The Stratofortress is a jet strategic bomber designed and developed by Boeing. Its long list of variants served the US Air Force proudly since the early 1950s. With notable specs and good performance, it isn't a mystery why a lot of B-52s were produced. In particular, the B-52D accounted for 170 out of the total 750 planes that rolled out of Boeing's factories. The D-variant was mainly developed in the company's factories in Seattle and Wichita. One way to distinguish the D from the rest of the series was that it had its pilots and operator ejected upwards while its lower deck crew was ejected downwards. The B-52D Stratofortress was powered by eight Pratt & Whitney J57s that gave it a maximum speed of 638mph. Its main firepower was the four .50-calibre machine guns and about 40,000lbs of bombs. Interestingly, it was the D-model that helped create a name for the Stratofortress. On September 1958, the B-52D achieved a record speed of 560.705mph over a 5,400nmi-long closed circuit. But the record didn't last long as it was beat by another B-52D on the same day. The second plane set a world speed record of 597.675mph over a 2,700nmi-long closed circuit. Both records were achieved by a plane without a payload.