Aerial refueling

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(Redirected from
Refueling boom
)

F-16 Fighting Falcon
using a flying boom

Aerial refueling, also referred to as air refueling, in-flight refueling (IFR), air-to-air refueling (AAR), and tanking, is the process of transferring aviation fuel from one aircraft (the tanker) to another (the receiver) while both aircraft are in flight.[a] The two main refueling systems are probe-and-drogue, which is simpler to adapt to existing aircraft, and the flying boom, which offers faster fuel transfer, but requires a dedicated boom operator station.

The procedure allows the receiving aircraft to remain airborne longer, extending its range or

payload which could be weapons, cargo, or personnel: the maximum takeoff weight is maintained by carrying less fuel and topping up once airborne. Aerial refueling has also been considered as a means to reduce fuel consumption on long-distance flights greater than 3,000 nautical miles (5,600 km; 3,500 mi). Potential fuel savings in the range of 35–40% have been estimated for long-haul flights (including the fuel used during the tanker missions).[1]

Usually, the aircraft providing the fuel is specially designed for the task, although refueling pods may be fitted to existing aircraft designs in the case of "probe-and-drogue" systems. The cost of the refueling equipment on both tanker and receiver aircraft and the specialized aircraft handling of the aircraft to be refueled (very close "line astern" formation flying) has resulted in the activity only being used in military operations; there are no regular civilian in-flight refueling activities. Originally employed shortly before World War II on a limited scale to extend the range of British civilian transatlantic flying boats, and then after World War II on a large scale to extend the range of strategic bombers, aerial refueling since the Vietnam War has been extensively used in large-scale military operations.

Development history

Early experiments

Capt. Lowell Smith
and Lt. John P. Richter receiving the first mid-air refueling on 27 June 1923

Some of the earliest experiments in aerial refueling took place in the 1920s; two slow-flying aircraft flew in formation, with a hose run down from a hand-held fuel tank on one aircraft and placed into the usual fuel filler of the other. The first mid-air refueling, based on the development of

Tijuana, Mexico, landing in San Diego, using mid-air refuelings at Eugene, Oregon, and Sacramento, California
.

Similar trial demonstrations of mid-air refueling technique took place at the

Armée de l'Air in France
in the same year, but these early experiments were not yet regarded as a practical proposition, and were generally dismissed as stunts.

As the 1920s progressed, greater numbers of aviation enthusiasts vied to set new aerial long-distance records, using inflight air refueling. One such enthusiast, who would revolutionize aerial refueling was Sir Alan Cobham, member of the Royal Flying Corps in World War I, and a pioneer of long-distance aviation. During the 1920s, he made long-distance flights to places as far afield as Africa and Australia and he began experimenting with the possibilities of in-flight refueling to extend the range of flight.[2]

Cobham was one of the founding directors of Airspeed Limited, an aircraft manufacturing company that went on to produce a specially adapted Airspeed Courier that Cobham used for his early experiments with in-flight refueling. This craft was eventually modified by Airspeed to Cobham's specification, for a non-stop flight from London to India, using in-flight refueling to extend the plane's flight duration.

Meanwhile, in 1929, a group of

Question Mark over Los Angeles. Between 11 June and 4 July 1930, the brothers John, Kenneth, Albert, and Walter Hunter set a new record of 553 hours 40 minutes over Chicago using two Stinson SM-1 Detroiters as refueler and receiver. Aerial refueling remained a very dangerous process until 1935, when brothers Fred and Al Key demonstrated a spill-free refueling nozzle, designed by A. D. Hunter.[3] They exceeded the Hunters' record by nearly 100 hours in a Curtiss Robin monoplane,[4] staying aloft for more than 27 days.[5]

The US was mainly concerned about transatlantic flights for faster postal service between Europe and America. In 1931 W. Irving Glover, the second assistant postmaster, wrote an extensive article for Popular Mechanics concerning the challenges and the need for such a regular service. In his article he even mentioned the use of aerial refueling after takeoff as a possible solution.[6]

At

flying boats that serviced the British Empire. By 1931 they had demonstrated refueling between two Vickers Virginias, with fuel flow controlled by an automatic valve on the hose which would cut off if contact was lost.[8]

Flight Refuelling Ltd. Atcherly's system was bought up by Cobham's company, and with some refinement and continuous improvement through the late '30s, it became the first practical refueling system.[10]

Grappled-line looped-hose

The US Air Force Boeing B-50 Superfortress Lucky Lady II being refueled by grappled-line looped-hose during the first non-stop circumnavigation of the world by air (1949)

Sir Alan Cobham's grappled-line looped-hose air-to-air refueling system borrowed from techniques patented by David Nicolson and John Lord, and was publicly demonstrated for the first time in 1935. In the system the receiver aircraft, at one time an Airspeed Courier, trailed a steel cable which was then grappled by a line shot from the tanker, a Handley Page Type W10. The line was then drawn back into the tanker where the receiver's cable was connected to the refueling hose. The receiver could then haul back in its cable bringing the hose to it. Once the hose was connected, the tanker climbed sufficiently above the receiver aircraft to allow the fuel to flow under gravity.[11][12]

When Cobham was developing his system, he saw the need as purely for long-range transoceanic commercial aircraft flights,[13] but modern aerial refueling is used exclusively by military aircraft.

In 1934, Cobham had founded

Armstrong Whitworth AW.23.[5] Handley Page Harrows were used in the 1939 trials to perform aerial refueling of the Empire flying boats for regular transatlantic crossings. From 5 August to 1 October 1939, sixteen crossings of the Atlantic were made by Empire flying boats, with fifteen crossings using FRL's aerial refueling system.[14] After the sixteen crossings further trials were suspended due to the outbreak of World War II.[15]

During the closing months of World War II, it had been intended that Tiger Force's Lancaster and Lincoln bombers would be in-flight refueled by converted Halifax tanker aircraft, fitted with the FRL's looped-hose units, in operations against the Japanese homelands, but the war ended before the aircraft could be deployed. After the war ended, the USAF bought a small number of FRL looped-hose units and fitted a number of B-29s as tankers to refuel specially equipped B-29s and later B-50s. The USAF made only one major change in the system used by the RAF. The USAF version had auto-coupling of the refueling nozzle, where the leader line with the refueling hose is pulled to the receiver aircraft and a refueling receptacle on the belly of the aircraft, allowing high-altitude air-to-air refueling and doing away with the aircraft having to fly to a lower altitude to be depressurized so a crew member could manually do the coupling.[16]

This air-to-air refueling system was used by the

the Azores, Saudi Arabia, the Pacific Ocean near Guam, and between Hawaii and the West Coast.[19]

Probe-and-drogue system

Cobham's company FRL soon realized that their looped-hose system left much to be desired and began work on an improved system that is now commonly called the probe-and-drogue air-to-air refueling system and today is one of the two systems chosen by air forces for air-to-air refueling, the other being the flying-boom system. In post-war trials the RAF used a modified Lancaster tanker employing the much improved probe-and-drogue system, with a modified

Cobham plc
.

Modern specialized

tanker aircraft have equipment specially designed for the task of offloading fuel to the receiver aircraft, based on drogue and probe, even at the higher speeds modern jet aircraft
typically need to remain airborne.

In January 1948, General Carl Spaatz, then the first Chief of Staff of the new United States Air Force, made aerial refueling a top priority of the service. In March 1948, the USAF purchased two sets of FRL's looped-hose in-flight refueling equipment, which had been in practical use with British Overseas Airways Corporation (BOAC) since 1946, and manufacturing rights to the system. FRL also provided a year of technical assistance. The sets were immediately installed in two Boeing B-29 Superfortresses, with plans to equip 80 B-29s.

Flight testing began in May 1948 at

Davis-Monthan Air Force Base, Arizona, and the 509th Air Refueling Squadron at Walker Air Force Base, New Mexico
. The first ARS aircraft used FRL's looped-hose refueling system, but testing with a boom system followed quickly in the autumn of 1948.

The first use of aerial refueling in combat took place during the Korean War, involving F-84 fighter-bombers flying missions from Japanese airfields, due to Chinese-North Korean forces overrunning many of the bases for jet aircraft in South Korea, refueling from converted B-29s using the drogue-and-probe in-flight refueling system with the probe located in one of the F-84's wing-tip fuel tanks.

Systems

Flying boom

Dutch Air Force KC-10 refueling boom

The flying boom is a rigid, telescoping tube with movable

KC-46 Pegasus
) have a single boom and can refuel one aircraft at a time with this mechanism.

History

In the late 1940s, General

stall speed during the approach to the tanker. It was no surprise that, after the KC-97, Boeing began receiving contracts from the USAF to build jet tankers based on the Boeing 367-80 (Dash-80) airframe. The result was the Boeing KC-135 Stratotanker
, of which 732 were built.

The flying boom is attached to the rear of the tanker aircraft. The attachment is

toggles
in the receptacle engage the nozzle, holding it locked during fuel transfer.

The "flying" boom is so named because

boom operator
using a control stick. The boom operator also telescopes the boom to make the connection with the receiver's receptacle.

To complete an aerial refueling, the tanker and receiver aircraft rendezvous, flying in formation. The receiver moves to a position behind the tanker, within safe limits of travel for the boom, aided by director lights or directions radioed by the boom operator. Once in position, the operator extends the boom to make contact with the receiver aircraft. Once in contact, fuel is pumped through the boom into the receiver aircraft.

KC-135 boom operator
view from the boom pod.

While in contact, the receiver pilot must continue to fly within the "air refueling envelope", the area in which contact with the boom is safe. Moving outside of this envelope can damage the boom or lead to mid-air collision, for example the 1966 Palomares B-52 crash. If the receiving aircraft approaches the outer limits of the envelope, the boom operator will command the receiver pilot to correct their position and disconnect the boom if necessary.

When the desired amount of fuel has been transferred, the two aircraft disconnect and the receiver aircraft departs the formation. When not in use, the boom is stored flush with the bottom of the tanker's fuselage to minimize drag.

In the KC-97 and KC-135 the boom operator lays prone, while the operator is seated in the

KC-46
seats two operators at the front of the aircraft viewing camera video on 3D screens.

The US Air Force fixed-wing aircraft use the flying boom system, along with countries operating F-16 or F-15 variants. The system is used by Australia (KC-30A), the Netherlands (KDC-10), Israel (modified Boeing 707), Japan (KC-767), Turkey (KC-135Rs), and Iran (Boeing 747). The system allows higher fuel flow rates (up to 1,000 US gallons (3,800 L) / 6,500 pounds (2,900 kg) per minute for the KC-135, but does require a boom operator, and can only refuel one aircraft at a time.

Probe-and-drogue

Using a probe-and-drogue, a Royal Air Force C-130K Hercules crew practice refuelling from an RAF VC10 tanker over the Falkland Islands, 2005

The probe-and-drogue refueling method employs a flexible hose that trails from the tanker aircraft. The drogue (or para-drogue), sometimes called a basket, is a fitting resembling a shuttlecock, attached at its narrow end (like the "cork" nose of a shuttlecock) with a valve to a flexible hose. The drogue stabilizes the hose in flight and provides a funnel to aid insertion of the receiver aircraft probe into the hose. The hose connects to a Hose Drum Unit (HDU). When not in use, the hose/drogue is reeled completely into the HDU.

The receiver has a probe, which is a rigid, protruding or pivoted retractable arm placed on the aircraft's nose or fuselage to make the connection. Most modern versions of the probe are usually designed to be retractable, and are retracted when not in use, particularly on high-speed aircraft.[citation needed]

At the end of the probe is a valve that is closed until it mates with the drogue's forward internal receptacle, after which it opens and allows fuel to pass from tanker to receiver. The valves in the probe and drogue that are most commonly used are to a

Flight Refuelling Limited in the UK and deployed in the late 1940s and 1950s.[citation needed
] This standardization enables drogue-equipped tanker aircraft from many nations to refuel probe-equipped aircraft from other nations.

The NATO-standard probe system incorporates shear rivets that attach the refueling valve to the end of the probe.[citation needed] This is so that if a large side or vertical load develops while in contact with the drogue, the rivets shear and the fuel valve breaks off, rather than the probe or receiver aircraft suffering structural damage. A so-called "broken probe" (actually a broken fuel valve, as described above) may happen if poor flying technique is used by the receiver pilot, or in turbulence. Sometimes the valve is retained in the tanker drogue and prevents further refueling from that drogue until removed during ground maintenance.

Buddy store

An F/A-18E Super Hornet of the US Navy acts as a buddy tanker for a Rafale of the French Navy over the Arabian Sea, 2015

A "buddy store" or "buddy pod" is an external pod loaded on an aircraft hardpoint that contains a hose and drogue system (HDU).[24] Buddy stores allow fighter / bomber aircraft to be reconfigured for "buddy tanking" other aircraft. This allows an air combat force without dedicated/specialized tanker support (for instance, a carrier air wing) to extend the range of its strike aircraft. In other cases, using the buddy store method allows a carrier-based aircraft to take-off with a heavier than usual load less fuel than might be necessary for its tasking. The aircraft would then topped-up with fuel from an HDU-equipped "buddy" tanker, a method previously used by the Royal Navy in operating its Supermarine Scimitar, de Havilland Sea Vixen, and Blackburn Buccaneers; in the Buccaneer's case using a bomb-bay-mounted tank and HDU.

A KC-130 Hercules refuels a pair of CH-53E Super Stallions

The tanker aircraft flies straight and level and extends the hose/drogue, which is allowed to trail out behind and below the tanker under normal aerodynamic forces. The pilot of the receiver aircraft extends the probe (if required) and uses normal flight controls to "fly" the refueling probe directly into the basket. This requires a closure rate of about two knots (walking speed) to push the hose several feet into the HDU and solidly couple the probe and drogue. Too little closure will cause an incomplete connection and no fuel flow (or occasionally leaking fuel). Too much closure is dangerous because it can trigger a strong transverse oscillation in the hose, severing the probe tip.

The optimal approach is from behind and below (not level with) the drogue. Because the drogue is relatively light (typically soft canvas webbing) and subject to aerodynamic forces, it can be pushed around by the bow wave of approaching aircraft, exacerbating engagement even in smooth air. After initial contact, the hose and drogue is pushed forward by the receiver a certain distance (typically, a few feet), and the hose is reeled slowly back onto its drum in the HDU. This opens the tanker's main refueling valve allowing fuel to flow to the drogue under the appropriate pressure (assuming the tanker crew has energized the pump). Tension on the hose is aerodynamically 'balanced' by a motor in the HDU so that as the receiver aircraft moves fore and aft, the hose retracts and extends, thus preventing bends in the hose that would cause undue side loads on the probe. Fuel flow is typically indicated by illumination of a green light near the HDU. If the hose is pushed in too far or not far enough, a cutoff switch will inhibit fuel flow, which is typically accompanied by an amber light. Disengagement is commanded by the tanker pilot with a red light.[24]

The

Xian H-6 bombers modified for aerial refueling, and plans to add Russian Ilyushin Il-78 aerial refueling tankers.[26]
Tankers can be equipped with multipoint hose-and-drogue systems, allowing them to refuel two (or more) aircraft simultaneously, reducing time spent refueling by as much as 75% for a four-aircraft strike package.[27]

Boom drogue adapter units

Large, 4-engine aircraft in flight with components for aerial refueling
A US Air Force KC-135 with a drogue adapter attached to its boom

USAF KC-135 and

naval aviators
because of its unforgiving nature. Soft drogues can be contacted slightly off center, wherein the probe is guided into the hose receptacle by the canvas drogue. The metal drogue, when contacted even slightly off center, will pivot out of place, potentially "slapping" the aircraft's fuselage and causing damage.

The other major difference with this system is that when contacted, the hose does not "retract" into an HDU. Instead, the hose bends depending on how far it is pushed toward the boom. If it is pushed too far, it can loop around the probe or nose of the aircraft, damage the windscreen, or cause contact with the rigid boom. If not pushed far enough, the probe will disengage, halting fueling. Because of a much smaller position-keeping tolerance, staying properly connected to a KC-135 adapter unit is considerably more difficult than staying in a traditional hose/drogue configuration. When fueling is complete, the receiver carefully backs off until the probe refueling valve disconnects from the valve in the basket. Off center disengagements, like engagements, can cause the drogue to "prang" the probe and/or strike the aircraft's fuselage.

Multiple systems

A KC-10 Extender

Some tankers have both a boom and one or more complete hose-and-drogue systems. The USAF

KC-10 has both a flying boom and a separate hose-and-drogue system manufactured by Cobham. Both are on the aircraft centerline at the tail of the aircraft, so only one can be used at once. However, such a system allows all types of probe- and receptacle-equipped aircraft to be refueled in a single mission, without landing to install an adapter. Many KC-135s are also equipped with dual under-wing hose-and-drogue attachments known as Multi-point Refueling System
(MPRSs); some KC-10s have similar Wing Air Refueling Pods (WARPs).

Wing-to-wing

A small number of Soviet

Tu-16s (the tanker variant was Tu-16Z). used a wing-to-wing method. Similar to the probe-and-drogue method but more complicated, the tanker aircraft released a flexible hose from its wingtip. An aircraft flying alongside had to catch the hose with a special lock under its wingtip. After the hose was locked and the connection was established, the fuel was pumped.[28]

Simple grappling

Some historic systems used for pioneering aerial refueling used the grappling method, where the tanker aircraft unreeled the fuel hose and the receiver aircraft would grapple the hose midair, reel it in and connect it so that fuel can be transferred either with the assistance of pumps or simply by

Question Mark
endurance flight in 1929.

Compatibility issues

The probe-and-drogue system is not compatible with flying boom equipment, creating a problem for military planners where mixed forces are involved.

probe-and-drogue refuelers. The potential cost of converting F-35As to probe-and-drogue refueling (as is used on US Navy & Marine Corps F-35Bs and F-35Cs) added to the early-2010s political controversy which surrounded F-35 procurement within the RCAF.[30][needs update
]

These concerns can be addressed by drogue adapters (see section "Boom drogue adapter units" above) that allow drogue aircraft to refuel from boom-equipped aircraft, and by refuelers that are equipped with both drogue and boom units and can thus refuel both types in the same flight, such as the KC-10, MPRS KC-135, or Airbus A330 MRTT.

Strategic

C-17 Globemaster III
receives fuel from a KC-135 during night operations.

The development of the

first strike
against the bombers' airfields could not obliterate the US's ability to retaliate by bomber.

In 1958, Valiant tankers in the UK were developed with one HDU mounted in the bomb-bay. Valiant tankers of 214 Squadron were used to demonstrate radius of action by refueling a Valiant bomber non-stop from UK to Singapore in 1960 and a Vulcan bomber to Australia in 1961. Other UK exercises involving refueling aircraft from Valiant tankers included Javelin and Lightning fighters, also Vulcan and Victor bombers. For instance, in 1962 a squadron of Javelin air defense aircraft was refueled in stages from the UK to India and back (exercise "Shiksha"). After the retirement of the Valiant in 1965, the Handley Page Victor took over the UK refueling role and had three hoses (HDUs). These were a fuselage-mounted HDU and a refueling pod on each wing. The center hose could refuel any probe-equipped aircraft, the wing pods could refuel the more maneuverable fighter/ground attack types.

A byproduct of this development effort and the building of large numbers of tankers was that these tankers were also available to refuel

matériel
, supplies, and personnel to Vietnam without landing to refuel. KC-135s were also frequently used for refueling of air combat missions from air bases in Thailand.

The USAF

Beale AFB in central California, SR-71s had to be forward-deployed to Europe and Japan prior to flying actual reconnaissance missions. These trans-Pacific and trans-Atlantic flights during deployment were impossible without aerial refueling. The SR-71's designers traded takeoff performance for better high-speed, high-altitude performance, necessitating takeoff with less-than-full fuel tanks from even the longest runways. Once airborne, the Blackbird would accelerate to supersonic speed using afterburners to facilitate structural heating and expansion. The magnitude of temperature changes experienced by the SR-71, from parked to its maximum speed, resulted in significant expansion of its structural parts in cruise flight. To allow for the expansion, the Blackbird's parts had to fit loosely when cold, so loosely, in fact, that the Blackbird constantly leaked fuel before heating expanded the airframe enough to seal its fuel tanks. Following the supersonic dash the SR-71 would then rendezvous with a tanker to fill its now nearly empty tanks before proceeding on its mission. This was referred to as the LTTR (for "Launch To Tanker Rendezvous") profile. LTTR had the added advantage of providing an operational test of the Blackbird's refueling capability within minutes after takeoff, enabling a Return-To-Launch-Site abort capability if necessary. At its most efficient altitude and speed, the Blackbird was capable of flying for many hours without refueling. The SR-71 used a special fuel, JP-7, with a very high flash point to withstand the extreme skin temperatures generated during Mach 3+ cruise flight.[31]
While JP-7 could be used by other aircraft, its burn characteristics posed problems in certain situations (such as high-altitude, emergency engine starts) that made it less than optimal for aircraft other than the SR-71.

Normally, all the fuel aboard a tanker aircraft may be either offloaded, or burned by the tanker as necessary. To make this possible, the KC-135 fuel system incorporated gravity draining and pumps to allow moving fuel from tank to tank depending on mission needs. Mixing JP-7 with JP-4 or Jet A, however, rendered it unsuitable for use by the SR-71, so the Air Force commissioned a specially modified KC-135 variant, the

KC-135Q
, which included changes to the fuel system and operating procedures preventing inadvertent inflight mixing of fuel intended for offload with fuel intended for use by the tanker. SR-71 aircraft were refueled exclusively by KC-135Q tankers.

A Russian Air Force Sukhoi Su-34 takes on fuel through a Probe-and-drogue system

Tactical

Tankers are considered "

payload
. Combat aircraft operating from airfields with shorter runways must limit their takeoff weight, which could mean a choice between range (fuel) and combat payload (munitions). Aerial refueling, however, eliminates many of these basing difficulties because a combat aircraft can take off with a full combat payload and refuel immediately.

Operational history

Cold War

Even as the first practical methods for aerial refueling were being developed, military planners had already envisioned what missions could be greatly enhanced by using such techniques. In the emerging Cold War climate of the late 1940s, the ability for bombers to perform increasingly long distance missions would enable targets to be struck even from air bases on a different continent. Thus, it became commonplace for nuclear-armed strategic bombers to be equipped with aerial refuelling apparatus and for it to be used to facilitate long distance patrols.[32]

During the late 1950s, aerial refuelling had become so prevalent amongst the bombers operated by the US Air Force's Strategic Air Command that many, such as the Convair B-58 Hustler, would operate largely or entirely out of bases in the continental United States while maintaining strategic reach.[32] This practice was promoted to address security concerns as well as diplomatic objections from some overseas nations that did not want foreign nuclear weapons being kept on their soil.[32] In one early demonstration of the Boeing B-52 Stratofortress's global reach, performed between 16 and 18 January 1957, three B-52Bs made a non-stop flight around the world during Operation Power Flite, during which 24,325 miles (21,145 nmi, 39,165 km) was covered in 45 hours 19 minutes (536.8 smph) with multiple in-flight refuelings being performed from KC-97s.[33][34]

While development of the Avro Vulcan strategic bomber was underway, British officials recognised that its operational flexibility could be improved by the provision of in-flight refuelling equipment.[35] Accordingly, from the 16th aircraft to be completed onwards, the Vulcan was furnished with in-flight refuelling receiving equipment.[36][37] While continuous airborne patrols were flown by the RAF for a time, these were deemed to be untenable, and the refuelling mechanisms across the Vulcan fleet largely fell into disuse during the 1960s.[37] When the RAF chose to optimise its bomber fleet away from high-altitude flight and towards low-level penetration missions, bombers such as the Handley Page Victor were fitted with aerial refuelling probes and additional fuel tanks to counter the decreased range from the shift in flight profile.[38][39]

During the mid-1950s, to deliver France's independent

tankers.[40] Mirage IVAs also often operated in pairs, with one aircraft carrying a weapon and the other carrying fuel tanks and a buddy refueling pack, allowing it to refuel its partner en route to the target.[43] While able to strike at numerous targets inside of the Soviet Union, the inability for the Mirage IV to return from some missions had been a point of controversy during the aircraft's design phase.[44][45]

Korean War

On 6 July 1951, the first combat air refueling of fighter-type aircraft took place over Korea. Three RF-80As launched from Taegu with the modified tip-tanks and rendezvoused with a tanker offshore of Wonsan, North Korea. Through in-flight refueling, the RF-80s effectively doubled their range, which enabled them to photograph valuable targets in North Korea.[46][47]

Vietnam War

HC-130P refuels HH-3E over Southeast Asia

During the

F-4 Phantoms to carry more bombs and rockets. Tankers were also available for refueling on the way back if necessary. In addition to ferrying aircraft across the Pacific Ocean, aerial refueling made it possible for battle-damaged fighters, with heavily leaking fuel tanks, to hook up to the tankers and let the tanker feed its engine(s) until the point where they could glide to the base and land. This saved numerous aircraft. [citation needed
]

The US Navy frequently used carrier-based aerial tankers like the

KC-130 Hercules
transports for air-to-air refueling on missions.

During late August 1970, a pair of

Danang in South Vietnam. In addition to making multiple en route stops to refuel on the ground, aerial refuelling was also used in this display of the type's long-range capabilities. The flight proved to be roughly four times faster than the traditional dispatching of rotorcraft to the theatre by ship.[48]

Middle East

During the 1980s Iran–Iraq War, the Iranian Air Force maintained at least one KC 707-3J9C aerial tanker, which the Islamic Republic had inherited from the Shah's government. This was used most effectively on 4 April 1981, refueling eight IRIAF F-4 Phantoms on long-range sorties into Iraq to bomb the H-3 Al Walid airfield near the Jordanian border, destroying 27–50 Iraqi fighter jets and bombers.[49][50] However, the Iranian Air Force was forced to cancel its 180-day air offensive and attempts to control Iranian airspace due to unsustainable rates of attrition.[51][52]

The

F-15s used heavily modified Boeing 707 aircraft to provide aerial refueling over the Mediterranean Sea in order to extend their range for Operation Wooden Leg, an air raid on the headquarters of the Palestine Liberation Organization (PLO) near Tunis, Tunisia, that necessitated a 2,000 km flight.[56] As of 2021 Israel has ordered four of a planned eight Boeing KC-46 Pegasus boom refueling tankers and has requested that the first two aircraft be fast-tracked for delivery in 2022 when they were to be delivered in 2023. The Jerusalem Post reports that Israeli commanders have made this request to enhance the strategic deterrence against Iran, the same article reports that the US, whose air force is also taking its first deliveries of the aircraft type, has refused to move forward the deliveries while supporting Israel's deterrence; the Jpost editor writing "The US State Department approved the possible sale of up to eight KC-46 tanker aircraft and related equipment to Israel for an estimated cost of $2.4 billion last March(i.e. 5/2020), marking the first time that Washington has allowed Jerusalem to buy new tankers."[55]

Falklands War

During the

Mirage IIIs and Daggers
lack of air refueling capability prevented them from achieving better results. The Mirages were unable to reach the islands with a strike payload, and the Daggers could do so only for a five-minute strike flight.

On the British side, air refueling was carried out by the

B-2 flights.[61]

Gulf War

During the time of Operation Desert Shield, the military buildup to the Persian Gulf War, US Air Force Boeing KC-135s & McDonnell Douglas KC-10As, and USMC KC-130 Hercules aircraft were deployed to forward air bases in

Combat Air Patrol
tracks. During the conflict's final week, KC-10s moved inside Iraq to support barrier CAP missions set up to block Iraqi fighters from escaping to Iran.

French Air Force EC725 is refueled by a Lockheed HC-130
during Exercise Angel Thunder

On 16–17 January 1991, the first combat sortie of Operation Desert Storm, and the longest combat sortie in history at that time, was launched from

Barksdale AFB, Louisiana. Seven B-52Gs flew a thirty-five-hour mission to the region and back to launch 35 Boeing Air Launched Cruise Missiles (ALCMs) with the surprise use of conventional warheads. This attack, which successfully destroyed 85–95 percent of intended targets, would have been impossible without the support of refueling tankers.[62][63]

An extremely useful tanker in Desert Storm was the USAF's KC-10A Extender. Besides being larger than the other tankers deployed, the KC-10A is equipped with the USAF "boom" refueling and also the "hose-and-drogue" system, enabling it to refuel not only USAF aircraft, and also USMC and US Navy jets that use the "probe-and-drogue" system, and also allied aircraft, such as those from the UK and Saudi Arabia. KC-135s may be equipped with a drogue depending on the mission profile. With a full jet fuel load, the KC-10A is capable of flying from a base on the American east coast, flying nonstop to Europe, transferring a considerable amount of fuel to other aircraft, and returning to its home base without landing anywhere else.[citation needed]

On 24 January 1991, the Iraqi Air Force launched the Attack on Ras Tanura, an attempt to bomb the Ras Tanura oil facility in Saudi Arabia. On their way to the target, the Iraqi attack aircraft were refueled by tanker at an altitude of 100 meters. The attack ultimately failed, with two aircraft turning back and the remaining two shot down.[64][65]

Helicopters

Helicopter in-flight refueling (HIFR) is a variation of aerial refueling when a naval helicopter approaches a warship (not necessarily suited for landing operations) and receives fuel through the cabin while hovering. Alternatively, some helicopters like the HH-60 Pave Hawk are equipped with a probe extending out the front can be refueled from a drogue-equipped tanker aircraft in a similar manner to fixed-wing aircraft by matching a high forward speed for a helicopter to a slow speed for the fixed-wing tanker.

Longest crewed flight record

A mission modified

Cessna 172 Skyhawk with a crew of two set the world record for the longest continuous crewed flight without landing of 64 days, 22 hours, 19 minutes, and five seconds in 1958. A Ford truck was outfitted with a fuel pump, tank, and other paraphernalia required to support the aircraft in flight. The publicity flight for a Las Vegas area hotel ended when the aircraft's performance had degraded to the point where the Cessna had difficulty climbing away from the refueling vehicle.[66][67]

Developments

Operators

F-16
 Algeria
 Argentina
 Australia
 Brazil
 Canada
 Chile
 China
 Colombia
  • Colombian Air Force[72]
 Egypt
 France
An IAF Ilyushin Il-78MKI provides mid-air refueling to two Mirage 2000
 Germany
 India
 Indonesia
 Iran
 Israel
 Italy
 Japan
 South Korea
 Kuwait
 Malaysia
Two Saab JAS-39 Gripen of the Swedish Air Force undergoing inflight refuelling.
 Morocco
 Netherlands
 Pakistan

 Portugal

 Russia
Tu-95М filling rod and filling cone from Il-78M aircraft
 Singapore
 Spain
 Sweden
 Turkey
 United Arab Emirates
 United Kingdom
 Saudi Arabia
Edwards AFB
 United States
 Venezuela

See also

Notes

  1. Instrument Flight Rules
    .

References

Citations

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Bibliography

External links

Wikimedia Commons has media related to Aerial refueling.
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