Aerospaceplane The US Air Force ' s aerospaceplane project encompassed a variety of projects from 1958 until 1963 to study a fully reusable spaceplane . A variety of designs were studied during the lifetime of the project , including most of the early efforts on liquid air cycle engine s ( LACE ) and even a nuclear - powered ramjet . The effort was started largely due to the work of Weldon Worth at the Wright - Patterson AFB , who published a short work outlining a manned spaceplane . AF officials were interested enough to start SR - 89774 ( study requirement - ) for a reusable spaceplane in 1957 . By 1959 this work had resulted in the Recoverable Orbital Launch System , or ROLS , based around a LACE engine , known at the time as a " Liquid Air Collection System " , or " LACES " . Further work showed that more performance could be gained by extracting only the oxygen from the liquid air , a system they referred to as " Air Collection and Enrichment System " , or " ACES " . A contract to develop an ACES testbed was placed with Marquardt and General Dynamics , with Garrett AiResearch building the heat exchanger for cooling the air . The original ACES design was fairly complex ; the air was first liquified in the heat exchanger cooled by liquid hydrogen fuel , then pumped into a low pressure tank for short term storage . From there it was then pumped into a high pressure tank where the oxygen was separated and the rest ( mostly nitrogen ) was dumped overboard . In late 1960 and early 1961 a 125 N demonstrator engine was being operated for up to five minutes at a time . In early 1960 Air Force offered a development contract to build a spaceplane with a crew of three that could take off from any runway and fly directly into orbit and return . They wanted the design to be in operation in 1970 for a total development cost of only $ 5 billion . Boeing , Douglas , Convair , Lockheed , Goodyear , North American , and Republic all responded . Most of these designs ignored the ACES system and instead used a scramjet for power . The scramjet had first been outlined at about the same time as the original LACES design in a NASA paper of 1958 , and many companies were highly interested in seeing it develop , perhaps none more than Marquardt , whose ramjet business was dwindling with the introduction of newer jet engines and who had already started work on the scramjet . Both Alexander Kartveli and Antonio Ferri were proponents of the scramjet approach . Ferri successfully demonstrated a scramjet producing net thrust in November 1964 , eventually producing 517 lbf , about 80 % of his goal . Later that year a review suggested that the basic concepts of the aerospaceplane were far too new for development of an operational system to begin . They pointed out that far too much was being spent on development of the aircraft , and not nearly enough on basic research . Moreover , the designs were all extremely sensitive to weight , and any increase ( and there always is one ) could result in all of the designs not working . In 1963 the Air Force changed their priorities in SR - 651 , and focused entirely on development of a variety of high - speed engines . Included were LACES and ACES engines , as well scramjets , turboramjet s and a " normal " ( subsonic combustion ) ramjet with an intake suitable for use up to Mach 8 . In October a further review concluded that the technology was simply too new for anyone to predict when any such aerospaceplane could ever be built , and funding was wound down in 1964 .