Armstrong Whitworth Albemarle The Armstrong Whitworth A . W . 41 Albemarle was a British twin - engine transport aircraft that entered service during the Second World War . The Albemarle was originally designed as a medium bomber , but never served in that role , instead being used for general and special transport duties , paratroop transport and glider towing , including significant actions such as Normandy and the assault on Arnhem during Operation Market Garden . Background . Air Ministry Specification B . 9 / 38 required a twin - engine medium bomber of wood and metal construction , that could be built by manufacturers outside the aircraft industry , and without using light alloys . The Air Ministry was concerned that if there was a war , the restricted supply of materials might affect construction of bombers . Armstrong Whitworth , Bristol and de Havilland were approached for designs . Bristol proposed two designs - a conventional 80 ft wingspan capable of 300 mph , and a tricycle design with 70 ft span with a maximum speed of 320 mph . Both designs , known as the Type 155 , used two Bristol Hercules engines . Armstrong Whitworth ' s AW . 41 design used a tricycle undercarriage - influenced by its use in America - and was built up of sub - sections to ease manufacture by firms without aircraft construction experience . The AW . 41 was designed with Rolls - Royce Merlin engines in mind , but with Bristol Hercules as an alternative ( " shadow " ) engine . In June 1938 , mockups of both the AW . 41 and Bristol 155 were examined , and new specifications B . 17 / 38 and B . 18 / 38 were drawn up for the respective designs . De Havilland did not submit a design . The specification stipulated at economical cruise while carrying 4 , 000 lb ( 1 , 800 kg ) of bombs . However , Bristol was already heavily engaged with other aircraft production and development , and stopped work on the 155 . Changes in policy made the Air Staff reconsider the Albemarle as principally a reconnaissance aircraft capable of carrying out bombing . Among other effects , this meant more fuel to give a 4 , 000 mile range . Two defensive positions were added ; an upper dorsal turret , and a ( retractable ) ventral turret to enable downward firing . In October 1938 , 200 aircraft were ordered " off the drawing board " ( i . e . without producing a prototype first ) . The aircraft was always expected to be of use as a contingency , and to be less than ideal . Design and development . The Albemarle was a mid - wing , cantilever monoplane with twin twin fins and rudders . The fuselage was built in three sections ; the structure being unstressed plywood over a steel tube frame . The forward section used stainless steel tubing to reduce interference with magnetic compass es . It had a Lockheed hydraulically operated , retractable tricycle landing gear , with the main wheels retracting back into the engine nacelles , and the nose wheel retracting backwards into the front fuselage . The two pilots side - by - side , a radio operator sat behind the pilots , and the navigator sat in the nose forward of the cockpit . The bomb aimer ' s sighting panel was incorporated into the crew hatch in the underside of the nose . In the rear fuselage were glazed panels , so a " fire controller " could coordinate the turrets against attackers . The dorsal turret was a Boulton - Paul design with four Browning machine guns . A fairing forward of the turret automatically retracted as the turret rotated to fire forwards . Fuel was in four tanks , and additional tanks could be carried in the bomb bay . A notable design feature of the Albemarle was its undercarriage , which included a retractable nose - wheel ( in addition to a semi - concealed " bumper " tail - wheel ) . It was the first British - built aircraft with this configuration to enter service with the Royal Air Force . The original bomber design required a crew of six including two gunners ; one in a four - gun dorsal turret and one in a twin - gun ventral turret . However , only the first 32 aircraft , the Mk I Series I , were produced in this configuration , and they were only used operationally in the bomber role on two occasions . That was because the Albemarle was considered inferior to other aircraft already in service , such as the Vickers Wellington . All subsequent aircraft were built as transports , designated either " General Transport " ( GT ) or " Special Transport " ( ST ) . When used as a paratroop transport , 10 fully armed troops could be carried . The paratroopers were provided with a dropping hatch in the rear fuselage , and a large loading door in the fuselage side . The entire production run of 600 Albemarles was assembled by A . W . Hawksley Ltd of Gloucester , a subsidiary of the Gloster Aircraft Company formed for the purpose of the construction of the Albemarle . Gloster was a part of the Hawker Siddley group which included Armstrong Whitworth . Individual parts and sub - assemblies for the Albemarle were produced by about 1 , 000 subcontractors . Operational history . The first Albemarle ( P1360 ) first flew on 20 March 1940 at Hamble Aerodrome , where it was assembled by Air Service Training , and was the first of two prototypes built by Armstrong Whitworth . To improve take - off , a wider span ( 77 from 67 ft ) wing was fitted after the 8th aircraft . Plans for using it as a bomber were dropped due to delays in reaching service , it was not an improvement over current medium bombers ( such as the Vickers Wellington ) and its obvious shortcomings compared to the four - engined heavy bombers about to enter service , but it was considered suitable for general reconnaissance . The first squadron to operate the Albemarle was No . 295 at RAF Harwell in January 1943 . Other squadrons to be equipped with the Albemarle were No . 296 , No . 297 and No . 570 . Other RAF squadrons operated small numbers of the aircraft . On 9 February 1943 , the first operational flight was a 296 Squadron Albemarle which dropped leaflets over Lisieux in Normandy . Albemarles took part in many of the major British airborne operations , such as the invasion of Sicily and of Normandy and the assault on Arnhem during Operation Market Garden . In October 1942 , the Soviet Air Force placed a contract for delivery of 200 Albemarles . No . 305 Ferry Training Unit was set up at RAF Errol near Dundee to train Soviet aircrews . During training , one aircraft was lost with no survivors . On 3 March 1943 , the first Soviet AF Albemarle flew successfully from Scotland to Vnukovo airfield , followed by 11 more . Two aircraft were lost over the North Sea ; one to German interceptors , and the other unaccounted for . Tests of the surviving Albemarles revealed their weaknesses as transports ( notably the cramped interior ) and numerous technical flaws ; in May 1943 , the Soviet government put further deliveries on hold , and eventually cancelled them in favour of abundant American Douglas C - 47 Skytrain s . The Soviet camp at Errol field continued until April 1944 ; apparently the Soviet command hoped to secure de Havilland Mosquito deliveries . Twelve Soviet Albemarles served for about two years ; at least two were lost in accidents . Surviving aircraft were retired at the end of 1945 . The pinnacle of the aircraft ' s career was a series of operations for D - Day on 5 June 1944 . 295 and 296 Squadrons sent aircraft to Normandy with the pathfinder force , and 295 Squadron claimed to be the first squadron to drop Allied troops during Operation Overlord . On 6 June 1944 , four Albemarle squadrons and the operational training unit all sent aircraft during Operation Tonga ; 296 Squadron used 19 aircraft to tow Airspeed Horsa s , 295 Squadron towed 21 Horsas , although it lost six in transit , 570 Squadron sent 22 aircraft with ten towing gliders , and 42 OTU used four aircraft . For Operation Mallard on 7 June 1944 , the squadrons towed 220 Horsas and 30 Hamilcars to Normandy . On 17 September 1944 , during Operation Market Garden at Arnhem , 54 Horsas and two Hadrian gliders were towed to the Netherlands by 28 Albemarles of 296 and 297 squadrons ; 45 aircraft were sent the following day towing gliders . Of the 602 aircraft delivered , 17 were lost on operations , and 81 lost in accidents . The last Royal Air Force unit to operate the type was the Heavy Glider Conversion Unit , which replaced the Albemarles with Handley Page Halifax es in February 1946 , and the type was retired from operational units . Variants . Over the course of its production life , a number of variants of the Albemarle were built : Most Marks were divided into " Series " to distinguish differences in equipment . The ST Mk I Series 1 ( eight aircraft ) had the four gun turret replaced with hand operated twin - guns under a sliding hood . As a special transport , a loading door was fitted on the starboard side ; the rear fuel tank was removed . The 14 ST Mk I Series 2 aircraft were equipped with gear for towing gliders . The Mk II could carry 10 paratroop s and the Mk V was essentially the same but with a fuel jettison capability . All production Albemarles were powered by a pair of 1 , 590 hp ( 1 , 186 kW ) Bristol Hercules XI radial engines . The Mk III and Mk IV Albemarles were development projects for testing different powerplants ; the former used the Rolls - Royce Merlin III , and the latter used the 1 , 600 hp ( 1 , 190 kW ) Wright Double Cyclone . Royal Air Force Aircraft were also operated for tests and trials by aircraft companies , the Royal Aircraft Establishment , and Aeroplane and Armament Experimental Establishment . One was operated by De Havilland Propellers for research into reversing propellers .