The KC-135 has been in service with the USAF for more than 60 years. While larger aircraft such as the KC-10 Extender can carry a larger quantity of fuel and carog is is The KC-135 that form the backbone of the USAF tanker fleet.
Four turbofans, mounted under 35-degree swept wings, power the KC-135 to takeoffs at gross weights of up to more than 320,000 lbs pounds. A deck above the refueling system can hold passengers and or/cargo. Depending on the fuel load the KC-135 can carry more than 80,000 pounds of cargo. Nearly all internal fuel can be pumped through the flying boom, the KC-135's primary fuel transfer method. One crewmember, known as the boom operator, is stationed in the rear of the plane and controls the boom during in-flight air refueling.