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. Designed as a medium bomber, the Albemarle was used for general and special transport duties, paratroop transport and glider towing. Albemarle squadrons participated in Normandy and the assault on Arnhem during Operation Market Garden.
|Armstrong Whitworth Albemarle Mark I series 2 (P1475) of 511 Squadron c. 1942|
|Role||Transport, glider tug|
|Manufacturer||A W Hawksley Ltd|
|Designer||Armstrong Whitworth Aircraft|
|First flight||20 March 1940|
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 undercarriage and an 80 ft (24 m) wingspan capable of 300 mph and a tricycle undercarriage design with 70 ft (21 m) span with a maximum speed of 320 mph (510 km/h). Both designs, known as the Type 155, used two Bristol Hercules engines. The Armstrong Whitworth AW.41 design used a tricycle undercarriage 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, mock-ups 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 250 mph (400 km/h) at 15,000 ft (4,600 m) economical cruise while carrying 4,000 lb (1,800 kg) 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 (6,400 km) range. An upper dorsal turret and a (retractable) ventral turret for downward firing were added. In October 1938, 200 aircraft were ordered "off the drawing board" (i.e. without producing a prototype). 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 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 undercarriage, 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 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 the 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 like this and they were only used as bombers on two occasions. The Albemarle was considered inferior to other aircraft already in service, such as the Vickers Wellington. Later 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 (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 ft (23 m) 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-engined heavy bombers about to enter service but it was considered suitable for general reconnaissance.
The Soviet Air Force placed a contract for delivery of 200 Albemarles in October 1942. An RAF unit No. 305 FTU, at RAF Errol near Dundee was set up to train Soviet ferry crews. During training, one aircraft was lost with no survivors. The first RAF squadron to operate the Albemarle was No. 295 at RAF Harwell in January 1943. Other squadrons to be equipped with the Albemarle included No. 296, No. 297 and No. 570. The first operational flight was on 9 February 1943, by a 296 Squadron Albemarle which dropped leaflets over Lisieux in Normandy.
A Soviet-crewed Albemarle flew from Scotland to Vnukovo airfield, near Moscow on 3 March 1943 and was followed soon afterwards by eleven more aircraft. Two Albemarles were lost over the North Sea, one to German fighters and the other to unknown causes. Tests of the surviving Albemarles revealed their weaknesses as transports (notably the cramped interior) and numerous technical flaws; in May 1943, the Soviet government suspended deliveries and eventually cancelled them in favour of abundant American Douglas C-47 Skytrains. (The Soviet camp at Errol Field continued until April 1944: apparently the Soviet government hoped to secure de Havilland Mosquitos.) At least two of the Albemarles that reached the USSR were lost in accidents and the surviving aircraft were retired two years later.
From mid-1943, RAF Albemarles took part in many British airborne operations, beginning with the invasion of Sicily. The pinnacle of the aircraft's career was a series of operations for D-Day, on the night of 5/6 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 airborne troops over Normandy. On 6 June 1944, four Albemarle squadrons and the operational training unit 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 Waco 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:
- ST Mk I – 99 aircraft
- GT Mk I – 69
- ST Mk II – 99
- Mk III – One prototype only.
- Mk IV – One prototype only.
- ST Mk V – 49
- ST Mk VI – 133
- GT Mk VI – 117
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 and 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 the same but for a fuel jettison system. All production Albemarles were powered by a pair of 1,590 hp (1,190 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 (1,200 kW) Wright Double Cyclone.
- Twelve aircraft were exported to the Soviet Union (two more lost in transit).
- Transport arm of 1st Air Division, later 10th Guards Air division (to 1944); naval air units until retirement in 1945.
- No. 161 Squadron RAF – Albemarle I from October 1942 to April 1943 at RAF Tempsford.
- No. 271 Squadron RAF operated one aircraft at Doncaster between October 1942 and April 1943.
- No. 295 Squadron RAF – Albemarle I from November 1943 to July 1944 at RAF Hurn and then RAF Harwell. Albemarle II from October 1943 to July 1944 at RAF Hurn and then RAF Harwell. Albemarle V from April 1944 to July 1944 at RAF Harwell.
- No. 296 Squadron RAF – Albemarle I from January 1943 to October 1944 at RAF Hurn, RAF Stoney Cross including operations in North Africa. Albemarle II from November 1943 to October 1944 at RAF Hurn and then RAF Brize Norton. Albemarle V from April 1944 to October 1944 at RAF Brize Norton. Albemarle VI from August 1944 to October 1944 at RAF Brize Norton.
- No. 297 Squadron RAF – Albemarle I from July 1943 to December 1944 at RAF Thruxton, RAF Stoney Cross and then RAF Brize Norton. Albemarle II from February 1943 to December 1944 at RAF Stoney Cross and then RAF Brize Norton. Albemarle V from April 1944 to December 1944 at RAF Brize Norton. Albemarle VI from July 1944 to December 1944 at RAF Brize Norton.
- No. 511 Squadron RAF – Albemarle I from November 1942 to March 1944 at RAF Lyneham.
- No. 570 Squadron RAF – Albemarle I from November 1943 to August 1944 at RAF Hurn and then RAF Harwell. Albemarle II from November 1943 to August 1944 at RAF Hurn and then RAF Harwell. Albemarle V from May 1944 to August 1944 at RAF Harwell.
- No. 1404 Flight RAF used three aircraft at RAF St Eval from September 1942 to March 1943
- No. 1406 Flight RAF used two aircraft at RAF Wick from September to October 1942.
- No. 13 Operational Training Unit RAF at RAF Finmere (two aircraft between October 1942 and April 1943)
- No. 42 Operational Training Unit RAF at RAF Ashbourne from September 1943 to February 1945.
- Heavy Glider Conversion Unit at RAF Brize Norton and RAF North Luffenham from January to April 1943 and August 1944 to October 1944 when it became No. 21 Heavy Glider Conversion Unit.
- No. 21 Heavy Glider Conversion Unit at RAF Brize Norton from 1944, moved to RAF Elsham Wolds in December 1945 and withdrew the last operational Albemarles in February 1946.
- No. 22 Heavy Glider Conversion Unit at RAF Keevil and RAF Blakehill from October 1944 to November 1945.
- No. 23 Heavy Glider Conversion Unit at RAF Peplow from October to December 1944.
- No. 3 Glider Training School operated eight Albemarles at RAF Exeter between January and August 1945.
- No. 301 Ferry Training Unit operated four Albemarles at RAF Lyneham from November 1942 to April 1943.
- No. 305 Ferry Training Unit bases at RAF Errol from January 1943 to train Soviet Air Force crews, disbanded in April 1944.
- Torpedo Development Unit at Gosport used one aircraft between April and September 1942
- Telecommunications Flying Unit at RAF Defford used one aircraft during May 1943,
- Airborne Forces Experimental Establishment at RAF Ringway and RAF Sherburn-in-Elmet between May 1942 and October 1944.
- Coastal Command Development Unit used two aircraft at RAF Tain between September and December 1942.
- Central Gunnery School at RAF Sutton Bridge used one aircraft between September and November 1942.
- Bomber Development Unit used three aircraft at RAF Gransden Lodge between August and November 1942.
- Operation Refresher Training Unit at RAF Hampstead Norris from May 1944 to February 1945
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.
Specifications (ST Mk I)
- 4 (2 pilots, navigator and radio operator) in ST.I.
- Six (2 pilots, navigator/bomb-aimer, radio operator and 2 gunners) in bomber configuration
- Capacity: 10 paratroops in ST.I
- Length: 59 ft 11 in (18.26 m)
- Wingspan: 77 ft 0 in (23.47 m)
- Height: 15 ft 7 in (4.75 m)
- Wing area: 803.5 sq ft (74.65 m2)
- Empty weight: 25,347 lb (11,497 kg)
- Fuel capacity: 769 imp gal (924 US gal; 3,500 L) normal, 1,399 imp gal (1,680 US gal; 6,360 L) with auxiliary tanks
- Powerplant: 2 × Bristol Hercules XI 14-cylinder air-cooled radial engines, 1,590 hp (1,190 kW) each
- Propellers: 3-bladed de Havilland Hydromatic
- Maximum speed: 265 mph (426 km/h, 230 kn) at 10,500 ft (3,200 m)
- Cruise speed: 170 mph (270 km/h, 150 kn)
- Stall speed: 70 mph (110 km/h, 61 kn) (flaps and undercarriage down)
- Range: 1,300 mi (2,100 km, 1,100 nmi)
- Service ceiling: 18,000 ft (5,500 m)
- Rate of climb: 980 ft/min (5.0 m/s)
Aircraft of comparable role, configuration and era
- Buttler 2004, p. 75.
- Flight 27 January 1944, p. 89
- Flight 27 January 1944, p. 90.
- Flight 27 January 1944, p. 88.
- Williams 1989, p. 37.
- Williams 1989, p. 36.
- Bridgman, Leonard. Jane's Fighting Aircraft of World War II. New York: Crescent Books, 1988. ISBN 0-517-67964-7.
- Tapper 1988, p. 277.
- "British Aircraft of WWII." jaapteeuwen.com. Retrieved: 15 March 2007.
- Mason 1994, pp. 335–337.
- Williams 1989, p. 41.
- Williams 1989, p. 40.
- "Albermarle", Air Transport Auxiliary Ferry Pilots Notes.
- Air Transport Auxiliary Ferry Pilots Notes. Elvington, Yorkshire, UK: Yorkshire Air Museum, Reproduction ed. 1996. ISBN 0-9512379-8-5.
- Bowyer, Michael J.F. Aircraft for the Royal Air Force: The "Griffon" Spitfire, The Albemarle Bomber and the Shetland Flying-Boat. London: Faber & Faber, 1980. ISBN 0-571-11515-2.
- Buttler, Tony. British Secret Projects: Fighters and Bombers 1935–1950. Hinckley, UK: Midland Publishing, 2004. ISBN 1-85780-179-2.
- Mason, Francis K. The British Bomber since 1914. London: Putnam Aeronautical Books. 1994. ISBN 0-85177-861-5.
- Morgan, Eric B. "Albemarle". Twentyfirst Profile, Volume 1, No. 11. New Milton, Hants, UK: 21st Profile Ltd. ISSN 0961-8120.
- Tapper, Oliver. Armstrong Whitworth Aircraft since 1913. London: Putnam, 1988. ISBN 0-85177-826-7.
- Williams, Ray. "The Unloved Albemarle". Air Enthusiast, Thirty-nine, May–August 1989, pp. 29–42. ISSN 0143-5450.
- "Armstrong Whitworth Albemarle", Flight. 27 January 1944. pp. 87–91.
- Neil, Tom. "The Silver Spitfire" 2013. Wing Cmdr Neil includes his impressions of the Albemarle and his hair raising attempts to fly one without any instruction or manual.
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