Boeing X-32
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The Boeing X-32 is a concept demonstrator aircraft that was designed for the Joint Strike Fighter competition. It lost to the
Lockheed Martin X-35 The Lockheed Martin X-35 is a concept demonstrator aircraft (CDA) developed by Lockheed Martin for the Joint Strike Fighter program. The X-35 was declared the winner over the competing Boeing X-32 and a developed, armed version went on to enter ...
demonstrator, which was further developed into the
Lockheed Martin F-35 Lightning II The Lockheed Martin F-35 Lightning II is an American family of single-seat, single-engine, all-weather stealth multirole combat aircraft that is intended to perform both air superiority and strike missions. It is also able to provide ele ...
.


Development


Background

In 1993, the
Defense Advanced Research Projects Agency The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military. Originally known as the Adv ...
(DARPA) launched the Common Affordable Lightweight Fighter project (CALF). The project's purpose was to develop a stealth-enabled design to replace all of
United States Department of Defense The United States Department of Defense (DoD, USDOD or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government directly related to national secu ...
lighter weight fighter and attack aircraft, including the
F-16 Fighting Falcon The General Dynamics F-16 Fighting Falcon is a single-engine multirole fighter aircraft originally developed by General Dynamics for the United States Air Force (USAF). Designed as an air superiority day fighter, it evolved into a successful ...
,
McDonnell Douglas F/A-18 Hornet The McDonnell Douglas F/A-18 Hornet is an all-weather, twin-engine, supersonic, carrier-capable, multirole combat aircraft, designed as both a fighter and attack aircraft (hence the F/A designation). Designed by McDonnell Douglas (now p ...
, and vertical/short takeoff / vertical landing (
V/STOL A vertical and/or short take-off and landing (V/STOL) aircraft is an airplane able to take-off or land vertically or on short runways. Vertical takeoff and landing (VTOL) aircraft are a subset of V/STOL craft that do not require runways at al ...
)
AV-8B Harrier II The McDonnell Douglas (now Boeing) AV-8B Harrier II is a single-engine ground-attack aircraft that constitutes the second generation of the Harrier family, capable of vertical or short takeoff and landing (V/STOL). The aircraft is primaril ...
. Around the same time the Joint Advanced Strike Technology (JAST) project was started. In 1994, the U.S. Congress ordered the two to be merged into the Joint Strike Fighter (JSF) program. Many companies took part in the first phase of this project, which involved drafting concept aircraft designs for submission to the
Department of Defense Department of Defence or Department of Defense may refer to: Current departments of defence * Department of Defence (Australia) * Department of National Defence (Canada) * Department of Defence (Ireland) * Department of National Defense (Philippin ...
. On 16 November 1996,
Boeing The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and product ...
and
Lockheed Martin The Lockheed Martin Corporation is an American aerospace, arms, defense, information security, and technology corporation with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It ...
were awarded contracts for them to produce two of their concept demonstrator aircraft (CDA) each. Under the contract, these fighters were required to demonstrate conventional take-off and landing (CTOL), carrier take-off and landing (CV version), and short take-off and vertical landing (STOVL). They were also expected to include ground demonstrations of a production representative aircraft's systems, such as the Preferred Weapon System Concept (PWSC). One major departure from previous projects was the prohibition of the companies from using their own money to finance development. Each was awarded $750 million to produce their two aircraft – including avionics, software and hardware. This limitation promoted the adoption of low cost manufacturing and assembly techniques, and also prevented either Boeing or Lockheed Martin from
bankrupting Bankruptcy is a legal process through which people or other entities who cannot repay debts to creditors may seek relief from some or all of their debts. In most jurisdictions, bankruptcy is imposed by a court order, often initiated by the debtor ...
themselves in an effort to win such an important contest.


Designing the X-32

Boeing's strategy for a competitive advantage was to offer substantially lower manufacturing and life-cycle costs by minimizing variations between the different JSF versions. The X-32 therefore was designed around a large one piece
carbon fiber Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers (Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon compo ...
composite Composite or compositing may refer to: Materials * Composite material, a material that is made from several different substances ** Metal matrix composite, composed of metal and other parts ** Cermet, a composite of ceramic and metallic materials ...
delta wing A delta wing is a wing shaped in the form of a triangle. It is named for its similarity in shape to the Greek uppercase letter delta (Δ). Although long studied, it did not find significant applications until the Jet Age, when it proved suitabl ...
. The wing had a span of 9.15 meters, with a 55-degree leading edge sweep, and could hold up to 20,000 pounds (9,000 kg) of fuel. The purpose of the high sweep angle was to allow for a thick wing section to be used while still providing limited
transonic Transonic (or transsonic) flow is air flowing around an object at a speed that generates regions of both subsonic and supersonic airflow around that object. The exact range of speeds depends on the object's critical Mach number, but transonic ...
aerodynamic drag In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fl ...
, and to provide a good angle for wing-installed conformal antenna equipment.Sweetman, Bill. ''Lockheed Stealth''. St. Paul, Minnesota: MBI, 2001. . The wing would prove a challenge to fabricate."Battle of the X-Planes."
''NOVA'', NOVA (TV series), airdate: 4 February 2003.
The compete-on-cost strategy also led Boeing to pick a direct-lift
thrust vectoring Thrust vectoring, also known as thrust vector control (TVC), is the ability of an aircraft, rocket, or other vehicle to manipulate the direction of the thrust from its engine(s) or motor(s) to control the attitude or angular velocity of the v ...
system, for the Marines'
short take-off and vertical landing A short take-off and vertical landing aircraft (STOVL aircraft) is a fixed-wing aircraft that is able to take off from a short runway (or take off vertically if it does not have a heavy payload) and land vertically (i.e. with no runway). The ...
(STOVL) requirement, as this would only necessitate the addition of a thrust vectoring module around the main engine. However, this choice required the engine to be mounted directly behind the cockpit, and moved the
center of gravity In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weight function, weighted relative position (vector), position of the distributed mass sums to zero. Thi ...
forward from its usual position in jet fighters (towards the rear of the airplane) to enable a neutral-attitude hover. Boeing had proposed, in the 1960s, a similar supersonic fighter with a mid-center-of-gravity mounted engine with vectored thrust nozzles, but this never proceeded beyond pictures published in ''Aviation Week''. By comparison, the Lockheed entry looked like, if anything, a smaller version of the F-22 Raptor stealth fighter.''Aviation History magazine,'' 9 March 2011. Retrieved: 27 May 2012. Yet another effect of the selection of the direct-lift system was the large chin-mounted air intake. This was required to feed sufficient air to the main engine (to provide the thrust necessary to hover) during the zero horizontal velocity phase, when it could not exploit ram-air pressure. A knock-on effect of this large intake was the potential direct visibility of the compressor blades to radar (see
radar cross-section Radar cross-section (RCS), also called radar signature, is a measure of how detectable an object is by radar. A larger RCS indicates that an object is more easily detected. An object reflects a limited amount of radar energy back to the source. ...
). Mitigation possibilities included variable baffles designed to block incoming
radio wave Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of 300 gigahertz (GHz) and below. At 300 GHz, the corresponding wavelength is 1 mm (short ...
s without adversely affecting airflow.


Design changes

The two X-32 aircraft featured a delta wing design. However, eight months into construction of the concept demonstrator aircraft, the JSF's maneuverability and payload requirements were refined at the request of the
Navy A navy, naval force, or maritime force is the branch of a nation's armed forces principally designated for naval warfare, naval and amphibious warfare; namely, lake-borne, riverine, littoral zone, littoral, or ocean-borne combat operations and ...
and Boeing's delta wing design fell short of the new targets. Engineers altered the aircraft's design with a conventional canted
twin tail A twin tail is a specific type of vertical stabilizer arrangement found on the empennage of some aircraft. Two vertical stabilizers—often smaller on their own than a single conventional tail would be—are mounted at the outside of the aircra ...
that reduced weight and improved agility, but it was too late to change the aircraft. It was judged that they would be sufficient to demonstrate Boeing's technology. On 14 December 1999, Boeing unveiled both its concept demonstrators at its plant in Palmdale, California, in front of 5,500 attendees. While the X-32A was expected to make an appearance, the roll out of the X-32B was a surprise, as construction of the latter aircraft had started some three months after the former and was completed six weeks after the X-32A. Boeing attributed the rapid construction of the STOVL version to the use of digital design and assembly methods. After having the Pratt & Whitney F119 engine installed in April 2000, the X-32A commenced low- and medium-speed taxi tests, which had been completed by late May.


Flight testing

Due to the heavy delta wing design of the X-32, Boeing demonstrated STOVL and supersonic flight in separate configurations, with the STOVL configuration requiring that some parts be removed from the fighter. The company promised that their conventional tail design for production models would not require separate configurations. By contrast, the Lockheed Martin X-35 concept demonstrator aircraft were capable of transitioning between their STOVL and supersonic configurations in mid-flight. The first flight of the X-32A (designed for CTOL and carrier trials) took place on 18 September 2000, from Boeing's Palmdale plant to
Edwards Air Force Base Edwards Air Force Base (AFB) is a United States Air Force installation in California. Most of the base sits in Kern County, but its eastern end is in San Bernardino County and a southern arm is in Los Angeles County. The hub of the base is E ...
. The aircraft, piloted by Boeing test pilot Fred Knox, took of runway before becoming airborne at at around 8:00 am. Shortly after takeoff, a minor hydraulic leak was discovered and the flight was shortened to 20 minutes from the expected 30–40 minutes. According to Knox, the F/A-18 chase plane required "a lot of afterburner" to keep up with the X-32 during the initial stages. During the flight, the aircraft reached , attained a speed of , and attained an angle of attack of 13°. Despite the shortened flight, about 80% of the planned test points were accomplished. It was powered by a conventional derivative of the F-22 afterburning turbofan, designated F119-PW-614C. On 29 March 2001, the X-32B STOVL version made its first flight. The flight lasted 50 minutes as the aircraft flew from Palmdale to Edwards AFB. The flight had originally been scheduled for the third quarter of 2000. A modified version of the -614C engine, known as the F119-PW-614S, powered the STOVL aircraft. In normal flight, the -614S was configured as a conventional afterburning turbofan. However, in the STOVL mode a butterfly valve diverted the core stream exhaust gases to a pair of thrust vectoring nozzles located close to the aircraft's center-of-gravity. Forward of these nozzles, a jet screen nozzle provided a sheet of cool bypass air to minimise hot gas recirculation. There was also a pair of ducts leading to roll nozzles near the wing tips. Two pairs of ducts fed the aft-pitch yaw nozzles and the forward-pitch nozzles. The afterburner was unlit, with no gas flow during lift. The X-32B achieved STOVL flight in much the same way as the
AV-8B Harrier II The McDonnell Douglas (now Boeing) AV-8B Harrier II is a single-engine ground-attack aircraft that constitutes the second generation of the Harrier family, capable of vertical or short takeoff and landing (V/STOL). The aircraft is primaril ...
with
thrust vectoring Thrust vectoring, also known as thrust vector control (TVC), is the ability of an aircraft, rocket, or other vehicle to manipulate the direction of the thrust from its engine(s) or motor(s) to control the attitude or angular velocity of the v ...
of the jet exhaust. A smooth transition (between STOVL and normal modes) was obtained by maintaining a constant engine match, facilitated by the control system algorithm maintaining a fixed total nozzle effective area. Thus the engine was unaware of various nozzles being opened up and closed off to complete the transition. The F119-PW-614S was a direct lift engine, whereas the Lockheed Martin STOVL team used a more complex and riskier alternative, known as the F119-PW-611, which comprised a remote shaft-driven lift fan powered by the main engine. However, this generated more lift thrust than possible with only direct exhaust gases. A successful design would have greater payload, and thus longer range than a simple thrust vectored
turbofan The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft engine, aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the ''turbo'' portion refers to a gas turbine engine which ac ...
. Flight testing of both companies' aircraft continued until July 2001.


JSF competition

On 26 October 2001, the Department of Defense announced that the Lockheed Martin X-35 won the JSF competition. The X-35 would be developed into the production
Lockheed Martin F-35 Lightning II The Lockheed Martin F-35 Lightning II is an American family of single-seat, single-engine, all-weather stealth multirole combat aircraft that is intended to perform both air superiority and strike missions. It is also able to provide ele ...
. The loss of the JSF contract to Lockheed Martin in 2001 was a major blow to Boeing, as it represented the most important international fighter aircraft project since the
Lightweight Fighter program The Lightweight Fighter (LWF) program was a United States Air Force technology evaluation program initiated in the late 1960s by a group of officers and defense analysts known as the "Fighter Mafia". It was spurred by then-Major John Boyd's 'e ...
competition of the 1960s and 1970s, which had led to the
F-16 Fighting Falcon The General Dynamics F-16 Fighting Falcon is a single-engine multirole fighter aircraft originally developed by General Dynamics for the United States Air Force (USAF). Designed as an air superiority day fighter, it evolved into a successful ...
and
F/A-18 Hornet The McDonnell Douglas F/A-18 Hornet is an all-weather, twinjet, twin-engine, supersonic aircraft, supersonic, carrier-based aircraft, carrier-capable, Multirole combat aircraft, multirole combat aircraft, designed as both a Fighter aircraft, ...
. At the time, the production run of the JSF was estimated at anywhere between 3,000 and 5,000. Prior to the awarding of the contract, many lawmakers pushed the idea of retaining the losing competitor as a sub-contractor; however, the "winner takes all" principle was not changed. Nonetheless, Boeing views its work on the X-32 as a strategic investment, yielding important technologies which it has been able to adopt in the Boeing F/A-18E/F Super Hornet and other studies.


Surviving aircraft

In 2005, the Boeing X-32A was transferred to the National Museum of the United States Air Force near
Dayton, Ohio Dayton () is the sixth-largest city in the U.S. state of Ohio and the county seat of Montgomery County. A small part of the city extends into Greene County. The 2020 U.S. census estimate put the city population at 137,644, while Greater Day ...
. Its condition deteriorated due to being outside for several years following the end of the JSF competition, but it is now indoors and planned to be restored. The X-32B was transferred to the Patuxent River Naval Air Museum adjacent to NAS Patuxent River in St. Mary's County, Maryland in 2005."Patuxent River Naval Air Museum."
''history.navy.mil.'' Retrieved: 30 June 2011.
It underwent restoration at the museum's restoration facility in June 2009 and is now on display.


Specifications


See also


References

;Notes ;Bibliography * * Jenkins, Dennis R. et al
"SP-2003-4531: American X-Vehicles, An InventoryX-1 to X-50."
''NASA'', June 2003. * Jenkins, Dennis R. and Tony R. Landis. ''Experimental & Prototype U.S. Air Force Jet Fighters.'' North Branch, Minnesota: Specialty Press, 2008. . * Keijsper, Gerald. ''Lockheed F-35 Joint Strike Fighter''. London: Pen & Sword Aviation, 2007. .


External links


Boeing X-32 history page



PBS Documentary. NOVA: JSF Selection


{{Authority control Single-engined jet aircraft X-32 X-32 X-32, Boeing Delta-wing aircraft Aircraft first flown in 2000 V/STOL aircraft by thrust vectoring Stealth aircraft