The Renault R26 is a Formula One racing car, used by the Renault F1 team in the 2006 Formula One season. The car was driven by Giancarlo Fisichella. Over the course of the season it scored 8 wins out of 18 races, was the most complete package in most of the year, followed by the rival Ferrari 248 F1; the R26 helped Renault in claiming the Constructors' Championship with a 5-point advantage over rival Ferrari, taking Fernando Alonso to his second Drivers' Championship in succession, 13 points ahead of rival Michael Schumacher. It brought the last Constructors' Championship in recent history to tyre manufacturer Michelin. Renault used'Mild Seven' logos in Bahrain, Australia, Monaco, United States, Hungary and Japan. Like its rival the Ferrari 248 F1, the R26 was notable for its rock-solid reliability, chassis R26-03 driven by Fernando Alonso started all of the races of the 2006 season without the need to be replaced, it led more laps and won more races than any single chassis in 2006 in addition to winning the world championship.
R26-03 now sits at Renault's "Collection" heritage collection in Paris. The R26 was succeeded by the R27 for the 2007 season. A tuned mass damper known as a harmonic absorber, is a device, attached to structures in order to reduce the strength of vibrations passing through them. Tuned mass dampers are used in buildings across the world to reduce the effects of earthquakes and strong gusts of wind. In the Renault R26, this technology was used for a more benign purpose, it was used to keep the front of car stable through slow and fast corners. Keeping the front of the car stable is crucial to the aerodynamic efficiency of the car because changes in ride height - caused by bumps on the road or changes in downforce levels due to speed - can alter the way that air passes over the front wing of the car and therefore the rest of the car's aerodynamic efficiency suffers; the Tuned mass damper in the Renault R26 was invented by Renault engineer Rob Marshall. The mass damper itself was standing upright, with the mechanical components inside.
Inside the cylinder sat a 9 kilogram disc which rested in between two springs. The disc was free to move on the Y-axis with its only hindrance, the springs that it was attached to and the damper fluid within the cylinder; the whole assembly was attached to the chassis inside the nosecone of the car. The device was then'tuned' to the needs of each track by either changing the clearance between the disc and the cylinder bore or by adjusting the size of two-way valve within the disc itself; the Tuned mass damper on the Renault R26 vibrated in the opposite direction from the chassis due to inertia, with its magnitude calculated by the'tuning' variables mentioned above. This counteracting force stabilized the front end of the car over kerbs and through slow and fast corners. Renault first introduced the technology in its 2005 challenger, Renault R25; the technology was raced in the last few races of the 2005 season and had been deemed to be legal by the stewards. During the first half of the 2006 season, Renault had built up a comfortable points lead over their main rivals Ferrari.
However, at the time of the German Grand Prix at the Hockenheimring the FIA decided to ban all the teams from using Tuned mass dampers in their car. Though the system was deemed legal for over half a year, the FIA decided that it broke the rule that no moving part can influence the aerodynamics of the car. Renault claimed; the ban hurt the Renault team more than their competitors because Renault had designed their whole car around the technology, their competitors had just included the technology as an after-thought after seeing Renault's implementation. This was visible because Ferrari won 5 of the 7 remaining races in the season. However, the French team managed to defend both championship titles successfully
The National Aeronautics and Space Administration is an independent agency of the United States Federal Government responsible for the civilian space program, as well as aeronautics and aerospace research. NASA was established in 1958; the new agency was to have a distinctly civilian orientation, encouraging peaceful applications in space science. Since its establishment, most US space exploration efforts have been led by NASA, including the Apollo Moon landing missions, the Skylab space station, the Space Shuttle. NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the Space Launch System and Commercial Crew vehicles; the agency is responsible for the Launch Services Program which provides oversight of launch operations and countdown management for unmanned NASA launches. NASA science is focused on better understanding Earth through the Earth Observing System. From 1946, the National Advisory Committee for Aeronautics had been experimenting with rocket planes such as the supersonic Bell X-1.
In the early 1950s, there was challenge to launch an artificial satellite for the International Geophysical Year. An effort for this was the American Project Vanguard. After the Soviet launch of the world's first artificial satellite on October 4, 1957, the attention of the United States turned toward its own fledgling space efforts; the US Congress, alarmed by the perceived threat to national security and technological leadership, urged immediate and swift action. On January 12, 1958, NACA organized a "Special Committee on Space Technology", headed by Guyford Stever. On January 14, 1958, NACA Director Hugh Dryden published "A National Research Program for Space Technology" stating: It is of great urgency and importance to our country both from consideration of our prestige as a nation as well as military necessity that this challenge be met by an energetic program of research and development for the conquest of space... It is accordingly proposed that the scientific research be the responsibility of a national civilian agency...
NACA is capable, by rapid extension and expansion of its effort, of providing leadership in space technology. While this new federal agency would conduct all non-military space activity, the Advanced Research Projects Agency was created in February 1958 to develop space technology for military application. On July 29, 1958, Eisenhower signed the National Aeronautics and Space Act, establishing NASA; when it began operations on October 1, 1958, NASA absorbed the 43-year-old NACA intact. A NASA seal was approved by President Eisenhower in 1959. Elements of the Army Ballistic Missile Agency and the United States Naval Research Laboratory were incorporated into NASA. A significant contributor to NASA's entry into the Space Race with the Soviet Union was the technology from the German rocket program led by Wernher von Braun, now working for the Army Ballistic Missile Agency, which in turn incorporated the technology of American scientist Robert Goddard's earlier works. Earlier research efforts within the US Air Force and many of ARPA's early space programs were transferred to NASA.
In December 1958, NASA gained control of the Jet Propulsion Laboratory, a contractor facility operated by the California Institute of Technology. The agency's leader, NASA's administrator, is nominated by the President of the United States subject to approval of the US Senate, reports to him or her and serves as senior space science advisor. Though space exploration is ostensibly non-partisan, the appointee is associated with the President's political party, a new administrator is chosen when the Presidency changes parties; the only exceptions to this have been: Democrat Thomas O. Paine, acting administrator under Democrat Lyndon B. Johnson, stayed on while Republican Richard Nixon tried but failed to get one of his own choices to accept the job. Paine was confirmed by the Senate in March 1969 and served through September 1970. Republican James C. Fletcher, appointed by Nixon and confirmed in April 1971, stayed through May 1977 into the term of Democrat Jimmy Carter. Daniel Goldin was appointed by Republican George H. W. Bush and stayed through the entire administration of Democrat Bill Clinton.
Robert M. Lightfoot, Jr. associate administrator under Democrat Barack Obama, was kept on as acting administrator by Republican Donald Trump until Trump's own choice Jim Bridenstine, was confirmed in April 2018. Though the agency is independent, the survival or discontinuation of projects can depend directly on the will of the President; the first administrator was Dr. T. Keith Glennan appointed by Republican President Dwight D. Eisenhower. During his term he brought together the disparate projects in American space development research; the second administrator, James E. Webb, appointed by President John F. Kennedy, was a Democrat who first publicly served under President Harry S. Truman. In order to implement the Apollo program to achieve Kennedy's Moon la
A tank is an armoured fighting vehicle designed for front-line combat, with heavy firepower, strong armour, tracks and a powerful engine providing good battlefield manoeuvrability. They are a key part of combined arms combat. Modern tanks are versatile mobile land weapon system platforms, mounting a large-calibre cannon in a rotating gun turret, supplemented by mounted machine guns or other weapons, such as ATGMs, or rockets, they combine this with heavy vehicle armour which provides protection for the crew, the vehicle's weapons, its propulsion systems, operational mobility, due to its use of tracks rather than wheels, which allows the tank to move over rugged terrain and adverse conditions such as mud, be positioned on the battlefield in advantageous locations. These features enable the tank to perform well in a variety of intense combat situations both offensively with fire from their powerful tank gun, defensively due to their near invulnerability to common firearms and good resistance to heavier weapons, all while maintaining the mobility needed to exploit changing tactical situations.
Integrating tanks into modern military forces spawned a new era of combat, armoured warfare. There are classes of tanks, some being larger and heavily armoured, with high calibre guns, while others smaller armoured, equipped with a smaller calibre, lighter gun; these smaller tanks move over terrain with speed and agility and can perform a reconnaissance role in addition to engaging enemy targets. The smaller faster tank would not engage in battle with a larger armoured tank, except during a surprise flanking manoeuvre; the modern tank is the result of a century of development from the first primitive armoured vehicles, due to improvements in technology such as the internal combustion engine, which allowed the rapid movement of heavy armoured vehicles. As a result of these advances, tanks underwent tremendous shifts in capability in the years since their first appearance. Tanks in World War I were developed separately and by Great Britain and France as a means to break the deadlock of trench warfare on the Western Front.
The first British prototype, nicknamed Little Willie, was constructed at William Foster & Co. in Lincoln, England in 1915, with leading roles played by Major Walter Gordon Wilson who designed the gearbox and hull, by William Tritton of William Foster and Co. who designed the track plates. This was a prototype of a new design that would become the British Army's Mark I tank, the first tank used in combat in September 1916 during the Battle of the Somme; the name "tank" was adopted by the British during the early stages of their development, as a security measure to conceal their purpose. While the British and French built thousands of tanks in World War I, Germany was unconvinced of the tank's potential, built only twenty. Tanks of the interwar period evolved into the much larger and more powerful designs of World War II. Important new concepts of armoured warfare were developed. Less than two weeks Germany began their large-scale armoured campaigns that would become known as blitzkrieg – massed concentrations of tanks combined with motorised and mechanised infantry and air power designed to break through the enemy front and collapse enemy resistance.
The widespread introduction of high-explosive anti-tank warheads during the second half of World War II led to lightweight infantry-carried anti-tank weapons such as the Panzerfaust, which could destroy some types of tanks. Tanks in the Cold War were designed with these weapons in mind, led to improved armour types during the 1960s composite armour. Improved engines and suspensions allowed tanks of this period to grow larger. Aspects of gun technology changed as well, with advances in shell design and aiming technology. During the Cold War, the main battle tank concept became a key component of modern armies. In the 21st century, with the increasing role of asymmetrical warfare and the end of the Cold War, that contributed to the increase of cost-effective anti-tank rocket propelled grenades worldwide and its successors, the ability of tanks to operate independently has declined. Modern tanks are more organized into combined arms units which involve the support of infantry, who may accompany the tanks in infantry fighting vehicles, supported by reconnaissance or ground-attack aircraft.
The tank is the 20th century realization of an ancient concept: that of providing troops with mobile protection and firepower. The internal combustion engine, armour plate, continuous track were key innovations leading to the invention of the modern tank. Many sources imply that Leonardo da Vinci and H. G. Wells in some way "invented" the tank. Leonardo's late 15th century drawings of what some describe as a "tank" show a man-powered, wheeled vehicle with cannons all around it; however the human crew would not have enough power to move it over larger distance, usage of animals was problematic in a space so confined. In the 15th century, Jan Žižka built armoured wagons containing cannons and used them in several battles; the continuous "caterpillar" track arose from attempts to improve the mobility of wheeled vehicles by spreading their weight, reducing ground pressure, increasing their traction. Experiments can be traced back as far as the 17th century, by the late nineteenth they existed in various recognizable and practical forms in several countries.
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Kenworth is an American manufacturer of medium and heavy-duty Class 8 trucks with offices based in Kirkland, Washington, a suburb of Seattle. Kenworth is one of three major truck brands under parent company Paccar. Kenworth was founded in Portland, Oregon in 1912 by brothers George T. and Louis Gerlinger, Jr. as a car and truck dealership known as Gerlinger Motor Car Works. In 1914, they decided to build their own truck with a more powerful inline six-cylinder engine, the first put into a commercial truck; the Gersix, as it was known when introduced in 1915, was framed in structural steel, which along with its power, made the truck ideal for logging in the rugged Northwest. In 1916 the company moved to Tacoma, where Seattle businessman Edgar K. Worthington was managing his mother's commercial building, he became intrigued by the Gerlinger company, doing quite well, or so it seemed, as the Gersix became a popular fixture in the Northwest. In 1917 Worthington and his business partner Captain Frederick Kent bought the business, renaming it the Gersix Motor Co.
In 1919 Kent retired from the business, his son Harry Kent became Worthington's new partner. In 1922, Gersix made 53 trucks at its factory on Fairview Avenue at Valley Street. Under the new name, the company moved to 506 Mercer Street and to 1263 Mercer Street. Trucks and motor coaches were assembled in individual bays rather than on a conventional assembly line. In 1923 Kent and Worthington reincorporated the business as the Kenworth Motor Truck Company, a combination of the names "Ken" and "Worth". In 1926 they started making buses, in 1933 Kenworth was the first American company to offer diesel engines as standard in their trucks. In 1945 Kenworth was bought by The Pacific Foundry Company; the 1970s television series "Movin On" featured a Kenworth tractor. In the 1989 James Bond movie Licence to Kill, Bond drives a Kenworth W900B semi-truck as he duels drug dealer Franz Sanchez; as of August 2016, North American Kenworth models include the T680, T880, T660, T800B and W900. As of November 2015, Kenworth's US and Canada product line includes: Class 8 ConventionalT680 T880 W900, its variants: W900B: extended Day Cab or AeroCab sleeper.
W990 T800, its variants: T800H, a High Hood variant. C500B Medium-Duty ConventionalT470 T440 T370 T270 T170 Medium-Duty Cabovers K370 K270 Class 8 ConventionalT600/T600A/T600B T450 C850 T660 T700 T2000 LW900 W925 truck W900A Cab oversK100/K100E/K136E K184 K330 K200 L700 LCF 993Medium-Duty Conventional T300Medium-Duty Cabovers Mid-Ranger series 13-210/22-210 in 1980s and K130/K220/K300 in 1990s K300 In the early 2000s Kenworth introduced to Mexico the T604, based on the Australian T604 with a few modifications in the hood; the headquarters for Kenworth Australia is located in Bayswater, Victoria where all Australian models are assembled. The first Kenworth model in Australia was the KWS925, imported built in 1962. Soon Kenworths were imported in complete knock-down kits and assembled in Preston, Victoria. Australian built Kenworth models are exported to nearby RHD markets in New Zealand and Papua New Guinea. Popular models include the T600, T601, T604, T608, T609, T610, T610SAR, T650,T658, T659, W925, T900, T904, T908, T909, T950, T350, T359, T400/T401/404S/T404ST/404SAR, K124, K100E, K100G, K104, K104B,K108, K200 and C500, C501, C508, C509, C510 and C540.
The T range includes the bonneted conventional models and the C for heavy haulage, off-road and road train use, the K range covers the cab over models. Several "Twin Steer" Models were produced through the end of the 20th Century. Most notably was the K100E Twin Steer; the current model K200 COE is available in twinsteer variants. Kenworth Australia started building the new range of trucks tying in their 2008 release with the model range being the'08 Series'; this includes the following conventional models. The only cab over truck built was the K108, popular in the B-Double market segment owing to its shorter length. Current Australian Kenworth models include: T Series - T359, T409, T409SAR, T610, T610SAR, T659, T909. C Series - C509 K Series - K200 Further upgraded new models featuring redesigned larger cabs and updated styling will be introduced to the T Series lineup in 2019. Bus production was a mainstay at Kenworth for much of the company's early years, at one time was the company's most lucrative form of business.
When the company was known as Gerlinger Motor Car Works, their first two full-chassis vehicles were school buses based on the Gersix truck chassis. In 1926, Kenworth developed a chassis for school and transit bus operators, known as the BU; the BU model sported a wheelbase of 212 inches, expanded two more inches in 1927, could be fitted with bodies ranging from 21 to 29 passengers. The BU model heralded the return of the Buda six-cylinder engine, remained the company's principal offering through 1931; the new model became so popular in the Pacific Northwest that production rose from 99 units in 1927 and 127 units in
The Peugeot 206 is a supermini car, produced by the French manufacturer Peugeot from May 1998 to the present day. The car remains in production in Iran by Iran Khodro, it was launched in September 1998 in hatchback form, followed by a coupé cabriolet in September 2000, a station wagon in September 2001, a sedan version in September 2005. In November 2006, the Chinese joint venture Dongfeng Peugeot-Citroën launched a derivative version of the Peugeot 206 known as the Citroën C2, but not technically related with the European-market model, its facelifted version was launched in South America in September 2008, in China in November 2008, in hatchback and station wagon body styles, known as the 207 Compact, as the 207 respectively. This version was subsequently launched in Europe in February 2009, only in hatchback form and marketed as the 206+. Though the 206 had finished production in most markets by 2010, in Europe it was available as the 206+, with front and rear styling that resembles the Peugeot 207, until 2013, whereas in South America it continued to be offered under the 207 Compact nameplate, until January 2017, furthermore in China, both under the 207 nameplate and as the Citroën C2.
The 206 is the best-selling Peugeot model of all time with 8,358,217 cars sold in 2012. Until 2016, the Peugeot 206 was still in the top 10 of used car sales in the UK comparing to other new models from other brands. During the early 1990s, Peugeot decided not to directly replace the Peugeot 205, citing the reason that superminis were no longer profitable or worthwhile. Instead, Peugeot followed a unique strategy and decided that its new, supermini, the Peugeot 106, would take sales from the lower end of the 205 range while the lowest models of the Peugeot 306 range, launched in 1993 to replace the Peugeot 309, would take sales from the top-end 205s. Between the 106 and 306, Peugeot hoped that the 205 would not need to be replaced, could be phased out while customers who would plump for the 205 would continue to have a choice with either a smaller or larger car; this strategy did not work. With the 205 phased out, other superminis like the Ford Fiesta and Volkswagen Polo continued to sell well and increased in popularity, without a direct competitor to these cars Peugeot was losing sales fast.
A new supermini was required, the 206 was launched in 1998 as a somewhat belated replacement for the 205. Peugeot hired the world-famous Italian designer Pininfarina to make it the most beautiful against its competitors. With no larger in-house rival from Citroën to base its new supermini on, Peugeot developed an all-new front drive platform for the 206, it was built in France until 18 December 2012, in the United Kingdom until 12 December 2006. The end of British production coincided with the closure of the Ryton plant which Peugeot had taken over when buying Chrysler's European division in 1979. From April 2010, the Peugeot 206 was no longer listed on Peugeot's current UK model range. LHD production finished in June 2010, its eventual successor, the Peugeot 207, was launched in 2006. As of 2010, the twelve-year-old 206 was Peugeot's best-selling car of all time; the 206 was launched as a hatchback with 1.1L, 1.4L, 1.6L petrol engines and a 1.9L diesel engine, an HDi version with common rail coming later.
In 1999 a 2.0L GTi capable of 210 km/h, in 2003 a tuned version of the GTi called the Peugeot 206 RC, were added to the range. It did 0–100 km/h in 7.4 seconds and it reached a top speed of 220 km/h with 177 PS. In 2001, two more versions of the 206 were launched – the 206 CC with a folding steel roof and the 206 SW station wagon. A 4-door notchback sedan version, developed by Iran Khodro, was unveiled in late 2005, it is available in the Iranian, North African, Russian, Romanian and Bulgarian markets; the Peugeot 206 was manufactured in Peugeot's Poissy and Mulhouse factories in France, as well as in Ryton, United Kingdom, whereas outside Europe it is produced in Iran, Argentina, Uruguay, China and Malaysia. In 2003, it received a minor facelift, getting clear headlights, different rear clusters, new side repeater lamps, chrome badges, a new range of colors, as well as other subtle interior revisions; the Peugeot 206 was assembled at its Ryton facility in Coventry, however, with the introduction of the 207 to the range, Peugeot decided to close the Ryton factory and move production to Slovakia, due to the fact that they could produce their vehicles with same or better quality for a lower price there.
The Peugeot 206 proved to be a sales success all over Europe. It was the best-selling car in Europe from 2001 to 2003 and it was the best car of the year in the UK for three consecutive years, between 1998 and 2001; the 1.4-litre XR was the best-selling model. On 26 May 2005, the 206 celebrated the five millionth unit produced since its commercial launch on 10 September 1998. Sales in the United Kingdom were strong from the start, with the 206 being among the nation's five most popular new cars during its first six years on sale. Second hand examples of the 206 traditionally hold their value well, due to high demand. Production in Brazil took place in Porto Real, Rio de Janeiro, starting in 2001 with the hatchback, followed by the station wagon version in 2005; the models produced there featured 1.0-litre 16-valve, 1.4-litre 8-valve and 1.6-litre 16-valv
A personal watercraft called water scooter, comically a boatercycle, is a recreational watercraft that the rider sits or stands on, rather than inside of, as in a boat. PWCs have two style categories and most popular being a runabout or "sit down" where the rider uses the watercraft sitting down, the watercraft holds two or more people; the second style is a "stand-up". The stand-up styles are built for one rider and are used more for doing tricks and use in competitions. Both styles have an inboard engine driving a pump-jet that has a screw-shaped impeller to create thrust for propulsion and steering. Most are designed for three people, though four-passenger models exist. Many of today's models are built for more extended use and have the fuel capacity to make long cruises, in some cases beyond 100 miles. Personal watercraft are referred by the trademarked brand names Jet Ski, WaveRunner, or Sea-Doo; the United States Coast Guard defines a personal watercraft, amongst other criteria, as a jet-drive boat, less than 13 feet in length, in order to exclude from that definition more conventional-sized jet-boats.
There is a wide variety of "jetboats". Water scooters - as they were termed - were first developed in the United Kingdom and Europe in the mid-1950s, with models such as the British 200cc propellor-driven Vincent Amanda, the German Wave Roller. Two thousand Vincent Amandas were exported to Australia, Asia and the United States. In the 1960s, the idea was developed further by Clayton Jacobson II of Lake Havasu City, Arizona, USA. A motocross enthusiast, Jacobson's idea was designed in the mid-1960s, powered by an internal pump-jet rather than an outboard motor, made of all aluminum, had a fixed, upright handle. Jacobson quit his job in banking to devote himself to developing the idea, had a working prototype by 1965, it differed from modern personal watercraft but had definite similarities. He completed a second prototype a year made of fiberglass; the first Clayton-type PWC to reach. Bombardier's original designs were not popular and Bombardier left the business before 1970. Stand-up PWCs were first produced by the Japanese company Kawasaki in 1972, appeared on the US market in 1973.
These were mass-produced boats to be used by only one rider. While they are still produced today, the more popular design, is the sit down variety of PWC; these sit down runabouts have been produced by Kawasaki, Yamaha, Honda and Arctic Cat. As of 2010, the major manufacturers of PWCs were Kawasaki and Yamaha. Both Yamaha and Kawasaki continue to sell stand-up models but it is a small percentage of the overall market. PWC racing competitions take place around the world. P1 AquaX is a personal watercraft racing series, first launched in the UK in May 2011 by London-based sports promoter Powerboat P1; the series attracted a mix of new and current racers to a new type of racing and in 2013, P1 rolled out a second series in the USA. Such was the uptake that the original format needed revising to cope with the influx of new riders and by the end of 2015 over 400 riders from 11 countries had registered to compete in an AquaX event. PWCs are small, fast handled easy to use and their propulsion systems do not have external propellers, making them safer for swimmers and wildlife.
For these reasons, they are preferred for non-recreational use over small motorboats. PWC's are used for Jet Ski fishing or PWC fishing and is the fastest growing segments in the industry, they are fast and economical and are being chosen over traditional boats. Lifeguards use PWCs equipped with rescue platforms to rescue water users who get into difficulties and carry them back to shore. Rescuers use PWCs to pick up flood survivors. PWCs are used for law enforcement. Due to their speed and excellent maneuverability and rangers use them to enforce laws in coastal waters and rivers. A PWC combined with a wash-reduction system, carrying waterproof loudspeaker equipment and GPS for instructions and distance measurement, has purportedly been used by assistant coaches for rowing sports on the River Tyne. PWCs are used by the U. S. Navy as surface targets. Equipped with GPS, electronic compass, radar reflector, a radio modem, the PWC is remotable with a two-way link, its small shipboard footprint allows it to be stored and deployed from the smallest of vessels, it has been used for target practice for everything from 5" to small arms.
The American PWC industry reached an agreement with the United States Coast Guard in 1999, agreeing to limit the speed of a PWC to 65 mph in a specified test protocol. Before 1991, PWC emissions were unregulated in the United States. Many were powered by two-stroke cycle engines, which are smaller and lighter than four-stroke cycle engines but more polluting. Simple two-stroke engines are lubricated on a "total loss" method, mixing lubricating oil with their fuel; the 1990 amendments to the Clean Air Act allowed the U. S. Environmental Protection Agency to begin regulating all recreational marine engines including PWC, as well as other off-road internal combustion engi
McDonnell Douglas F-15 Eagle
The McDonnell Douglas F-15 Eagle is an American twin-engine, all-weather tactical fighter aircraft designed by McDonnell Douglas to gain and maintain air supremacy in all aspects of aerial combat. Following reviews of proposals, the United States Air Force selected McDonnell Douglas's design in 1967 to meet the service's need for a dedicated air-superiority fighter; the Eagle first flew in July 1972, entered service in 1976. It is among the most successful modern fighters, with over 100 victories and no losses in aerial combat, with the majority of the kills by the Israeli Air Force; the Eagle has been exported to Israel and Saudi Arabia. The F-15 was envisioned as a pure air-superiority aircraft, its design included a secondary ground-attack capability, unused. The aircraft design proved flexible enough that an all-weather strike derivative, the F-15E Strike Eagle, an improved and enhanced version, developed, entered service in 1989 and has been exported to several nations; as of 2017, the aircraft is being produced in different variants with production set to end in 2022.
The F-15 can trace its origins to the early Vietnam War, when the U. S. Air Force and the U. S. Navy fought each other over future tactical aircraft. Defense Secretary Robert McNamara was pressing for both services to use as many common aircraft as possible if performance compromises were involved; as part of this policy, the USAF and Navy had embarked on the TFX program, aiming to deliver a medium-range interdiction aircraft for the Air Force that would serve as a long-range interceptor aircraft for the Navy. In January 1965, Secretary McNamara asked the Air Force to consider a new low-cost tactical fighter design for short-range roles and close air support to replace several types like the F-100 Super Sabre and various light bombers in service. Several existing designs could fill this role; the A-4 and A-7 were more capable in the attack role, while the F-5 less so, but could defend itself. If the Air Force chose a pure attack design, maintaining air superiority would be a priority for a new airframe.
The next month, a report on light tactical aircraft suggested the Air Force purchase the F-5 or A-7, consider a new higher-performance aircraft to ensure its air superiority. This point was reinforced after the loss of two Republic F-105 Thunderchief aircraft to obsolete MiG-15s or MiG-17s on 4 April 1965. In April 1965, Harold Brown, at that time director of the Department of Defense Research and Engineering, stated the favored position was to consider the F-5 and begin studies of an "F-X"; these early studies envisioned a production run of 800 to 1,000 aircraft and stressed maneuverability over speed. On 1 August, Gabriel Disosway took command of Tactical Air Command and reiterated calls for the F-X, but lowered the required performance from Mach 3.0 to 2.5 to lower costs. An official requirements document for an air superiority fighter was finalized in October 1965, sent out as a request for proposals to 13 companies on 8 December. Meanwhile, the Air Force chose the A-7 over the F-5 for the support role on 5 November 1965, giving further impetus for an air superiority design as the A-7 lacked any credible air-to-air capability.
Eight companies responded with proposals. Following a downselect, four companies were asked to provide further developments. In total, they developed some 500 design concepts. Typical designs featured variable-sweep wings, weight over 60,000 pounds, included a top speed of Mach 2.7 and a thrust-to-weight ratio of 0.75. When the proposals were studied in July 1966, the aircraft were the size and weight of the TFX F-111, like that aircraft, were designs that could not be considered an air-superiority fighter. Through this period, studies of combat over Vietnam were producing worrying results. Theory optimized aircraft for this role; the result was loaded aircraft with large radar and excellent speed, but limited maneuverability and lacking a gun. The canonical example was the McDonnell Douglas F-4 Phantom II, used by the USAF, USN, U. S. Marine Corps to provide air superiority over Vietnam, the only fighter with enough power and maneuverability to be given the primary task of dealing with the threat of Soviet fighters while flying with visual engagement rules.
In practice, due to policy and practical reasons, aircraft were closing to visual range and maneuvering, placing the larger US aircraft at a disadvantage to the much less expensive day fighters such as the MiG-21. Missiles proved to be much less reliable than predicted at close range. Although improved training and the introduction of the M61 Vulcan cannon did much to address the disparity, these early outcomes led to considerable re-evaluation of the 1963 Project Forecast doctrine; this led to John Boyd's energy–maneuverability theory, which stressed that extra power and maneuverability were key aspects of a successful fighter design and these were more important than outright speed. Through tireless championing of the concepts and good timing with the "failure" of the initial F-X project, the "fighter mafia" pressed for a lightweight day fighter that could be built and operated in large numbers to ensure air superiority. In early 1967, they proposed that the ideal design had a thrust-to-weight ratio near 1:1, a maximum speed further reduced to Mach 2.3, a weight of 40,000 pounds, a wing loading of 80 lb/ft².
By this time