The Convair XB-46 was a single example of an experimental medium jet bomber which was developed in the mid-1940s but which never saw production or active duty. It competed with similar designs, the North American XB-45 and Martin XB-48, all of which saw little use after the successful development of the Boeing XB-47. Development In 1944, the War Department was aware of aviation advances in Germany and issued a requirement for a range of designs for medium bombers weighing from to more than . Other designs resulting from this competition, sometimes named the class of '45, included the North American XB-45 and the Martin XB-48. Procurement began with a letter contract (cost-plus-fixed-fee) on 17 January 1945 with mockup inspection and approval in early February. Orders for three prototypes followed on 27 February 1945 with certain changes recommended by the board. Serials 45-59582 to 59584 were assigned. Budgetary concerns also led to the contract being changed to a fixed-price type. In the fall of 1945, Convair found it was competing with itself when the USAAF became interested in an unorthodox forward-swept wing jet attack design, the XA-44-CO that the company had also been working on. With the end of World War II severely curtailing budgets, the company considered canceling the XB-46 in favor of the other project as there was insufficient funding for both. Company officials argued that it made more sense to allow them to complete the XB-46 prototype as a stripped-down testbed omitting armament and other equipment and for the AAF to allow them to proceed with two XA-44 airframes in lieu of the other two XB-46s on contract. In June 1946, the AAF agreed to the substitution but that project was ultimately cancelled in December 1946 before the prototypes were completed. The B-46 would be completed with only the equipment necessary to prove its airworthiness and handling characteristics. The XB-46 had a long streamlined oval torpedo-shaped fuselage, long narrow straight shoulder-mounted wings with four Chevrolet-built J35-C3 axial-flow eleven stage turbojets of static thrust paired in an integral nacelle under each wing. The fuselage turned out to be a problem, as it distorted under flight loads. The pilots sat in tandem in a pressurized fighter-style cockpit under a single Plexiglas teardrop canopy with the bombardier-navigator-radio operator in a transparent Plexiglas nose section. The straight wing had an aspect ratio of 11.6, and was equipped with Fowler flaps which extended