Saenger began university studying civil engineering in Graz. After reading Oberth's book on the feasibility of manned spaceflight, he transferred to the Technical University in Vienna and graduated with a degree in aeronautics in 1931. His original thesis on rocket propulsion was rejected, so he had to write a completely different one on the less controversial topic of experimental airfoil design. He began pioneering testing of rocket engines at Vienna and published his original thesis as Raketenflugtechnik (Rocket Flight Engineering) in 1933. The book was a quantum leap ahead of other work at the time, covering in great mathematical detail the design of rocketplanes, space stations, and even interplanetary travel using ion engines that could attain relativistic velocities.
Saenger's rocketplane design was a horizontal takeoff-and-landing, hypersonic glider. Assuming a liquid propellant rocket engine with an exhaust velocity of 3700 m/s, and a mass ratio of 7:1, Saenger calculated that his rocketplane would have a range of 4000 to 6000 km while gliding at Mach 13 at 40 to 60 km altitude.
From 1932 to 1934 Saenger perfected (through countless static tests of various propellant combinations) a regeneratively-cooled liquid-propellant rocket engine. The unit reached a thrust of 30 kgf and demonstrated exhaust velocities of 3000 m/s at 50 atmospheres chamber pressure. Saenger also demonstrated expansion-cycle fuel pumps, the effects of a variety of expansion nozzles, and improved performance through the addition of metals to the fuel. Saenger applied to the Austrian Ministry of Defence for financial support to continue his research, but their experts pronounced his ideas unworkable.
Articles on Saenger's work in the Austrian journal Flight in June 1935 brought him to the attention of the German High Command. He was invited by the Luftwaffe in February 1936 to come to Germany and build a secret aerospace research institute at Trauen to develop his Silverbird manned intercontinental hypersonic bomber concept. Saenger headed a little-noticed team at Trauen that worked in parallel with (and in advance of) the Von Braun Army team at Peenemuende. The facilities at Trauen were enormous, with a liquid oxygen storage capacity of 56 tonnes. By 1942 Saenger had tested rocket engines at chamber pressures of 100 atmospheres, powered by high-energy propellants with exotic additives, and components of a 100-tonne thrust engine. A test rig allowed tests of rail designs up to 800 m/s to assist in the design of Silverbird's launch track. Air tunnel tests and theoretical work allowed the aerodynamic shape of the spaceplane to be refined and made suitable for both subsonic and hypersonic flight. His collaborator Irene Bredt worked with Saenger to develop the equations necessary to calculate winged flight at the near-vacuum of the edge of space.
However Saenger estimated it would take twenty years of development to produce an operational system, a time scale much too long for the Hitler government. Officially Saenger's work after 1942 was restricted primarily to ramjet development. The government did not allow the design study on the Silverbird to be issued until August 1944, too late to be of any interest as the Third Reich entered its death throes (although there is a hint that a partially completed spaceplane airframe was found by the Americans at the secret development center at Lofer, Austria).
Saenger's ramjet engines were ground and flight-tested from 1939 to April 1944. The ramjet promised a more efficient method of propulsion than the rocket at the high speeds and altitudes Saenger hoped to attain.
After the war Saenger refused to work with the Americans or the Russians. The Americans debriefed and interrogated Saenger 25 times between May 15 and November 23, 1945, and detained or imprisoned him twice. The head of the DFS, Walter Georgii, head of the Luftwaffe's aeronautical research, had good connections in France. He arranged through the French Ministry of Air for Saenger to be employed by would later be Nord Aviation at Chatillon, near Paris. Saenger and Bredt moved to France in July 1946 and were married there in 1951. Here they would work on several advanced French projects of the 1950's, including the SS-10 antitank missile, the Griffon turboramjet experimental aircraft, and the R-010 ramjet missile.
Stalin was personally fascinated with Saenger's antipodal bomber. At a meeting on 4 April 1947 Stalin ordered his son, Vassiliy, to personally go to France and 'persuade' Saenger to work for the Soviet Union. The scheme was thwarted when aviation engineer G A Tokayev of the Zhukovskiy Academy, who was present at the meeting, defected to the British and blew the operation. The French secret police managed to thwart any further kidnap attempts by their Russian counterparts. Stalin meanwhile ordered the leading Soviet aerodynamicist, Keldysh, to head a team to develop a Soviet copy of Silverbird. Keldysh designed a ramjet-powered version of the spaceplane, but finally determined that the design was not feasible in the near term.
Taking the Saenger bomber as the starting point, the Americans developed the Dynasoar spaceplane, and the Russians the Burya and Buran intercontinental cruise missiles. All were eventually canceled.
While in France, in collaboration with space writer Alexandre Ananoff, Saenger was instrumental in founding the International Astronautical Federation. Saenger chaired the founding meeting, on 30 September 1950, and became its first President in 1951. Although Saenger's plans for a UN-sponsored Astronautical Research Institute were not realized, the IAF did become one of the few forums for sharing of international research on spaceflight during the Cold War. At its 1956 meeting, Saenger described his conceptual design for an interstellar spacecraft powered by the conversion of matter to pure energy. Due to time dilation effects, the ship would reach a star system 100 light-years away in only ten years apparent time aboard the ship.
In September 1954 the Allies had allowed Germany to resume aerospace research, and Saenger took a post as head of a new Institute for the Physics of Jet Propulsion at Stuttgart. Here he worked on steam rockets, plasma engines, and other advanced concepts. Extensive facilities were built, including large-scale engine test stands at Lampoldshausen.
In 1961 Saenger was implicated in assisting the Egyptians to develop ballistic missiles. Saenger admitted going to Egypt on several trips as a consultant, but vigorously denied being involved with the German enterprise that was developing weapons for Egypt. The public clamor forced Saenger to resign in November 1961 and his institute to be taken over by a federal German Agency, the DFLR.
By October 1962 Saenger had been cleared of other charges of spying for the Soviet Union and was considered 'rehabilitated'. He accepted a professorship in October 1963 at the Technical University of Berlin.
Meanwhile renewed German work on spaceplane design began at Messerschmidt-Boelkow-Bloehm (MBB) in 1961, as a result of a vigorous campaign by Saenger to have German industry finally realise his thirty-year old dream of manned winged spaceflight. Putting together the innovative ideas of years of research, Saenger proposed an updated version of Silverbird. A steam-rocket rail launcher would catapult the 200 tonne spaceplane to a horizontal takeoff. The single-stage spaceplane would use a liquid oxygen/hydrogen engine with an exhaust velocity of 4200 m/s to put a three tonne payload into orbit. A second phase design would use an integrated rocket-ramjet for a true single-stage-to-orbit vehicle. Saenger completed the 32nd chapter of his study of this spacecraft on the last morning of his life. He died suddenly while lecturing to his students in Berlin on 10 February 1964. MBB continued it studies in the period 1962-1969, and Saenger's designs were renewed again in the 1980's, but post-war Germany never had interest in funding a major spaceflight project.
Birth Place: Pressnitz.