short Takeoff and Vertical Landing (STOVL) variant, safety was a particularly critical concern. The AV-8B Harrier II, which represented the state-of-the-art STOVL capability at the time, suffered from a concerning safety record, with a high incidence of accidents and operational losses. Improving the safety, reliability, and maintainability of future STOVL aircraft was therefore a key requirement. Modern Capabilities at Affordable Costs The envisioned JAST aircraft would need to operate effectively in contested environments, capable of penetrating sophisticated, layered air defense networks. This necessitated the integration of advanced sensors, next-generation computing power, and secure, resilient communications systems. At the same time, the aircraft had to remain cost-effective and suitable for mass production to ensure affordability and scalability for broad operational deployment. Achieving this ambitious combination of survivability, capability, and affordability presented a formidable challenge—one that would ultimately shape the design philosophy of the Joint Strike Fighter (JSF) program. 1. Lockheed Martin's X-35 Stealth Features: The X-35 emphasized advanced stealth capabilities with a design that reduced radar cross-section, including a blended wing-body and internal weapon bays. Propulsion: The X-35 incorporated Pratt & Whitney's F135 engine, designed to provide high thrust and compatibility with short takeoff/vertical landing (STOVL) requirements. For the STOVL variant, a unique lift fan system was integrated, using a shaft-driven fan to enable vertical flight while maintaining compactness for carrier operations. Versatility: The design achieved significant commonality across three variants (Air Force’s CTOL, Navy’s CATOBAR, and Marine Corps’ STOVL), allowing tailored performance while reducing costs. Avionics: The platform would eventually incorporate next-gen sensor fusion and avionics for superior situational awareness and targeting capabilities. 2. Boeing's X-32 Distinctive Wing Design: Boeing's design featured a large delta wing, optimized for low-speed carrier landings and maximizing internal fuel storage for extended range. Propulsion: The X-32 also utilized the F135 engine but adopted a direct-lift system for STOVL operations, which relied on vectored thrust (like the AV8B harrier II) instead of a separate lift fan. Simplified Airframe: To reduce production costs, Boeing emphasized an unconventional design with fewer parts and advanced composite materials. Focus on Affordability: Boeing prioritized cost reduction through modular components and a simpler design philosophy, though some compromises in agility and stealth compared to the X-35 were noted. 3. McDonnell Douglas X-36 TDM NOTE: At this time in the JAST competition, there were no official X plane numbers assigned. A tail less version McDonnell JAST entry would eventually be built as sub scale demonstrator called the X-36 for a different program. But for the sake of simplicity we will call the JAST McDonnell entry the X-36, even though thats not what it was called at the time. It should be noted that the future Boeing F-47 NGAD (Next Generation Air Dominance) aircraft bears a strong resemblance to the X-36. This was a consortium of McDonnell Douglas, British Aerospace, and Northrop Grumman. Naval Adaptability: McDonnell Douglas, known for the F/A-18 Hornet, proposed a design leveraging proven carrier-operational features such as foldable wings and robust landing gear for harsh environments. Shallow V tail and Lambda wing with canards Concept: The X-36, an experimental demonstrator, incorporated advanced flight controls for high maneuverability. It was also designed with a very modular/flexible bomb bay section. It also had a lambda style wing reminiscent of the old F101 Voodoo. Early artist renderings show a canard with the lambda wing. This would have been perceived as risky for a stealth design of the time. Gas Driven Lift Fan : Where as the X-35 used a mechanical shaft power the vertical lift fan, the X-36 used a gas driven one. Basically using exhaust gas or bypass air from the main engine. Stealth and Payload: Its design intended to strike a balance between low observability and a payload capacity compatible with various mission profiles, including deep strike and air superiority roles. From just looking at these aircraft, TDM thinks the X-36 is the sexiest, the X-35 is the most conventional, and the X-32 is the most utilitarian (and ugly). Here are detailed design and technical highlights of the 3 contenders for the JSF program: Key Challenges Addressed by all contenders Stealth Requirements: Stealth design remained central for survivability in contested air spaces. Innovations in radar-absorbing materials and minimized radar cross-section designs were essential across all proposals. Multi-role Capabilities: The contenders needed to meet the Air Force's need for a strike fighter, the Navy's carrier-operable demands, and the Marine Corps' vertical lift requirements, pushing the limits of design adaptability. Cost Control: To keep per-unit costs within acceptable limits, all teams sought economies of scale through component commonality across variants​. Each contender had its primary design emphasis. The X-36 was a radical very stealthy and maneuverable design. The X-32 was, reflecting Boeing's commercial aircraft experience, built for cheap production. The F-35 derived a lot of its capability from the proven F-22, and had some parts and manufacturing process commonality between the variants. On Jan27,1994 the JAST program became the Joint Strike Fighter (JSF) program and moved from technology demonstration to building a real aircraft. Early elimination of the X-36 The first elimination round was purely a paper exercise. The X-36 was eliminated from the JSF competition on NOV 16, 1996. A fateful day for McDonnell Douglas. The McDonnell Douglas X-36 was considered too risky for the JSF program due to several factors that highlighted its innovative but unproven technologies and approach. Here's a breakdown of the reasons: 1. Experimental Nature The X-36 was an experimental shallow V Tail aircraft designed to test advanced flight control technologies, such as thrust vectoring and artificial stability systems. While it showcased cutting-edge potential, these technologies were not mature enough to meet the JAST program’s stringent timelines and operational requirements. 2. Lack of Proven Adaptability The X-36’s shallow V tail design and exhaust gas driven lift fan behind the cockpit was seen as a high technical risk. Integrating such an unconventional design into a multi-role aircraft that could satisfy all service branches (Air Force, Navy, and Marine Corps) was seen as a significant technical challenge. 3. Risk vs. Requirements The JSF program sought an affordable, low-risk solution capable of integrating advanced technologies while ensuring compatibility with existing infrastructure. The X-36’s ambitious features increased development complexity, cost, and risk—potentially conflicting with the program’s emphasis on affordability and interoperability. 4. Focus on Commonality The JSF program prioritized designs that could be scaled and modified across service branches with minimal cost and performance trade-offs. The unique design and systems of the X-36 were deemed less adaptable to the concept of a common airframe across CTOL, STOVL, and carrier-based operations. So while the X-36 was an innovative platform demonstrating future potential for tailless aircraft and thrust-vectoring technology, its experimental status and associated design risks made it unsuitable for the JAST program, which emphasized balanced innovation and operational reliability​. This aircraft was 30 years ahead of its time. In fact it looks similar to many representations of the current USAF/USN NGAD (Next Generation Air Dominance) fighter program. The result of this loss put McDonnell in a very bad spot. It just lost the biggest fighter program in history. This combined with a general budget austerity is the post cold war 90s meant McDonnell could not survive as going concern. In 1997 it merged with Boeing. Then There Were Two With the elimination of the X-36, only the X-32 and X-35 remained. There could only be one winner. Both manufacturers were to build a few prototypes of each variant of each aircraft. There would then be a real world fly off of the competing models. The winner would take all. What was the prize ?? The production of over 3,000 aircraft for the US military over decades. In addition at least another 1,000 for the foreign partners. It could even possibly be the last manned fighter aircraft built. Whoever won this would dominate worldwide fighter aircraft production for decades. This was truly an awesome prize. Summary: The Joint Advanced Strike Technology (JAST) program, launched by the U.S. Department of Defense in the early 1990s, aimed to develop an affordable, next-generation multi role strike aircraft that could serve the Air Force, Navy, and Marine Corps. Its core goals included enhancing survivability against advanced air defense threats, improving secure communication and interoperability, streamlining the aging aircraft fleet, and delivering modern capabilities at reduced costs through commonality across variants. In 1994, JAST merged with the Common Affordable Lightweight Fighter (CALF) initiative, eventually becoming the Joint Strike Fighter (JSF) program—the foundation for the F-35. Three major contenders participated in the technology demonstration phase: Lockheed Martin’s X-35, Boeing’s X-32, and the McDonnell Douglas entry, often referred to retroactively as the X-36. The X-35 emphasized stealth, versatility, and a novel lift-fan system; the X-32 prioritized cost-efficiency with a simplified airframe and delta wing; and the X-36 explored highly maneuverable, stealthy designs with a gas-driven lift fan and canards. However, the X-36 was eliminated early in the competition due to its experimental nature and high technical risk. Its failure, coupled with defense budget cuts, led to McDonnell Douglas’s decline and eventual 1997 merger with Boeing. References Barret & Carpenter. Survivability in the Digital Age : The Imperative for Stealth, The Mitchell Institute for Aerospace Studies, Air Force Association, July 2017 Burbage,Clark, & Pitman. F-35 The inside story of the Lightning II. SkyHorse Publishing, 2023. https://www.secretprojects.co.uk/threads/mcdd-northrop-bae-astovl-mrf-jast-jsf-studies.2392/- accessed 10-DEC-2024 https://en.wikipedia.org/wiki/McDonnell_Douglas_X-36-accessed 10-DEC-2024