History of US Air Force Tankers: While advanced fighter jets like the F-22 Raptor, F-35 Lightning II, and F-15 Strike Eagle often grab the spotlight, they wouldn’t be very effective without fuel. A key part of the US Air Force’s global power is its vast fleet of aerial tankers, which are the most widely used refueling aircraft in the world. These tankers dramatically increase the range of fighter jets and the amount of time they can stay over critical areas.
The US Air Force has relied on refueling aircraft since the 1950s. Aircraft like the Boeing B-52 have been refueled by multiple tanker types, including the KC-97 Stratofreighter, KC-135 Stratotanker, KC-10 Extender, and the KC-46 Pegasus.
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US Aerial Refueling History
Aerial refueling in the US dates back nearly 100 years, with the first tests conducted in 1929 by the US Army Air Corps using a C-2A biplane named Question Mark. While the concept was introduced, it didn’t gain traction until the jet age.
With the rise of jet-powered fighters, bombers, and other aircraft, there was a growing need for long-range capabilities. While jet engines were a major advancement over the older piston engines, they also consumed much more fuel. To address this, the US modified old B-29 and B-50 bombers into tankers.
| Boeing KC-97 Stratofreighter | |
|---|---|
| Number built: | 811 |
| Propulsion: | 4x Pratt & Whitney R-4360-59 Wasp Major piston engines |
| Date serviced: | 1958-1971 |
| Developed from: | Boeing C-97 Stratofreighter |
| Status: | Retired |
The Boeing C-97 Stratofreighter, a long-range military cargo aircraft derived from the B-29 and B-50, was developed starting in 1942. The first flight of the YC-97 was in late World War II, and it entered service in 1947. According to Simpleflying, A tanker version, the KC-97 Stratofreighter, was introduced in 1951. However, since the KC-97 was propeller-driven, it struggled to keep pace with the Air Force’s newer, faster jets. The KC-97 continued in front-line service until 1973, though it remained in reserve until the end of the decade.
Interestingly, modern turboprop aircraft like the Airbus A400M Atlas and KC-130J Super Hercules are still capable of refueling jet aircraft today.
The Air Force’s Jet-Powered Tankers
KC-135 Stratotankers
The first jet-powered tanker for the Air Force was the KC-135 Stratotanker, which was based on the Boeing 707 airliner. As the Air Mobility Command notes, after seeing Boeing’s new 367-80 design in 1954, which later became the successful Boeing 707, the US saw the potential for a jet-powered tanker.
The KC-135 made its first flight on August 31, 1956, and continues to serve in the front lines today. There are around 377 KC-135 Stratotankers still in operation, making them the primary tankers in US service. They’ve also been supplied to various US allies and partners around the world, though many are being replaced by the Airbus A330 MRTT or Boeing KC-46A Pegasus.
| KC-135 Stratotanker: | KC-10 Extender: | KC-46A Pegasus: | |
|---|---|---|---|
| Number built: | 803 (total, including export) | 60 | 93+ (179 planned) |
| Propulsion: | 4x CFM International F108-CF-100 turbofan engines | 3x General Electric F103 turbofan engines | 2x Pratt & Whitney PW4062 turbofan |
| Date served: | 1957-present | 1981-2024 | 2019-present |
| Developed from: | Boeing 707 airliner | McDonnell Douglas DC-10 airliner | Boeing 767 airliner |
| Status: | In service | Retired | In |
KC-10 Extenders
The KC-10 Extender was based on the McDonnell Douglas DC-10 widebody jetliner, which entered service in 1971. The DC-10 was chosen over competitors like the Lockheed C-5, L-1011, and Boeing 747 in 1977. The first KC-10 flew in 1980, becoming a key part of the Air Force’s tanker fleet. However, the modifications reduced the airframe’s lifespan, leading to the retirement of the last KC-10 in 2024.
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The KC-10 was developed to offer greater range and fuel capacity than the KC-135, with a range of 3,800 nautical miles at maximum capacity. It was equipped with additional refueling pods on the wings, each containing a fueling hose system. Initially, the Air Force planned to keep the KC-10s in service until 2043, but they were retired about two decades earlier than expected. A total of 60 KC-10s were built, along with a few KDC-10s for the Royal Netherlands Air Force.
KC-46A Pegasus
The latest tanker in the Air Force’s fleet is the Boeing KC-46 Pegasus, built on the Boeing 767 airliner platform, which was selected in 2011 after a selection process that initially considered the Airbus A330. According to Airplanesonline, The KC-46A first flew in 2015 and was delivered to the Air Force in 2019.
It is a key part of the Air Force’s effort to modernize its tanker fleet. The KC-46 can carry over 210,000 lbs of fuel, 65,000 lbs of cargo, 58 patients, or 114 passengers. It is also equipped with data links and integrates with the Advanced Battle Management System (ABMS) to enhance situational awareness and real-time information sharing.
Internationally, Japan and Israel have also ordered KC-46 tankers to replace their aging fleets. However, the KC-46 hasn’t seen the same level of export success as the A330 MRTT, which has become the most common non-US tanker globally. To date, 93 KC-46s have been delivered, and the Air Force plans to acquire around 179 of them to partially replace the aging fleet of KC-135 Stratotankers.
Air Force’s Future Tanker Projects
While the KC-46 Pegasus will play a significant role, it may be the last conventional, tube-based tanker built from a passenger airliner. The Air Force is exploring new concepts for future tankers. Two such projects include the blended-wing body JetZero aircraft, which is designed for greater fuel efficiency and could become a commercial airliner, and Lockheed Martin’s Next-Generation Aerial Refueling System (NGAS), a stealthy tanker that could operate in contested airspace.
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The JetZero aircraft, being developed in partnership with Northrop Grumman, aims to become operational by 2030, while the NGAS, possibly an unmanned platform, is expected to enter service by 2035. However, there are concerns about the affordability of these new systems. In the meantime, the Air Force will continue to operate a large number of KC-135s until these new tankers are available in sufficient numbers. Currently, the Air Force has around 600 tankers, which make up approximately 75% of the world’s military tanker fleet.
