WS - 110A WS - 110A ( " Weapon System 110A " ) was a project by the United States Air Force in the 1950s to develop a supersonic bomber aircraft capable of delivering nuclear weapons . Proposals for such an aircraft were submitted by Boeing and North American Aviation . Although the program was put on indefinite hold before any actual designs were completed , it paved the way for the B - 70 program . Background . Boeing Aircraft Corporation ' s MX - 2145 Project with Rand Corporation that started in January 1954 explored what sort of aircraft would be needed to deliver the various nuclear weapons then under development . Providing for a long range and high payload were obvious requirements , but they also concluded that after bomb - release the plane would need supersonic speed to escape the weapon ' s critical blast - radius . Jet engines of the time had poor fuel efficiency . An aircraft capable of carrying a reasonable bomb load to the Soviet Union from the continental United States had to carry a large fuel load ( and thus be very large itself ) due to the unrefueled range required . The aviation industry had been examining this problem for some time . There was considerable interest in the use of nuclear - powered aircraft in the bomber role from the mid - 1940s . Nuclear engines in aircraft used the heat generated by a nuclear reactor in place of jet fuel , giving it virtually unlimited cruising range . In addition to solving the range issue , these aircraft could be flown to holding areas away from the airbases and kept in the air for extended periods of time , making them immune to sneak attack . Accordingly , Boeing developed plans for a nuclear - powered bomber equipped with afterburners that used chemical fuel . Lockheed and Convair proposed similar designs . Another possibility was the use of boron - enriched " zip fuel s " , which improved the energy density of the fuel by about 40 % . Various U . S . government agencies had been experimenting with zip fuels for some time , and they believed that once the problems were solved , zip fuel would become almost universal for high - speed aircraft . Although the advantages of a zip - fueled aircraft would not be as great as those of a nuclear - powered one , it would offer a real performance increase and was a relatively straightforward development of existing engines and fuels . Air Force studies . In October 1954 , the Air Force issued General Operational Requirement No . 38 , which was quite general and called simply for an intercontinental manned bomber which would replace the B - 52 beginning in 1965 . March 1955 ' s GOR . 81 was more specific , calling for a nuclear - powered bomber with a combat radius of , capable of flying up to at a speed greater than Mach 2 at altitudes greater than with a payload , revising this to in GOR . 82 later that month . The Air Research and Development Command ( ARDC ) decided to separate the two approaches , and issued a requirement for " Weapon System 110A " , which asked for a Mach 0 . 9 cruising speed and " maximum possible " speed during a entrance and exit from the target . The target date for the first operational wing of these bombers was July 1964 , reduced a year in comparison to earlier GOR ' s . The nuclear approach became " Weapon System 125A " , while the ICBM work was organized under " Weapon System 107A " . In early 1955 , the Air Force issued GOR . 96 , which called for an intercontinental reconnaissance system with the same general requirements as WS - 110A , called WS - 110L . The two requirements were combined soon afterwards , becoming Weapon System 110A / L . The nuclear - powered version was dropped during this period , given the problems in that program ' s development , as well as a general feeling of optimism about the zip fuels . In June 1955 the Air Staff directed that the details of WS - 110A / L be released to the aviation industry and that a request for proposals be issued . Although six contractors were given the requirements , only Boeing and North American Aviation ( NAA ) submitted proposals . On 8 November 1955 , the Air Force issued letter contracts to both Boeing and North American for Phase 1 development . The contracts called for models , design reports , wind tunnel tests , plus a mock - up . In 1956 , initial designs were presented by the two companies . Although zip fuel s improved range , the overall effect was not very large , perhaps 10 % , so both designs featured huge wingtip fuel tanks that could be jettisoned before a supersonic run on the target . In the case of the North American design , the entire outer portion of the wings was jettisoned as well , resulting in an aircraft that looked somewhat like a very large F - 104 Starfighter after being " broken up " . The Air Force evaluated their designs and in September 1956 deemed them too large and complicated ; the huge fuel load resulted in takeoff weights of 700 , 000 pounds , making safe operation from existing runways extremely difficult . They were also far too large to fit in existing hangars . Curtis LeMay was not enthusiastic about the design , claiming " Hell , this isn ' t an airplane , it ' s a three - ship formation . " NAA and Boeing ' s study contracts were extended to further develop their bomber designs . The next month the program was put " on hold " , although the companies were told to continue any low - level development they could .