Douglas A-20 / DB-7 / Boston / Havoc
|BOMBER, ATTACK||Virtual Aircraft Museum / USA / Douglas|
The original DB-7 was built as a private venture, produced to the order of the French government. The first production DB-7 flew on 17 August 1939. When France fell the undelivered aircraft outstanding from French contracts were taken over by the British government and given the name Boston. Production for the RAF, USAAF, US Navy and Russia ceased on 20 September 1944 after well over 7,000 had been built. Russia received twice as many as the RAF and only some 800 less than the US Army.
As delivered to the RAF from the French contracts, the Boston I was powered by two Pratt & Whitney R-1830-S3G-4G engines. It was used mainly for training duties, although some were converted for night fighting and given the British name Havoc. The A-20 was the first of the series built to a US Army specification and was powered by two 1,112kW Wright R-2600-7 Cyclone engines with exhaust-driven turbo-superchargers. It was fitted with American armament and equipment.
As the Boston II for the RAF, the A-20 had R-2600-A5B engines and British armament. Those converted into night fighters became Havocs each with a lengthened nose fitted with 12 forward-firing 7.62mm guns, AI radar and other special equipment depending on the sub-variant - one carried a high-power searchlight in the nose. As an intruder it carried a crew of three and full armament and bombs.
The A-20A for the USAAC/USAAF was powered by two 1,192kW Wright R-2600-11 engines with integral two-speed superchargers. The A-20B was an experimental development of the A-20A, armed with two 12.7mm guns firing forward, one 12.7mm upper flexible gun, one 7.62mm lower flexible gun, and one 7.62mm gun in the tail of each engine nacelle, firing aft. Nacelle guns were remotely controlled by a foot trigger in the rear compartment. The A-20C was powered by two similarly rated R-2600-23 engines. Armament comprised four fixed guns (two on each side of the transparent nose), two on a flexible mounting in the rear cockpit, and one in the lower rear-firing position - all 7.62mm (A20G) or 7.69mm (British Boston Ill). Ejector-type exhaust stacks replaced the collector rings used on the earlier models and range was increased by the addition of a self-sealing fuel tank in the forward and rear bomb-bay compartments. Provision was also made on some aircraft to carry a 900kg naval torpedo.
The Boston III was powered by R-2600-A5B engines and carried a crew of four as a bomber. The Boston IIIA was similar but built by Boeing. Some Boston III/IIIA were fitted as intruders with four 20mm cannon under the forward fuselage, four 7.69mm guns in the nose, and two 7.69mm guns in the upper flexible position.
Following the experimental XA-20E, with a 37mm nose cannon and General Electric turrets, the A-20G appeared. This was similar to the A-20C except that the transparent bombardier nose was replaced by a solid nose fitted (in earlier versions) with four 20mm cannon and two 12.7mm machine-guns and ultimately with six 12.7mm guns. A few also had a single 12.7mm upper flexible gun, but this was soon replaced by a power-driven turret armed with two 12.7mm guns. Thicker armour for increased crew protection on ground-attack missions was also added.
The A-20H was powered by two 1,267kW R-2600-29 engines and incorporated minor improvements. The A-20J was identical to the later version of the A-20G except that the attack nose was replaced by a moulded-plastic bombardier's nose incorporating bombing controls and flight navigation instruments. One in ten A-20G were completed as A-20J to serve as squadron lead planes. Armament consisted of two 12.7mm machine-guns (one in each side of the transparent nose), two in the power-operated dorsal turret and one in the lower rear firing position.
The A-20K was identical to the A-20H except that the attack nose was replaced by a bombardier's nose, as with the A-20J. The British Boston V was similar. Special US versions of the A-20 appeared as the P-70 night fighter with R-2600-11 engines and armed with four 20mm cannon mounted in a fairing beneath the fuselage bomb bay; the P-70A conversion of the A-20G with R-2600-23 engines and six 12.7mm machine-guns in a solid nose and dorsal and lower guns; the P-70B development of the P-70A for training, with six 12.7mm 'package' guns and special radar (converted A-20G/J); the F-3A night photographic-reconnaissance conversion of the A-20J/K; and BD-1/2 target tugs for the US Navy.