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Paul Bevilaqua | |
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Born | Paul Michael Bevilaqua May 11, 1945 |
Occupation | Aeronautics engineer |
Paul Michael Bevilaqua (born May 11, 1945) is an aeronautics engineer at Lockheed Martin in California, United States. In 1990, he invented the lift fan for the Joint Strike Fighter F-35B along with fellow Skunk Works engineer, Paul Shumpert. [1]
In 2005, Bevilaqua was elected as a member of the National Academy of Engineering for his theoretical contributions, practical innovations, and increased operational utility in vertical takeoff and landing aircraft.
Bevilaqua obtained his Doctorate in Aeronautics and Astronautics with a focus on Turbulent wakes at Purdue University in 1973. [2] He was also an Air Force Lieutenant at Wright-Patterson Air Force Base (WP-AFB), where he began professional work in 1971. [3] He became Deputy Director of the Energy Conversion Lab at WP-AFB, managed by jet inventor Hans von Ohain. In 1975, Paul left the Air Force to be a Manager of Advanced Programs at Rockwell International's Navy Aircraft Plant. [3] In 1985, he was appointed Chief Aeronautical Scientist at Lockheed, trying to come up with a new line of business. [3]
Hans von Ohain inspired Bevilaqua to think like an engineer rather than a mathematician [4] [5] - "in school I learned how to move the pieces, and Hans taught me how to play chess", [6] although he said that about Purdue as well. [2] Ohain also showed Bevilaqua "what those TS-diagrams actually mean". [3]
While at WP, Ohain, [7] Bevilaqua and others investigated and patented [8] various flow related concepts, some of them being flow multipliers related to vertical take-off and landing.
In the 1980s, the United States Marine Corps wanted a Vertical/Short Takeoff and Landing (V/STOVL) aircraft with more speed and payload than the Harrier/AV-8B. [9] [10] [11]
Bevilaqua was working for Lockheed Skunk Works in 1986, when DARPA and the similar British agency launched a program called ASTOVL [11] and issued a 9-month contract to develop concepts [12] for a stealthy supersonic STOVL plane, in accordance with USMC wishes, but without the usual strict technical requirements. [3]
The challenge in combining supersonic flight and STOVL is that an engine powerful enough to lift an aircraft would be too wide to be supersonic, as shown by the Harrier. [3] [5] A smaller engine with higher air flow was needed, but seemed impossible.
Inspired by the General Electric CJ805-23 aft-turbofan [13] and the Rolls-Royce tandem-fan, [3] [14] an appropriate system seemed to be a dual thrust system with a lift vector at the front and a swivel nozzle at the back for the jet engine, counterbalancing each other.
Many options were investigated, [13] but with one month left and no results, Bevilagua took another look at the situation. Three elements were clear: [5]
Exploiting bypass air is the usual way of increasing thrust, but when air flow drops so does pressure, which increases engine speed at the risk of failure. This apparent flaw suddenly turned to a benefit when it dawned upon him that the extra engine power could be put to good use by turning a lift fan. [5] "It took eight months of brainstorming to program the computer in my head, and ten seconds to come up with the idea." [2]
The solution involved transforming some of the jet blast to vertical air flow by extracting energy from the hot jet blast with a turbine that turns a shaft driving a fan pointing down, thereby increasing impulse and thus lift, without increasing drag. [2] The transition between horizontal and vertical lift needs to be precisely controlled, and the two lift columns need to be carefully balanced, to maintain control of the aircraft.
The system works similarly to a turbofan, with an extra bypass fan moved and tilted 90 degrees to move cool unburned air vertically instead of horizontally, [12] or a turbine helicopter whose rotor is shrunk and encased. This effect is similar to the previous flow multiplier concepts investigated by Bevilaqua (see #List of Papers) and others (although methods are different), achieving a lift/thrust-ratio of 1.5:1 [12] where previous successful aircraft were limited to 1:1 at best.
Bevilaqua is not [6] a propulsion engineer, and got help from various Lockheed experts in propulsion, materials, and other specialized fields to verify the theories of the concept, which were then patented in 1990-93. [1]
Both DARPA and the Marine Corps approved of the concept, [10] and from there, it developed through various defense programs such as CALF and JAST [11] into the Joint Strike Fighter Program and through to the X-35B and F-35B. Bevilaqua was a key figure in persuading [10] the Air Force in 1992 that the concept aircraft could be useful as a conventional aircraft without the LiftFan. When the US Navy also came on board, [10] the road was paved for the JSF concept of similar aircraft with different applications, in accordance with JAST Concept Exploration findings. [11]
The practical development and testing of the F135 engine and system was performed by Pratt & Whitney, Allison Engine Company, [16] NASA, [17] Rolls-Royce and others.
One of the key factors in handing the $200B [3] JSF contract to LM is said [18] to be when the X-35B took off from 150 feet of runway, went supersonic, and landed vertically in one flight on July 20, 2001 [19] - a performance that only the X-35B had done, and only because of the LiftFan concept.
The JSF team was awarded the Collier Trophy in 2001 [20] [21] for the working system, and Bevilaqua received the Paul E. Haueter Memorial Award (American Helicopter Society) in 2004. [22]
The Lockheed Martin F-35 Lightning II is an American family of single-seat, single-engine, stealth multirole combat aircraft designed for air superiority and strike missions; it also has electronic warfare and intelligence, surveillance, and reconnaissance capabilities. Lockheed Martin is the prime F-35 contractor with principal partners Northrop Grumman and BAE Systems. The aircraft has three main variants: the conventional takeoff and landing (CTOL) F-35A, the short take-off and vertical-landing (STOVL) F-35B, and the carrier-based (CV/CATOBAR) F-35C.
A jet engine is a type of reaction engine, discharging a fast-moving jet of heated gas that generates thrust by jet propulsion. While this broad definition may include rocket, water jet, and hybrid propulsion, the term jet engine typically refers to an internal combustion air-breathing jet engine such as a turbojet, turbofan, ramjet, pulse jet, or scramjet. In general, jet engines are internal combustion engines.
A short take-off and vertical landing aircraft is a fixed-wing aircraft that is able to take off from a short runway and land vertically. The formal NATO definition is:
A Short Take-Off and Vertical Landing aircraft is a fixed-wing aircraft capable of clearing a 15 m obstacle within 450 m of commencing take-off run, and capable of landing vertically.
A vertical take-off and landing (VTOL) aircraft is one that can take off and land vertically without relying on a runway. This classification can include a variety of types of aircraft including helicopters as well as thrust-vectoring fixed-wing aircraft and other hybrid aircraft with powered rotors such as cyclogyros/cyclocopters and gyrodynes.
The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and a turbine. The compressed air from the compressor is heated by burning fuel in the combustion chamber and then allowed to expand through the turbine. The turbine exhaust is then expanded in the propelling nozzle where it is accelerated to high speed to provide thrust. Two engineers, Frank Whittle in the United Kingdom and Hans von Ohain in Germany, developed the concept independently into practical engines during the late 1930s.
Hans Joachim Pabst von Ohain was a German physicist, engineer, and the designer of the first aircraft to use a turbojet engine. Together with Frank Whittle he has been described as the co-inventor of the turbojet engine. However, the historical timelines show that von Ohain was still a university student when, in January 1930, Whittle filed his first patent for a turbojet engine and successfully tested his first engine in April 1937, some 6 months before von Ohain. Additionally, prior to designing his engine and filing his own patent in 1935, von Ohain had read and critiqued Whittle's patents. Von Ohain stated in his biography that "My interest in jet propulsion began in the fall of 1933 when I was in my seventh semester at Göttingen University. I didn't know that many people before me had the same thought." Unlike Whittle, von Ohain had the significant advantage of being supported by an aircraft manufacturer, Heinkel, who funded his work.
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 all. Generally, a V/STOL aircraft needs to be able to hover. Helicopters are not considered under the V/STOL classification as the classification is only used for aeroplanes, aircraft that achieve lift (force) in forward flight by planing the air, thereby achieving speed and fuel efficiency that is typically greater than the capability of helicopters.
The bypass ratio (BPR) of a turbofan engine is the ratio between the mass flow rate of the bypass stream to the mass flow rate entering the core. A 10:1 bypass ratio, for example, means that 10 kg of air passes through the bypass duct for every 1 kg of air passing through the core.
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 production in the early 21st century as the F-35 Lightning II.
The Rolls-Royce Pegasus is a British turbofan engine originally designed by Bristol Siddeley. It was manufactured by Rolls-Royce plc. The engine is not only able to power a jet aircraft forward, but also to direct thrust downwards via swivelling nozzles. Lightly loaded aircraft equipped with this engine can manoeuvre like a helicopter. In particular, they can perform vertical takeoffs and landings. In US service, the engine is designated F402.
The General Electric/Rolls-Royce F136 was an advanced turbofan engine being developed by General Electric and Rolls-Royce plc for the Lockheed Martin F-35 Lightning II. The two companies stopped work on the project in December 2011 after failing to gather Pentagon support for further development.
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 vehicle.
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 demonstrator, which was further developed into the Lockheed Martin F-35 Lightning II.
The Pratt & Whitney F119, company designation PW5000, is an afterburning turbofan engine developed by Pratt & Whitney for the Advanced Tactical Fighter (ATF) program, which resulted in the Lockheed Martin F-22 Raptor. The engine delivers thrust in the 35,000 lbf (156 kN) class and was designed for sustained supersonic flight without afterburners, or supercruise. Delivering almost 22% more thrust with 40% fewer parts than its F100 predecessor, the F119 allows the F-22 to achieve supercruise speeds of up to Mach 1.8. The F119's nozzles incorporate thrust vectoring that enable them to direct the engine thrust ±20° in the pitch axis to give the F-22 enhanced maneuverability.
The Pratt & Whitney F135 is an afterburning turbofan developed for the Lockheed Martin F-35 Lightning II, a single-engine strike fighter. It has two variants; a Conventional Take-Off and Landing (CTOL) variant used in the F-35A and F-35C, and a two-cycle Short Take-Off Vertical Landing (STOVL) variant used in the F-35B that includes a forward lift fan. The first production engines were delivered in 2009.
A turboshaft engine is a form of gas turbine that is optimized to produce shaft horsepower rather than jet thrust. In concept, turboshaft engines are very similar to turbojets, with additional turbine expansion to extract heat energy from the exhaust and convert it into output shaft power. They are even more similar to turboprops, with only minor differences, and a single engine is often sold in both forms.
Joint Strike Fighter (JSF) is a development and acquisition program intended to replace a wide range of existing fighter, strike, and ground attack aircraft for the United States, the United Kingdom, Italy, Canada, Australia, the Netherlands, Denmark, Norway, and formerly Turkey. After a competition between the Boeing X-32 and the Lockheed Martin X-35, the latter aircraft was selected for a contract award and developed into the F-35 Lightning II, which will replace various tactical aircraft, including the US F-16, A-10, F/A-18A-D, AV-8B, EA-6B and British Harrier GR7, GR9s and Tornado GR4. The projected average annual cost of the program is $12.5 billion in 2012 with an estimated cost in 2024 of $2 trillion over its lifespan.
The Rolls-Royce LiftSystem, together with the F135 engine, is an aircraft propulsion system designed for use in the STOVL variant of the F-35 Lightning II. The complete system, known as the Integrated Lift Fan Propulsion System (ILFPS), was awarded the Collier Trophy in 2001.
Shipborne rolling vertical landing (SRVL) is a method used to land a V/STOL aircraft that uses both the vertical thrust from the jet engine and lift from the wings.
Lift fan is an aircraft configuration in which lifting fans are located in large holes in an otherwise conventional fixed wing or fuselage. It is used for V/STOL operation.
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