Early in the summer of 1943, the Air Materiel Command at Wright Field requested that Douglas study the possibility of installing a transparent, bomb-aimer's nose in approximately one out of ten A-20Gs. This would enable the aircraft to be used as formation leaders on bombing runs, with solid-nosed A-20Gs dropping their bombs on signal from the leader. The A-20J was the result.
For the A-20J, Douglas designed an entirely new nose, which consisted of a frameless, molded Plexiglas canopy. This nose added seven inches to the aircraft's length, and carried a bombardier operating a Norden bombsight. Only the two side-mounted forward-firing nose guns were retained. In the field, these nose guns were often removed to lighten the load if there was no apparent need for them. The crew now consisted of four--pilot, dorsal turret gunner, ventral tunnel gunner, and bombardier.
The first A-20J was created by converting A-20G-25-DO serial number 43-9230. This comprised the sole member of the A-20J-1-DO production block. The A-20J-5-DO was equivalent to the A-20G-30-DO in systems and equipment, whereas the A-20J-15-DO was equivalent to the A-20G-40-DO. The A-20J-20-DO was similar to the -15 except for revisions to the gun charging mechanisms and change of airspeed indicators from Type F-2 to Type F-1.
A total of 450 A-20Js were built, all of them by Douglas-Santa Monica. Included in this total were 169 A-20Js which were delivered to the RAF as Boston IV. RAF serials were BZ400 to BZ568. The Boston IVs retained the same armament (including the twin-gun Martin dorsal turret) as the USAAF version. They were used by Nos 13, 55, 88 and 114 Squadrons. It entered RAF service in the summer of 1944.
The A-20J was slower than the A-20G, with a maximum speed of 317 mph at 12,700 feet.
As USAAF A-20 units in Europe gradually transitioned to the A-26 Invader, the A-20J was retained as a lead ship until the glass-nosed A-26C entered service.
43-9230 Douglas A-20J-1-DO Havoc 43-9438/9457 Douglas A-20J-5-DO Havoc 43-9638/9664 Douglas A-20J-5-DO Havoc 43-9857/9880 Douglas A-20J-10-DO Havoc 43-9910/9917 Douglas A-20J-10-DO Havoc 43-10105/10144 Douglas A-20J-10-DO Havoc 43-21432/21471 Douglas A-20J-15-DO Havoc 43-21552/21581 Douglas A-20J-15-DO Havoc 43-21702/21751 Douglas A-20J-15-DO Havoc 43-21828/21877 Douglas A-20J-20-DO Havoc 43-21988/22147 Douglas A-20J-20-DO Havoc 22140 to to RAAF as A28-78 10/44. Returned to USAAF 2/45.
Engines: Two 1600 hp Wright R-2600-23 Double Cyclone 14 cylinder twin-row
air-cooled radial engines equipped with two-speed superchargers.
Rated at 1600 hp for takeoff, 1675 hp war emergency, and 1400 hp at
Performance: Maximum speed 317 mph at 10,700 feet. Cruising speed
257 mph. Landing speed 95 mph. An altitude of 10,000 feet could be
attained in 8.8 minutes. Service ceiling 23,100 feet. Range 1000
miles with 2000-lb bombload at 238 mph. Maximum ferry range 2100
Dimensions: Wingspan 61 feet 4 inches, length 48 feet 4 inches,
height 17 feet 7 inches, wing area 465 square feet.
Weights: 17,117 pounds empty, 23,748 pounds gross, 27,000 pounds
Armament: Two 0.50-inch machine gun in dorsal power turret with 400
rpg. One 0.50-inch machine gun in the ventral tunnel position with
400 rounds. Two forward-firing 0.50-inch machine guns in lower
fuselage. Maximum internal bomb load 2000 pounds in split bomb bay
plus (on later models) 2000 pounds on four underwing hardpoints.