Armstrong Whitworth Albemarle

Albemarle
Mark I Armstrong Whitworth Albemarle, of 511 Squadron c. 1942
Role	Medium bomber/transport
Manufacturer	A W Hawksley Ltd
Designer	Armstrong Whitworth Aircraft
First flight	20 March 1940
Primary user	RAF
Produced	1941-1945
Number built	602

The Armstrong Whitworth A.W.41 Albemarle was a British twin-engine transport aircraft that entered service during the Second World War.

Originally designed as a medium bomber that could be built by non-aviation companies without using light alloys, the Albemarle 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.

Design and development

The origin of the Albemarle lay in the pre-war Air Ministry Specification B.9/38 which 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 Ministry was concerned that if there was a war the supply of material might be affected stopping construction of bombers.

Bristol, Armstrong-Whitworth 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, known as the Type 155, used two of Bristol's Hercules engines. Armstrong Whitworth's AW.41 design used a tricycle undercarriage - influenced by its use in America - and was built up of sub-sections easing 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.

De Havilland did not submit a design. Mockups of both the AW.41 and Bristol 155 were examined in June 1938, and new specifications B.17/38 and B.18/38 were drawn up for the respective designs. The specification stipulated 250 mph at 5,000 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 led to the Air Staff reconsidering the type 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; a dorsal turret to cover above and a (retractable) ventral one to give downward fire. An instruction for 200 aircraft to be produced "off the drawing board" (ie without producing a prototype first) was given in October 1938. The aircraft was always expected to be of use as insurance only and to be less than ideal.

In order to conserve aluminium large parts of the aircraft were constructed in steel with a consequent reduction of performance due to the higher weight.

The Albemarle was a mid-wing, cantilever monoplane with twin 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 raised backwards into the front fuselage.

The navigator sat in the nose forward of the two pilots side-by-side and a radio operator behind the pilots. The bomb aimer's sighting panel was incoprated into the crew hatch in the bottom of the nose. In the tailplane 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 came from four tanks. Additional tanks could be carried in the bomb bay

When used as a paratroop transport, 10 fully armed troops could be carried. The paratroopers had a dropping hole in the rear fuselage and a large loading door in the fuselage side.

The first of two prototypes built by Armstrong Whitworth were assembled by Air Service Training at Hamble Aerodrome where P1360 first flew on 20 March 1940. To improve take-off a wider span (77 from 67 ft) wing was from the 9th aircraft. Delays in reaching service, that it was not an improvement over current medium bombers (such as the Vickers Wellington) and its obvious shortcomings compared to the four-engined heavies about to enter service meant that plans for using it as a bomber was dropped but it was still considered as suitable for general reconnaissance.

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. This 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).

The most 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 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 Siddley group which included Armstrong Whitworth. The actual parts for the Albemarle were produced by some 1,000 subcontractors.

Operational history

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. The first operational flight was a 296 Sqn aircraft on 9 February 1943 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. The first Albemarle from Scotland flew successfully to Vnukovo airfield on 3 March 1943, 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 favour 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 the operations concerned with D-Day on 5 June 1944 295 and 296 Squadrons sent aircraft to Normandy with the pathfinder force with 295 Squadron claiming to be the first squadron to drop Allied troops during Operation Overlord. On 6 June 1944 four Albermarle 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, although it lost six in transit, 570 Squadron sent 22 aircraft with ten towing gliders and 42 OTU used four aircraft. Operation Mallard on 7 June 1944 the squadrons towed 220 Horsas and 30 Hamilcars to Normandy.

During Operation Market Garden at Arnhem on 17 September 1944 54 Horsas and two Hadrian gliders were towed to the Netherlands by 28 Albermarles 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 in accidents. The last Royal Air Force Unit to operate the type was the Heavy Glider Conversion Unit which replaced the Albermarles with Handley Page Halifaxs in February 1946 and the type was retired from operational unit.

Variants

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; 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 testing different powerplants; the former using the Rolls-Royce Merlin III and the latter with the 1,600 hp (1,190 kW) Wright Double Cyclone.

Operators

Soviet Union

• 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

United Kingdom

Royal Air Force

• No. 161 Squadron RAF - Albermarle 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 - Albermarle I from November 1943 to July 1944 at RAF Hurn and then RAF Harwell. Albermarle II from October 1943 to July 1944 at RAF Hurn and then RAF Harwell. Albermarle V from April 1944 to July 1944 at RAF Harwell
• No. 296 Squadron RAF - Albermarle I from January 1943 to October 1944 at RAF Hurn, RAF Stoney Cross including operations in North Africa. Albermarle II from November 1943 to October 1944 at RAF Hurn and then RAF Brize Norton. Albermarle V from April 1944 to October 1944 at RAF Brize Norton. Albermarle VI from August 1944 to October 1944 at RAF Brize Norton.
• No. 297 Squadron RAF - Albermarle I from July 1943 to December 1944 at RAF Thruxton, RAF Stoney Cross and then RAF Brize Norton. Albermarle II from February 1943 to December 1944 at RAF Stoney Cross and then RAF Brize Norton. Albermarle V from April 1944 to December 1944 at RAF Brize Norton. Albermarle VI from July 1944 to December 1944 at RAF Brize Norton.
• No. 511 Squadron RAF - Albermarle I from November 1942 to March 1944 at RAF Lyneham.
• No. 570 Squadron RAF - Albermarle I from November 1943 to August 1944 at RAF Hurn and then RAF Harwell. Albermarle II from November 1943 to August 1944 at RAF Hurn and then RAF Harwell. Albermarle 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 1845.
• 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 Woods in December 1945 and withdrew the last operational Albermarles 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 Albermarles at RAF Exeter between January and August 1945.
• No. 301 Ferry Training Unit operated four Albermarles at RAF Lyneham from November 1942 to April 1943.
• No. 305 Ferry Training Unit bases at RAF Errol from January 1943 to train Russian 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 test and trails by aircraft companies and the Royal Aircraft Establishment and Aeroplane and Armament Experimental Establishment and one was operated by De Havilland Propellers for research into reversing propellers.

Specifications (ST Mk I)

Orthographic projection of the Albemarle.

Data from The Unloved Albemarle

General characteristics

• Crew: 4
• Capacity: 10 paratroopers in ST
• Payload: 4,000 lb freight (1,820 kg)
• 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: 804 ft² (74.6 m²)
• Empty weight: 25,347 lb (10,270 kg)
• Loaded weight: 36,500 lb (16,556 kg)
• Max. takeoff weight: 36,500 lb (16,590 kg)
• Powerplant: 2 × Bristol Hercules XI radial engine, 1,590 hp (1,190 kW) each
• Propellers: De Havilland hydromatic propeller

Performance

• Maximum speed: 230 kn (265 mph, 426 km/h) at 10,500 ft (3,200 m)
• Cruise speed: 148 kn (170 mph, 274 km/h)
• Stall speed: 61 kn (70 mph, 113 km/h)
• Range: 1,300 mi (2,092 km)
• Service ceiling: 18,000 ft (5,486 m)
• Rate of climb: 980 ft/min (5.0 m/s)

Armament

• Guns:
  
  • 4 × .303 in (7.7 mm) Browning machine guns in dorsal turret.
  • 2 × .303 in (7.7 mm) machine guns in ventral turret (first prototype only)
• Bombs: Internal bomb bay for 4,500 lb (2,041 kg) of bombs

See also

Related lists

• List of aircraft of World War II
• List of aircraft of the RAF
  

References

Notes

Bibliography

• 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. ISBN 0-961-82100-4.
• Tapper, Oliver. Armstrong Whitworth Aircraft since 1913. London: Putnam, 1988. ISBN 0-85177-826-7.
• Williams, Ray. "The Unloved Albemarle". Air Enthusiast, May-August 1989, pp. 29–42. ISSN 0143-5450.
• "Armstrong Whitworth Albemarle", Flight 27 January 1944

External links

• "Whitley and Albemarle", Flight 4 April 1946