A T-33 pilot takes on fuel from a tanker over South Korea in 1967. Photo: Ray Lee
The first aerial refueling flight in US military history was completed in June 1923, when a DH-4 biplane deployed a device invented by Russian émigré Alexander P. de Seversky to refuel another DH-4 inflight. Four months later, the same airplane used four inflight refuelings to fly from Sumas, Wash., to San Diego, effectively quadrupling the range of the aircraft.
In January 1929, two Douglas C-1 transports, equipped with fuel hoses, allowed an Air Corps C-2A to fly for six days. The flight of Question Mark required 43 contacts with the tankers, demonstrating aerial refueling’s potential.
But the tanker revolution had not yet arrived because the need was less than clear.
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During World War II, B-17 and B-24 bombers were able to reach Berlin from forward bases in England and Italy, but only the B-29 could cover the longer distances involved in the Pacific Theater. In addition to this limitation, refueler-enabled fighters could have taken some of the heat off US bombers that took heavy fire from German air defenses. But US factories were working full tilt to produce strike aircraft and could not redirect resources toward what was considered a secondary need.
During the Cold War, however, a tanker requirement moved to the forefront. Because Warsaw Pact ground forces outnumbered those of the US and NATO, strategy relied heavily on the US long-range nuclear bomber deterrent. The effectiveness of that deterrent, in turn, relied on efficient air refueling.
In February 1949, Air Force KB-29 tankers supported a B-50 bomber on the first nonstop flight around the world. KB-29s made use of a looped hose to deliver fuel to the receiving aircraft, but that system was grossly inefficient and required extra crew to grab and connect the hose. It could not be used to refuel single-seat fighters.
The probe and drogue system was more efficient and eliminated the need for additional crew members. It allowed the receiving pilot alone to position a probe into the basket-shaped drogue from the tanker, and it could transfer 250 gallons per minute.
That was still pretty slow. By 1950, the flying boom system had been perfected. It allowed an operator on the tanker to “fly” (direct) the boom into position to connect with the receiving aircraft. It could pump fuel at 700 gallons per minute. Booms were added to some KB-29s and to KB-50s and KC-97s.
In 1956, the KC-135 debuted as the first jet-powered tanker. It was designed to carry passengers and cargo and could transfer six times more fuel than the KB-50. Strategic Air Command bought 732 KC-135s for its fleet of 744 B-52s. The tankers and bombers were stationed together, took off together, flew together, then the tankers would peel off and return home as the bombers neared enemy airspace.
During the Vietnam War’s Rolling Thunder campaign (1965-68), almost every strike sortie flown into the North required refueling. Over nine years of war, KC-135s flew nearly 200,000 sorties and performed 800,000 air refuelings.
Refueling in the air was quickly emerging as an essential capability, and the transformation of the force was dramatic. In 1960, USAF had 2,000 refuelable aircraft. By 1980, it had 4,500.
In 1981, the first KC-10s were delivered. This was a larger tanker that could double as an airlifter. It even had its own refueling receptacle, allowing KC-10s to be topped-off by KC-135s or KC-10s in flight.
This capability was demonstrated in the 1986 Operation El Dorado Canyon bombing of Libya in retaliation for terrorist attacks. When France and Spain refused to let US strike aircraft overfly their nations, USAF was forced to fly around the Iberian Peninsula, and used 29 air refuelers to provide an air bridge for the attacking F-111s.
At the beginning of Operation Desert Storm, 100 USAF tankers operating from nine countries supported US airlifters carrying 500,000 personnel and 540,000 tons of cargo into the theater. Over the course of the conflict, the service flew 16,865 refueling sorties.
Today, the global reach of USAF refuelers is impressive. In January 2017, two B-2 bombers flew a 34-hour round-trip mission from Whiteman AFB, Mo., to drop munitions on ISIS training camps near Sirte, Libya, and then return home. The bombers were supported by five aerial refuelings, and their strikes killed more than 80 ISIS fighters.
Tankers’ rate of use has not slowed, either. In Operation Inherent Resolve, USAF tankers flew 14,000 sorties and completed 90,000 refuelings in the first year alone.
Now, the service looks to the arrival of its modern tanker, the KC-46. First delivery is expected in early 2018, and USAF should have 179 KC-46s by 2027. The KC-46 is 20 percent larger than the KC-135 and can deliver three times as much fuel. It brings significant advances in survivability, allowing tankers to refuel aircraft much closer to combat zones.
Given how heavily the US military has come to rely on aerial refueling in its global campaigns today, those KC-46s cannot come online fast enough.
Warren Thompson is an author and aviation specialist. He provided these photos, and their captions, from his collection.