Aerial refueling tankers are the quiet enablers of joint air power. By allowing fighters, bombers, cargo planes and other aircraft to refuel without landing, they greatly extend the operational range of U.S. forces. The current tanker fleet consists of 520 Eisenhower-era KC-135 jets and 59 Reagan-era KC-10 jets. The KC-135s are based on the venerable Boeing 707 commercial airframe, while the KC-10s are based on the more modern McDonnell Douglas DC-10 widebody. The Air Force needs to begin replacing its KC-135s, all of which have been operating for over 40 years — making them the oldest component of the military air fleet.
The U.S. Air Force began developing aerial refueling tankers in the 1940s to support heavy bombers on nuclear-deterrence missions. Beginning with the Vietnam War, though, tankers became an integral part of conventional air campaigns. During recent air campaigns in the Balkans, Afghanistan and Iraq, Air Force tankers heavily supported coalition aircraft, enabling relatively short-range planes such as the Navy’s carrier-based strike fighters to operate deep inside enemy territory. In the early months of Operation Iraqi Freedom, 149 KC-135s and 33 KC- 10s conducted over 6,000 sorties in support of the joint force, delivering 376,391,000 lbs. of fuel to U.S. and allied planes.
The advanced age of KC-135s has begun to undermine their readiness and safety. The Air Force plans to competitively procure a modified commercial transport to serve as the next-generation tanker. However, selecting the best plane involves complex tradeoffs. In the air, the range and fuel-carrying capacity of planes must be balanced with the need to have enough aircraft to cover all contingencies. The biggest planes can fly further and deliver more fuel, but they also cost more to build and operate so fewer planes can be bought. Current tankers seldom offload all their fuel during air operations, but having hundreds of planes in the refueling fleet is crucial to meeting the needs of a joint force scattered across the globe.
On the ground, the amount of space a tanker takes up and the speed at which it can be filled with its fuel load are important logistical considerations. Some overseas bases lack extensive space for parking planes, or have only limited capacity to store and transfer fuel. Figuring out which aircraft are best suited to meeting future refueling needs is further complicated by the fact that long-range missions employing big aircraft generate very different refueling needs than short-range missions employing smaller, more numerous planes. These different needs have important implications for tanker performance requirements both in the air and on the ground. Whatever future missions are most pressing, though, experts generally agree that it would be useful to employ empty space on future tankers for carrying cargo so that the air fleet is as flexible and versatile as possible.
This report was designed to identify and concisely address the most important questions bearing upon selection of a next-generation aerial refueling tanker. It was written by Dr. Rebecca Grant, president of IRIS Independent Research and a research fellow at the Lexington Institute, and Dr. Loren Thompson, chief operating officer of the Lexington Institute.
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