page_title: Aerial refueling
section_title: Strategic
hierarchical_section_title: Aerial refueling / Compatibility issues / Strategic
caption_attribution_description: English: Refuelling a Sukhoi Su-34
context_page_description: Aerial refueling, also referred to as air refueling, in-flight refueling, air-to-air refueling, and tanking, is the process of transferring aviation fuel from one military aircraft to another during flight. The two main refueling systems are probe-and-drogue, which is simpler to adapt to existing aircraft, and the flying boom, which offers faster fuel transfer, but requires a dedicated boom operator station.
  The procedure allows the receiving aircraft to remain airborne longer, extending its range or 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 takeoff with a greater payload which could be weapons, cargo, or personnel: the maximum takeoff weight is maintained by carrying less fuel and topping up once airborne. 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 3,000 nautical miles.
context_section_description: The development of the KC-97 and Boeing KC-135 Stratotankers was pushed by the Cold War requirement of the United States to be able to keep fleets of nuclear-armed B-47 Stratojet and B-52 Stratofortress strategic bombers airborne around-the-clock either to threaten retaliation against a Soviet strike for mutual assured destruction, or to bomb the U.S.S.R. first had it been ordered to do so by the President of the United States. The bombers would fly orbits around their assigned positions from which they were to enter Soviet airspace if they received the order, and the tankers would refill the bombers' fuel tanks so that they could keep a force in the air 24 hours a day, and still have enough fuel to reach their targets in the Soviet Union. This also ensured that a first strike against the bombers' airfields could not obliterate the U.S.'s ability to retaliate by bomber.
  In 1958, Valiant tankers in the UK were developed with one HDU mounted in the bomb-bay. Valiant tankers of 214 Squadron were used to demonstrate radius of action by refueling a Valiant bomber non-stop from UK to Singapore in 1960 and a Vulcan bomber to Australia in 1961. Other UK exercises involving refueling aircraft from Valiant tankers included Javelin and Lightning fighters, also Vulcan and Victor bombers. For instance, in 1962 a squadron of Javelin air defense aircraft was refueled in stages from the UK to India and back (exercise "Shiksha"). After the retirement of the Valiant in 1965, the Handley Page Victor took over the UK refueling role and had three hoses (HDUs).  These were a fuselage-mounted HDU and a refueling pod on each wing. The center hose could refuel any probe-equipped aircraft, the wing pods could refuel the more maneuverable fighter/ground attack types.
  A byproduct of this development effort and the building of large numbers of tankers was that these tankers were also available to refuel cargo aircraft, fighter aircraft, and ground attack aircraft, in addition to bombers, for ferrying to distant theaters of operations. This was much used during the Vietnam War, when many aircraft could not have covered the transoceanic distances without aerial refueling, even with intermediate bases in Hawaii and Okinawa. In addition to allowing the transport of the aircraft themselves, the cargo aircraft could also carry matériel, supplies, and personnel to Vietnam without landing to refuel. KC-135s were also frequently used for refueling of air combat missions from air bases in Thailand.
  The USAF SR-71 Blackbird strategic reconnaissance aircraft made frequent use of air-to-air refueling. Indeed, design considerations of the aircraft made its mission impossible without aerial refueling. Based at Beale AFB in central California, SR-71s had to be forward deployed to Europe and Japan prior to flying actual reconnaissance missions. These trans-Pacific and trans-Atlantic flights during deployment were impossible without aerial refueling. The SR-71's designers traded takeoff performance for better high-speed, high-altitude performance, necessitating takeoff with less-than-full fuel tanks from even 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. This was referred to as the LTTR (for "Launch To Tanker Rendezvous") profile. LTTR had the added advantage of providing an operational test of the Blackbird's refueling capability within minutes after takeoff, enabling a Return-To-Launch-Site abort capability if n
caption: A Russian Air Force Sukhoi Su-34 takes on fuel through a Probe-and-drogue system
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