The KC-135 Stratotanker's principal mission is air refueling. This asset greatly enhances the U. S. Air Force's capability to accomplish its mission of Global Engagement. It also provides aerial refueling support to U.S. Navy, U.S. Marine Corps and allied aircraft.
Four turbofans, mounted under 35-degree swept wings, power the KC-135 to takeoffs at gross weights up to 322,500 pounds (146,285 kilograms). Nearly all internal fuel can be pumped through the tanker's flying boom, the KC-135's primary fuel transfer method.