Boeing KC-135 Stratotanker

Boeing KC-135 Stratotanker
Name	KC-135 Stratotanker
Caption	A United States Air Force KC-135R refuels an F-22 Raptor.
Type	Aerial refueling and strategic transport aircraft
National origin	United States
Manufacturer	Boeing
First flight	31 August 1956
Introduction	June 1957
Status	In service
Primary user	United States Air Force
Number built	803
Developed from	Boeing 367-80
Variants with their own articles	Boeing C-135 Stratolifter

Boeing KC-135 Stratotanker is a military aerial refueling aircraft developed by Boeing for the United States Air Force. It entered service in 1957, derived from the Boeing 367-80 prototype, and has been a cornerstone of United States and NATO power projection for over six decades. The aircraft is primarily used to refuel other USAF aircraft, extending their range, endurance, and payload, but also performs strategic transport and aeromedical evacuation missions. Its longevity is ensured through extensive modernization programs, most notably the re-engining effort that created the prevalent CFM56-powered KC-135R variant.

Development and design

The KC-135's development was directly driven by the Cold War need for a jet-powered tanker to support the Strategic Air Command's growing fleet of B-52 Stratofortress bombers. Based on the Boeing 367-80 prototype, which also spawned the Boeing 707 commercial airliner, the KC-135 was designed as a dedicated military aircraft. Key features included a flying boom refueling system operated by a boom operator, a strengthened floor for cargo, and Pratt & Whitney J57 turbojet engines. The aircraft's design emphasized high-subsonic speed and altitude performance to match its receiver aircraft, a significant advancement over the propeller-driven KC-97 Stratofreighter. The first flight occurred on 31 August 1956 at Renton, Washington, with the United States Air Force accepting the first production aircraft in June 1957.

Operational history

The KC-135 entered service with the Strategic Air Command and quickly became integral to United States nuclear deterrence posture, constantly alert to support B-52 and B-58 Hustler operations. Its role expanded dramatically during the Vietnam War, where it enabled long-range strikes by F-105 Thunderchiefs and B-52s flying from distant bases like Andersen AFB in Guam. The tanker fleet was crucial during Operation Desert Storm, the War in Afghanistan, and Iraq War, supporting massive air campaigns. Beyond combat, KC-135s have routinely supported global United States Air Force operations, NASA research flights, and allied air forces. The fleet underwent a major upgrade in the 1980s with new CFM56 engines, creating the KC-135R, which offered greater fuel offload, range, and reduced noise.

Variants

The primary variants are defined by their engine installations and upgrades. The original KC-135A, powered by Pratt & Whitney J57 engines, was the first production model. The KC-135Q was a specialized variant modified to carry the JP-7 fuel required by the SR-71 Blackbird. The KC-135R and KC-135T are re-engined models featuring CFM56 (military designation F108) engines, with the "T" model incorporating some systems from the KC-10 Extender. The KC-135E was an interim model re-engined with older Pratt & Whitney TF33 engines from retired 707 airliners. Numerous other designations exist for test aircraft, reconnaissance platforms like the RC-135, and cargo versions such as the C-135 Stratolifter.

Operators

The primary operator remains the United States Air Force, with aircraft assigned to Air Mobility Command, the Air Force Reserve Command, and the Air National Guard. Key NATO allies also operate the type: the French Air and Space Force flies the KC-135FR (a French-specific variant), the Turkish Air Force operates KC-135Rs, and the Republic of Singapore Air Force leases KC-135Rs. The Chilean Air Force previously operated a single example. The Royal Saudi Air Force has ordered the modernized KC-46 Pegasus as a eventual replacement for its KC-135s.

Specifications (KC-135R)

* **Crew:** 3 (Pilot, Co-pilot, Boom Operator) + optional navigator * **Length:** 136 ft 3 in (41.53 m) * **Wingspan:** 130 ft 10 in (39.88 m) * **Height:** 41 ft 8 in (12.70 m) * **Empty weight:** 119,228 lb (54,080 kg) * **Max takeoff weight:** 322,500 lb (146,285 kg) * **Powerplant:** 4 × CFM International F108-CF-100 turbofan engines * **Maximum speed:** 580 mph (933 km/h, Mach 0.87) * **Range:** 1,500 mi (2,400 km) with 150,000 lb (68,000 kg) transfer fuel * **Service ceiling:** 50,000 ft (15,200 m) * **Fuel capacity:** 31,275 US gal (118,385 L) usable fuel

Accidents and incidents

The KC-135 has been involved in several notable accidents throughout its long service. A significant early loss occurred in 1958 when a KC-135A crashed near Bunker Hill AFB, killing all on board. In 1966, a KC-135 and a B-52 collided during refueling off the coast of Spain, dropping nuclear weapons near Palomares. A major disaster happened in 1982 when a United States Air Force KC-135 caught fire and crashed shortly after takeoff from RAF Mildenhall, killing all crew members. In 1994, a Royal Saudi Air Force KC-135 exploded on the ground at King Khalid International Airport, resulting in fatalities. More recently, a United States Air Force KC-135R from the Air National Guard made a gear-up landing at Milwaukee in 2015, causing substantial damage but no fatalities.

:

Category:United States Air-to-be-135R