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101-539: The Multi-Role Tanker Transport ( MRTT ) is a military aerial refueling and transport airplane constructed by Airbus manufactured in two versions, both conversions of existing civilian passenger aircraft: Airbus A310 MRTT , based on the Airbus A310 airliner Airbus A330 MRTT , based on the Airbus A330 airliner [REDACTED] Index of articles associated with

202-399: A V-tail configuration, are used to move the boom by creating aerodynamic forces. They are actuated hydraulically and controlled by the 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

303-520: 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

404-455: 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. At the end of

505-587: 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. 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

606-540: 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

707-580: A feat made possible by four aerial refuelings from four pairs of KB-29M tankers of the 43d ARS. Before the mission, crews of the 43rd had experienced only a single operational air refueling contact. The flight started and ended at Carswell Air Force Base in Fort Worth, Texas with the refuelings accomplished over the Azores , Saudi Arabia , the Pacific Ocean near Guam , and between Hawaii and

808-403: 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

909-404: A four-aircraft strike package. USAF KC-135 and French Air Force KC-135FR refueling-boom equipped tankers can be field-converted to a probe-and-drogue system using a special adapter unit. In this configuration, the tanker retains its articulated boom, but has a hose/drogue at the end of it instead of the usual nozzle. The tanker boom operator holds the boom still while the receiver aircraft flies

1010-493: A hose-and-drogue system, dubbed UPAZ, and thus later Russian aircraft may be equipped with probe and drogue. The Chinese PLAF has a fleet of Xian H-6 bombers modified for aerial refueling, and plans to add Russian Ilyushin Il-78 aerial refueling tankers. 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

1111-539: A modern strategic bombing mission need not always necessarily be a heavy bomber type, and any modern aircraft capable of nuclear strikes at long range is equally able to carry out tactical missions with conventional weapons . An example is France 's Mirage IV , a small strategic bomber replaced in service by the ASMP -equipped Mirage 2000N fighter-bomber and Rafale multirole fighter . The first strategic bombing efforts took place during World War I (1914–18), by

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1212-416: 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

1313-444: A new jet endurance record. FRL still exists as part of 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

1414-484: 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. 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

1515-407: 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. While in contact, the receiver pilot must continue to fly within the "air refueling envelope",

1616-560: A powerplant selection and particular powerplant installation design features on the 30-meter wingspan Greif , that led to endless problems with engine fires. The trans-Atlantic ranged Amerika Bomber program started in March 1942 sought to ameliorate the lack of a long-range bomber for the Luftwaffe , but led only to three Messerschmitt - and two Junkers -built prototypes ever flying, and no operational "heavy bombers" for strategic use for

1717-584: A similar dropped line from the receiver, allowing the refueling to commence. In 1935, Cobham sold off the airline Cobham Air Routes Ltd to Olley Air Service and turned to the development of inflight refueling, founding the company 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. Sir Alan Cobham 's grappled-line looped-hose air-to-air refueling system borrowed from techniques patented by David Nicolson and John Lord, and

1818-417: A single mission, without landing to install an adapter. Other tankers are equipped with hose-and-drogue attachments that do not interfere with the operation of the centerline boom: many KC-135s are equipped with dual under-wing attachments known as Multi-point Refueling System (MPRSs), while some KC-10s and A330 MRTTs have similar under-wing refueling pods (referred to as Wing Air Refueling Pods or WARPs on

1919-509: 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

2020-575: 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

2121-600: 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 Wright-Patterson Air Force Base , Ohio , and

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2222-640: A version of Tupolev Tu-16 on license from the Soviet Union in the 1960s, which they named the Xian H-6 . During the 1960s France produced its Dassault Mirage IV nuclear-armed bomber for the French Air Force as a part of its independent nuclear strike force, the Force de Frappe , using French-made bombers and IRBMs to deliver French-made nuclear weapons . Mirage IVs served until mid-1996 in

2323-471: Is different from Wikidata All set index articles Aerial refueling Aerial refueling ( en-us ), or aerial refuelling ( en-gb ), 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. The two main refueling systems are probe-and-drogue , which

2424-472: Is not compatible with flying boom equipment, creating a problem for military planners where mixed forces are involved. Incompatibility can also complicate the procurement of new systems. The Royal Canadian Air Force currently wish to purchase the F-35A , which can only refuel via the flying boom, but only possess probe-and-drogue refuelers . The potential cost of converting F-35As to probe-and-drogue refueling (as

2525-447: 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

2626-413: 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 loiter time. A series of air refuelings can give range limited only by crew fatigue /physical needs and engineering factors such as engine oil consumption. Because

2727-479: 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. 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

2828-483: The 2003 invasion of Iraq , American B-52s and B-1s were mostly employed in tactical roles. During the Soviet-Afghan war in 1979–88, Soviet Air Forces Tu-22Ms carried out several mass air raids in various regions of Afghanistan . Bombers listed below were used in the main or represented a shift in long-range bomber design (Maximum bomb load). In practice, bomb loads carried are dependent on factors such as

2929-643: The Aéro-Club de France and the 34th Aviation Regiment of the French Air Force were able to demonstrate passing fuel between machines at the annual aviation fete at Vincennes in 1928. The UK's Royal Aircraft Establishment was also running mid-air refueling trials, with the aim to use this technique to extend the range of the long-distance 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

3030-653: The B-52 last manufactured in 1962 and the Tupolev Tu-95 , remain in service and can also deploy the latest air-launched cruise missiles and other " stand-off " or precision guided weapons such as the JASSM and the JDAM . The Russian Air Force 's new Tu-160M2 strategic bombers are expected to be delivered on a regular basis over the course of 10 to 20 years . The Tu-95 and Tu-160 bombers will be periodically updated, as

3131-708: The Cold War began, it became an intercontinental range strategic bomber with the development of new techniques, such as aerial refueling (which also greatly extended the range of other medium- to long-range bombers , fighter-bombers and attack aircraft ). During the 1950s the U.S. Strategic Air Command also briefly brought back the outdated term " medium bomber " to distinguish its Boeing B-47 Stratojets from somewhat larger contemporary Boeing B-52 Stratofortress " heavy bombers " in bombardment wings; older B-29 and B-50 heavy bombers were also redesignated as "medium" during this period. SAC 's nomenclature here

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3232-531: The Cold War , the United States and United Kingdom on one side and the Soviet Union on the other kept strategic bombers ready to take off on short notice as part of the deterrent strategy of mutually assured destruction (MAD). Most strategic bombers of the two superpowers were designed to deliver nuclear weapons . For a time, some squadrons of Boeing B-52 Stratofortress bombers were kept in

3333-787: The Dassault Mirage 2000N and Rafale fighter-bombers ; the Rafale is also capable of refueling others in flight using a buddy refueling pod . Newer strategic bombers such as the Rockwell B-1 Lancer , the Tupolev Tu-160 , and the Northrop Grumman B-2 Spirit designs incorporate various levels of stealth technology in an effort to avoid detection, especially by radar networks. Despite these advances earlier strategic bombers, for example

3434-454: The House of Commons early in the 1930s that " the bomber will always get through " no matter what defensive systems were undertaken. It was widely believed by the late 1930s that strategic "terror" bombing of cities in any war would quickly result in devastating losses and might decide a conflict in a matter of days or weeks. But theory far exceeded what most air forces could actually put into

3535-700: The Junkers Ju 88 A. Support for the Ural bomber project before the start of WW II dwindled after Wever's death, with the only aircraft design that could closely match the Allied bomber force's aircraft – the Heinkel He 177 A, originated in early November 1937, deployed in its initial form in 1941–42, hampered by a RLM requirement for it to also perform medium-angle dive bombing , not rescinded until September 1942 – unable to perform either function properly, with

3636-597: The Russians with their Sikorsky Ilya Muromets bomber (the first heavy four-engine aircraft), and by the Germans using Zeppelins or long-range multi-engine Gotha aircraft . Zeppelins reached England on bombing raids by 1916, forcing the British to create extensive defense systems including some of the first anti-aircraft guns which were often used with searchlights to highlight the enemy machines overhead. Late in

3737-618: The Short Empire flying boat Cambria from an Armstrong Whitworth AW.23 . 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. After the sixteen crossings further trials were suspended due to

3838-476: The West Coast . 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

3939-433: The "receptacle" in the receiver aircraft during fuel transfer. A poppet valve in the end of the nozzle prevents fuel from exiting the tube until the nozzle properly mates with the receiver's refueling receptacle. Once properly mated, toggles in the receptacle engage the nozzle, holding it locked during fuel transfer. The "flying" boom is so named because flight control surfaces , small movable airfoils that are often in

4040-572: 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

4141-582: The Boeing plant at Renton, Washington . Boeing went on to develop the world's first production aerial tanker, the KC-97 Stratofreighter , a piston-engined Boeing Stratocruiser (USAF designation C-97 Stratofreighter ) with a Boeing-developed flying boom and extra kerosene (jet fuel) tanks feeding the boom. The Stratocruiser airliner itself was developed from the B-29 bomber after World War II . In

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4242-509: The Buccaneer's case using a bomb-bay-mounted tank and HDU. 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

4343-452: The F-84's wing-tip fuel tanks. The flying boom is a rigid, telescoping tube with movable flight control surfaces that a boom operator on the tanker aircraft extends and inserts into a receptacle on the receiving aircraft. All boom-equipped tankers (e.g. KC-135 Stratotanker , KC-10 Extender , KC-46 Pegasus ) have a single boom and can refuel one aircraft at a time with this mechanism. In

4444-405: 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. The US Navy , Marine Corps , and some Army aircraft refuel using the "hose-and-drogue" system, as do most aircraft flown by western European militaries. The Soviet Union also used

4545-457: The KC-10). A small number of Soviet Tu-4s and 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

4646-452: The KC-97, the mixed gasoline/kerosene fuel system was clearly not desirable and it was obvious that a jet-powered tanker aircraft would be the next development, having a single type of fuel for both its own engines and for passing to receiver aircraft. The 230 mph (370 km/h) cruise speed of the slower, piston-engined KC-97 was also a serious issue, as using it as an aerial tanker forced

4747-556: The SR-71. Strategic bomber The modern strategic bomber role appeared after strategic bombing was widely employed , and atomic bombs were first used during World War II . Nuclear strike missions (i.e., delivering nuclear -armed missiles or bombs ) can potentially be carried out by most modern fighter-bombers and strike fighters , even at intercontinental range, with the use of aerial refueling , so any nation possessing this combination of equipment and techniques theoretically has such capability. Primary delivery aircraft for

4848-865: The Soviet Union or its allies, two V bomber types, the Avro Vulcan and the Handley Page Victor , were used in the Falklands War towards the end of their operational lives. The Soviet Union produced hundreds of unlicensed copies of the American Boeing B-29 Superfortress , which the Soviet Air Forces called the Tupolev Tu-4 . The Soviets later developed the jet -powered Tupolev Tu-16 "Badger". The People's Republic of China produced

4949-673: The Third Reich beyond the roughly one thousand He 177s built. By the end of the Second World War in 1945, the "heavy" bomber, epitomized by the British Avro Lancaster and American Boeing B-29 Superfortress used in the Pacific Theater , showed what could be accomplished by area bombing of Japan's cities and the often small and dispersed factories within them. Under Major General Curtis LeMay ,

5050-580: The U.S. 20th Air Force , based in the Mariana Islands , undertook low-level incendiary bombing missions, results of which were soon measured in the number of square miles destroyed. The air raids on Japan had withered the nation's ability to continue fighting, although the Japanese government delayed surrender until atomic bombs were dropped on Hiroshima and Nagasaki in August 1945. During

5151-562: 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 gimballed , allowing the boom to move with the receiver aircraft. The boom contains a rigid pipe to transfer fuel. The fuel pipe ends in a nozzle with a flexible ball joint. The nozzle mates to

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5252-461: The USSR first had it been ordered to do so. The bombers would fly orbits around their assigned positions from which they were to enter Soviet airspace if they received the order, and the tankers would refill the bombers' fuel tanks so that they could keep a force in the air 24 hours a day, and still have enough fuel to reach their targets in the Soviet Union. This also ensured that a first strike against

5353-642: The air around the clock, orbiting some distance away from their fail-safe points near the Soviet border. The British produced three different " V bombers " for the Royal Air Force which were designed and designated to be able to deliver British-made nuclear bombs to targets in European Russia. These bombers would have been able to reach and destroy cities such as Kiev or Moscow before American strategic bombers. While they were never used against

5454-475: The air. Germany focused on short-range tactical bombers. Britain 's Royal Air Force began developing four-engine long-range bombers only in the late 1930s. The U.S. Army Air Corps ( Army Air Forces as of mid-1941) was severely limited by small budgets in the late 1930s, and only barely saved the B-17 bomber that would soon be vital. The equally important B-24 first flew in 1939. Both aircraft would constitute

5555-501: The aircraft having to fly to a lower altitude to be depressurized so a crew member could manually do the coupling. This air-to-air refueling system was used by the B-50 Superfortress Lucky Lady II of the 43rd Bomb Wing to make its famous first non-stop around-the-world flight in 1949. From 26 February to 3 March 1949, Lucky Lady II flew non-stop around the world in 94 hours and 1 minute,

5656-483: The aircraft made its mission impossible without aerial refueling. Based at 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

5757-408: 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 trialed shortly before World War II on a limited scale to extend the range of British civilian transatlantic flying boats , and then employed after World War II on a large scale to extend

5858-449: 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

5959-409: The aircraft's fuselage. 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

6060-416: 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,

6161-415: The bomber role, and to 2005 as reconnaissance aircraft . The French Republic limited its strategic armaments to a squadron of four nuclear-powered ballistic missile submarines , with 16 SLBM tubes apiece. France also maintains an active force of supersonic fighter-bombers carrying ASMP stand-off nuclear missiles , with Mach 3 speed and a range of 500 kilometers. These missiles can be delivered by

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6262-574: 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

6363-528: 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 . They exceeded the Hunters' record by nearly 100 hours in a Curtiss Robin monoplane, staying aloft for more than 27 days. The US

6464-590: The bulk of the bomber force for USAAF strategic bombing in Europe and Allied day bomber units more generally. At the start of World War II , so-called "strategic" bombing was initially carried out by medium bomber aircraft which were typically twin-engined, armed with several defensive guns, but only possessed limited bomb -carrying capacity and range . Both Britain and the US were developing larger two- and four-engined designs, which began to replace or supplement

6565-585: The development of Alexander P. de Seversky , between two planes occurred on 25 June 1923, between two Airco DH-4B biplanes of the United States Army Air Service . An endurance record was set by three DH-4Bs (a receiver and two tankers) on 27–28 August 1923, in which the receiver airplane remained aloft for more than 37 hours using nine mid-air refueling to transfer 687 US gallons (2,600 L) of aviation gasoline and 38 US gallons (140 L) of engine oil. The same crews demonstrated

6666-467: The distance to target and the individual type, size or weight of bombs used. Nomenclature for size classification of aircraft types used in strategic bombing varies, particularly since the time of World War II due to sequential technological advancements and changes in aerial warfare strategy and tactics. The B-29 , for example was a benchmark aircraft of the heavy bomber type at end of World War II due to its size, range and load carrying ability; as

6767-402: 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

6868-554: The flying boom system, along with Australia (KC-30A), the Netherlands (KDC-10), Israel (modified Boeing 707), Japan (KC-767), Turkey (KC-135Rs), and Iran (Boeing 707 and 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. The probe-and-drogue refueling method employs

6969-399: 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

7070-458: The hose was connected, the tanker climbed sufficiently above the receiver aircraft to allow the fuel to flow under gravity. When Cobham was developing his system, he saw the need as purely for long-range transoceanic commercial aircraft flights, but modern aerial refueling is used exclusively by military aircraft. In 1934, Cobham had founded Flight Refuelling Ltd (FRL) and by 1938 had used its looped-hose system to refuel aircraft as large as

7171-460: The hose which would cut off if contact was lost. Royal Air Force officer Richard Atcherley had observed the dangerous aerial-refueling techniques in use at barnstorming events in the US and determined to create a workable system. While posted to the Middle East he developed and patented his 'crossover' system in 1934, in which the tanker trailed a large hooked line that would reel in

7272-478: The late 1940s, General Curtis LeMay , commander of the Strategic Air Command (SAC), asked Boeing to develop a refueling system that could transfer fuel at a higher rate than had been possible with earlier systems using flexible hoses, resulting in the flying boom system. The B-29 was the first to employ the boom, and between 1950 and 1951, 116 original B-29s, designated KB-29Ps, were converted at

7373-432: 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

7474-475: 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 cargo aircraft , fighter aircraft , and ground attack aircraft , in addition to bombers, for ferrying to distant theaters of operations. This was much used during the Vietnam War , when many aircraft could not have covered

7575-527: The much improved probe-and-drogue system, with a modified Gloster Meteor F.3 jet fighter, serial EE397 , fitted with a nose-mounted probe. On 7 August 1949, the Meteor flown by FRL test pilot Pat Hornidge took off from Tarrant Rushton and remained airborne for 12 hours and 3 minutes, receiving 2,352 imperial gallons (10,690 L) of fuel in ten refuelings from a Lancaster tanker. Hornidge flew an overall distance of 3,600 mi (5,800 km), achieving

7676-404: The newer jet-powered military aircraft to slow down to mate with the tanker's boom, a highly serious issue with the newer supersonic aircraft coming into service at that time, which could force such receiving aircraft in some situations to slow down enough to approach their stall speed during the approach to the tanker. It was no surprise that, after the KC-97, Boeing began receiving contracts from

7777-506: The outbreak of World War II. 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

7878-445: The probe into the basket. Unlike the soft canvas basket used in most drogue systems, the adapter units use a steel basket, grimly known as the "iron maiden" by 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"

7979-585: 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 NATO standard and were originally developed by the company Flight Refuelling Limited in the UK and deployed in the late 1940s and 1950s. 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

8080-414: The range of strategic bombers , aerial refueling since the Vietnam War has been extensively used in large-scale military operations. 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

8181-420: The range of 35–40% have been estimated for long-haul flights (including the fuel used during the tanker missions). 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

8282-462: The receiver aircraft is topped-off with extra fuel in the air, air refueling can allow a takeoff with a greater 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

8383-430: The refueling valve to the end of the probe. 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

8484-537: The same flight, such as the KC-10, MPRS KC-135, or Airbus A330 MRTT. The development of the KC-97 and Boeing KC-135 Stratotankers was pushed by the Cold War requirement of the United States to be able to keep fleets of nuclear -armed B-47 Stratojet and B-52 Stratofortress strategic bombers airborne around-the-clock either to threaten retaliation against a Soviet strike for mutual assured destruction , or to bomb

8585-460: The same name This set index article includes a list of related items that share the same name (or similar names). If an internal link incorrectly led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=MRTT&oldid=896828695 " Category : Set index articles Hidden categories: Articles with short description Short description

8686-541: 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

8787-485: The smaller aircraft by 1941–42. After American entry into the war in December 1941, the U.S. 8th Air Force began to develop a daylight bombing capacity using improved B-17 and B-24 four-engine aircraft. In order to assemble the formations to carry out these bombing campaigns, assembly ships were used to quickly form defensive combat boxes . The RAF concentrated its efforts on night bombing . But neither force

8888-624: The transoceanic distances without aerial refueling, even with intermediate bases such as Hickam Air Force Base , Hawaii and Kadena Air Base , Okinawa. In addition to allowing the transport of the aircraft themselves, the cargo aircraft could also carry 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 SR-71 Blackbird strategic reconnaissance aircraft made frequent use of air-to-air refueling. Indeed, design considerations of

8989-522: 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 lies prone, while the operator is seated in the KC-10 , all viewing operations through a window at the tail. 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

9090-479: The untimely death of the top German advocate for strategic bombing, General Walther Wever in early June 1936, the focus of Nazi Germany's Luftwaffe bomber forces, the so-named Kampfgeschwader (bomber wings) became the battlefield support of the German Army as part of the general Blitzkrieg form of warfare, carried out with both medium bombers such as the Heinkel He 111 , and Schnellbombers such as

9191-775: The utility of the technique on 25 October 1923, when a DH-4 flew from Sumas, Washington , on the Canada–United States border , to 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 Royal Aircraft Establishment in England and by the Armée de l'Air in France in

9292-465: The valve is retained in the tanker drogue and prevents further refueling from that drogue until removed during ground maintenance. A "buddy store" or "buddy pod" is an external pod loaded on an aircraft hardpoint that contains a hose and drogue system (HDU). 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,

9393-521: The war, American fliers under the command of Brig. Gen. Billy Mitchell were developing multi-aircraft "mass" bombing missions behind German lines, although the Armistice ended full realization of what was being planned. Study of strategic bombing continued in the interwar years. Many books and articles predicted a fearful prospect for any future war, paced by political fears such as those expressed by British Prime Minister Stanley Baldwin who told

9494-537: Was able to develop adequate bombsights or tactics to allow for often-bragged "pinpoint" accuracy. The post-war U.S. Strategic Bombing Survey studies supported the overall notion of strategic bombing, but underlined many of its shortcomings as well. Attempts to create pioneering examples of " smart bombs " resulted in the Azon ordnance, deployed in the European Theater and CBI Theater from B-24s. Following

9595-634: Was done during the 1990s with the Tu-22M bombers. Strategic bombers of the Cold War were primarily armed with nuclear weapons. During the post-1940s Indochina Wars , and also since the end of the Cold War, modern bombers originally intended for strategic use have been exclusively employed using non-nuclear , high explosive weapons. During the Vietnam War , Operation Menu , Operation Freedom Deal , Gulf War , military action in Afghanistan , and

9696-470: 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 US Army Air Corps fliers, led by then Major Carl Spaatz , set an endurance record of over 150 hours with a Fokker C-2A named the Question Mark over Los Angeles. Between 11 June and 4 July 1930,

9797-417: 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. At Le Bourget Airport near Paris,

9898-416: 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

9999-495: Was pumped. 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 gravity feed . This was the method used on the Question Mark endurance flight in 1929. The probe-and-drogue system

10100-697: Was purely semantic and bureaucratic, however as both the B-47 and B-52 strategic bombers were much larger and had far greater performance and load-carrying ability than any of the World War II-era heavy or medium bombers. Other aircraft such as the twin- jet US FB-111 , Douglas A-3 Skywarrior and France 's Dassault Mirage IV had nominal warloads of less than 20,000 lb (9,100 kg), and were significantly smaller in size and gross weight compared with their strategic bomber contemporaries, based on which they might be classified as medium bombers . In

10201-473: Was so successful that in June orders went out to equip all new B-50s and subsequent bombers with receiving equipment. Two dedicated air refueling units were formed on 30 June 1948: the 43d Air Refueling Squadron 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

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