16. The Nazis designed one of the first spaceplanes in an attempt to create a bomber capable of reaching the U.S. mainland
The Silbervogel (“Silverbird”) was a sub-orbital bomber designed by Eugen Sänger and Irene Bredt on behalf of Nazi Germany as part of the Amerika Bomber mission: the plan to initiate a strategic bombing campaign against the mainland United States. Employing the combined combustive might of liquid propellant and rocketry, the Silbervogel was intended to be accelerated along a fixed track by a rocket-powered sled to speeds of 800 km/h before being released into the air and igniting its own rocket engine to climb to an altitude of 145 kilometers. Once in the stratosphere, the aircraft would exploit the increasing air density to generate lift and repeatedly bounce to maintain sufficient altitude to cross the Atlantic, release a 4,000-kilogram bomb over the U.S., and subsequently land in Japanese territory in the Pacific; the total planned journey for the Silbervogel via this method was between 19,000 and 24,000 kilometers.
Ultimately considered too complex and expensive when taking into account existing technology and time constraints, remaining only a theoretical design, the Sänger-Bredt design is utilized by almost all modern rocket engines and the fundamental principles of the Silbervogel were later incorporated into the X-20 Dyna-Soar spaceplane designed by the United States Air Force in the 1960s; Sänger also faced considerable post-war efforts by the Soviets to recruit him to recreate his design for Stalin, including a failed attempt by Stalin’s son, Vasily, to kidnap both Sänger and Bredt in 1946.