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Boeing KC-135 Stratotanker

History of the Boeing KC-135 Stratotanker

The KC-135 "Stratotanker" became an important aircraft product for Boeing, primarily because it provided the United States Air Force (USAF) with unparalleled war planning capabilities and logistical support through aerial refueling and transport. In addition, the KC-135 tanker airframe became the basis for the C-135 "Stratolifter" strategic transport aircraft and the 707 civilian airliner. From 1955 to 1965, the total production of Stratotankers reached 803.

The production aircraft continues to serve countries with critical support skills for the U.S. Air Force and other allies.

The KC-135 series succeeded the KC-97 Stratofreighter in aerial refueling.

Air refueling was introduced during the Cold War (1947-1991) and was rationalized with the arrival of jumbo jets. The result gives military war planners unprecedented global influence in directing the actions of their armed forces. To this day, aerial refueling remains an essential part of any Air Force success, especially at long-range activities, and is critical to the scale of USAF operations around the world.

Remember, both pilots and tanker crews need steady hands and eyes to complete the precise process required to refuel fighter jets in the air.

Design work began in the early 1950s to meet the US Air Force's continuing need for a new dedicated carrier tanker with jet-powered capabilities. The result became the Boeing 367-80 demonstrator, which in turn became the KC-135. The KC-135 is equipped with tank equipment and a powered arm entirely designed by Boeing. Fuel is carried on the belly and wing sections, and propulsion comes from 4 x CFM International CFM56 turbofan engines.

The plane typically has a crew of only four two pilots, a navigator and a boom operator although this can be increased if necessary (for example, the medical evacuation version includes five crew members).

The KC-135 (KC-135R) has a barrel length of 127.9 feet, a wingspan of 129.7 feet, and a height of 38 feet. It has a kerb weight of 98,465 pounds and an MTOW of 322,500 pounds. Top speed is 580 mph and cruising is near 530 mph. Range is 1,500 miles and service is capped at 50,000 feet.

The climb rate is 4,900 feet per minute.

Modernization programs (including "redesigns" and software upgrades) have brought the KC-135 series into the new millennium. The platform remains an important factor in global operations involving the U.S. Air Force, increasing the range of all aircraft in the field.

Other countries have also relied on the KC-135 family, although it has not had as much impact anywhere else as the U.S. military has traveled around the world.

Operators of the KC-135 series include Chile, France, Singapore and Turkey. Variants include the original KC-135A, KC-135B Airborne Command Post, and KC-135D. The KC-135E served in the Air National Guard, and the NKC-135E is a KC-135E modified for testing.

The NKC-135N served the US space program, and the E-135N was equipped to support the Apollo missile program. The KC-135Q carried JP-7 fuel for the Lockheed SR-71 Blackbird spy plane, about 56 of which were converted to standard.

The KC-135R are four KC-135A aircraft converted for nuclear reconnaissance, powered by four Pratt & Whitney J57 engines. Later versions of the KC-135R were approximately 361 production models KC-135A and KC-135E, equipped with CFM-56 series engines.

KC-135R(RT) were used for secure SATCOM radio transmission, three of which were converted from RC-135D production models.

The KC-135T is the KC-135Q with the CFM-56 engine, with 54 aircraft converted to standard. The EC0135Y is another airborne command post developed in 1984 to support U.S. Central Command operations. This example is powered by 4 Pratt & Whitney TF-33-PW-102 series engines.

Since entering service in 1957, the KC-135 family of special mission aircraft has served as part of the Strategic Air Command (SAC) from the Vietnam War (1955-1975) to the end of the Cold War (1991) (1947-1992) and Operation Joint Force (1999).

The KC-135 series will be replaced by the Boeing KC-46 "Pegasus" series under development, described elsewhere on this website.

Special thanks to Anthony S. of Boeing for his contribution.