Hidden Figures: The American Dream and the Untold Story of the Black Women Mathematicians Who Helped Win the Space Race

by Margot Lee Shetterly

Like Darwin’s finches, the mechanical birds had begun to differentiate themselves, branching into distinct species adapted for success in particular environments. Their designations reflected their use: fighters—also called pursuit planes—were assigned letters F or P: for example, the Chance Vought F4U Corsair or the North American P-51 Mustang. The letter C identified a cargo plane like the Douglas C-47 Skytrain, built to transport military goods and troops and, eventually, commercial passengers. B was for bomber, like the mammoth and perfectly named B-29 Superfortress. And X identified an experimental plane still under development, designed for the purpose of research and testing. Planes lost their X designation—the B-29 was the direct descendant of the XB-29—once they went into production.