Aerial refueling
Overview
 
Aerial refueling, also called air refueling, in-flight refueling (IFR), air-to-air refueling (AAR) or tanking, is the process of transferring fuel
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...

 from one aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

 (the tanker) to another (the receiver) during flight.

The procedure allows the receiving aircraft to remain airborne longer, extending its range or loiter time on station.
Encyclopedia
Aerial refueling, also called air refueling, in-flight refueling (IFR), air-to-air refueling (AAR) or tanking, is the process of transferring fuel
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...

 from one aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

 (the tanker) to another (the receiver) during flight.

The procedure allows the receiving aircraft to remain airborne longer, extending its range or loiter time on station. A series of air refuelings can give range limited only by crew fatigue and engineering factors such as engine oil consumption. Because the receiver aircraft can be topped up with extra fuel in the air, air refueling can allow a take-off with a greater payload which could be weapons, cargo or personnel: the maximum take-off weight is maintained by carrying less fuel and topping up once airborne. Alternatively, a shorter take-off roll can be achieved because take-off can be at a lighter weight before refueling once airborne. Aerial refueling has also been considered as a means to reduce fuel consumption on long distance flights greater than 3000 nautical miles. Potential fuel savings in the range of 35-40% have been estimated for long haul flights (including the fuel used during the tanker missions).

The two main refueling systems are probe-and-drogue, which is simpler to adapt to existing aircraft, and the flying boom, which offers greater fuel transfer capacity, but requires a dedicated operator station.

Usually, the aircraft providing the fuel is specially designed for the task, although refueling pods can be fitted to existing aircraft designs if the "probe-and-drogue" system is to be used (see later). 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 is no known regular civilian in-flight refueling activity. Originally employed shortly before World War Two on a very limited scale to extend the range of British civilian trans-Atlantic flying boats, and then after World War Two on a large scale to extend the range of strategic bombers, aerial refueling since the Vietnam War
Vietnam War
The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...

 has been extensively used in large-scale military operations for many different military aircraft operations. For instance, in the Gulf War
Gulf War
The Persian Gulf War , commonly referred to as simply the Gulf War, was a war waged by a U.N.-authorized coalition force from 34 nations led by the United States, against Iraq in response to Iraq's invasion and annexation of Kuwait.The war is also known under other names, such as the First Gulf...

 and the Iraqi invasion of Kuwait
Invasion of Kuwait
The Invasion of Kuwait, also known as the Iraq-Kuwait War, was a major conflict between the Republic of Iraq and the State of Kuwait, which resulted in the seven-month long Iraqi occupation of Kuwait, which subsequently led to direct military intervention by United States-led forces in the Gulf...

 and the Iraq War, all coalition air sorties were air-refueled except for a few short-range ground attack sorties in the Kuwait area.

Pioneer experiments

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 between two planes occurred on June 27, 1923, between two Airco DH-4B biplane
Biplane
A biplane is a fixed-wing aircraft with two superimposed main wings. The Wright brothers' Wright Flyer used a biplane design, as did most aircraft in the early years of aviation. While a biplane wing structure has a structural advantage, it produces more drag than a similar monoplane wing...

s of the United States Army Air Service
United States Army Air Service
The Air Service, United States Army was a forerunner of the United States Air Force during and after World War I. It was established as an independent but temporary wartime branch of the War Department by two executive orders of President Woodrow Wilson: on May 24, 1918, replacing the Aviation...

. An endurance record was set by three DH-4Bs (a receiver and two tankers) on August 27–28, 1923, in which the receiver airplane remained aloft for more than 37 hours using nine mid-air refuelings to transfer 687 gallons of aviation gasoline and 38 gallons of engine oil. The same crews demonstrated the utility of the technique on October 25, 1923, when a DH-4 flew from Sumas, Washington, on the Canadian
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 border to Tijuana, Mexico, landing in San Diego, using mid-air refuelings at Eugene, Oregon
Eugene, Oregon
Eugene is the second largest city in the U.S. state of Oregon and the seat of Lane County. It is located at the south end of the Willamette Valley, at the confluence of the McKenzie and Willamette rivers, about east of the Oregon Coast.As of the 2010 U.S...

, and Sacramento, California
Sacramento, California
Sacramento is the capital city of the U.S. state of California and the county seat of Sacramento County. It is located at the confluence of the Sacramento River and the American River in the northern portion of California's expansive Central Valley. With a population of 466,488 at the 2010 census,...

.

In 1929, a group of U.S. Army Air Corps
United States Army Air Corps
The United States Army Air Corps was a forerunner of the United States Air Force. Renamed from the Air Service on 2 July 1926, it was part of the United States Army and the predecessor of the United States Army Air Forces , established in 1941...

 fliers, led by then Major Carl Spaatz, set an endurance record of over 150 hours with the Question Mark over Los Angeles. Between June 11 and July 4, 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
The Flying Keys
Brothers Fred and Al Key became interested in aviation after World War I. They started doing some barnstorming in the 1920s and continued their interest as the managers of the Meridian Municipal Airport, in Meridian, Mississippi....

 demonstrated a spill-free refueling nozzle, designed by A. D. Hunter. They exceeded the Hunters' record by nearly 100 hours in a Curtiss Robin
Curtiss Robin
|-See also:-References:NotesBibliography*Bowers, Peter M. Curtiss Aircraft 1907–1947. London: Putnam, 1979. ISBN 0-370-10029-8.-External links:* * ****...

 monoplane http://www.nasm.si.edu/imagedetail.cfm?imageID=1150, staying aloft for more than 27 days.

The US was mainly concerned about Trans-Atlantic flight for the 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 take off as a possible solution.

There were parallel experiments conducted in Europe; at Le Bourget
Le Bourget
Le Bourget is a commune in the northeastern suburbs of Paris, France. It is located from the center of Paris.A very small part of Le Bourget airport lies on the territory of the commune of Le Bourget, which nonetheless gave its name to the airport. Most of the airport lies on the territory of the...

 the Aéro-Club de France
Aéro-Club de France
The Aéro-Club de France was founded as the Aéro-Club on 20 October 1898 as a society 'to encourage aerial locomotion' by Ernest Archdeacon, Léon Serpollet, Henri de la Valette, Jules Verne and his wife, André Michelin, Albert de Dion, Alberto Santos-Dumont, Henry Deutsch de la Meurthe, and Henry de...

 and the 34th Aviation Regiment of the French Air Force
French Air Force
The French Air Force , literally Army of the Air) is the air force of the French Armed Forces. It was formed in 1909 as the Service Aéronautique, a service arm of the French Army, then was made an independent military arm in 1933...

 were able to demonstrate passing fuel between machines at the annual aviation fete at Vincennes
Vincennes
Vincennes is a commune in the Val-de-Marne department in the eastern suburbs of Paris, France. It is located from the centre of Paris. It is one of the most densely populated municipalities in Europe.-History:...

 in 1928. The UK's Royal Aircraft Establishment
Royal Aircraft Establishment
The Royal Aircraft Establishment , was a British research establishment, known by several different names during its history, that eventually came under the aegis of the UK Ministry of Defence , before finally losing its identity in mergers with other institutions.The first site was at Farnborough...

 was also trialing refueling-in-mid-air, with the aim to use this technique to extend the range of the long-distance flying boats that serviced the British Empire
British Empire
The British Empire comprised the dominions, colonies, protectorates, mandates and other territories ruled or administered by the United Kingdom. It originated with the overseas colonies and trading posts established by England in the late 16th and early 17th centuries. At its height, it was the...

. By 1931 they had demonstrated refueling between two Vickers Virginia
Vickers Virginia
|-See also:-References:NotesBibliography* Andrews, C.F. and E.B. Morgan. Vickers Aircraft since 1908. London: Putnam, 1989. ISBN 0-85177-851-1....

s, with fuel flow controlled by an automatic valve on the hose which would cut off if contact was lost.

Grappled-Line Looped-Hose

The aviation pioneer Alan Cobham
Alan Cobham
Sir Alan John Cobham, KBE, AFC was an English aviation pioneer.A member of the Royal Flying Corps in World War I, Alan Cobham became famous as a pioneer of long distance aviation. After the war he became a test pilot for the de Havilland aircraft company, and was the first pilot for the newly...

 bought a patent from David Nicolson and John Lord for £480 each and then started development of the Grappled-line looped-hose air to air refueling system, which while complex in operation, was the world's first practical air-to-air refueling system and gave public demonstrations of the system. In the system the receiver aircraft, at one time an Airspeed Courier
Airspeed Courier
|-See also:-External links:**...

, 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. (see reference #8 Gas Station in the Sky for detailed drawing of this type of operation.)

While today aerial refueling is used exclusively by military aircraft, when Cobham was developing his system, he saw the need as purely for long range trans-ocean commercial aircraft flights.

In 1934 Cobham founded Flight Refuelling Ltd. (FRL), and by 1938 had used the FRL's looped-hose system to refuel aircraft as large as the Short Empire
Short Empire
The Short Empire was a passenger and mail carrying flying boat, of the 1930s and 1940s, that flew between Britain and British colonies in Africa, Asia and Australia...

 flying boat Cambria from an Armstrong Whitworth AW.23
Armstrong Whitworth AW.23
-See also:-External links:*...

. Handley Page Harrow
Handley Page H.P.54 Harrow
|-See also:-Bibliography:* Barnes, C.H. Handley Page Aircraft since 1907. London: Putnam Publishing, 1987. ISBN 0-85177-803-8.* Clayton, Donald C. Handley Page, an Aircraft Album. Shepperton, Surrey, UK: Ian Allan Ltd., 1969. ISBN 0-7110-0094-8....

s were used in the 1939 trials to aerial refuel the Empire flying boats for regular transatlantic crossings. From August 5 to October 1, 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 the war.

During the closing months of World War II it had been intended that Tiger Force
Tiger Force (air)
Tiger Force, also known as the Very Long Range Bomber Force, was the name given to a World War II British Commonwealth long-range heavy bomber force, formed in 1945, from squadrons serving with RAF Bomber Command in Europe, for proposed use against targets in Japan...

's Lancaster
Avro Lancaster
The Avro Lancaster is a British four-engined Second World War heavy bomber made initially by Avro for the Royal Air Force . It first saw active service in 1942, and together with the Handley Page Halifax it was one of the main heavy bombers of the RAF, the RCAF, and squadrons from other...

 and Lincoln
Avro Lincoln
The Avro Type 694, better known as the Avro Lincoln, was a British four-engined heavy bomber, which first flew on 9 June 1944. Developed from the Avro Lancaster, the first Lincoln variants were known initially as the Lancaster IV and V, but were renamed Lincoln I and II...

 bombers would be in-flight refueled by converted Halifax
Handley Page Halifax
The Handley Page Halifax was one of the British front-line, four-engined heavy bombers of the Royal Air Force during the Second World War. A contemporary of the famous Avro Lancaster, the Halifax remained in service until the end of the war, performing a variety of duties in addition to bombing...

 tanker aircraft, fitted with the FRL's looped-hose units, in operations against the Japanese homeland
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

s, 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. This was the air-to-air refueling system that the Lucky Lady II
Lucky Lady II
Lucky Lady II is a United States Air Force Boeing B-50 Superfortress that became the first airplane to circle the world nonstop, when it made the journey in 1949, assisted by refueling the plane in flight. Total time airborne was 94 hours and 1 minute...

 used to make its famous first non-stop around the world flight in 1949.

Probe-and-Drogue

FRL realized that their looped-hose system left a lot 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 Meteor III
Gloster Meteor
The Gloster Meteor was the first British jet fighter and the Allies' first operational jet. It first flew in 1943 and commenced operations on 27 July 1944 with 616 Squadron of the Royal Air Force...

, EE397
United Kingdom military aircraft serials
In the United Kingdom to identify individual aircraft, all military aircraft are allocated and display a unique serial number. A unified serial number system, maintained by the Air Ministry , and its successor the Ministry of Defence , is used for aircraft operated by the Royal Air Force , Fleet...

, fitted with a nose-mounted probe. On 7 August 1949, the Meteor flown by FRL test pilot
Test pilot
A test pilot is an aviator who flies new and modified aircraft in specific maneuvers, known as flight test techniques or FTTs, allowing the results to be measured and the design to be evaluated....

 Pat Hornidge took-off from Tarrant Rushton
RAF Tarrant Rushton
RAF Tarrant Rushton was a Royal Air Force station near the village of Tarrant Rushton east of Blandford Forum in Dorset, England from 1943 to 1947.It was used for glider operations during World War II and later revived for civilian operations...

 and remained airborne for 12 hours and 3 minutes, receiving 2,352 gallons of fuel in ten refuelings from a Lancaster tanker. Hornidge flew an overall distance of 3600 miles (5,793.6 km), achieving a new jet endurance record. FRL still exists as part of Cobham plc
Cobham plc
Cobham plc is a British manufacturing company based in Wimborne Minster, Dorset, England. It is listed on the London Stock Exchange and is a constituent of the FTSE 250 Index...

.

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
Jet aircraft
A jet aircraft is an aircraft propelled by jet engines. Jet aircraft generally fly much faster than propeller-powered aircraft and at higher altitudes – as high as . At these altitudes, jet engines achieve maximum efficiency over long distances. The engines in propeller-powered aircraft...

 typically need to remain airborne.

First operational use

In January 1948, General Carl Spaatz, then the first Chief of Staff
Chief of Staff of the United States Air Force
The Chief of Staff of the Air Force is a statutory office held by a four-star general in the United States Air Force, and is the most senior uniformed officer assigned to serve in the Department of the Air Force, and as such is the principal military advisor and a deputy to the Secretary of the...

 of the new United States Air Force
United States Air Force
The United States Air Force is the aerial warfare service branch of the United States Armed Forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947 under the National Security Act of...

 made aerial refueling a top priority of the service. In March 1948 USAF purchased two sets of FRL's looped-hose in-flight refueling equipment, which had been in practical use with British Overseas Airways Corporation
British Overseas Airways Corporation
The British Overseas Airways Corporation was the British state airline from 1939 until 1946 and the long-haul British state airline from 1946 to 1974. The company started life with a merger between Imperial Airways Ltd. and British Airways Ltd...

 (BOAC) since 1946, and manufacturing rights to the system. FRL also provided a year of technical assistance. The sets were immediately installed in two B-29 Superfortress
B-29 Superfortress
The B-29 Superfortress is a four-engine propeller-driven heavy bomber designed by Boeing that was flown primarily by the United States Air Forces in late-World War II and through the Korean War. The B-29 was one of the largest aircraft to see service during World War II...

es, with plans to equip 80 B-29s.

Flight testing began in May 1948 at Wright-Patterson Air Force Base
Wright-Patterson Air Force Base
Wright-Patterson Air Force Base is a United States Air Force base in Greene and Montgomery counties in the state of Ohio. It includes both Wright and Patterson Fields, which were originally Wilbur Wright Field and Fairfield Aviation General Supply Depot. Patterson Field is located approximately...

, Ohio
Ohio
Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...

, and was so successful that in June orders went out to equip all new B-50's and subsequent bombers with receiving equipment. Two dedicated Air Refueling units were formed on June 30, 1948: the 43d Air Refueling Squadron
43d Air Refueling Squadron
The 43d Air Refueling Squadron is an inactive United States Air Force unit. It was last assigned to the 92nd Bombardment Wing, stationed at Fairchild AFB, Washington. It was inactivated on 1 September 1991.-Air Transport Command:...

 at Davis-Monthan Air Force Base
Davis-Monthan Air Force Base
Davis–Monthan Air Force Base is a United States Air Force base located within the city limits, and approximately south-southeast of downtown, Tucson, Arizona....

, Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...

, and the 509th Air Refueling Squadron
509th Weapons Squadron
The 509th Weapons Squadron is a United States Air Force unit. It is assigned to the USAF Weapons School, stationed at Fairchild AFB, Washington.The 509th WPS is a Geographically Separated Unit of the 57th Wing, assigned to Nellis AFB, Nevada...

 at Walker Air Force Base
Walker Air Force Base
Walker Air Force Base is a closed United States Air Force base located three miles south of the central business district of Roswell, a city in Chaves County, New Mexico, US...

, New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...

. The first ARS aircraft used FRL's looped-hose refueling system, but testing with a boom system followed quickly in the autumn of 1948.
In 1949 from February 26 to March 3 an American B-50 Superfortress
B-50 Superfortress
The Boeing B-50 Superfortress strategic bomber was a post-World War II revision of the Boeing B-29 Superfortress, fitted with more powerful Pratt & Whitney R-4360 radial engines, stronger structure, a taller fin, and other improvements. It was the last piston-engined bomber designed by Boeing for...

 Lucky Lady II of the 43rd Bomb Wing flew non-stop around the World in 94 hours, 1 min., a feat made possible by three aerial refuelings from four pairs of KB-29M tankers of the 43d ARS. Before the mission, crews of the 43d had experienced only a single operational air refueling contact. The flight started and ended at Carswell Air Force Base
Carswell Air Force Base
Carswell Air Force Base, was a United States Air Force Strategic Air Command base located about northwest central of Fort Worth, Texas, United States; the air force base is mostly within the Fort Worth city limits and has portions within Westworth and White Settlement...

 in Fort Worth, Texas
Fort Worth, Texas
Fort Worth is the 16th-largest city in the United States of America and the fifth-largest city in the state of Texas. Located in North Central Texas, just southeast of the Texas Panhandle, the city is a cultural gateway into the American West and covers nearly in Tarrant, Parker, Denton, and...

 with the refuelings accomplished over West Africa
West Africa
West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags of West Africa:...

, the Pacific ocean near Guam
Guam
Guam is an organized, unincorporated territory of the United States located in the western Pacific Ocean. It is one of five U.S. territories with an established civilian government. Guam is listed as one of 16 Non-Self-Governing Territories by the Special Committee on Decolonization of the United...

 and between Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

 and the West Coast
West Coast of the United States
West Coast or Pacific Coast are terms for the westernmost coastal states of the United States. The term most often refers to the states of California, Oregon, and Washington. Although not part of the contiguous United States, Alaska and Hawaii do border the Pacific Ocean but can't be included in...

.
This first non-stop circumnavigation of the globe proved that, because of aerial refueling, vast distances and geographical barriers were no longer an obstacle to military air power. In 1949 four additional ARS units were organized by the USAF and both the 43d and 509th ARS became fully operational.

The first use of aerial refueling in combat took place during the Korean War, involving F-84 fighter-bombers flying missions from Japanese airfields (i.e. due to Chinese-North Korean forces over-running 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

Two different methods are used to connect tanker to receiver: the flying boom system (sometimes called boom and receptacle), and the probe-and-drogue system. The less popular wing-to-wing system is no longer used.

Flying boom

The flying boom is a rigid, telescoping tube with movable flight control surfaces that an 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-135 Stratotanker
The Boeing KC-135 Stratotanker is an aerial refueling military aircraft. It and the Boeing 707 airliner were developed from the Boeing 367-80 prototype. The KC-135 was the US Air Force's first jet-powered refueling tanker and replaced the KC-97 Stratotanker...

, KC-10 Extender
KC-10 Extender
The McDonnell Douglas KC-10 Extender is the military adaptation of the three-engined DC-10 airliner for the United States Air Force . The KC-10 incorporates military-specific equipment for its primary roles of transport and aerial refueling. It was developed to supplement the KC-135 Stratotanker...

), have a single boom, and can refuel one aircraft at a time with this mechanism.

History

In the late 1940s, General Curtis LeMay
Curtis LeMay
Curtis Emerson LeMay was a general in the United States Air Force and the vice presidential running mate of American Independent Party candidate George Wallace in 1968....

, commander of the Strategic Air Command
Strategic Air Command
The Strategic Air Command was both a Major Command of the United States Air Force and a "specified command" of the United States Department of Defense. SAC was the operational establishment in charge of America's land-based strategic bomber aircraft and land-based intercontinental ballistic...

 (SAC), asked Boeing
Boeing
The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...

 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 the Boeing plant at Renton, Washington
Renton, Washington
Renton is an Eastside edge city in King County, Washington, United States. Situated 11 miles southeast of Seattle, Washington, Renton straddles the southeast shore of Lake Washington. Founded in the 1860s, Renton became a supply town for the Newcastle coal fields...

. Boeing went on to develop the world’s first production aerial tanker, the KC-97 Stratotanker
KC-97 Stratotanker
The Boeing KC-97 Stratotanker was a United States strategic tanker aircraft based on the Boeing C-97 Stratofreighter. It was succeeded by the Boeing KC-135 Stratotanker.-Design and development:...

, a piston-engined Boeing Stratocruiser (USAF designation C-97 Stratofreighter
C-97 Stratofreighter
The Boeing C-97 Stratofreighter was a long range heavy military cargo aircraft based on the B-29 bomber. Design work began in 1942, with the prototype's first flight being on 9 November 1944, and the first production aircraft entered service in 1947. Between 1947 and 1958, 888 C-97s in several...

) 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
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. In 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. 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
Boeing 367-80
The Boeing 367-80, or "Dash 80" as it was called within Boeing, is an American prototype jet transport built to demonstrate the advantages of jet aircraft for passenger transport over piston-engine airliners....

 (Dash-80) airframe. The result was the Boeing KC-135 Stratotanker
KC-135 Stratotanker
The Boeing KC-135 Stratotanker is an aerial refueling military aircraft. It and the Boeing 707 airliner were developed from the Boeing 367-80 prototype. The KC-135 was the US Air Force's first jet-powered refueling tanker and replaced the KC-97 Stratotanker...

, of which 732 were built.

Operation

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 the "receptacle" in the receiver aircraft during fuel transfer. A poppet valve
Poppet valve
A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. The shaft guides the plug portion by sliding through a valve guide...

 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, are used to move the boom by creating aerodynamic forces. They are actuated hydraulically
Hydraulics
Hydraulics is a topic in applied science and engineering dealing with the mechanical properties of liquids. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties. In fluid power, hydraulics is used for the generation, control,...

 and controlled by the system operator using a control stick. The 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.

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 (see 1966 Palomares B-52 crash). Approaching the limits of the envelope, the boom operator will command the receiver pilot to correct his position, and disconnect the boom if necessary.

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

Systems in service

USAF fixed-wing aircraft use the flying boom system. In addition to the US Air Force, the boom system is used by the Netherlands (KDC-10), Israel (modified Boeing 707), Turkey (ex-USAF KC-135R), and Iran (Boeing 747). New tankers are under development; see KC-X
KC-X
KC-X is the United States Air Force program to procure its next-generation aerial refueling tanker aircraft to replace some of the older Boeing KC-135 Stratotankers. The contest was for a production contract for 179 new tankers with estimated value of US$35 billion...

.

Advantages

  • Higher fuel flow rates (up to 1000 US gallons/6,500 lb per minute for the KC-135 tanker) can be achieved with the large diameter of the pipe in the flying boom, requiring less time to complete refueling operations than probe-and-drogue systems. Fighter aircraft cannot accept fuel at the boom’s maximum flow rate, requiring a reduction in refueling pressure when servicing these aircraft, reducing (but not eliminating) the flying boom's advantage over the drogue system when refueling fighter aircraft.
  • The boom method eliminates the requirement for the receiver aircraft pilot to precisely fly a probe into a drogue, something that is easily performed by fighter-sized aircraft, but is more difficult for larger and less-maneuverable aircraft.
  • A tanker with a flying boom can be equipped with an adapter for probe-equipped aircraft.

Disadvantages

  • The cost to train and employ the boom operator.
  • Complexity of tanker design.
  • Only one receiver aircraft can refuel at a time.
  • Cannot be used to refuel most helicopters.
  • Requires modification to support USN/USMC or NATO tactical jet aircraft.

Probe-and-drogue

This 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 windsock or shuttlecock
Shuttlecock
A shuttlecock, sometimes called a bird or birdie, is a high-drag projectile used in the sport of badminton. It has an open conical shape: the cone is formed from sixteen or so overlapping feathers, usually goose or duck and from the left wing only, embedded into a rounded cork base...

, attached at its narrow end 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 arm placed on the aircraft's nose or fuselage. This probe is often retracted when not in use, particularly on high speed aircraft. At the end of the probe is a valve that is closed until it mates with the drogue, 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
Cobham plc
Cobham plc is a British manufacturing company based in Wimborne Minster, Dorset, England. It is listed on the London Stock Exchange and is a constituent of the FTSE 250 Index...

 in the UK and deployed in the late 1940s and 1950s. This standardization allows drogue-equipped tanker aircraft from many nations the ability 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. This is so that if a large side-load or up-and-down 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

A "buddy store" or “buddy pod” is an external pod loaded on an aircraft hardpoint
Hardpoint
A hardpoint, or weapon station, is any part of an airframe designed to carry an external load. This includes a point on the wing or fuselage of military aircraft where external ordnance, countermeasures, gun pods, targeting pods or drop tanks can be mounted.-Rail launchers:Large missiles and...

 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, a carrier air wing
Carrier air wing
A Carrier Air Wing is an operational naval aviation organization composed of several aircraft squadrons and detachments of various types of fixed wing and rotary wing aircraft...

) to extend the range of its strike aircraft. In other cases, using the buddy store method allows a carrier
Aircraft carrier
An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...

-based aircraft to take-off with a heavier than usual load, the aircraft then being 'topped up' with fuel from a HDU-equipped 'buddy' tanker, a method previously used by the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 in operating its Supermarine Scimitar
Supermarine Scimitar
-References:NotesBibliography* Andrews, C.F. and E.B. Morgan. Supermarine Aircraft since 1914. London: Putnam, 1987. ISBN 0-85177-800-3.* Birtles, Philip. Supermarine Attacker, Swift and Scimitar . London: Ian Allan, 1992. ISBN 0-7110-2034-5.* Buttler, Tony. "Database: Supermarine Scimitar"....

 and Blackburn Buccaneer
Blackburn Buccaneer
The Blackburn Buccaneer was a British low-level subsonic strike aircraft with nuclear weapon delivery capability serving with the Royal Navy and the Royal Air Force between 1962 and 1994, including service in the 1991 Gulf War...

s, in the Buccaneer's case using a bomb-bay-mounted tank and HDU.

Operation

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 his probe (if required) and uses normal flight controls to "fly" the refueling probe directly into the basket. This requires a closure rate of approximately two knots (walking speed) in order to establish solid probe/drogue couple and pushing the hose several feet into the HDU. 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
Oscillation
Oscillation is the repetitive variation, typically in time, of some measure about a central value or between two or more different states. Familiar examples include a swinging pendulum and AC power. The term vibration is sometimes used more narrowly to mean a mechanical oscillation but sometimes...

 in the hose, severing the probe tip. Another significant danger is that the drogue may hit the recipient aircraft and damage it—instances have occurred in which the drogue has shattered the canopy of a fighter aircraft, causing great danger to its pilot.

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.

Systems in service

USAF helicopters, and all US Navy and Marine Corps aircraft refuel using the “hose-and-drogue.” NATO countries and other western allies also refuel with the probe-and-drogue method. The USSR also reverse engineered the NATO hose and drogue system, which is called UPAZ , so all Russian aircraft are also equipped with probe and drogue.

Advantages

  • Simpler/cheaper tanker design.
  • The probe-and-drogue method allows aircraft not originally designed as tankers to be converted by attaching a refueling pod.
  • Tankers can be equipped with multipoint hose-and-drogue systems allowing two (or more) aircraft to refuel simultaneously from the same tanker, reducing time spent by as much as 75% for a four aircraft strike package. Multiple refueling points also offers redundancy over the single boom system.
  • Can be used to refuel properly equipped helicopters, such as the MH-53E Sea Dragon.
  • No boom operator is needed for the refueling as the drogue can be operated by the pilot of the tanker.

Disadvantages

  • The lower flow rates (1,500–4,500 lbs/min) available from the lower pressure and limited diameter of the hose used in the probe-and-drogue system result in longer refueling times compared to the flying boom for larger aircraft.
  • Drogue subject to turbulence and aerodynamic forces (bow wave) of approaching aircraft.
  • Drogue subject to damage by poor receiver technique, making further refueling difficult or impossible.
  • Drogue only equipped tankers cannot be easily fitted with boom systems.
  • The probe is generally located in the front of the refueling plane, presenting several problems: sensitive avionics equipment (pitot static and angle of attack
    Angle of attack
    Angle of attack is a term used in fluid dynamics to describe the angle between a reference line on a lifting body and the vector representing the relative motion between the lifting body and the fluid through which it is moving...

     probes, etc.), can easily be damaged by the drogue, and FOD
    Foreign object damage
    Foreign Object Debris is a substance, debris or article alien to a vehicle or system which would potentially cause damage.Foreign Object Damage is any damage attributed to a foreign object that can be expressed in physical or economic terms that may or may not degrade the product's required...

    , including fuel or probe/drogue parts can be ingested into the plane's engines.

Boom drogue adapter units

USAF KC-135 and French Air Force
French Air Force
The French Air Force , literally Army of the Air) is the air force of the French Armed Forces. It was formed in 1909 as the Service Aéronautique, a service arm of the French Army, then was made an independent military arm in 1933...

 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 in a static position, while the receiver aircraft then flies the probe into the basket. Unlike the soft canvas basket used in most drogue systems, the adapter units used on adapter units use a steel basket, grimly known as the “iron maiden” by naval aviator
Naval Aviator
A United States Naval Aviator is a qualified pilot in the United States Navy, Marine Corps or Coast Guard.-Naming Conventions:Most Naval Aviators are Unrestricted Line Officers; however, a small number of Limited Duty Officers and Chief Warrant Officers are also trained as Naval Aviators.Until 1981...

s 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

Some tankers have both a boom and one or more complete hose-and-drogue systems. Where these are attached to the wings, the system is known as the Multi-Point Refueling System or MPRS. The USAF KC-10 has both a flying boom and also a separate hose and drogue system manufactured by Cobham plc. Both are on the aircraft centerline at the tail of the aircraft, so only one system 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-135 and some KC-10s are also equipped with dual under-wing hose-and-drogue attachments known as Wing Air Refueling Pods (WARPs).

Wing-to-wing

In this method, similar to the probe-and-drogue method but more complicated, the tanker aircraft released a flexible hose from its wingtip. An aircraft, flying beside it, 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. It was used on a small number of Soviet Tu-4 and Tu-16 only (the tanker variant was Tu-16Z).

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 gravity feed
Siphon
The word siphon is sometimes used to refer to a wide variety of devices that involve the flow of liquids through tubes. But in the English language today, the word siphon usually refers to a tube in an inverted U shape which causes a liquid to flow uphill, above the surface of the reservoir,...

. This was the method used on the 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. Incompatibility can also complicate the procurement of new systems - the Canadian Forces currently wish to purchase the F-35A, which can only refuel via the flying boom, but Canada only possess probe-and-drogue refuelers. The potential cost of converting Canadian F-35As to probe-and-drogue refueling (as will be used on U.S. Navy F-35Cs) has added to the political controversy which already surrounds F-35 procurement in Canada.

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 which 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.

Uses and considerations

Strategic

The development of the KC-97
KC-97 Stratotanker
The Boeing KC-97 Stratotanker was a United States strategic tanker aircraft based on the Boeing C-97 Stratofreighter. It was succeeded by the Boeing KC-135 Stratotanker.-Design and development:...

 and KC-135 Stratotanker
KC-135 Stratotanker
The Boeing KC-135 Stratotanker is an aerial refueling military aircraft. It and the Boeing 707 airliner were developed from the Boeing 367-80 prototype. The KC-135 was the US Air Force's first jet-powered refueling tanker and replaced the KC-97 Stratotanker...

s was pushed by the Cold War
Cold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...

 requirement of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 to be able to keep fleets of nuclear-armed B-47 Stratojet
B-47 Stratojet
The Boeing Model 450 B-47 Stratojet was a long-range, six-engined, jet-powered medium bomber built to fly at high subsonic speeds and at high altitudes. It was primarily designed to drop nuclear bombs on the Soviet Union...

 and B-52 Stratofortress
B-52 Stratofortress
The Boeing B-52 Stratofortress is a long-range, subsonic, jet-powered strategic bomber operated by the United States Air Force since the 1950s. The B-52 was designed and built by Boeing, who have continued to provide maintainence and upgrades to the aircraft in service...

 strategic bombers airborne around-the-clock either to threaten retaliation against a Soviet
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 strike for mutual assured destruction
Mutual assured destruction
Mutual Assured Destruction, or mutually assured destruction , is a doctrine of military strategy and national security policy in which a full-scale use of high-yield weapons of mass destruction by two opposing sides would effectively result in the complete, utter and irrevocable annihilation of...

, or to bomb the U.S.S.R. first had it been ordered to do so by the President of the United States
President of the United States
The President of the United States of America is the head of state and head of government of the United States. The president leads the executive branch of the federal government and is the commander-in-chief of the United States Armed Forces....

. 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
First strike
In nuclear strategy, a first strike is a preemptive surprise attack employing overwhelming force. First strike capability is a country's ability to defeat another nuclear power by destroying its arsenal to the point where the attacking country can survive the weakened retaliation while the opposing...

 against the bombers' airfields could not obliterate the U.S.'s ability to retaliate by bomber. A noted example of refueling used in this manner in the movies can be seen in the opening credits of Dr. Strangelove.

In the UK, in 1958 Valiant tankers were developed with one HDU mounted in the bomb-bay. Valiant tankers 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
Gloster Javelin
The Gloster Javelin was an "all-weather" interceptor aircraft that served with Britain's Royal Air Force in the late 1950s and most of the 1960s...

 and Lightning
English Electric Lightning
The English Electric Lightning is a supersonic jet fighter aircraft of the Cold War era, noted for its great speed and unpainted natural metal exterior finish. It is the only all-British Mach 2 fighter aircraft. The aircraft was renowned for its capabilities as an interceptor; Royal Air Force ...

 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
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

 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 cargo aircraft
Cargo aircraft
A cargo aircraft is a fixed-wing aircraft designed or converted for the carriage of goods, rather than passengers. They are usually devoid of passenger amenities, and generally feature one or more large doors for the loading and unloading of cargo...

, fighter aircraft
Fighter aircraft
A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...

, and ground attack aircraft
Ground attack aircraft
Ground-attack aircraft are military aircraft with primary role of attacking targets on the ground with greater precision than bombers and prepared to face stronger low-level air defense...

, in addition to bombers, for ferrying to distant theaters of operations. This was much used during the Vietnam War
Vietnam War
The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...

, when many aircraft could not have covered the transoceanic distances without aerial refueling, even with intermediate bases in Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

 and Okinawa. In addition to allowing the transport of the aircraft themselves, the cargo aircraft could also carry matériel
Materiel
Materiel is a term used in English to refer to the equipment and supplies in military and commercial supply chain management....

, supplies, and personnel to Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...

 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
SR-71 Blackbird
The Lockheed SR-71 "Blackbird" was an advanced, long-range, Mach 3+ strategic reconnaissance aircraft. It was developed as a black project from the Lockheed A-12 reconnaissance aircraft in the 1960s by the Lockheed Skunk Works. Clarence "Kelly" Johnson was responsible for many of the...

 strategic reconnaissance aircraft made frequent use of air-to-air refueling. Indeed, design considerations of the aircraft made its mission impossible without aerial refueling. Based at Beale AFB in central California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, 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, and to stop the fuel leaks, the SR-71 would then rendezvous with a tanker to fill its now nearly empty tanks before proceeding on its mission. 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
JP-7
JP-7 is a jet fuel developed by the U.S. Air Force for use in supersonic aircraft because of its high flash point and thermal stability. It is the fuel used in the Pratt & Whitney J58 engines, used in the Lockheed SR-71 Blackbird. The air compression of Mach 3+ cruising flight generates very high...

, with a very high flash point
Flash point
The flash point of a volatile material is the lowest temperature at which it can vaporize to form an ignitable mixture in air. Measuring a flash point requires an ignition source...

 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 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 US 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.

Tactical

Tankers are considered "force multipliers," because they convey considerable tactical advantages. Primarily, aerial refueling adds to the combat radius of attack, fighter and bombers aircraft, and allows patrol aircraft to remain airborne longer, thereby reducing the numbers of aircraft necessary to accomplish a given mission. Aerial refueling can also mitigate basing issues which might otherwise place limitations on combat 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 takeoff with a full combat payload and refuel immediately.

Aside from these issues, the psychological advantage of full fuel tanks – and a tanker likely available nearby – gives a pilot a distinct edge in combat. In most combat situations, speed is a necessity for optimal completion of the mission at hand.
As high speeds require fuel, pilots must always balance fuel and speed requirements. Pilots operating aircraft with aerial refueling capability eliminate low-fuel concerns.

Vietnam War

During the Vietnam War
Vietnam War
The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...

, it was common for USAF fighter-bombers flying from Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...

 to North Vietnam
North Vietnam
The Democratic Republic of Vietnam , was a communist state that ruled the northern half of Vietnam from 1954 until 1976 following the Geneva Conference and laid claim to all of Vietnam from 1945 to 1954 during the First Indochina War, during which they controlled pockets of territory throughout...

 to refuel from KC-135s en-route to their target. Besides extending their range, this enabled the F-105s and 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
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

, 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.

The US Navy frequently used carrier-based aerial tankers like the KA-3 Skywarrior
A-3 Skywarrior
The Douglas A-3 Skywarrior was originally designed as a strategic bomber for the United States Navy and was among the longest serving carrier-based jet aircraft in history. It entered service in the mid-1950s and was retired in 1991...

 to refuel Navy and Marine aircraft such as the F-4, A-4 Skyhawk
A-4 Skyhawk
The Douglas A-4 Skyhawk is a carrier-capable ground-attack aircraft designed for the United States Navy and United States Marine Corps. The delta winged, single-engined Skyhawk was designed and produced by Douglas Aircraft Company, and later McDonnell Douglas. It was originally designated the A4D...

, A-6 Intruder
A-6 Intruder
The Grumman A-6 Intruder was an American, twin jet-engine, mid-wing attack aircraft built by Grumman Aerospace. In service with the U.S. Navy and U.S. Marine Corps between 1963 and 1997, the Intruder was designed as an all-weather medium attack aircraft to replace the piston-engined A-1 Skyraider...

, and A-7 Corsair II
A-7 Corsair II
The Ling-Temco-Vought A-7 Corsair II is a carrier-based subsonic light attack aircraft introduced to replace the United States Navy's Douglas A-4 Skyhawk, initially entering service during the Vietnam War...

. This was particularly useful when a pilot returning from an airstrike was having difficulty landing and was running low on jet fuel. This gave him fuel for more attempts at landing for a successful "trap" on an aircraft carrier. The KA-3 could also refuel fighters on extended Combat Air Patrol.
USMC jets based in South Vietnam and Thailand also used USMC KC-130 Hercules transports for air-to-air refueling on missions.

Iran-Iraq War

During the 1980s 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 April 4, 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.

Israeli Tunisian Strike

In 1985, Israeli F-15s used heavily modified Boeing 707
Boeing 707
The Boeing 707 is a four-engine narrow-body commercial passenger jet airliner developed by Boeing in the early 1950s. Its name is most commonly pronounced as "Seven Oh Seven". The first airline to operate the 707 was Pan American World Airways, inaugurating the type's first commercial flight on...

 aircraft to provide aerial refueling over the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...

 in order to extend their range for the 2,000km flight during the Operation Wooden Leg
Operation Wooden Leg
Operation Wooden Leg was an attack by Israel on the Palestine Liberation Organization headquarters in Hammam al-Shatt, Tunisia, 12 miles from the capital of Tunis. It took place on October 1, 1985. Taking place 1,280 miles away, this was the furthest operation from Israel undertaken by the...

 air raid on the headquarters of the PLO
Palestine Liberation Organization
The Palestine Liberation Organization is a political and paramilitary organization which was created in 1964. It is recognized as the "sole legitimate representative of the Palestinian people" by the United Nations and over 100 states with which it holds diplomatic relations, and has enjoyed...

 near Tunis
Tunis
Tunis is the capital of both the Tunisian Republic and the Tunis Governorate. It is Tunisia's largest city, with a population of 728,453 as of 2004; the greater metropolitan area holds some 2,412,500 inhabitants....

, Tunisia
Tunisia
Tunisia , officially the Tunisian RepublicThe long name of Tunisia in other languages used in the country is: , is the northernmost country in Africa. It is a Maghreb country and is bordered by Algeria to the west, Libya to the southeast, and the Mediterranean Sea to the north and east. Its area...

.

Falklands War

During the Falklands War
Falklands War
The Falklands War , also called the Falklands Conflict or Falklands Crisis, was fought in 1982 between Argentina and the United Kingdom over the disputed Falkland Islands and South Georgia and the South Sandwich Islands...

, aerial refueling played a vital role in all of the successful Argentine attacks against the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

. The Argentine Air Force
Argentine Air Force
The Argentine Air Force is the national aviation branch of the Armed Forces of the Argentine Republic. , it had 14,606 military and 6,854 civilian staff.-History:...

 had only two KC-130H Hercules available and they were used to refuel both Air Force and Navy A-4 Skyhawk
A-4 Skyhawk
The Douglas A-4 Skyhawk is a carrier-capable ground-attack aircraft designed for the United States Navy and United States Marine Corps. The delta winged, single-engined Skyhawk was designed and produced by Douglas Aircraft Company, and later McDonnell Douglas. It was originally designated the A4D...

s and Navy Super Etendards in their Exocet
Exocet
The Exocet is a French-built anti-ship missile whose various versions can be launched from surface vessels, submarines, helicopters and fixed wing aircraft. Hundreds were fired in combat during the 1980s.-Etymology:...

 strikes. The Hercules on several occasions approached the islands (where the Sea Harriers were in patrol) to search and guide the A-4s in their returning flights. On one of those flights (callsign Jaguar) one of the KC-130s went to rescue a damaged A-4 and delivered 39000 lb (17,690.1 kg) of fuel while carrying it to its airfield at San Julian
Puerto San Julián
Puerto San Julián, also known historically as Port St Julian, is a natural harbour in Patagonia in the Santa Cruz Province of Argentina located at . In the days of sailing ships it formed a stopping point, south of Puerto Deseado...

.

On the other hand, the Mirage IIIs and Dagger
IAI Nesher
The Israel Aircraft Industries Nesher is the Israeli version of the Dassault Mirage 5 multi-role fighter aircraft...

s 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 Handley Page Victor
Handley Page Victor
The Handley Page Victor was a British jet bomber aircraft produced by the Handley Page Aircraft Company during the Cold War. It was the third and final of the V-bombers that provided Britain's nuclear deterrent. The other two V-bombers were the Avro Vulcan and the Vickers Valiant. Some aircraft...

 K.2 and after the Argentine surrender by modified C-130 Hercules tankers. These aircraft aided deployments from the UK to the Ascension Island
Ascension Island
Ascension Island is an isolated volcanic island in the equatorial waters of the South Atlantic Ocean, around from the coast of Africa and from the coast of South America, which is roughly midway between the horn of South America and Africa...

 staging post in the Atlantic and further deployments south of bomber, transport and maritime patrol aircraft. The most famous refueling missions were the 8,000 nm/15,000 km "Operation Black Buck
Operation Black Buck
During the Falklands War, Operations Black Buck 1 to Black Buck 7 were a series of seven extremely long-range ground attack missions by Royal Air Force Vulcan bombers planned against Argentine positions in the Falkland Islands...

" sorties which used 14 Victor tankers to allow an Avro Vulcan
Avro Vulcan
The Avro Vulcan, sometimes referred to as the Hawker Siddeley Vulcan, was a jet-powered delta wing strategic bomber, operated by the Royal Air Force from 1956 until 1984. Aircraft manufacturer A V Roe & Co designed the Vulcan in response to Specification B.35/46. Of the three V bombers produced,...

 bomber (with a flying reserve bomber) to attack the Argentine-captured airfield at Port Stanley on the Falkland Islands
Falkland Islands
The Falkland Islands are an archipelago in the South Atlantic Ocean, located about from the coast of mainland South America. The archipelago consists of East Falkland, West Falkland and 776 lesser islands. The capital, Stanley, is on East Falkland...

. With all the aircraft flying from Ascension, the tankers themselves needed refueling. The raids were the longest-range bombing raids in history until surpassed by the B-52 in the 1991 Gulf War
Gulf War
The Persian Gulf War , commonly referred to as simply the Gulf War, was a war waged by a U.N.-authorized coalition force from 34 nations led by the United States, against Iraq in response to Iraq's invasion and annexation of Kuwait.The war is also known under other names, such as the First Gulf...

 and later B-2
B-2 Spirit
The Northrop Grumman B-2 Spirit is an American heavy bomber with low observable stealth technology designed to penetrate dense anti-aircraft defenses and deploy both conventional and nuclear weapons. The bomber has a crew of two and can drop up to eighty -class JDAM GPS-guided bombs, or sixteen ...

 flights.

The Victor tankers, retired in 1993, were replaced in RAF service by Lockheed L-1011
Lockheed L-1011
The Lockheed L-1011 TriStar, commonly referred to as the L-1011 or TriStar, is a medium-to-long range, widebody passenger trijet airliner. It was the third widebody airliner to enter commercial operations, following the Boeing 747 and the McDonnell Douglas DC-10. Between 1968 and 1984, Lockheed...

 and Vickers VC10
Vickers VC10
The Vickers VC10 is a long-range British airliner designed and built by Vickers-Armstrongs Ltd, and first flown in 1962. The airliner was designed to operate on long-distance routes with a high subsonic speed and also be capable of hot and high operations from African airports...

 transports which were bought second-hand and fitted as tankers. The L-1011s, converted by Marshall Aerospace
Marshall Aerospace
The Marshall companies have been internationally associated with aerospace engineering for nearly a century. The company employs over 1,800 people and is based on an site with of covered hangar space...

, and VC10s, converted by British Aerospace, can refuel any aircraft fitted with the NATO standard probe system.

Libya

During Operation El Dorado Canyon
Operation El Dorado Canyon
The 1986 United States bombing of Libya, code-named Operation El Dorado Canyon, comprised the joint United States Air Force, Navy and Marine Corps air-strikes against Libya on April 15, 1986. The attack was carried out in response to the 1986 Berlin discotheque bombing.-Origins:Shortly after his...

, several F-111 Aardvark
General Dynamics F-111
The General Dynamics F-111 "Aardvark" was a medium-range interdictor and tactical strike aircraft that also filled the roles of strategic bomber, reconnaissance, and electronic warfare in its various versions. Developed in the 1960s by General Dynamics, it first entered service in 1967 with the...

 fighter-bombers stationed in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 used aerial refueling to enable them to operate non-stop against targets in Libya
Libya
Libya is an African country in the Maghreb region of North Africa bordered by the Mediterranean Sea to the north, Egypt to the east, Sudan to the southeast, Chad and Niger to the south, and Algeria and Tunisia to the west....

. Since the aircraft were allowed to cross neither French nor Spanish airspace, they had to make a detour around the Iberian Peninsula
Iberian Peninsula
The Iberian Peninsula , sometimes called Iberia, is located in the extreme southwest of Europe and includes the modern-day sovereign states of Spain, Portugal and Andorra, as well as the British Overseas Territory of Gibraltar...

 and stay above International waters during all transit.

Persian Gulf War

During the time of Operation Desert Shield, the military build up 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 England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

, Diego Garcia
Diego Garcia
Diego Garcia is a tropical, footprint-shaped coral atoll located south of the equator in the central Indian Ocean at 7 degrees, 26 minutes south latitude. It is part of the British Indian Ocean Territory [BIOT] and is positioned at 72°23' east longitude....

, and Saudi Arabia
Saudi Arabia
The Kingdom of Saudi Arabia , commonly known in British English as Saudi Arabia and in Arabic as as-Sa‘ūdiyyah , is the largest state in Western Asia by land area, constituting the bulk of the Arabian Peninsula, and the second-largest in the Arab World...

. Aircraft stationed in Saudi Arabia normally maintained an orbit in the Saudi–Iraqi neutral zone, informally known as "Frisbee", and refueled Coalition Aircraft whenever necessary. Two side by side tracks over central Saudi Arabia called "Prune" and "Raisin" featured 2–4 basket equipped KC-135 tankers each and were used by Navy aircraft from the Red Sea Battle Force. Large Navy strike groups from the Red Sea would send A-6 tankers to the Prune and Raisin tracks ahead of the strike aircraft arriving to top off and take up station to the right of the Air Force tankers thereby providing an additional tanking point. RAF Handley Page Victor and Vickers VC10
Vickers VC10
The Vickers VC10 is a long-range British airliner designed and built by Vickers-Armstrongs Ltd, and first flown in 1962. The airliner was designed to operate on long-distance routes with a high subsonic speed and also be capable of hot and high operations from African airports...

 tankers were also used to refuel British and coalition aircraft and were popular with the US Navy for their docile basket behavior and having three point refueling stations. An additional track was maintained close to the northwest border for the E-3 AWACS aircraft and any Navy aircraft needing emergency fuel. These 24-hour air-refueling zones helped make the intense air campaign during Operation Desert Storm possible. An additional 24/7 tanker presence was maintained over the Red Sea itself to refuel Navy F-14 Tomcats maintaining Combat Air Patrol
Combat air patrol
Combat air patrol is a type of flying mission for fighter aircraft.A combat air patrol is an aircraft patrol provided over an objective area, over the force protected, over the critical area of a combat zone, or over an air defense area, for the purpose of intercepting and destroying hostile...

 tracks. During the last week of the conflict, KC-10 tankers moved inside Iraq to support barrier CAP missions set up to block Iraqi fighters from escaping to Iran.

On January 16–17, 1991, the first combat sortie of 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 Persian Gulf region, and back, to launch Boeing Air Launched Cruise Missiles (ALCMs) with the surprise use of conventional warheads. All of this was made possible by in-flight refueling, and by the secret switch away from nuclear warheads on the ALCMs.

An extremely useful aerial tanker in Desert Storm was the USAF KC-10A Extender. Besides being larger than the other tankers, the KC-10A is equipped with the USAF "boom" refueling and also the "hose-and-drogue" system. This makes it possible for the KC-10A to refuel 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.

The KC-10A was originally designed for the support of NATO in Europe by the USAF. In the case of armed conflict, with a full jet fuel load, the KC-10A is capable of flying from a base on the east coast of the US or Canada, flying nonstop to Europe, transferring a considerable amount of fuel in air-to-air refueling, and then returning to its home base, all without landing anywhere. This could have been very useful in the case when numerous European bases become disabled by Warsaw Pact strikes in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, and Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

.

Kosovo War

The USAF provided nearly 90 percent of the NATO tanker force, 112 active and 63 Reserve-component KC-135 and KC-10 tankers. Tankers were also provided from Britain’s RAF (TriStars
Lockheed TriStar (RAF)
|-See also:-References:* Prothero, R.M. "Tristar:The answer to an operational requirement". Air International, March 1991, Vol 40 No. 3. pp. 128–134....

 and VC10s
Vickers VC10
The Vickers VC10 is a long-range British airliner designed and built by Vickers-Armstrongs Ltd, and first flown in 1962. The airliner was designed to operate on long-distance routes with a high subsonic speed and also be capable of hot and high operations from African airports...

), French Air Force
French Air Force
The French Air Force , literally Army of the Air) is the air force of the French Armed Forces. It was formed in 1909 as the Service Aéronautique, a service arm of the French Army, then was made an independent military arm in 1933...

 and Turkish Air Force
Turkish Air Force
The Turkish Air Force is the aerial warfare service branch of the Turkish Armed Forces. It ranks 3rd in NATO in terms of fleet size behind the USAF and Royal Air Force with a current inventory of 798 aircraft .-Initial stages:...

 KC-135s, Italian Air Force
Aeronautica Militare
The Italian Air Force is the air force of the Italian Republic. It has held a prominent role in modern Italian military history...

 B.707 T/T
Boeing 707
The Boeing 707 is a four-engine narrow-body commercial passenger jet airliner developed by Boeing in the early 1950s. Its name is most commonly pronounced as "Seven Oh Seven". The first airline to operate the 707 was Pan American World Airways, inaugurating the type's first commercial flight on...

, Spanish Air Force
Spanish Air Force
-The early stages:Hot air balloons had been used with military purposes in Spain as far back as 1896. In 1905, with the help of Alfredo Kindelán, Leonardo Torres y Quevedo directed the construction of the first Spanish dirigible in the Army Military Aerostatics Service, created in 1896 and located...

 KC-130 Hercules and Royal Netherlands Air Force
Royal Netherlands Air Force
The Royal Netherlands Air Force , Dutch Koninklijke Luchtmacht , is the military aviation branch of the Netherlands Armed Forces. Its ancestor, the Luchtvaartafdeling of the Dutch Army was founded on 1 July 1913, with four pilots...

 KDC-10s
KC-10 Extender
The McDonnell Douglas KC-10 Extender is the military adaptation of the three-engined DC-10 airliner for the United States Air Force . The KC-10 incorporates military-specific equipment for its primary roles of transport and aerial refueling. It was developed to supplement the KC-135 Stratotanker...

. Although some European nations provided air-refueling aircraft, the conflict highlighted the problem Europe has with a lack of such aircraft and dependence on the United States for tanker support during a major operation. Some European nations sought to address this lack of capability, such as the Italian Air Force
Aeronautica Militare
The Italian Air Force is the air force of the Italian Republic. It has held a prominent role in modern Italian military history...

 purchase of the Boeing KC-767
Boeing KC-767
The Boeing KC-767 is a military aerial refueling and strategic transport aircraft developed from the Boeing 767-200ER. The tanker received the designation KC-767A in 2002, after being selected by the US Air Force initially to replace older KC-135Es...

, but there is still a huge difference in air-refueling capability between the US and Europe.

Aerial rearming

In 2003 the U.S. Air Force and Far Technologies applied secretly for patents on mid-air rearming of aircraft. The technique proposed is similar in many respects to airborne refueling, with a number of notable modifications. The airborne rearming system comprises a rearming plane with an internal bomb storage area and loading device consisting of a large aft door and a modified remote-driven robotic arm (boom) equipped with a day-night camera as well as sensors. A special pylon to receive the arms from the boom is fitted onto the attack aircraft. At present financial and technological problems stand in the way of aerial rearming, mainly the need for an automatic system to perform the rearm currently under development for aerial refueling.

Helicopters

Helicopter In-Flight Refueling (HIFR) is a variation of aerial refueling when a naval helicopter
Helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...

 approaches a warship (not necessarily suited for landing operations) and receives fuel through the cabin while hovering.

Alternatively, some helicopters 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.

Developments

  • Commercial tankers are increasingly being used by military forces. The Omega Company is contracted by the US Navy.
  • Autonomous (hands off) refueling using probe/drogue systems is being investigated by NASA
    NASA
    The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

    , potentially for use by Unmanned aerial vehicle
    Unmanned aerial vehicle
    An unmanned aerial vehicle , also known as a unmanned aircraft system , remotely piloted aircraft or unmanned aircraft, is a machine which functions either by the remote control of a navigator or pilot or autonomously, that is, as a self-directing entity...

    s.

Popular culture

  • The film Dr. Strangelove from 1964 has genuine footage of a "boom and receptacle" operation between USAF KC-135 Stratotanker and B-52 Stratofortress in turbulent air.
  • The film The Perfect Storm
    The Perfect Storm (film)
    The Perfect Storm is a 2000 dramatic disaster film directed by Wolfgang Petersen. It is an adaptation of the 1997 non-fiction book of the same title by Sebastian Junger about the crew of the Andrea Gail that got caught in the Perfect Storm of 1991. The film stars George Clooney, Mark Wahlberg,...

    contains a scene where an HH-60 helicopter attempts to refuel during adverse weather, but is unable to succeed. This was based on true events that occurred during the 1991 Perfect Storm.
  • The film The Final Countdown from 1980 has genuine footage of a "probe-and-drogue" operation between US Navy KA-6 Intruder and F-14 Tomcats from .
  • The film The Sum of All Fears
    The Sum of All Fears (film)
    The Sum of All Fears is a 2002 American action film/political thriller directed by Phil Alden Robinson and based on the novel The Sum of All Fears by Tom Clancy...

    features a mid-air refueling sequence with the E-4B NEACP. In the commentary, author Tom Clancy
    Tom Clancy
    Thomas Leo "Tom" Clancy, Jr. is an American author, best known for his technically detailed espionage, military science, and techno thriller storylines set during and in the aftermath of the Cold War, along with video games on which he did not work, but which bear his name for licensing and...

     mocks mid-air refueling as "sex between two planes at 35,000 feet".
  • The film Air Force One
    Air Force One (film)
    Air Force One is a 1997 American action-thriller film written by Andrew W. Marlowe and directed by Wolfgang Petersen. It stars Harrison Ford, Gary Oldman, and Glenn Close, and also features Xander Berkeley, William H. Macy, Dean Stockwell and Paul Guilfoyle...

    contains a sequence where a KC-10 tanker
    KC-10 Extender
    The McDonnell Douglas KC-10 Extender is the military adaptation of the three-engined DC-10 airliner for the United States Air Force . The KC-10 incorporates military-specific equipment for its primary roles of transport and aerial refueling. It was developed to supplement the KC-135 Stratotanker...

     is ordered to carry out the mid-air refueling of Air Force One
    Air Force One
    Air Force One is the official air traffic control call sign of any United States Air Force aircraft carrying the President of the United States. In common parlance the term refers to those Air Force aircraft whose primary mission is to transport the president; however, any U.S. Air Force aircraft...

    , but the hijacked plane becomes unstable. The hijacker runs Air Force One
    Air Force One
    Air Force One is the official air traffic control call sign of any United States Air Force aircraft carrying the President of the United States. In common parlance the term refers to those Air Force aircraft whose primary mission is to transport the president; however, any U.S. Air Force aircraft...

     into the refueling boom causing a fire which then causes the KC-10 tanker to explode.
  • In 2011 BMW launched a commercial featuring the 2011 BMW 5-Series named "refuel." In the advert the driver has his coffee cup refilled by an aerial refueling aircraft, similar to that of a KC-135 Stratotanker boom but a KC-10 nozzle.

Media

See also

  • Docking maneuver for spacecraft
    Spacecraft
    A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....

  • In-space refueling
  • Underway replenishment
    Underway replenishment
    Underway replenishment or replenishment at sea is a method of transferring fuel, munitions, and stores from one ship to another while under way.-History:...

     – the transfer of refuel and stores at sea
  • List of firsts in aviation
  • Military logistics
    Military logistics
    Military logistics is the discipline of planning and carrying out the movement and maintenance of military forces. In its most comprehensive sense, it is those aspects or military operations that deal with:...


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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