WHY Are They Changing The B-52 NOW?!

Video from the channel Mentour Now! about Boeing B-52 Stratofortress, linked on its Above Ten Thousand entry. Duration: 24:30. Language: English. Video type: Documentary.

Explainer piece from the Mentour Now! channel about the B-52's re-engining: why the US Air Force is now changing the bomber's engines and why it keeps eight instead of switching to four.

All B-52s in service are B-52Hs delivered in the early 1960s (the most recent rolled off the line in 1962). Each carries eight low-bypass Pratt & Whitney TF33 turbofans, first run on a test stand in 1958. Its civilian version, the JT3D, powered some Boeing 707s and Douglas DC-8s, and earlier B-52 versions used the J57. The video reviews the aircraft meant to replace it (B-58, B-70, B-1 and B-2) and explains that the fleet has been kept flying by cannibalizing spares, including engines from retired 707s. The Air Force already studied fitting four engines in the 1970s and again in the 1990s with the Rolls-Royce RB211. Both times it was dropped due to cost, schedule and risk.

The TF33 has a bypass ratio of 1.5:1 and produces about 17,000 pounds of thrust. According to Air Force experts, it will be impossible to maintain by around 2030 because its industrial base is disappearing. Switching to four engines would require reworking the wing, tail, possibly the landing gear and the electrical, pneumatic and hydraulic systems — almost like certifying a new aircraft. In September 2021 the Rolls-Royce F130 was chosen, a military version of the BR700 used in the Gulfstream G550 and G650. It burns 30 to 40% less fuel and provides more electrical power for the new radar. 608 units will be purchased, built in Indianapolis. Integration has proven complicated: the air intakes had to be redesigned after computer and wind-tunnel tests, causing nearly a year's delay. New wiring, digital engine control and digital cockpit displays are also needed. The 76 aircraft will go through the program in batches. The first B-52Js will be operational by around 2033 and the rest by the mid-2030s, with service expected into the 2050s.