<p>The first American-built aircraft to be used operationally by the RAF during World War II, the Lockheed Hudson was a design which stemmed from the urgent British requirement for a maritime patrol/navigational trainer aircraft. Faced with the problem of producing these aircraft as quickly as possible for British requirements, Lockheed offered a militarized version of the Lockheed 14 Super Electra civil airliner, identified by Lockheed as the Model 414. While the aircraft's general configuration differed little from that of the civil airliner, there were a number of specific changes to provide suitable armament, plus the installation of more powerful engines. With approval accorded, production went ahead to such good effect that the first of these aircraft, to which the RAF had given the name Hudson, was able to record its initial flight on 10 December 1938.
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<p>Of all-metal construction, the wings were set in a mid position and featured a Lockheed-modified version of the Fowler-type trailing-edge flap. The fuselage was conventional, but included a bomb bay to provide internal stowage for up to 1,400 lb (635 kg) of bombs, a new bomb-aimer's position in the fuselage nose, and provision for two forward-firing machine guns mounted in the upper fuselage forward of the pilot, plus a power-operated dorsal turret sited well aft, near the tail unit which had twin vertical fins and rudders. Landing gear was of the tailwheel type, with the main units retracting aft to be housed in the engine nacelles. The powerplant, wing-mounted in long nacelles, comprised two 1,100-hp (820-kW) Wright GR-1820-G102A Cyclone engines, each driving a three-bladed variable-pitch propeller. Standard accommodation was for a crew of four, comprising pilot, navigator, bomb-aimer and radio operator/air gunner.
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<p>Procurement for the RAF and RAAF amounted to something like 1,500 aircraft before introduction of the Lend-Lease program, and subsequent requirements were procured by the USAAF for supply to Britain.
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<p>The first USAAF order was for 52 A-28s, all supplied to Britain, as were the 450 A-28As which followed, and these were designated Hudson IV and VI, respectively, by the RAF. The A-28s had 1,050-hp (783-kW) Pratt & Whitney R-1830-45 Twin Wasp engines, but the A-28As not only had 1,200-hp (895-kW) R-1830-67 Twin Wasps but also had convertible interiors for alternative use as troop transports. Other versions procured by the USAAF included 416 A-29s with 1,200-hp (895-kW) Wright R-1820-87 engines and 384 A-29As with the same engines, the latter having the convertible interiors of the A-28A. All were allocated to the RAF but only 382 were received by that service and designated Hudson IIIA. The balance were impressed for service by the USAAF for bomber crew training and anti-submarine patrol, and 20 went to the US Navy which designated them PBO-1. Some 24 of the US Army's A-29s were converted in 1942 for use in a photo-reconnaissance role, and were accordingly redesignated A-29B. The designation C-63 was allocated by the USAAF for a projected cargo variant, but this was cancelled before any were built. The final variant procured by the USAAF was required as a trainer for air gunners, or as a target tug. These were generally similar to A-29As and were equipped with a Martin dorsal turret. Lockheed built 217 of them as AT-18s, followed by 83 AT-18As, as navigation trainers, with different internal equipment and the turret deleted.
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<p>One of the USAAF'S A-29s was the first US Army aircraft to sink a German U-boat in World War II, and the PBO-1s of the US Navy's VP-82 Squadron based at Ventia, Newfoundland, sank the first two U-boats credited to that service in World War II on 1 and 15 March 1942.
<item><hi format=bold>Performance:</hi> maximum speed 253 mph (407 km/h) at 15,000 ft (4,570 m); cruising speed 205 mph (330 km/h); service ceiling 26,500 ft (8,075 m); range 1,550 miles (2,494 km)
<item><hi format=bold>Weights:</hi> empty 12,825 lb (5,817 kg); maximum take-off 20,500 lb (9,299 kg)
<item><hi format=bold>Dimensions:</hi> span 65 ft 6 in (19.96 m); length 44 ft 4 in (13.51 m); height 11 ft 11 in (3.63 m); wing area 551 sq ft (51.19 m<su>2</su>)
<item><hi format=bold>Armament:</hi> two 0.30-in (7.62-mm) machine guns in fuselage nose, one 0.30-in (7.62-mm) gun in ventral position and two 0.30-in (7.62-mm) guns in optional dorsal turret, plus up to 1,600 lb (726 kg) bombs
