Convair XB-46

XB-46
Role	Medium bomber
Manufacturer	Convair
First flight	2 April 1947
Retired	1947
Status	Cancelled
Primary user	United States Air Force
Number built	1
Unit cost	US$4.9 million for the program

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.

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 80,000 lb (36,287 kg) to more than 200,000 lb (90,718 kg). 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 was a graceful design and 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 3,820 pounds-force (17.0 kN) 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.