The success of the Superfortress made the parallel heavy bomber development by Convair superfluous. The first XB-32 had the same engines and pressurization of the B-29, with the high wing and twin tails of its B-24 ancestors. Issac B. Laddon designed a smaller wing area using the Davis airfoil and Fowler flaps, a circular fuselage, and dual main and nose wheels on the retractable tricycle gear.
Prototypes were ordered September 6, 1940, and 13 YB-32s were added on June 30, 1941. The first XB-32 was flown on September 7, 1942, two weeks ahead of the B-29, by Russell Rogers at San Diego. Powered by R-3350-13 Duplex Cyclones with Hamilton three-blade propellers and dual turbosuperchargers, it had extensive test instrumentation and no armament. While that plane crashed when taking off on May 10, 1943, the second XB-32 flew July 2, 1943, and after 30 flights went to Muroc (now Edwards) for acceptance tests in February 1944.
Range was calculated as 5,030 miles with a one-ton bomb load, which could be increased to ten tons if fuel load was cut down. Since no fighter escort could go so far, remarkably heavy protection was planned, including 1,221 pounds of armor for the crew, with 14 .50-caliber and two 20-mm guns in remote-control stations.
The “cannons” and a pair of fifties were installed in the rear of each outboard engine nacelle, and could be swung out to 70 degrees outboard and aimed 16 degrees up and 30 degrees down. Four guns placed in a retractable top turret behind the wing covered the upper hemisphere, while four more were in a retractable bottom turret underneath.
All this firepower would be concentrated on planes attacking from the rear by the tail gunner’s computer sight. Most unusual was the installation of two .50-caliber guns on the leading edge of the wings; one outboard of each side’s propeller disks! Each could be aimed up or down 13 degrees, or swung 60 degrees sideward to cover the forward area blocked from the main turrets by propeller disks.
A fire-control officer sat under a scanner dome behind the flight deck, with top and bottom periscope sights. His computer was linked to the tail gunner’s, and a third gunner behind the bottom turret had a periscopic sight. But by October 17, 1942, Convair engineers raised doubts about the Sperry company’s success in perfecting an accurate fire control system and favored a single vertical tail for the production version.
On March 17, 1943, a contract was approved for 300 B-32 bombers to be delivered at Fort Worth, instead of the busier San Diego factory, from September 1943 to October 1944. But drastic changes made in the production design put back that schedule a year. These changes included elimination of the pressurized fuselage and remote control turrets in favor of conventional manned turrets, and cancellation of the YB-32 version.
The tall single tail was introduced on the third XB-32, first flown by Beryl Erickson with twin fins on September 17, 1943, and then with a single fin from the Boeing B-29 on January 6, 1944. Convair engineers then designed their own taller fin for that prototype. By June 1944, contract changes called for 1,213 production ships, including 500 to be built in San Diego, instead of Fort Worth.
The first production B-32-1-CF Dominator was flown August 5, 1944 at Fort Worth by Beryl Erickson. Powered by R-3350-23A Duplex Cyclones with Curtiss 16-foot, 8-inch, four-blade propellers, a B-32 could hold forty 500, or twelve 1,000, or eight 2,000, or four 4,000-pound bombs in the double bay. Ten .50-caliber guns with 5,450 rounds were paired in power-operated turrets: two Martin turrets on top, Sperry ball turrets in the nose and in the tail, and another as a retractable belly turret. Armor protection was limited to turrets and 520 pounds on engine nacelles.