When the Boeing KC-135 Stratotanker first deployed in August of 1956 as a flying gas station for refueling military aircraft, few imagined it would still be flying its original mission more than six decades later. But with tender-loving Air Force maintenance and several upgrades, there are still 396 of them flying refueling missions. The modifications include new engines, which let them deliver 50% more fuel, use 25% less fuel themselves, cost 25 less to operate, and are 86% quieter than the original engines. The electronics and cockpit have also been dramatically modified with data links, radars, and display screens. And the wings have been reskinned with an improved aluminum alloy.
There were 820 of the four-engine planes built; 732 serve(d) as tankers, and 88 were modified to be cargo carriers, reconnaissance platforms, SAC airborne command centers, transports for high-ranking officials, and for testing and test observations. Almost 400 still serve as tankers operating from 33 bases around the world and are available 24/7. The plane was an offshoot fop the Dash 80, Boeing’s prototype that also served as the basis for the 707 airliners.
The tankers are vital to many Defense Dept. missions, giving U.S. military planes the ability to reach any part of the globe and return. Last year, the KC-135 fleet flew 35,879 sorties or missions, refueled 88,180 aircraft, delivered 128 million gallons of jet fuel, and hauled 385 tons of cargo.
The KC-135 fleet was going to be replaced by the KC-46 Pegasus, also from Boeing. Cost overruns and delays, however, led to the Air Force slashing the number of planes it was going to buy to just 179. So, after some discussion, the Defense Dept. has decided to continue upgrading the tankers with a $910 million extension program that includes better navigation and autopilot subsystems, a glass cockpit (no more analog gauges), and other enhancements.
The Air Force estimates that the currently active KC-135s have only used up 35% of their lifetime flying hours, which seems hard to believe. But this means the airframes can remain operational through 2040 with regular maintenance and scheduled overhauls. In fact, the aircraft could remain operational for 100 years. Hard to believe in these days of disposable technology.