Silbervogel Silbervogel , German for silver bird , was a design for a rocket - powered sub - orbit al bomber aircraft produced by Eugen Sänger and Irene Bredt in the late 1930s for The Third Reich / Nazi Germany . It is also known as the RaBo ( " Raketenbomber " or " rocket bomber " ) . It was one of a number of designs considered for the " Amerika Bomber " mission , which started out in the spring of 1942 being focused solely on trans - Atlantic range piston - engined strategic bombers , like the Messerschmitt Me 264 and Junkers Ju 390 , the only two airframe types actually built and flown for the competition . When Walter Dornberger attempted to create interest in military spaceplane s in the United States after World War II , he chose the more diplomatic term " antipodal bomber " . Concept . The design was a significant one , as it incorporated new rocket technology , and the principle of the lifting body , foreshadowing future development of winged spacecraft such as the X - 20 Dyna - Soar of the 1960s and the Space Shuttle of the 1970s . In the end , it was considered too complex and expensive to produce . The design never went beyond mock up test . The Silbervogel was intended to fly long distances in a series of short hops . The aircraft was to have begun its mission propelled along a long rail track by a large rocket - powered sled to about . Once airborne , it was to fire its own rocket engine and continue to climb to an altitude of , at which point it would be travelling at some . It would then gradually descend into the stratosphere , where the increasing air density would generate lift against the flat underside of the aircraft , eventually causing it to " bounce " and gain altitude again , where this pattern would be repeated . Because of drag , each bounce would be shallower than the preceding one , but it was still calculated that the Silbervogel would be able to cross the Atlantic , deliver a bomb to the continental United States , and then continue its flight to a landing site somewhere in the Japan ese held Pacific , a total journey of . Postwar analysis of the Silbervogel design involving a mathematical control analysis unearthed a computational error and it turned out that the heat flow during the initial re - entry would have been far higher than originally calculated by Sänger and Bredt ; if the Silbervogel had been constructed according to their flawed calculations the craft would have been destroyed during re - entry . The problem could have been solved by augmenting the heat shield , but this would have reduced the craft ' s already small payload capacity . History . On 3 December 1941 Sänger sent his initial proposal for a suborbital glider to the Reich Air Ministry ( RLM ) as " Geheime Kommandosache Nr . 4268 / LXXX5 " . The 900 - page proposal was regarded with disfavor at the RLM due to its size and complexity and was filed away . Then Sänger went to work on more modest projects such as the Skoda - Kauba Sk P . 14 ramjet fighter . Professor Walter Gregorii had Sänger rework his report and a greatly reduced version was submitted to the RLM in September 1944 , as UM 3538 . It was the first serious proposal for a vehicle which could carry a pilot and payload to the lower edge of space . Two manned and one unmanned version were proposed : the " Antipodenferngleiter " ( antipodal long - range glider ) and the " Interglobalferngleiter " ( intercontinental long - range glider ) . Both were to be launched from a rocket - powered sled . The two manned versions were identical except in payload . The " Antipodenferngleiter " was to be launched at a very steep angle ( which would shorten the range ) and after dropping its bomb load on New York City was to land at a Japanese base in the Pacific . Postwar . After the war ended , Sänger and Bredt worked for the French government and in 1949 founded the Fédération Astronautique . Whilst in France , Sänger was the subject of a botched attempt by Soviet agent s to win him over . Joseph Stalin had become intrigued by reports of the Silbervogel design and sent his son , Vasily , and scientist Grigori Tokaty to kidnap Sänger and Bredt and bring them to the USSR . When this plan failed , a new design bureau was set up by Mstislav Vsevolodovich Keldysh in 1946 to research the idea . A new version powered by ramjets instead of a rocket engine was developed , usually known as the Keldysh bomber , but not produced . The design , however , formed the basis for a number of additional cruise missile designs right into the early 1960s , none of which were ever produced . In the US , a similar project , the X - 20 Dyna - Soar , was to be launched on a Titan II booster . As the manned space role moved to NASA and unmanned reconnaissance satellite s were thought to be capable of all required missions , the United States Air Force gradually withdrew from manned space flight and Dyna - Soar was cancelled . One lasting legacy of the Silverbird design is the " Regenerative cooling - regenerative engine " design , in which fuel or oxidizer is run in tubes around the engine bell in order to both cool the bell and pressurize the fluid . Almost all modern rocket engines use this design today and some sources still refer to it as the Sänger - Bredt design . Sänger II Space Plane . On 18 October 1985 Messerschmidt - Boelkow - Bloehm ( MBB ) began renewed studies of the Sänger spaceplane , this time a " piggyback " two - stage - to - orbit horizontal takeoff concept .