The Secret Projects series is now well established with both aviation historians and modelers. American Secret Projects: Bombers, Attack and Anti-Submarine Aircraft 1945–1974 describes the important area of post–World War 2 bomber development in the United States. During the period to the 1970s, the U.S Air Force operated several classes of bomber—heavy long-range types for strategic operations, medium bombers, and fighter bombers for interdiction and ground support. The U.S. Navy had its own series of attack aircraft and bombers for delivering nuclear weapons, while the antisubmarine aircraft was another area to be examined in considerable depth. As a superpower, America was also able to look at some of the more unusual approaches in the creative process—for example, bombers propelled by nuclear propulsion. Many of the aircraft that entered service or flew only as prototypes resulted from design competitions involving many other proposals that for one reason or another, never left the drawing board.