Armstrong Whitworth AW.41 Albemarie
With a possible shortage of light alloys Air Ministry Specification B.9/38 for a twin-engined medium bomber, was issued. This required that the aircraft was to be of simple construction, using materials other than light alloy wherever possible. AWA's chief designer, John Lloyd, and his team were able to submit the initial proposals for their project, the AW.41, to the Air Ministry in February 1938. These initial proposals were for a mid-wing monoplane of 61ft 8in span powered by two Rolls Royce Merlin engines and capable of carrying the normal bomb load of 1,500 lb for a range of 1,500 miles cruising at 320 mph at 20,000ft. The sole defensive armament consisted of a four-gun power-operated turret in the tail. From the outset the AW.41 was to have a retractable tricycle undercarriage. The construction of the airframe was to have been almost exclusively of wood and steel.
The project was changed to meet Specifica-tion B.18/38 for a twin-engined reconnaissance bomber. The design study to meet B.18/38, although using the same type of construction, was very different to the original concept. The wing span was increased to 67ft and the Rolls-Royce Merlins were replaced by Bristol Hercules XI radial engines driving three-bladed de Havilland constant-speed hydromatic airscrews.
On August 18, 1938, Contract 816726/38 was placed with AWA for the manufacture of two prototypes.
Construction of the two prototypes was transferred to AWA's factory at Hamble, and it was provisionally planned that the ensuing production would he undertaken at the new “shadow" factory being built at Yeadon, near Leeds. The plan for Yeadon was abandoned and in November 1939, production contract No B40671/39 for 198 aircraft was placed with Gloster Aircraft at Brockworth. A second contract, No B53250/39 for a further 800 aircraft, was placed with Gloster on January 30, 1940. Shortly after this the Hawker Siddeley Group formed a new company at Brockworth, A. W. Hawkesley Ltd, to be responsible for the assembly of the AW.41, which by then had been named the Albemarle.
The first prototype, P1360, com-menced taxiing trials at Hamble on March 18, 1940, and AWA's chief test pilot, F1t Lt C. K. Turner Hughes, continued the trials of P1360 on March 20, when, after satisfactorily completing the taxiing tests, he carried out a series of straights before taking P1360 off on its maiden flight.
Retraction of the undercarriage was carried out for the first time during the second flight on April 5.
The company's flight trials showed take-off performance to be unsatisfactory and in July and August 1940, P1360 was grounded while the wings were modified, increasing the span by 10ft to 77ft.
In September an A&AEE crew from Boscombe Down started the official performance and handling trials. During a flight on September 30 the pilot became lost and was compelled to make a forced landing in a small field. This was successfully accomplished with only minor damage to the aircraft.
October was to see further modifica-tions to P1360, when the areas of the fins and rudders were increased. On November 16 the machine was delivered to the A&AEE at Boscombe Down for continuation of its official trials. It was during a flight from Boscombe Down on February 4, 1941, that a portion of plywood upper skin broke away from the port mainplane. The noise and effect of this led the pilot to believe that the aircraft was having engine trouble, so he immediately shut down the port engine. As a result the aircraft broke away into a spin from which the pilot was unable to recover. He ordered his two observers to abandon the aircraft, and the first cleared the aircraft safely, but the "D" ring of the other's parachute caught in the fuselage, the observer finding that he was suspended by his harness from the fuselage. The parachute released and developed over the tailplane, acting in an anti-spin role and enabling the pilot to regain control.
Unaware of the drama being enacted behind him, the pilot found that he could control the aircraft if he did not allow the speed to fall below 30 or 40kt above stalling speed. With this knowledge the pilot decided to make a wheels-up landing, still unaware that his observer was suspended below the fuselage. Just prior to landing, and when he was some 6 to 8ft above the ground, the observer released himself and fell to the ground. Although seriously injured, he sur-vived, the pilot completed his wheels-up landing with only minor injuries to himself, although the aircraft was totally destroyed in the ensuing fire.
The second prototype, P1361, first flew on April 20, 1941, continued the flight test programme. This machine also had the 77ft span wing, and was the only Albemarle to be fitted with the ventral power-operated turret.
Production problems were caused by over 1,000 sub-contractors who lacked aircraft experience but were to manufacture all the details and sub-assemblies required for the Albemarles. The technical problems with the prototype, particularly the increased wing span, required many of the jigs to be rebuilt.
Only two Albemarles, the prototypes, had flown by June 1941, the first 200 were not completed until March 1943, and production ceased with the completion of the 602nd Albemarle in March 1945. Although contracts were placed for 1,000 Albemarles, this quantity was reduced to 602, including the two prototypes, in June 1943, when it was decided that the facilities at Brockworth were required for Meteor production.
In 1941 the Albemarle programme was investigated by a Select Com-mittee on National Expenditure, chaired by Sir John Wardlow-Milne. The Committee issued its report on August 20, 1941, and it concluded that the Albemarle was not value for money, calling for immediate and urgent reconsideration of the programme." It is interesting to note that an Albemarle airframe, less engines and equipment, cost £24,950, compared with £19,159 for a Lancaster.
The Prime Minister, Winston Churchill, was concerned about the Committee's findings, and on August 26, 1941, asked the Secretary of State for Air to provide him with the current views and intentions of the departments involved with the Albemarle. Explanations from the Air Staff and the Ministry of Aircraft Production, defending the Albernarle and their decisions made in regard to it, did not appear to satisfy Churchill, and it apparently took a letter from Lord Beaverbrook on October 12 to finally reassure him. In his letter, Beaverbrook advised that the Alhemarle would be useful for short-range work, and would supplement the Wellingtons in attacks on invasion ports, for bombing in France and for bombing in the event of an invas on. He also explained that the tooling was practically complete at a cost of over £1,500,000, and that more than 75 per cent of the raw materials had been delivered and 50 per cent of the details manufactured.
Deliveries of production aircraft from Brockworth commenced in September 1941, although it was not until June 1942 that monthly deliveries exceeded double figures, with 14 aircraft being delivered. The first 32 production aircraft were completed as B.Mk.1's, but the delays had already rendered the Albemarle obsolete as a bomber, and consequently no further aircraft were completed as such, all subsequent machines being produced as glider tugs or special transports.
Projects to cater for any shortage of Hercules engines that may have arisen were the Mk.III with Merlins and the Mk.IV with Wright GR2600 Double Cyclone engines. Cyclones were installed in Mk.I P1406, and a single GTIV, V1760, was completed. The Merlin installation was not proceeded with.
Albemarle I V1599 was experimentally fitted with a long-travel undercarriage by AWA during 1943. This was to enable it to fly directly on to the ground without the necessity of a flare-out before touch-down. Flight testing commenced on November 8, 1943, but it did not prove to be a complete success because the undercarriage oleos failed to compress sufficiently under drag load during flight.
600 Albemarles were produced between 1941 and 1943.
It was widely used as a glider tug, although it suffered from overheating through sustained high power at low airspeed.
There were many GT (general transport) and ST (special transport) versions, some equipped with four-gun dorsal turrets (a few had a two-gun belly turret) or twin manually aimed dorsal guns. Most could carry freight, paratroops or special equip-ment. The first ST.I and GT.I entered RAF service in mid-1942 and early 1943 respectively, and subsequent versions brought the total number of Albemarles built to 600.
One batch was supplied to the Soviet Union.
The Albemarle took part in the invasion of Sicily to which they were used to tow support gliders into action. Additionally, the aircraft took part in the D-Day invasion landings of June 1944 (again as glider tugs) and served with airborne elements during the airdrops over Arnhem campaign to end the war before Christmas.
Armstrong Whitworth AW 41 Albemarle
Engine: 2 x Bristol Hercules XI, 1568 hp
Length: 59 ft 11 in / 18.26 m
Height: 15 ft 7 in / 4.75 m
Wingspan : 77.00 ft / 23.47 m
Wing area : 803.533 sqft / 74.65 sqm
Max take off weight : 22603.5 lb / 10251.0 kg
Max. speed : 230 kts / 426 km/h
Cruising speed : 148 kts / 274 km/h
Service ceiling : 17995 ft / 5485 m
Wing load : 28.09 lb/sq.ft / 137.00 kg/sq.m
Range : 1130 nm / 2092 km
Crew : 4
Armament: 2x cal.303 MG Vickers "K" (7,7mm)
Armstrong Whitworth Albemarle Mk II
Engines: 2 x Bristol Hercules XI 14-cylinder radial, 1,590hp each.
Length: 59.91 ft (18.26m)
Width: 77.00 ft (23.47m)
Height: 15.58 ft (4.75m)
Empty Weight: 22,600 lbs (10,251kg)
Maximum Take-Off Weight: 36,500 lbs (16,556kg)
Maximum Speed: 256mph (412kmh; 222kts)
Maximum Range: 1,350miles (2,173km)
Service Ceiling: 17,999ft (5,486m)
Armament: 2 or 4 x 7.7mm Vickers machine guns
Up to 4,500lbs internal ordnance