Fighting the U-boats
Aircraft & Air forces
Lockheed Hudson Patrol Bomber
prepared by Forest Garner & Emmanuel Gustin
The Hudson's ancestry may be traced back to the Lockheed's Model 10 Electra, a ten-passenger civil airliner which first flew on 23 February, 1934. Designed by Hall Hibbard, Richard von Hake, Lloyd Stearman, and Clarence "Kelly" Johnson, this was Lockheed's first twin engine aircraft. It was Johnson's idea to adopt the twin tail configuration, which would be a Lockheed trademark for many years. Lockheed built 148 production Electras (plus the prototype), the most famous of which was flown almost around the world by Amelia Earhart. An interesting development of the Model 10 was the XC-35, which flew with a pressurized cabin in 1937.
The Model 10 was the immediate parent of the somewhat smaller Model 12 Electra Junior, a six-passenger executive transport. Lockheed built 114 examples of the Model 12 and 16 of a bomber version for the Netherlands East Indies. The latter aircraft later saw combat against the Japanese in late 1941 and early 1942. The Model 12 also served as military cargo aircraft and two, one purchased by France and one by Britain, served as clandestine photo-reconnaissance aircraft over Germany, Italy, and North Africa before the war.
Lockheed followed these with the larger Model 14 Super Electra, a 12-passenger civil airliner. First flown on 29 July, 1937, this aircraft had engines more powerful than those of her predecessors and featured Fowler flaps and a wing designed for higher speeds. Competing against the legendary Douglas DC-3, a larger and more economical aircraft, the relatively advanced Model 14 was not a big success, and only 112 were sold. One of these aircraft, piloted by Howard Hughes, flew around the world in less than 4 days, averaging 206.1 mph. It was a Model 14 that flew Neville Chamberlain to Munich to meet with Adolf Hitler in September, 1938.
In February 1938, Lockheed's design team learned of an impending visit of the British Purchasing Commission and, after five days and nights of rushed design work, proposed the B-14L, a reconnaissance bomber based on the Model 14. The British requested changes which were incorporated within 24 hours. Because the British were already impressed with the Model 14, and because the proposed Lockheed aircraft was cheaper than its competitors and could be delivered in quantity more quickly, on 23 June 1938 the British Purchasing Commission placed an order for Lockheed's proposed patrol bomber. This order specified 200 aircraft to be delivered by 31 December 1939, plus up to 50 additional aircraft if these could also be delivered by that date. All 250 were delivered well before that date (plus one replacement for an aircraft which was lost before delivery), at a price of about $100,000 each. The outbreak of war interrupted delivery because of a 1935 law which put an embargo on arms sales to belligerents. The Neutrality Act, signed by Roosevelt on 4 November, 1939, allowed the British and French to buy weapons on a "cash and carry" basis.
The Hudson was a mid-wing monoplane with all-metal stressed-skin construction. The fuselage was elliptical in cross-section, with a transparent nose to facilitate bomb aiming. The wing tapered toward the wingtips, and had a high loading for its day. To reduce the length of take-off and landing runs, Fowler flaps of generous size were fitted. The Hudson was built with a choice of engines, similar in displacement (about 30 liters) and power (1,100 to 1,200 hp), but each having its own small advantages. The nine-cylinder Wright R-1820 Cyclone was the lighter of the two, while the 14-cylinder Pratt & Whitney R-1830 Twin Wasp ran a little smoother and, because of its double-row layout, had a little less wind resistance. The crew was normally a pilot, navigator, bomb aimer, radio operator, and gunner.
The first 351 aircraft, known as Hudson Mk I, had Wright Cyclone GR-1820-102A engines of 1,100 hp, giving a maximum speed of 246 mph at 6,500 feet. This performance was comparable with that of the contemporary Heinkel 111H-2 bomber. The Hudson spanned 65.5 feet and weighed 17,500 pounds loaded. Weapons included 1,400 pounds of bombs in an internal weapons bay, two fixed forward-firing .303 (7.7mm) machine guns in the nose and two similar machine guns in a Boulton-Paul dorsal turret. Range was a respectable 1,960 miles at a 220 mph cruise. The first flight (there was no prototype) was on 10 December, 1938, and the first arrived in Liverpool the following February.
The Mk I was followed by 20 of the Mk II with a stronger airframe and constant-speed propellers instead of the two-position propellers of the Mk I (a small but important change), 429 of the Mk III with 1,200 hp GR-1820-G-205A engines and a ventral .303 machine gun, 130 of the Mk IV with 14-cylinder Pratt & Whitney Twin Wasp engines, and 409 of the Mk V with detail improvements (207 were built with larger fuel tanks). After the Lend-Lease act of March 1941, aircraft were delivered under USAAF designations. The A-28 (52 built) and A-28A (450 built) both had 1,200 hp Pratt & Whitney R-1830 Twin Wasp engines, but the A-28A had an interior that could be converted to a troop transport configuration. The A-29 (416 built) and A-29A (384 built) had 1,200 hp Wright R-1820-87 engines, but the A-29A had a convertible interior. These aircraft were delivered to the RAF, RCAF, RAAF, /RNZAF, USAAF, and US Navy (who accepted the first 20 A-29s under the designation PBO-1), China, Brazil, and Portugal. Additionally, 300 advanced trainers were built for the USAAF as the AT-18 and AT-18A. This brought total production to 2,941 Hudsons before production ended in May, 1943.
Performance improved so that the Hudson Mk IV (similar to the A-28) was capable of 284 mph at 15,000 feet, and had a range of 2,160 miles at a cruising speed of 224 mph. Loaded weight was 18,500 pounds.
The Hudson Mk I began squadron service with the RAF Coastal Command's No. 224 Squadron in the Summer of 1939. By September, No. 233 Squadron was similarly equipped, while No. 220 Squadron had begun to replace its Avro Ansons with the Hudson Mk III. Not long after war broke out, Hudsons also equipped No. 206 and 269 Squadrons. These squadrons all flew maritime patrol and anti-shipping sorties from the British Isles. Additional squadrons were formed during the war until the RAF saw a peak of 17 Hudson squadrons. Other Hudsons flew reconnaissance missions over Germany, occupied Europe, and (in civil registration) southern parts of the Soviet Union.
The Hudson was considered a "hot ship", and was not an easy aircraft to master compared to the docile Avro Anson it replaced. There were many accidents during conversion training. A chief cause was the Hudson's propensity to swing off of the runway during take-off and landing. Pilots also found the cockpit layout inconvenient. In flight, the Hudson was well-behaved and comfortable.
The Hudson's first combat success was on 8 October 1939, when a Hudson Mk I of No. 224 Squadron shot down a Dornier Do-18D off Jutland. In a famous incident, a Hudson Mk III of No. 220 Squadron guided a British destroyer to the prison-ship Altmark in Norwegian waters, freeing many British sailors. Hudsons assisted in the Norwegian campaign and in the evacuation of Dunkirk.
Hudsons began to receive ASV radar in early 1940, and were assigned specifically to antisubmarine duty beginning in August of 1940 from Aldergrove, Northern Ireland. In March, 1941 No. 269 Squadron began operations from Iceland. One of the Hudson's first successes against U-boats was on August 27, 1941, when an Iceland-based Hudson bombed and damaged U-570 and, after repeated strafing passes, observed the U-boat crew to surrender. The Hudson circled the U-boat and called additional aircraft and ships to the scene. U-570 was indeed captured intact, although the crew had thrown the Enigma machine and codebooks overboard. Hudsons went on to achieve two dozen additional successes against U-boats. An Africa-based RAF Hudson of No. 608 Squadron was the first aircraft to sink a U-boat with rockets.
The Hudson was also used by the RAF as a bomber, some 35 taking part in the RAF's second "thousand bomber" raid. Hudsons flown by the RAF, RCAF, RAAF, and RNZAF fought in virtually every maritime theater of the war, including the Mediterranean, South Pacific, Indian Ocean, North Atlantic, Caribbean, and even the East Coast of the United States in support of US forces. Hudsons of No. 161 Squadron were used in clandestine operations, landing in open fields of occupied Europe at night to deliver or retrieve agents or to provide weapons or information to partisans. Many nations used the Hudson to train the crews of bombers and patrol aircraft. Many also served as transport aircraft.
The first two U-boat sinkings achieved by American forces were both achieved by US Navy Hudsons, and the first sinking by the USAAF was also by a Hudson. The first submarine sinkings by Brazilian and RNZAF forces were also by Hudsons (the former assisted by a PBY Catalina).
In service, the Hudson was practical, popular, and surprisingly effective for a converted civil aircraft. Its reliability earned it the nickname "Old Boomerang" because it always came back. The long series of Lockheed maritime patrol aircraft started with the quickly improvised Hudson.
U-boats sunk by this aircraft type (Hudson)
- Francillon, R. J. Lockheed Aircraft since 1913 (1982 and 1987)
Naval Institute Press, Annapolis, MD.
- Yenne, W. Lockheed (1987)
Crescent Books, Greenwich, CT.