Armstrong Whitworth A.W.41 “Albemarie”
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[Armstrong Whitworth A.W.41 “Albemarie” historic photos (Photos via Wikipedia ¹)]
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”.
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 A.W.41 Albemarie 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 A.W.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 A.W.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 250 miles per hour (400 km/h) at 15,000 feet (4,600 m) 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 ³
The Albemarle was a mid-wing, cantilever monoplane with 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 compasses. 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 Siddeley group which included Armstrong Whitworth. Individual parts and sub-assemblies for the Albemarle were produced by about 1,000 subcontractors.
Operational History ³
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 favor of abundant American Douglas C-47 Skytrains. 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 Horsas, 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 Halifaxes in February 1946, and the type was retired from operational units.
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 paratroops 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.
Specifications (ST Mk.I) ³
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