Lockheed C-5 Galaxy
The Lockheed C-5 Galaxy is a large military transport aircraft designed and built by Lockheed, now maintained and upgraded by its successor, Lockheed Martin. It provides the United States Air Force with a heavy intercontinental-range strategic airlift capability, one that can carry outsized and oversized loads, including all air-certifiable cargo; the Galaxy has many similarities to its smaller Lockheed C-141 Starlifter predecessor, the Boeing C-17 Globemaster III. The C-5 is among the largest military aircraft in the world; the C-5 Galaxy's development was complicated, including significant cost overruns, Lockheed suffered significant financial difficulties. Shortly after entering service, cracks in the wings of many aircraft were discovered and the C-5 fleet was restricted in capability until corrective work was completed; the C-5M Super Galaxy is an upgraded version with new engines and modernized avionics designed to extend its service life beyond 2040. The USAF has operated the C-5 since 1969.
In that time, the airlifter supported US military operations in all major conflicts including Vietnam, Iraq and Afghanistan, as well as allied support, such as Israel during the Yom Kippur War and operations in the Gulf War. The Galaxy has been used to distribute humanitarian aid and disaster relief, supported the US Space Shuttle program. In 1961, several aircraft companies began studying heavy jet transport designs that would replace the Douglas C-133 Cargomaster and complement Lockheed C-141 Starlifters. In addition to higher overall performance, the United States Army wanted a transport aircraft with a larger cargo bay than the C-141, whose interior was too small to carry a variety of their outsized equipment; these studies led to the "CX-4" design concept, but in 1962, the proposed six-engined design was rejected, because it was not viewed as a significant advance over the C-141. By late 1963, the next conceptual design was named CX-X, it was equipped with four engines, instead of six in the earlier CX-4 concept.
The CX-X had a gross weight of 550,000 pounds, a maximum payload of 180,000 lb, a speed of Mach 0.75. The cargo compartment was 17.2 ft wide by 13.5 feet high and 100 ft long with front and rear access doors. Meeting the power and range specifications with only four engines required a new engine with improved fuel efficiency; the criteria were finalized and an official request for proposal was issued in April 1964 for the "Heavy Logistics System". In May 1964, proposals for aircraft were received from Boeing, General Dynamics and Martin Marietta. General Electric, Curtiss-Wright, Pratt & Whitney submitted proposals for the engines. After a downselect, Boeing and Lockheed were given one-year study contracts for the airframe, along with General Electric and Pratt & Whitney for the engines. All three of the designs shared a number of features; the cockpit was placed well above the cargo area to allow for cargo loading through a nose door. The Boeing and Douglas designs used a pod on the top of the fuselage containing the cockpit, while the Lockheed design extended the cockpit profile down the length of the fuselage, giving it an egg-shaped cross section.
All of the designs had swept wings, as well as front and rear cargo doors, allowing simultaneous loading and unloading. Lockheed's design featured a T-tail, while the designs by Douglas had conventional tails; the Air Force considered Boeing's design to be better than that of Lockheed, but Lockheed's proposal was the lowest total-cost bid. Lockheed was selected the winner in September 1965 awarded a contract in December 1965. General Electric's TF39 engine was selected in August 1965 to power the new transport plane. At the time, GE's engine concept was revolutionary, as all engines before had a bypass ratio less than two-to-one, while the TF39 promised and would achieve a ratio of eight-to-one, which had the benefits of increased engine thrust and lower fuel consumption; the first C-5A Galaxy was rolled out of the manufacturing plant in Marietta, Georgia, on 2 March 1968. On 30 June 1968, flight testing of the C-5A began with the first flight, flown by Leo Sullivan, with the call sign "eight-three-oh-three heavy".
Flight tests revealed that the aircraft exhibited a higher drag divergence Mach number than predicted by wind tunnel data. The maximum lift coefficient measured in flight with the flaps deflected 40° was higher than predicted, but was lower than predicted with the flaps deflected 25° and with the flaps retracted. Aircraft weight was a serious issue during development. At the time of the first flight, the weight was below the guaranteed weight, but by the time of the delivery of the 9th aircraft, had exceeded guarantees. In July 1969, during a fuselage upbending test, the wing failed at 128% of limit load, below the requirement that it sustain 150% of limit load. Changes were made to the wing. A passive load-reduction system, involving uprigged ailerons, was incorporated, but the maximum allowable payload was reduced from 220,000 to 190,000 lb. At the time, a 90% probability was predicted that no more than 10% of the fleet of 79 airframes would reach their fatigue life of 19,000 hours without cracking of the wing.
Cost overruns and technical problems of the C-5A were the subject of a congressional investigation in 1968 and 1969. The C-5 program has the dubious distinction of being the first development program with a $1‑billion overrun. Due to the C-5's troubled development, the Department
In aviation, a drop tank is used to describe auxiliary fuel tanks externally carried by aircraft. A drop tank is expendable and jettisonable. External tanks are commonplace on modern military aircraft and found in civilian ones, although the latter are less to be discarded except in the event of emergency; the primary disadvantage with drop tanks is that they impose a drag penalty on the aircraft carrying them. External fuel tanks will increase the moment of inertia, thereby reducing roll rates for air maneuvres; some of the drop tank's fuel is used to overcome the added weight of the tank itself. Drag in this sense varies with the square of the aircraft's speed; the use of drop tanks reduces the number of external hardpoints available for weapons, reduces the weapon-carrying capacity, increases the aircraft's radar signature. The fuel in the drop tanks is consumed first, only when all the fuel in the drop tanks has been used, the fuel selector is switched to the airplane's internal tanks; some modern combat aircraft use conformal fuel tanks instead of or in addition to conventional external fuel tanks.
CFTs do not take up external hardpoints. The drop tank was used during the Spanish Civil War to allow fighter aircraft to carry additional fuel for long-range escort flights without requiring a larger, less maneuverable fuselage. During World War II, the German Luftwaffe began using external fuel tanks with the introduction of a 300-liter light alloy model for the Ju 87R, a long-range version of the Stuka dive bomber, in early 1940; the Messerschmitt Bf 109 fighter used this type of drop tank, starting with the Bf 109E-7 variant introduced in August 1940. Fitted to the Focke-Wulf Fw 190, the 300 liter tank, available in at least four differing construction formats — including at least one impregnated paper material, single-use version — and varying only in appearance, became the standard volume for most subsequent drop tanks in Luftwaffe service, with a used 900 litre, fin-stabilized large capacity drop tank used with some marks of the Messerschmitt Bf 110 heavy fighter and other twin-engined Luftwaffe combat aircraft.
The first drop tanks were designed to be discarded when empty or in the event of combat or emergency in order to reduce drag, to increase maneuverability. Modern external tanks may be retained in combat; the Allies used them to allow fighters increased range and patrol time over continental Europe. The RAF used such external fuel tanks during the transit of Supermarine Spitfires to Malta; the Imperial Japanese navy design specification for what came to be the Japanese Mitsubishi A6M Zero fighter, included endurance with drop tanks of two hours at full power, or six to eight hours at cruising speed. Drop tanks were used with the Zero on Combat Air Patrol; the Zero entered service in 1940. Bomber theorists insisted formations of heavy bombers with elaborate defensive armaments would be self-defending, believing long-range escort fighters to be "a myth" as they could be forced to drop the tanks by minor harassment at the beginning of the raid being more concerned that long-range medium bombers might compete for resources and so compromise their goal of creating vast fleets of heavy bombers.
In the face of such entrenched attitudes in 1941 airmen such as Benjamin S. Kelsey and Oliver P. Echols worked to get drop tank technology added to American fighters such as the Lockheed P-38 Lightning, it was only with drop tanks supplying 450 US gallons of extra fuel per fighter that P-38s could carry out Operation Vengeance, the downing of Admiral Isoroku Yamamoto's airplane. (For this mission, each fighter carried one drop tank of 150 to 165 US gal, a larger one of 300 to 330 US gal. After such experience showed the necessity for drop tanks, inflexible thinkers such as 8th Air Force General Ira C. Eaker had to be transferred out of commanding positions so that drop tanks and range extension plans could be implemented in 1944 for American escort fighters. External drop tanks turned the Republic P-47 Thunderbolt from a short-range interceptor aircraft into a long-range escort and air superiority fighter, enabling it to accompany bombers from British Isles into Germany, made it possible for heavy bomber formations to undertake daylight raids under escort by North American P-51 Mustangs.
The P-38 could carry two 300-to-330-gallon drop tanks for its longest sorties. This teardrop-shaped tank design was 13 feet long and 3 feet in diameter at its widest point. Faced by wartime metal shortages and a need to extend the range of fighter craft, the British came up with drop tanks made of glue-impregnated kraft paper, which had excellent tolerance characteristics for extreme heat and cold necessary for operation on an aircraft as well as being waterproof. Since the glue would dissolve from the solvent effects of the fuel these were a single-use item, used in chilly Northern European conditions, filled before take off, jettisoned in the event of an aborted mission and only being required for the outbound portion of any flight; such papier-mâché tanks were assembled from three main components, the nose cone, tail cone and the body, each shaped over wooden forms, the centre section created by wrapping layers of the impregnated paper around a cylinder, the end ca
Antonov An-124 Ruslan
The Antonov An-124 Ruslan is a strategic airlift quadjet. It was designed in the 1980s by the Antonov design bureau in the Ukrainian SSR part of the Soviet Union; until the Boeing 747-8F, the An-124 was, for thirty years, the world's heaviest gross weight production cargo airplane and second heaviest operating cargo aircraft, behind the one-off Antonov An-225. The An-124 remains the largest military transport aircraft in current service; the lead designer of the An-124 was Viktor Tolmachev. During development it was known as Izdeliye 400 in house, An-40 in the West. First flown in 1982, civil certification was issued on 30 December 1992. In July 2013, 26 An-124s were in commercial service with 10 on order. In August 2014, it was reported that plans to resume joint production of the Antonov An-124 had been shelved due to the ongoing political tensions between Russia and Ukraine; the sole remaining production facility is Russia's Aviastar-SP in Ulianovsk. The various operators of the An-124 are in discussions with respect to the continuing airworthiness certification of the individual An-124 planes.
The original designer of the An-124 is responsible for managing the certification process for its own products, but Russian/Ukrainian conflicts are making this process difficult to manage. Military operators are able to self-certify the airworthiness of their own aircraft, but Russian civil operators must find a credible outside authority for certification if Ukraine is unable to participate in the process. During the 1970s, the Military Transport Aviation arm of the Soviet Air Forces had a shortfall in strategic heavy airlift capacity, its largest planes consisted of about 50 Antonov An-22 turboprops, which were used for tactical roles. A declassified 1975 CIA analysis concluded that the USSR did "...not match the US in ability to provide long-range heavy lift support." The An-124 was manufactured in parallel by two plants: the Russian company Aviastar-SP and by the Kyiv Aviation Plant AVIANT, in Ukraine. Design work started in 1971 and construction of facilities began in 1973. Manufacturing on the first airframe began in 1979.
This project brought together over 100 factories contracted to produce systems and parts. The first flight took place in December 1982 and the first exposure to the West followed in 1985 at the Paris Air Show. In the early 2000s, Volga-Dnepr upgraded its freighters with engine improvements to meet Chapter 4 noise regulations, structural improvements to increase service life, avionics and systems changes for four persons operations down from six or seven. Russia and Ukraine agreed to resume the production in the third quarter of 2008. In May 2008, a new variant—the An-124-150—was announced. However, in May 2009, Antonov's partner, the Russian United Aircraft Corporation announced it did not plan production of An-124s in the period 2009–2012. In late 2009, Russian President Dmitry Medvedev ordered, it is expected. In August 2014, Jane's reported that, Russian Deputy Minister of Industry and Trade Yuri Slusar announced that Antonov An-124 production was stopped due to ongoing political tensions between Russia and Ukraine.
As of late 2017, An-124s are being upgraded by the Aviastar-SP plant in Ulyanovsk, with three upgraded planes due to be ready by 2018. After Russia–Ukraine relations soured, Antonov had to source new suppliers and pushes to westernize the An-124. In 2018, GE Aviation was studying reengining it with CF6s for CargoLogicAir, a Volga-Dnepr subsidiary; this would provide a range increase, Volga-Dnepr Group operates 12 aircraft, implying a 50-60 engines with spares program. In January 2019, Antonov revealed its plans to restart the An-124 production without support from Russia. At MAKS Air Show in 2017, the TsAGI announced its Slon design to replace the similar An-124; the design was detailed in January 2019 before Wind tunnel testing scheduled for August-September. It should be produced at the Aviastar-SP factory in Ulyanovsk but would be a difficult investment without substantial foreign orders, it should transport 150 t over 180 t over 2,650 nmi at 460 kn. The Russian MoD wants a range of 4,100 nmi with five Sprut-SDM-1 light tanks, their 100 crew and 300 armed soldiers.
It would be larger at 82.3 m long from 69 m, with a 87–88 m span versus 73.3 m and 24.0 m high compared with 21.0 m. A new higher aspect ratio, composite wing and a 214–222 t airframe would allow a 490–500 t gross weight, it should be powered by Russian PD-35s developed for the CR929 widebody, producing 35 tf up from 23 tf. Two fuselages are planned, one for Volga-Dnepr with a width of 5.3 m from the An-124's 4.4 m, one for the Russian MoD of 6.4 m wide to carry vehicles in two lines. Externally, the An-124 is similar to the American Lockheed C-5 Galaxy, having a double fuselage to allow for a rear cargo door that can open in flight without affecting structural integrity, it is shorter, with a greater wingspan, a 25% larger payload. Instead of the Galaxy's T-tail, the An-124 uses a conventional empennage, similar in design to that of the Boeing 747; the aircraft uses oleo strut suspension for its 24 wheels. The
Angle of attack
In fluid dynamics, angle of attack is the angle between a reference line on a body and the vector representing the relative motion between the body and the fluid through which it is moving. Angle of attack is the angle between the oncoming flow; this article focuses on the most common application, the angle of attack of a wing or airfoil moving through air. In aerodynamics, angle of attack specifies the angle between the chord line of the wing of a fixed-wing aircraft and the vector representing the relative motion between the aircraft and the atmosphere. Since a wing can have twist, a chord line of the whole wing may not be definable, so an alternate reference line is defined; the chord line of the root of the wing is chosen as the reference line. Another choice is to use a horizontal line on the fuselage as the reference line; some authors do not use an arbitrary chord line but use the zero lift axis where, by definition, zero angle of attack corresponds to zero coefficient of lift. Some British authors have used the term angle of incidence instead of angle of attack.
However, this can lead to confusion with the term riggers' angle of incidence meaning the angle between the chord of an airfoil and some fixed datum in the airplane. The lift coefficient of a fixed-wing aircraft varies with angle of attack. Increasing angle of attack is associated with increasing lift coefficient up to the maximum lift coefficient, after which lift coefficient decreases; as the angle of attack of a fixed-wing aircraft increases, separation of the airflow from the upper surface of the wing becomes more pronounced, leading to a reduction in the rate of increase of the lift coefficient. The figure shows a typical curve for a cambered straight wing. Cambered airfoils are curved such. A symmetrical wing has zero lift at 0 degrees angle of attack; the lift curve is influenced by the wing shape, including its airfoil section and wing planform. A swept wing has a lower, flatter curve with a higher critical angle; the critical angle of attack is the angle of attack. This is called the "stall angle of attack".
Below the critical angle of attack, as the angle of attack decreases, the lift coefficient decreases. Conversely, above the critical angle of attack, as angle of attack increases, the air begins to flow less smoothly over the upper surface of the airfoil and begins to separate from the upper surface. On most airfoil shapes, as the angle of attack increases, the upper surface separation point of the flow moves from the trailing edge towards the leading edge. At the critical angle of attack, upper surface flow is more separated and the airfoil or wing is producing its maximum lift coefficient; as angle of attack increases further, the upper surface flow becomes more separated and the lift coefficient reduces further. Above this critical angle of attack, the aircraft is said to be in a stall. A fixed-wing aircraft by definition is stalled at or above the critical angle of attack rather than at or below a particular airspeed; the airspeed at which the aircraft stalls varies with the weight of the aircraft, the load factor, the center of gravity of the aircraft and other factors.
However the aircraft always stalls at the same critical angle of attack. The critical or stalling angle of attack is around 15° - 20° for many airfoils; some aircraft are equipped with a built-in flight computer that automatically prevents the aircraft from increasing the angle of attack any further when a maximum angle of attack is reached, regardless of pilot input. This is called the'angle of attack limiter' or'alpha limiter'. Modern airliners that have fly-by-wire technology avoid the critical angle of attack by means of software in the computer systems that govern the flight control surfaces. In takeoff and landing operations from short runways, such as Naval Aircraft Carrier operations and STOL back country flying, aircraft may be equipped with angle of attack or Lift Reserve Indicators; these indicators measure the angle of attack or the Potential of Wing Lift directly and help the pilot fly close to the stalling point with greater precision. STOL operations require the aircraft to be able to operate close to the critical angle of attack during landings and at the best angle of climb during takeoffs.
Angle of attack indicators are used by pilots for maximum performance during these maneuvers since airspeed information is only indirectly related to stall behaviour. Some military aircraft are able to achieve controlled flight at high angles of attack, but at the cost of massive induced drag; this provides the aircraft with great agility. A famous military example is sometimes thought to be Pugachev's Cobra. Although the aircraft experiences high angles of attack throughout the maneuver, the aircraft is not capable of either aerodynamic directional control or maintaining level flight until the maneuver ends; the Cobra is an example of supermaneuvering as the aircraft's wings are well beyond the critical angle of attack for most of the maneuver. Additional aerodynamic surfaces known as "high-lift devices" including leading edge wing root extensions allow fighter aircraft much greater flyable'true' alpha, up to over 45°, compared to about 20° for aircraft without these devices; this can be helpful at high altitudes where slight maneuvering may require high angles of attack due to the low density of air in the upper atmosphere as well as at low speed at low altitude where the margin between level flight AoA and stall AoA is reduced.
The high AoA capability of the aircraft provides a buff
The Tupolev Tu-134 is a twin-engined, narrow-body, jet airliner built in the Soviet Union from 1966 to 1989. The original version featured a glazed-nose design and, like certain other Russian airliners, it can operate from unpaved airfields. One of the most used aircraft in former Comecon countries, the number in active service is decreasing because of political intention and noise restrictions; the model has seen long-term service with some 42 countries, with some European airlines having scheduled as many as 12 daily takeoffs and landings per plane. In addition to regular passenger service, it has been used in various air force and navy support roles. In recent years, a number of Tu-134s have been converted for use as VIP transports and business jets. A total of 854 Tu-134s were built of all versions with Aeroflot as the largest user. Following the introduction of engines mounted on pylons on the rear fuselage by the French Sud Aviation Caravelle, airliner manufacturers around the world rushed to adopt the new layout.
Its advantages included clean wing airflow without disruption by nacelles or pylons and decreased cabin noise. At the same time, placing heavy engines that far back created challenges with the location of the centre of gravity in relation to the centre of lift, at the wings. To make room for the engines, the tailplanes had to be relocated to the tail fin, which had to be stronger and therefore heavier, further compounding the tail-heavy arrangement. During a 1960 visit to France, Soviet leader Nikita Khrushchev was so impressed by the quiet cabin of the Caravelle, that on 1 August 1960 the Tupolev OKB received an official directive to create the Tu-124A with a similar engine arrangement; the requirement was driven by the need to replace slow, aging piston-engined Il-14s on domestic routes. In 1961, the Soviet state airline, updated its requirement specifications to include greater payload and passenger capacity; the first Tu-124A prototype, SSSR-45075, first flew on 29 July 1963. On 22 October 1963, the prototype British BAC One-Eleven, which had a similar layout, crashed with the loss of all crew while testing its stalling properties.
The aircraft had entered pitch-up: the high-mounted tailplane became trapped in the turbulent wake produced by the wings, which prevented recovery from the stall. As a result, the tailplane on Tu-124A was enlarged by 30% for greater control authority. Since Aeroflot's requirements dictated a larger aircraft than planned, the Soloviev Design Bureau developed the more powerful D-30 low-bypass turbofan engines. On 20 November 1963, the new airliner was designated Tu-134. Design curiosities of the Tu-134 included a sharp wing sweepback of 35 degrees, compared to 25–28 degrees in its counterparts; the engines on early production Tu-134s lacked thrust reversers, which made the aircraft one of the few airliners to use a brake parachute for landing. The majority of onboard electronics operated on direct current; the lineage of early Soviet airliners could be traced directly to the Tupolev Tu-16 strategic bomber, the Tu-134 carried over the glass nose for the navigator and the landing gear fitted with low-pressure tires to permit operation from unpaved airfields.
Serial production began in 1966 at the Kharkov Aviation Production Association, production of the Tu-124 was discontinued. The Tu-134 was designed for short-haul lines with low passenger traffic; the aircraft had 56 seats in a single class configuration, or 50 seats in a two-class configuration. In 1968, Tupolev began work on an improved Tu-134 variant with a 72-seat capacity; the fuselage received a 2.1-meter plug for greater passenger capacity and an auxiliary power unit in the tail. As a result, the maximum range was reduced from 3,100 kilometers to 2,770 kilometers; the upgraded D-30 engines now featured thrust reversers. The first Tu-134A, converted from a production Tu-134, flew on 22 April 1969; the first airline flight was on 9 November 1970. An upgraded version, the Tu-134B began production in 1980, with the navigator position abandoned, seating capacity increased to 96 seats. Efforts subsequently began to develop a Tu-134D with increased engine thrust, but the project was cancelled. In September 1967, the Tu-134 made its first scheduled flight from Moscow to Adler.
The Tu-134 was the first Soviet airliner to receive international certification from the International Civil Aviation Organization, which permitted it to be used on international routes. Due to this certification, Aeroflot used most of its Tu-134s on international routes. In 1968, the first export customers, Interflug of East Germany and LOT Polish Airlines purchased the Tu-134. In 1969, the Tu-134 was displayed at the Paris Air Show. From 1972, Aeroflot began placing the Tu-134 in domestic service to Baku, Kiev, Krasnodar, Omsk and Sochi from Sheremetyevo International Airport in Moscow. In its early years, the Tu-134 developed a reputation for reliability and efficiency when compared with previous Soviet designs. After the establishment of tougher noise standards in the ICAO regulations in 2002, the Tu-134 was banned from most western European airports for its high noise levels. In early 2006, 245 Tu-134s were still in operation. After a fatal accident in March 2007, at the instigation of Russian Minister of Transportation Igor Levitin, Aeroflot announced that it would be retiring its fleet, the last Tu-134 was removed from service on 1 January 2008.
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British Aerospace Harrier II
The British Aerospace Harrier II is a second-generation vertical/short takeoff and landing jet aircraft used by the Royal Air Force and, between 2006 and 2010, the Royal Navy. The aircraft was the latest development of the Harrier Jump Jet family, was derived from the McDonnell Douglas AV-8B Harrier II. Initial deliveries of the Harrier II were designated in service as Harrier GR5. Under the Joint Force Harrier organisation, both the RAF and RN operated the Harrier II under the RAF's Air Command, including deployments on board the navy's Invincible class aircraft carriers; the Harrier II participated in numerous conflicts, making significant contributions in combat theatres such as Kosovo and Afghanistan. The type's main function was as a platform for air interdiction and close air support missions; the Harrier II served alongside the Sea Harrier in Joint Force Harrier. In December 2010, budgetary pressures led to the early retirement of all Harrier IIs from service, at which point it was the last of the Harrier derivatives remaining in British service.
The decision to retire was controversial as there was no immediate fixed-wing replacement in its role or fixed-wing carrier-capable aircraft left in service. Development of a much more powerful successor to the Harrier began in 1973 as a cooperative effort between McDonnell Douglas in the US and Hawker Siddeley in the UK. First-generation Harriers were being introduced into United States Marine Corps; the British government had only a minor requirement, for up to 60 Harriers at most and competing pressures on the defence budget left little room for frivolous expenditure such as the Advanced Harrier. A lack of government backing for developing the necessary engine of the new aircraft, the Pegasus 15, led Hawker to withdraw from this project in 1975. Due to US interest, work proceeded on the development of a less ambitious successor, a Harrier fitted with a larger wing and making use of composite materials in its construction. Two prototypes were built from existing aircraft and flew in 1978; the US government was content to continue if a major foreign buyer was found and Britain had a plan to improve the Harrier with a new, larger metal wing.
In 1980, the UK considered if the American program would meet their requirements – their opinion was that it required modification, thus the MDD wing design was altered to incorporate the British-designed leading-edge root extensions. In 1982, the UK opted to become involved in the joint US–UK programme; the US and UK agreement to proceed included a British contribution of US$280 million to cover development costs to meet their own requirements and to purchase at least 60 aircraft. The UK agreement included the involvement of British Aerospace as a major subcontractor, manufacturing sections such as the rear fuselage for all customers of the AV-8B; the Harrier II was an Anglicised version of the AV-8B, British Aerospace producing the aircraft as the prime contractor, with McDonnell Douglas serving as a sub-contractor. The first prototype flew in 1981, first BAe-built development GR5 flew for the first time on 30 April 1985 and the aircraft entered service in July 1987; the GR5 had many differences from the USMC AV-8B Harriers, such as avionics fit and equipment.
In December 1989, the first RAF squadron to be equipped with the Harrier II was declared operational. The Harrier II is an extensively modified version of the first generation Harrier GR1/GR3 series; the original aluminium alloy fuselage was replaced by a fuselage which makes extensive use of composites, providing significant weight reduction and increased payload or range. A new one-piece wing provides around 14 per cent increased thickness; the wing and leading-edge root extensions allows for a 6,700-pound payload increase over a 1,000 ft takeoff compared with the first generation Harriers. The RAF's Harrier IIs feature an additional missile pylon in front of each wing landing gear, as well as strengthened leading edges on the wings in order to meet higher bird strike requirements. Among the major differences with the American cousin, was the new ZEUS ECM system proposed for the USMC AV-8. ZEUS was one of the main systems in the British design, being a modern and costly apparatus, with an estimated cost of $1.7 million per set.
The Harrier II's cockpit has day and night operability and is equipped with head-up display, two head-down displays known as multi-purpose colour displays, a digital moving map, an inertial navigation system, a hands-on-throttle-and-stick system. Like the British Aerospace Sea Harrier, the Harrier II used an elevated bubble canopy to provide a improved all-round view. A combination of the new design of the control system and the greater lateral stability of the aircraft made the Harrier II fundamentally easier to fly than the first generation Harrier GR1/GR3 models; the RAF used Harriers in the ground attack and reconnaissance roles, so they relied on the short-range AIM-9 Sidewinder missile for air combat. The Sidewinder had proven effective for Royal Navy's Sea Harriers against Argentinian Mirages in the Falklands
A phugoid or fugoid is an aircraft motion in which the vehicle pitches up and climbs, pitches down and descends, accompanied by speeding up and slowing down as it goes "downhill" and "uphill". This is one of the basic flight dynamics modes of an aircraft, a classic example of a negative feedback system; the phugoid has a nearly constant angle of attack but varying pitch, caused by a repeated exchange of airspeed and altitude. It can be excited by an elevator singlet resulting in a pitch increase with no change in trim from the cruise condition; as speed decays, the nose drops below the horizon. Speed increases, the nose climbs above the horizon. Periods can vary from under 30 seconds for light aircraft to minutes for larger aircraft. Microlight aircraft show a phugoid period of 15–25 seconds, it has been suggested that birds and model airplanes show convergence between the phugoid and short period modes. A classical model for the phugoid period can be simplified to about seconds, but this only works for larger aircraft.
Phugoids are demonstrated to student pilots as an example of the speed stability of the aircraft and the importance of proper trimming. When it occurs, it is considered a nuisance, in lighter airplanes it can be a cause of pilot-induced oscillation; the phugoid, for moderate amplitude, occurs at an constant angle of attack, although in practice the angle of attack varies by a few tenths of a degree. This means that the stalling angle of attack is never exceeded, it is possible to fly at speeds below the known stalling speed. Free flight models with badly unstable phugoid stall or loop, depending on thrust. An unstable or divergent phugoid is caused by a large difference between the incidence angles of the wing and tail. A stable, decreasing phugoid can be attained by building a smaller stabilizer on a longer tail, or, at the expense of pitch and yaw "static" stability, by shifting the center of gravity to the rear; the term "phugoid" was coined by Frederick W. Lanchester, the British aerodynamicist who first characterized the phenomenon.
He derived the word from the Greek words φυγή and εἶδος to mean "flight-like" but recognized the diminished appropriateness of the derivation given that φυγή meant flight in the sense of "escape" rather than vehicle flight. In the 1975 Tan Son Nhut C-5 accident, USAF C-5 68-0218 with flight controls damaged by failure of the rear cargo/pressure door, encountered phugoid oscillations while the crew was attempting a return to base, crash-landed in a rice paddy adjacent to the airport. Of the 328 people on board, 153 died, making it the deadliest accident involving a US military aircraft. In 1985, Japan Airlines Flight 123 lost all hydraulic controls and its vertical stabiliser, went into phugoid motion. While the crew were able to maintain near-level flight through the use of engine power, the plane lost height over a mountain range northwest of Tokyo before crashing into Mount Takamagahara. With 520 deaths, it remains the deadliest single-aircraft disaster in history. In 1989, United Airlines Flight 232 suffered an uncontained engine failure that caused total hydraulic system failure.
The crew flew the aircraft with throttle only. Suppressing the phugoid tendency was difficult; the pilots crashed during the landing attempt. The pilots and a majority of the passengers survived. Another aircraft that lost all hydraulics was a DHL operated Airbus A300B4, hit by a surface-to-air missile fired by the Iraqi resistance in the 2003 Baghdad DHL attempted shootdown incident; this was the first time that a crew landed an air transport aircraft safely by only adjusting engine thrust. The 2003 crash of the Helios solar-powered aircraft was precipitated by reacting to an inappropriately diagnosed phugoid oscillation that made the aircraft structure exceed design loads. Chesley Sullenberger, Captain of US Airways Flight 1549 that ditched in the Hudson River on January 15, 2009, said in a Google talk that the landing could have been less violent had the anti-phugoid software installed on the Airbus A320-214 not prevented him from manually getting maximum lift during the four seconds before water impact.
Analysis of phugoid motion