Tag Archives: Boeing Model 717

30 December 1964

A Boeing KC-135A Stratotanker refuels a Boeing B-52E Stratofortress. (U.S. Air Force)

30 December 1964: The United States Air Force accepted the last of 732 Boeing KC-135 Stratotankers: KC-135A serial number 64-14840. The new tanker was assigned to the 380th Air Refueling Squadron at Plattsburgh Air Force Base, New York, 12 January 1965.

As of 14 May 2018, 396 KC-135s were still in service with the United States Air Force: 153 active duty, 72 Air Force Reserve, and 171 Air National Guard. It is estimated that the fleet is 33% through their design lifetime limits.

Built as an aerial refueling tanker to support the U.S. Air Force fleet of B-52 Stratofortress strategic bombers, an initial order for 24 tankers was soon increased to 250. Eventually 732 KC-135As were built by Boeing, and an additional 81 of other versions.

With the company internal designation of Model 717, the KC-135 was developed from the Model 367-80 proof-of-concept prototype, the “Dash Eighty.” The Stratotanker is very similar in appearance to the Model 707 and 720 airliners but is structurally a different aircraft. It is also shorter than the 707 and has a smaller diameter fuselage.

Boeing KC-135R Stratotankers of the 40th Air Expeditionary Group, forward deployed to support B-52 operations. (SMSGT John Rohrer, U.S. Air Force)
Boeing KC-135R Stratotankers of the 40th Air Expeditionary Group, forward deployed to support B-52 operations. (SMSGT John Rohrer, U.S. Air Force)

The Stratotanker was originally operated by a flight crew of four: pilot, co-pilot, navigator and refueling boom operator. Upgrades over the decades have simplified operation and the crew has been reduced to two pilots and the boom operator.

The KC-135R is 136 feet, 3 inches (41.529 meters) long, with a wingspan of 130 feet, 10 inches (39.878 meters), and overall height of 41 feet, 8 inches (12.700 meters). Its maximum takeoff weight is 322,500 pounds (146,284 kilograms).

The Stratotanker can carry up to 200,000 pounds (90,718 kilograms) of fuel for inflight refueling. It can also be configured to carry 83,000 pounds (37,648 kilograms) of cargo, or as many as 37 passengers.

Boeing KC-135R Stratotanker 64-14840 at Rickenbacker Air National Guard Base, Columbus, Ohio, 2018. (Ohio Air National Guard)

The KC-135A was originally powered by four Pratt & Whitney J57-P-59W turbojet engines producing 13,750 pounds of thrust (61.163 kilonewtons) for takeoff, using water injection. The fleet has been re-engined with more efficient CFM International CFM56-2B1 (F108-CF-100) engines. The CFM56-2 is a two-spool, axial-flow, high-bypass turbofan with a single fan stage, 12-stage compressor section (3 low pressure and 9 high pressure stages), annular combustor, and a 5-stage turbine (1 high pressure and 4 low pressure stages). The engine is rated at 21,634 pounds of thrust (96.233 kilonewtons).

The tanker has a maximum speed of 530 miles per hour ( kilometers per hour) at 30,000 feet (9,144 meters) and a range of 1,500 miles when carrying 150,000 pounds of transfer fuel. The service ceiling is 50,000 feet (15,200 meters).

The newest Stratotanker in service with the United States Air Force, KC-135R 64-14840 is 54 years old. It is presently assigned to the 121st Air Refueling Wing, Ohio Air National Guard.

The final Boeing Stratotanker, KC-135R 64-14840, remains in service with the 121st Air Refueling Wing, Ohio Air National Guard, based at Rickenbacker Air National Guard Base, Columbus Ohio. (Ohio Air National Guard)

© 2018, Bryan R. Swopes

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31 August 1956

City of Renton, the first Boeing KC-135A Stratotanker, 55-3118, takes off for the first time. (Seattle Post Intelligencer)
City of Renton, the first Boeing KC-135A Stratotanker, 55-3118, takes off for the first time. (U.S. Air Force/Seattle Post Intelligencer)

31 August 1956: The first production Boeing KC-135A Stratotanker, 55-3118, named City of Renton, made its first flight with company test pilots Alvin Melvin (“Tex”) Johnston and Richards Llewellyn (“Dix”) Loesch, Jr., on the flight deck.

Built as an aerial refueling tanker to support the U.S. Air Force fleet of B-52 strategic bombers, an initial order for 29 tankers was soon followed by three additional orders, bringing the total to 275 airplanes by the end of Fiscal Year 1958.¹ Eventually 732 KC-135As were built by Boeing, and an additional 81 of other versions.

KC-135 City of Renton. (Seattle Post-Intelligencer)
Boeing KC-135A Stratotanker 55-3118, City of Renton, just prior to touchdown. (Seattle Post-Intelligencer)

With the company internal designation of Model 717, the KC-135 was developed from the Model 367-80 proof-of-concept prototype, the “Dash Eighty.” The Stratotanker is very similar in appearance to the Model 707 and 720 airliners but is structurally a different aircraft. It is also shorter than the 707 and has a smaller diameter fuselage.

Boeing Aircraft Co. President Bill Allen talks to test pilots Tex Johnston and Dix Loesch after first flight of the Model-367-80 prototype. (Seattle Post-Intelligencer)
Boeing Aircraft Co. President Bill Allen talks to test pilots Tex Johnston and Dix Loesch after first flight of the Model 367-80, prototype of the KC-135A Stratotanker. (Seattle Post-Intelligencer)

The Stratotanker was originally operated by a flight crew of four: pilot, co-pilot, navigator, and refueling boom operator. Upgrades over the decades have simplified operation and the crew has been reduced to two pilots and the boom operator. The tanker’s maximum transfer fuel load is 200,000 pounds (90,719 kilograms). The KC-135 can carry 83,000 pounds (37,648 kilograms) of cargo, and up to 37 passengers.It can also be configured to carry cargo or up to 32 passengers.

The KC-135A is 136 feet, 3 inches (41.529 meters) long, with a wingspan of 130 feet, 10 inches (39.878 meters) and overall height of 41 feet, 8 inches (12.700 meters). The Stratotanker’s maximum takeoff weight is 322,500 pounds (146,284 kilograms).

The KC-135A was powered by four Pratt & Whitney J57-P-59W turbojet engines. The J57 was a two-spool, axial-flow engine with a 16-stage compressor section (9 low- and 7-high-pressure stages) and a 3-stage turbine section (1 high- and 2 low-pressure stages). These engines were rated at 13,750 pounds of thrust (61.16 kilonewtons), each. The J57-P-59W was 183.5 inches (4.661 meters) long, 38.9 inches (0.988 meters) long and weighed 4,320 pounds (1,920 kilograms).

The Stratotanker fleet has been re-engined with more efficient CFM International CFM56 turbofan engines which produce 21,634 pounds of thrust (96.23 kilonewtons), each. The upgraded aircraft are designated KC-135R.

Boeing KC-135A Stratotanker 55-3118, City of Renton, escorted by the “Dash 80.” (Flight Global)

The tanker has a cruise speed of 530 miles per hour (853 kilometers per hour) at 30,000 feet (9,144 meters). The service ceiling was 50,000 feet (15,240 meters). Its range is 1,500 miles (2,414 kilometers) when carrying 150,000 pounds (68,039 kilograms) of transfer fuel, and the maximum ferry range is 11,015 miles (17,727 kilometers).

Of the 803 KC-135 aircraft built, 396 remain in service with the U.S. Air Force (as of 14 May 2018). It is estimated that the fleet is 33% through their design lifetime limits.

The first production airplane, 55-3118, was used for flight testing. It was later modified into an EC-135K Head Dancer airborne command post. Today, the first Stratotanker is on display at the front gate of McConnell Air Force Base, Kansas.

Boeing KC-135A-BN Stratotanker 55-3118, City of Renton, refuels B-52C-50-BO Stratofortress 54-2676. (U.S. Air Force)

¹ KC-135A-BN: 57-1418–57-1514; 57-2589–57-2609; 58-0001–58-0130; total: 275

© 2018, Bryan R. Swopes

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