TYPE: Medium bomber, transport aircraft

ACCOMMODATION: Crew of four plus 10 paratroopers

POWER PLANT: Two Bristol Hercules XI radial engine, rated at 1,590 hp each

PERFORMANCE: 265 mph at 10,500 ft

COMMENT: The Armstrong Whitworth A.W.41 Albemarle was a British twin-engine transport aircraft that entered service during the WW II.
The Albemarle was originally designed as a medium bomber that was used for general and special transport duties, paratroop transport and glider towing, including 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 design used a tricycle undercarriage 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, mock-ups 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 mph at 15,000 ft economical cruise while carrying 4,000 lb of bombs. Bristol was already busy 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 mi 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.
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 sat side-by-side with the radio operator 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 for a “fire controller” to 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 but only the first 32 aircraft, the Mk I Series I, were produced in this configuration, and they were only used operationally as bombers on two occasions. The Albemarle was considered inferior to other aircraft already in service, such as the Vickers Wellington. All subsequent aircraft were built as transports, called either “General Transport” (GT) or “Special Transport” (ST).
When used as a paratroop transport, ten 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 production run of 600 Albemarles was assembled by A.W. Hawksley Ltd of Gloucester, a subsidiary of the Gloster Aircraft Company formed to build 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
The first Albemarle first flew on 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 ft wing was fitted after the eighth 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 it had obvious shortcomings compared to the four-engine heavy bombers about to enter service but it was considered suitable for general reconnaissance.
From mid-1943, RAF Albemarle’s took part in many British airborne operations, such as invasion of Sicily (1943), D-Day (1944), Operation Tonga (1944), Operation Mallard (1944) and Operation Market Garden (1944).The gliders that were to towed included Airspeed Horsa’s, General Aircraft Hamilcar’s, and Waco Hadrian’s.
Of the 602 Albemarles delivered, 17 were lost on operations and 81 lost in accidents (Ref. 24).

TYPE: Flying Wing, Fast Transport, Bomber Project

ACCOMMODATION: Crew of two (Pilot and navigator/flight test observer

POWER PLANT: Two Rolls-Royce Nene centrifugal-flow turbojets, rated at 2.240 kp thrust each

PERFORMANCE: 500 mph at sea level

COMMENT: The Armstrong Whitworth A.W.52 was a British flying wing aircraft design of the late 1940s for research into a proposed flying wing bomber and/or jet liner. Three aircraft, the A.W.52G glider and two turbojet-powered research aircraft, were built for the programme. The airliner was cancelled but research flying continued until 1954.
Armstrong-Witworth Aircraft proposed a turbojet-powered six or four-engine flying wing bomber/airliner design, using a laminar flow wing, during the Second World War. This had to be a large aircraft in order to provide bomb bay resp. passenger head-room within the wing. The low-speed characteristics of the design were tested on a 16.41 m span wooden glider known as the A.W. 52G; the glider was designed to be roughly half the size of the powered A.W.52, which in turn would be about half the size of the airliner. Construction of the AW.52G began in March 1943, with the glider making its maiden flight, towed by an Armstrong Whitworth Whitley bomber, on 2 March 1945. Flight testing, with tug releases from 20,000 ft giving flights of around 30 min continued, mostly satisfactorily until 1947. In 1944, Armstrong Whitworth received a contract that would allow them to produce two A.W.52 prototypes for evaluation, nominally asmail carrying aircraft.
The A.W.52 was intended for high speeds and was an all-metal turbojet-powered aircraft, with a retractable undercarriage; aerodynamically it had much in common with the glider. Both aircraft were moderately-swept flying wings with a centre section having a straight trailing edge. The wing tips carried small (not full chord) end-plate fin and rudders, which operated differentially, with a greater angle on the outer one. Roll and pitch were controlled with evelons that extended inward from the wing tips over most (in the case of the A.W.52 about three-quarters) of the outer, swept part of the trailing edge. The elevons moved together as elevators and differentially as ailerons. They were quite complicated surfaces – which included trim tabs – and hinged not from the wing but from “correctors”, which were wing-mounted; the correctors provided pitch trim. To delay tip stall, air was sucked out of a slot just in front of the elevons, by pumps powered by undercarriage-mounted fans on the glider and directly from the engine in the A.W.52. The inner centre section wing carried Fowler flaps and the upper surface of the outer section carried spoilers.
Maintenance of laminar flow over the wings was vital to the design and so they were built with great attention to surface flatness. Rather than the usual approach, where skinning is added to a structure defined by ribs, the A.W.52’s wings were built in two halves (upper and lower) from the outside in, starting from pre-formed surfaces, adding stringers and ribs then joining the two halves together. The result was a surface smooth to better than 2/1000 of an inch.
The crew sat in tandem in a nacelle so that the pilot was just forward of the wing leading edge, providing a better view than in the glider. The pressurised cockpit was slightly off-set to port. The engines were mounted in the wing centre section, close to the centre line and so not disturbing the upper wing surface.
The first prototype flew on 13 November 1947 powered by two Rolls-Royce Nene turbojet engines of 2.240 kp thrust each. This was followed by the second prototype on 1 September 1948 with the lower-powered  Rolls-Royce Dervent engines, rated at 1.580 kp each. Trials were disappointing: laminar flow could not be maintained, so maximum speeds, though respectable, were less than expected. As in any tail-less aircraft, take-off and landing runs were longer than for a conventional aircraft (at similar wing loadings) because at high angles of attack, downward elevon forces were much greater than those of elevators with their large moment.
The first prototype crashed without loss of life on 30 May 1949, making it the first occasion of an emergency ejection by a British pilot. Despite the termination of development, the second prototype remained flying with the Royal Aircraft Establishment until 1954 (Ref.: 27).

TYPE: Medium bomber

ACCOMMODATION: Crew of two

POWER PLANT: Two Bristol “Centaurus” IX radial engines, rated at 2,520 hp each

PERFORMANCE: 336 mph at 12,000 ft

COMMENT : In early 1939 Bristol suggested a bomber variant of the “Beaufighter” with their Bristol “Hercules” engines. British policy at the time was an expectation for medium bombers to be provided from the US allowing British industry to concentrate on heavy bomber designs but a design was requested preferably based on an existing design which meant working with the Bristol “Beaufort” or “Beaufighter”.
Air Ministry specification B.7/40 called for a medium bomber to replace the Bristol “Blenheim”. The specification stipulated a speed of at least 300 mph at 5,000 ft, a normal load of 500 kg of bombs and a center turret armed with at least two 12.7 mm machine guns. Only Armstrong Whitworth Company tendered a full design but it did not meet with approval. So when Bristol brought their Type 162 (tentatively named “Beaumont”), which was fortunately well matched to B.7/40 specification, to the Air Staff, this led to a request to complete a mockup in 1940 and then a confirmed contract for three prototypes in February 1941. The “Beaumont” was based on the rear fuselage and tail of a “Beaufighter”, with a new center and front fuselage. The armament was a mid-upper turret with four machine guns, four more machine guns firing forward and two firing to the rear.
Construction began in late 1940, with a new Air Ministry Specification B.2/41 to be written around it. Changes in the requirements, removing dive bombing and ground attack support which incoming US bombers were expected to be capable of and increasing the performance to allow for the future, meant the “Beaumont” would no longer suffice. The changes in performance, requiring a bomb load of 4,000 lb, a speed of 360 mph and a range of 1,600 miles meant a redesign by Bristol to use the Bristol “Centaurus” engine.
The Bristol redesign with a larger wing and the more powerful engines was the Bristol ”Buckingham”. It had gun installations in the nose, dorsal and ventral turrets. Generally conventional in appearance, one unusual feature was that the bomb-aimer/navigator was housed in a mid-fuselage ventral gondola, resembling those on the earlier German Heinkel He 111H and American Boeing B-17C and -D in appearance. This was part of an attempt to give all the crew positions unobstructed views and access to each other’s positions. The bomb bay could hold up to 2,000 kg bombs. The rear of the gondola had a hydraulically powered turret with two Browning machine guns. The Bristol-designed dorsal turret carried four Brownings. A further four fixed, forward-firing Brownings were controlled by the pilot. Following more changes, specification B.2/41 was replaced by B.P/41. An order for 400, at an initial rate of 25 per month, was made with deliveries expected in March 1943. The first flight took place on 4 February 1943. During testing, the “Buckingham” exhibited poor stability which led to the enlargement of the twin fins, along with other modifications. The Bristol “Buckingham B1” was first flown 12 February 1944 with “Centarus” VI or XI engines, 400 ordered but reduced first to 300 then to 119, with only 54 built as bombers. Overtaken by events, it was mainly used primarily for transport and liaison duties (Ref.: 24).