By William Pearce
The Douglas XA-26D and E were improved versions of the Douglas A-26B and C respectively. Both the XA-26D and E were upgraded with a more powerful version of the Pratt & Whitney R-2800 radial engine, the -83, built by Chevrolet and rated at 2,100 hp (1,566 kW). The engine’s output increased to 2,400 hp (1,780 kW) with water injection. The carburetor air scoops in the cowling were revised along with the carburetors, superchargers, engine mounts, and generators. The aircraft were fitted with wide-cord, 12.7 ft (3.87 m), four-blade propellers with spinners, although three-blade propellers were also tested. The top speed of the XA-26D and E was 403 mph (649 km/h) at 15,000 ft (4,572 m)—about 50 mph (80 km/h) faster than the B and C models—and the climb rate doubled to 2,326 fpm (11.8 m/s).
The D model was a solid nose version primarily intended for ground attack. The aircraft was equipped with 14 forward-firing .50-cal. machine guns: eight in the nose and six more in the wings. The aircraft also had dorsal and ventral barbettes with two machine guns each.
The first XA-26D Invader was modified from an A-26B, serial number 44-34100, starting in January 1945. Serial number 44-34100 was accepted by the USAAF on 31 January 1945 but was not available until 31 October 1945. The individual aircraft record card has a notation indicating the aircraft was to remain at the contractor’s plant for 180 days. The first record entry listing the aircraft as an A-26D was on 11 November 1945. Another XA-26D was created using A-26B serial number 41-39543, and the D modifications were completed by July 1945.
Some sources list another A-26B, serial number 44-34776, as being converted to the XA-26D standard. However, the data card for this aircraft makes no reference to a conversion program.
One B-26C, serial number 44-35563, was modified by the Douglas plant to XA-26E specifications. The E model was the glass nose version with two machine guns in the nose, six in the wings, and two in each dorsal and ventral barbettes.
A contract for 750 production A-26Ds was placed on 13 April 1945, following an order of 1,250 A-26Es placed on 5 April 1945. Both contracts were cancelled at the end of World War II; none of the aircraft were built.
– American Bomber Aircraft Development in World War 2 by Bill Norton (2012)