GRISSSOM AIR RESERVE BASE, Ind. -- A KC-135R Stratotanker assigned to the 434th Air Refueling Wing at Grissom is engulfed by a heavy fog that covered the airfield Sunday of the August unit training assembly. KC-135s provides the core aerial refueling capability for the U.S. Air Force and have excelled in this role for more than 50 years. There are 16 of the aircraft assigned to the 434th ARW, making it the largest KC-135 unit in the Air Force Reserve Command. (U.S. Air Force photo/Tech. Sgt. Mark R. W. Orders-Woempner) GRISSSOM AIR RESERVE BASE, Ind. -- The tail section and boom of a 434th Air Refueling Wing KC-135R Stratotanker can be seen here in the early morning of the August unit training assembly. During flight the boom lowers and extends to connect with other aircraft and can refuel them at a rate of approximately 1,000 gallons per minute. This KC-135, tail number 63-7996, was originally built in 1963 and has been serving in the Air Force fleet since that time. There were 732 KC-135s built for the U.S. Air Force between 1957 and 1965. (U.S. Air Force photo/Tech. Sgt. Mark R. W. Orders-Woempner) GRISSSOM AIR RESERVE BASE, Ind. -- Surrounded by a dense fog, a KC-135R Stratotanker at Grissom sits on the flight line Aug. 7. Sixteen KC-135s are assigned to the 434th Air Refueling Wing at Grissom, making it the largest Stratotanker unit in the Air Force Reserve. Four turbofans, mounted under 35-degree swept wings, power the KC-135 to takeoffs at gross weights up to 322,500 pounds. Nearly all internal fuel can be pumped through the flying boom, the KC-135's primary fuel transfer method. (U.S. Air Force photo/Tech. Sgt. Mark R. W. Orders-Woempner) Not exactly fog of war 434th ARW Public Affairs 8/22/2011 - GRISSOM AIR RESERVE BASE, Ind.  -- While not quite the fog of war, a fog did envelop Grissom's war machines  in the early morning hours of the August unit training assembly and covered the area for several hours, impacting several planned squadron photos. This specific KC-135 was originally built in 1963 and has been serving in the Air Force fleet since that time. There were 732 KC-135s built for the U.S. Air Force between 1957 and 1965. The aircraft provide the core aerial refueling capability for the U.S. Air Force, refueling U.S., NATO and allied aircraft throughout the world. There are 16 of the aircraft assigned to the 434th ARW, making it the largest KC-135 unit in the Air Force Reserve Command. Four turbofans, mounted under 35-degree swept wings, power the KC-135 to takeoffs at gross weights up to 322,500 pounds and can propel the jet up to 600 mph with a range of 1,500 miles with 150,000 pounds of transfer fuel or over 11,000 miles on a ferry mission. Nearly all internal fuel can be pumped through the flying boom, the KC-135's primary fuel transfer method. During flight, the boom lowers and extends to connect with other aircraft and can refuel them at a rate of approximately 1,000 gallons per minute. For more information on the KC-135 click here. Stay connected with the 434th ARW on Twitter and Facebook.