On the specification issued by the Air Ministry number B.9/38, it was required a twin-engine medium bomber made out of wood and metal that could be constructed by manufacturers outside of the aircraft industry and without using light alloys. The reason behind this was the concern of the Air Ministry about the shortage of supplies during wartime and how it could affect the production of bombers.
Three aircraft manufacturers, Armstrong Whitworth, Bristol and De Havilland were contacted to submit their designs. Bristol proposed two designs, one with a conventional undercarriage and another one with a tricycle undercarriage -which was relatively innovative for the time-. Both designs, labelled as the type 155 were powered by the Bristol Hercules radial engine and, with the conventional undercarriage a maximum speed of 300 mph (483 km/h) could be attained, while with the tricycle one the maximum speed was of 320 mph (515 km/h). The Armstrong Whitworth AW.41 design employed a tricycle undercarriage arrangement and was built up in sections to make easier to manufacture by firms without aircraft construction experience. The AW.41 was designed with Rolls-Royce engines in mind but with Bristol ones as an alternative.
In June 1938 mock up models of both AW.41 and Bristol 155 were examined and new specifications, B.17/38 and B.18/38 were issued for their respective designs. De Havilland didn't submit any design. As Bristol was busy with other aircraft production, namely the Beaufighter, so they stopped working on the 155. Changes in policy made the Air Staff to change the role of the AW.41 from a pure medium bomber to a reconnaissance aircraft with some secondary bombing capabilities. Among other changes, this meant that the required range had to be of 4.000 milles (6.400 km) and defensive armament had to be included too, like ventral and dorsal turrets. In October 1938 two-hundred machines were ordered "off the drawing board" (without producing a prototype) as the aircraft was always intended to be used as a contingency and was considered to be less than ideal.
The Albemarle was a mid-wing cantilever monoplane with twin fins and rudders. The fuselage was built in three sections with a hydraulically operated tricycle undercarriage arrangement designed by Lockheed.
It comprised a crew of 4 when acting as a transport and six when acting as a bomber. The two pilots sat side by side with the radio operator behind them and the navigator 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 while the rear fuselage was composed of glazed panels for a fire controller to coordinate the turrets against the attackers. The dorsal turret was designed by Boulton-Paul with four Browning machine guns. A fairing forward of the turret retracted automatically as it rotated to fire forwards.
Its undercarriage included a retractable nose-wheel, in addition to a semi-concealed "bumper" tail wheel, making the first British-built aircraft having this configuration.
The original design required a crew of six with two additional gunners, one for each of the turrets, dorsal and ventral. On this variant, the Mk.I, only 32 machines were built and were used as bombers in just two occasions, as the Albemarle was considered inferior to other aircraft already in service like the Vickers Wellington. Later aircraft were re-purposed as transports being either "General Transports" (GT) or "Special Transports" (ST), as they could carry up to 10 fully armoured paratroops, which were provided with a large loading door on the fuselage side and a dropping hatch in the rear fuselage.
The first prototype flew for the first time on 20th March 1940 at Hamble aerodrome, close to Portsmouth. Testing as a bomber showed that it couldn't improve performance over another medium bombers already in service, such as the Vickers Wellington and suffered obvious shortcomings compared to the four-engined heavy bombers about to enter service but it was, nonetheless, considered suitable for general reconnaissance.
The first Royal Air Force Squadron to operate the type was the No. 295 Squadron, at RAF Harwell, Oxfordshire in January 1943. Other squadrons equipped with the Albemarle were the Nos. 296, 297 and 570. The first operational action of the type was a flight of the No.296 Squadron which dropped propaganda leaflets over Lisieux, in Normandy.
From mid-1943 the Albemarles took part in many British airborne operations, beginning with the Operation Husky, the Allied invasion of Sicily. The top of the aircraft's performance was when it took part on the Operation Overlord, during the night of 5/6th June 1944 as both Nos. 295 and 296 squadrons sent aircraft to Normandy with the pathfinder force and the No.295 claiming to be the first squadron to drop Allied airborne troops over Normandy. During the 6th of June the Nos.295, 296 and 570 Squadrons took part on towing both the Airspeed Horsa and Hamilcar gliders, together with the No.42 Operational Training Unit. Later, during Operation Market Garden on 17th September 1944, the Albemarles were used again as tow aircraft for the gliders.
The last RAF unit to operate the type was the Heavy Glider Conversion unit, which replaced the Albemarles with Handley Page Halifaxes in February 1946 and the type was retired from operational units.
Sources:
1. https://en.wikipedia.org/wiki/Armstrong_Whitworth_Albemarle
2. Hall Park Books - Warpaint 115 - Armstrong Whitworth Albemarle
3. https://www.valka.cz/Armstrong-Whitworth-A-W-41-Albemarle-t55777 (translated)
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