Wikipedia

Armstrong Whitworth Albemarle

TheArmstrong Whitworth A.W.41 Albemarlewas a twin-enginetransport aircraftdeveloped by the British aircraft manufacturerArmstrong Whitworthand primarily produced byA.W. Hawksley Ltd,a subsidiary of theGloster Aircraft Company.It was one of many aircraft which entered service with theRoyal Air Force(RAF) during theSecond World War.

Albemarle
Armstrong Whitworth Albemarle Mark I series 2 (P1475) of511 Squadronc. 1943
General information
TypeTransport, glider tug
National originUnited Kingdom
ManufacturerArmstrong Whitworth Aircraft
Built byA W Hawksley Ltd
Primary usersRoyal Air Force(RAF)
Number built602[1]
History
Manufactured1941–1944[2]
Introduction dateJanuary 1943
First flight20 March 1940
RetiredFebruary 1946

The Albemarle had been originally designed as amedium bomberto fulfilSpecification B.9/38for an aircraft that could be built of wood and metal without using any light alloys; however, military planners decided to deemphasise the bomber role in favour ofaerial reconnaissanceand transport missions, leading to the aircraft being extensively redesigned mid-development. Performing itsmaiden flighton 20 March 1940, its entry to service was delayed by the redesign effort, thus the first RAF squadron to operate the Albemarle,No. 295atRAF Harwell,did not receive the type in quantity until January 1943. As superior bombers, such as theVickers Wellington,were already in use in quantity, all plans for using the Albemarle as a bomber were abandoned.

Instead, the Albemarle was used by RAF squadrons primarily for general and special transport duties,paratrooptransport andglidertowing, in addition to other secondary duties. Albemarlesquadronsparticipated inNormandy landingsand the assault onArnhemduringOperation Market Garden.While the Albemarle remained in service throughout the conflict, the final examples in RAF service were withdrawn less than a year after the war's end. During October 1942, theSoviet Air Forcealso opted to order 200 aircraft; of these, only a handful of Albemarles were delivered to the Soviets prior to the Soviet government deciding to suspend deliveries in May 1943, and later cancelling the order in favour of procuring the AmericanDouglas C-47 Skytraininstead.

Development

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Background

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The origins of the Albemarle can be traced back to the mid-1930s and the issuing ofSpecification B.9/38by the BritishAir Ministry.[3]This sought a twin-enginemedium bomberof wood and metal construction, without the use of any lightalloys,in order that the aircraft could be readily built by less experienced manufacturers from outside the aircraft industry. Furthermore, the envisioned aircraft had to be engineered in a manner that would allow it to be divided into relatively compact subsections, all of which had to fit on to a standardQueen Mary trailerto facilitate the adoption of a dispersed manufacturing strategy.[4]At the time, the Air Ministry was particularly concerned that, in the event of a major conflict arising, there would be restrictions on the supply of critical materials that could undermine mass production efforts.[4]

Several aircraft manufacturing firms, includingArmstrong Whitworth,Bristolandde Havilland,were approached to produce designs to meet the specification. Bristol proposed two designs – aconventional undercarriageand an 80 ft (24 m) wingspan capable of 300 mph and atricycle undercarriagedesign with 70 ft (21 m) span with a maximum speed of 320 mph (510 km/h). Both designs, known as the Type 155, used twoBristol Herculesengines. The rival 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.[4]The AW.41 was designed withRolls-Royce Merlinengines in mind, but also with provisions for the use of Bristol Hercules as an alternative powerplant.[5]

In June 1938, mock-ups of both the AW.41 and Bristol 155 were examined, while revised specifications B.17/38 and B.18/38 were drawn up for the respective designs; de Havilland opted against submitting 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.[1][3]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.[6]

Into production

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In October 1938, 200 aircraft were ordered "off the drawing board" (i.e. without producing a prototype). The aircraft had a positive reputation and there were initially high hopes for its performance, however it never quite lived up to expectations.[7]Furthermore, according to aviation author Oliver Tapper, the brief was a relatively difficult one for any company to fulfil.[3]Initially, physical work centred around the construction of a pair of lead aircraft, which were to be test flown prior to the commencement of full-rate manufacture of the type. The first Albemarle,serial numberP1360,was assembled at Hamble Aerodrome by Air Service Training; the aircraft performed itsmaiden flighton 20 March 1940.[8][3]

This first flight had actually been unintended, the test pilot having picked up too much speed during a ground taxi run, and had only taken off with the barest margin after traversing the entire runway.[9]Months later,P1360was damaged after a forced landing during the test flight programme, but was promptly repaired. Early flights of the type by test pilots typically described it as being relatively average and being free of flaws.[9]A number of modifications were made to the design during this late stage of development, including the extensive redesign of the aircraft's structure by Lloyd at Coventry.[3]Further measures were made to improve the Albemarle's take-off performance, such as the adoption of a wider span 77 ft (23 m) wing, and the thickening of therudder'strailing edgeto correct a tendency to over-balance. Occurrences of the engines overheating were never fully resolved, the main change in this area being the raising of the maximum permissible operational temperature from 280C to 300C.[10]

The Albemarle's production run was principally undertaken by A.W. Hawksley Ltd ofGloucester,a subsidiary of theGloster Aircraft Company,which was specifically formed to construct the Albemarle.[5]Originally, Gloster was to have undertaken this work itself at itsBrockworthfacility. Both Gloster and Armstrong Whitworth were member companies of theHawker Siddeleygroup, one of the largest aircraft manufacturing interests in Britain.[5]Individual parts and sub-assemblies for the Albemarle were produced by in excess of 1,000subcontractors.[5][11]Amongst the companies that were subcontracted wereMG Motor,to produce the forward fuselage,Rover,which constructed the wing centre section, andHarris Lebus,which built the tailplane units.[5]Production of the Albemarle was terminated during December 1944, by which point 602 aircraft had been completed.[2]

Design

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The Armstrong Whitworth Albemarle was a mid-wingcantilevermonoplanewith twin fins andrudders.The fuselage was built in three primary sections; the structure being composed of unstressedplywoodover a steel tube frame, including four circular steellongerons;most elements were bolted together viagusset plates.[12][13]The structure was intentionally divided in order that it might readily permit individual sections to be removed and replaced in the event of battle damage being sustained. The centre section of the wing was a single piece that ran through the fuselage, being built around a steel tube girder; it formed the attachment points for the central and nose fuselage sections, as well as the engines, main undercarriage legs, and extension wings.[14]Aside from a portion of theleading edgethat used light alloys, the majority of the wing was covered inplywood.The extension wings were almost entirely made of wood, save for the bracing of the two spars by steel tubing; the Frise-typeaileronsand tailplane were also composed of wood.[14]The structure of the forward section usedstainless steeltubing as to reduce interference withmagnetic compasses.[15]

The Albemarle featured aLockheed-designedhydraulically-operated, retractabletricycle undercarriage,the main wheels retracting back into the engine nacelles, and the nose wheel retracting backwards into the front fuselage, while the tail wheel was fixed in position, albeit semi-concealed by a "bumper" configuration. It was one of the particularly notable design features of the Albemarle, according to Tapper, it was the first British-built aircraft with a retractable nose-wheel to be built in quantity for theRoyal Air Force.[5]Power was provided by a pair ofBristol Hercules XIair-cooledradial engines,each capable of 1,590 hp and driving a three-bladede Havilland Hydromaticpropeller unit.[5]Fuel was typically stored in four tanks, two in the center fuselage and two within the wings centre section; in circumstances where extended range would be required, a maximum of additional auxiliary tanks could be installed within the aircraft'sbomb bay.This sizable bomb bay was equipped withhydraulically-operated doors and spanned from just aft of the cockpit to roughly halfway between the wings and the tail.[14]

The two pilots sat side by side in the forward portion of the cockpit, while the radio operator was seated behind the pilots. The navigator's position was in the aircraft's nose, and thus was 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, several glazed panels were present so that a "fire controller" could help coordinate the aircraft's defensive turrets against attackers. The dorsal turret was aBoulton-Pauldesign, which was electrically operated and originally armed with four Browning machine guns.[6]A fairing forward of the turret automatically retracted as the turret rotated to fire forwards.[16]The original bomber configuration of the Albemarle required a crew of six including two gunners; one in the four-gun dorsal turret and one in a manually operated twin-gun ventral turret but only the first 32 aircraft, theMk I Series I,were produced in such a configuration.[17][18]

As a bomber, the Albemarle was commonly considered to be inferior to several other aircraft already in RAF service, such as theVickers Wellington;[19]according to aviation author Ray Williams, the type was only used ever used as a bomber on two occasions.[17]Accordingly, later built aircraft were configured as transports, called either "General Transport" (GT) or "Special Transport" (ST). Amongst the modifications made was the elimination of the ventral turret, while the dorsal unit was downgraded to a manually-operated twin gun arrangement; the internal space was heavily altered by the elimination of bomb-aiming apparatus and the rear fuselage tank. Additions also included a quick-release hook, installed at the rearmost part of the fuselage for the towing ofgliders.[14]When used as a paratroop transport, a maximum of ten fully armed troops could be carried; these paratroopers were provided with a dropping hatch in the rear fuselage along with a single large loading door in the starboard side of the fuselage.[20][14]

Operational history

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Ambitions to use Albemarle in the bomber role were dropped almost immediately upon the type reaching service; this was due to it not representing an improvement over current medium bombers (such as theVickers Wellington) and possessing inferior performance to the new generation four-engined heavy bombers that were also about to enter service with the RAF. However, the aircraft was considered to be suitable for general reconnaissance and transport duties, and thus was re-orientated towards such missions.[1]

TheSoviet Air Forceplaced a contract for delivery of 200 Albemarles in October 1942. An RAF unit –No. 305 FTU,atRAF ErrolnearDundee– was set up to train Soviet ferry crews.[21][22][23]During training, one aircraft was lost with no survivors. The first RAF squadron to operate the Albemarle wasNo. 295atRAF Harwellin January 1943.[22]Other squadrons to be equipped with the Albemarle includedNo. 296,No. 297andNo. 570.The first operational flight was on 9 February 1943, in which a 296 Squadron Albemarle dropped leaflets overLisieuxin Normandy.[citation needed]

A Soviet-crewed Albemarle flew from Scotland toVnukovoairfield, near Moscow, on 3 March 1943, and was followed soon afterwards by eleven more aircraft.[21]Two Albemarles were lost over theNorth 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 AmericanDouglas C-47 Skytrains.The Soviet camp at Errol Field continued until April 1944: apparently the Soviet government had hoped to securede Havilland Mosquitos.[citation needed]Tapper speculated that a major reason for the Soviet's interest in the Albemarle had been its Bristol Hercules engines, which werereverse engineeredand subsequently copied by Soviet industries.[22]

Armstrong Whitworth Albemarle of No. 296 or 297 Squadron RAF, taking off fromBrize Norton,Oxfordshire,with an Airspeed Horsa Mark I in tow.

From mid-1943, RAF Albemarles took part in many British airborne operations, beginning with theinvasion of Sicily.[24]The pinnacle of the aircraft's career was a series of operations forD-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 duringOperation Tonga;296 Squadron used 19 aircraft to towAirspeed 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. ForOperation Mallardon 7 June 1944, the squadrons towed 220 Horsas and 30 Hamilcars to Normandy. On 17 September 1944, duringOperation Market Gardenat Arnhem, 54 Horsas and twoWaco Hadriangliders were towed to the Netherlands by 28 Albemarles of 296 and 297 squadrons; 45 aircraft were sent the following day towing gliders.[25]Of the 602 aircraft delivered, 17 were lost on operations and 81 lost in accidents.[citation needed]

The final RAF unit to operate the Albemarle was the Heavy Glider Conversion Unit, which replaced its examples withHandley Page Halifaxesduring February 1946, at which point the type was formally retired from all operational units.[citation needed]

Variants

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Over the course of its production life, a number of variants of the Albemarle were built:[26]

  • 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. TheST 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.[16]The 14ST Mk I Series 2aircraft were equipped with gear for towing gliders. The Mk II could carry tenparatroopsand 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 HerculesXIradial engines.TheMk IIIandMk IVAlbemarles were development projects for testing different powerplants; the former used theRolls-Royce MerlinIII and the latter used the 1,600 hp (1,200 kW)Wright Double Cyclone.[27]

Operators

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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.[citation needed]
United Kingdom

Royal Air Force

  • No. 161 Squadron RAF– Albemarle I from October 1942 to April 1943 atRAF Tempsford.
  • No. 271 Squadron RAFoperated one aircraft at Doncaster between October 1942 and April 1943.
  • No. 295 Squadron RAF– Albemarle I from November 1943 to July 1944 atRAF Hurnand thenRAF 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 Crossincluding operations in North Africa. Albemarle II from November 1943 to October 1944 at RAF Hurn and thenRAF 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 atRAF 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 atRAF 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 RAFused three aircraft atRAF St Evalfrom September 1942 to March 1943
  • No. 1406 Flight RAFused two aircraft atRAF Wickfrom September to October 1942.
  • No. 13 Operational Training Unit RAFat RAF Finmere (two aircraft between October 1942 and April 1943)
  • No. 42 Operational Training Unit RAFat RAF Ashbourne from September 1943 to February 1945.
  • Heavy Glider Conversion Unit at RAF Brize Norton andRAF North Luffenhamfrom 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 toRAF Elsham Woldsin December 1945 and withdrew the last operational Albemarles in February 1946.
  • No. 22 Heavy Glider Conversion Unit atRAF KeevilandRAF Blakehillfrom October 1944 to November 1945.
  • No. 23 Heavy Glider Conversion Unit atRAF Peplowfrom October to December 1944.
  • No. 3 Glider Training School operated eight Albemarles atRAF Exeterbetween 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 atRAF Deffordused one aircraft during May 1943,
  • Airborne Forces Experimental EstablishmentatRAF RingwayandRAF Sherburn-in-Elmetbetween May 1942 and October 1944.
  • Coastal Command Development Unit used two aircraft atRAF Tainbetween September and December 1942.
  • Central Gunnery School atRAF Sutton Bridgeused one aircraft between September and November 1942.
  • Bomber Development Unit used three aircraft atRAF Gransden Lodgebetween 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, theRoyal Aircraft Establishment,andAeroplane and Armament Experimental Establishment.One was operated by De Havilland Propellers for research into reversing propellers.[citation needed]

Specifications (ST Mk I)

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Orthographic projection of the Albemarle.

Data fromThe Unloved Albemarle,[28]Armstrong Whitworth Aircraft since 1913[29]

General characteristics

  • Crew:
    • Four (two pilots, navigator and radio operator) in Transport configuration
    • Six (two pilots, navigator/bomb-aimer, radio operator and two gunners) in Bomber configuration
  • Capacity:ten troops
  • 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)
  • Max takeoff weight:36,500 lb (16,556 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 HerculesXI 14-cylinder air-cooledradial engines,1,590 hp (1,190 kW) each
  • Propellers:3-bladed de Havilland Hydromatic

Performance

  • 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)[30]
  • 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)

Armament

  • Guns:
  • Bombs:Internal bomb bay for 4,500 lb (2,000 kg) of bombs

See also

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Aircraft of comparable role, configuration, and era

Related lists

References

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Citations

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  1. ^abcButtler 2004, p. 75.
  2. ^abTapper 1988, pp. 285.
  3. ^abcdeTapper 1988, p. 276.
  4. ^abcTapper 1988, pp. 276–277.
  5. ^abcdefgTapper 1988, p. 277.
  6. ^abTapper 1988, pp. 278–279.
  7. ^Tapper, Oliver (1973).Armstrong Whitworth Aircraft Since 1913.Putnam. p. 276.ISBN978-0-370-10004-3.
  8. ^Mason 1994, pp. 335–337.
  9. ^abTapper 1988, pp. 279–280.
  10. ^Tapper 1988, pp. 280–281.
  11. ^"British Aircraft of WWII."jaapteeuwen.com.Retrieved: 15 March 2007.
  12. ^Flight27 January 1944, p. 89.
  13. ^Tapper 1988, pp. 277–278.
  14. ^abcdeTapper 1988, p. 278.
  15. ^Flight27 January 1944, p. 90.
  16. ^abFlight27 January 1944, p. 88.
  17. ^abWilliams 1989, p. 37.
  18. ^Tapper 1988, p. 279.
  19. ^Williams 1989, p. 36.
  20. ^Bridgman, Leonard.Jane's Fighting Aircraft of World War II.New York: Crescent Books, 1988.ISBN0-517-67964-7.
  21. ^abWilliams 1989, p. 41.
  22. ^abcTapper 1988, p. 283.
  23. ^Mark Felton video on Soviet use of Albemarles
  24. ^Tapper 1988, pp. 283–284.
  25. ^Tapper 1988, pp. 284–285.
  26. ^Tapper 1988, pp. 281, 286.
  27. ^Tapper 1988, p. 281.
  28. ^Williams 1989, p. 40.
  29. ^Tapper 1988, p. 286.
  30. ^"Albemarle",Air Transport Auxiliary Ferry Pilots Notes.

Bibliography

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  • Air Transport Auxiliary Ferry Pilots Notes.Elvington, Yorkshire, UK: Yorkshire Air Museum, Reproduction ed. 1996.ISBN0-9512379-8-5.
  • 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.ISBN0-571-11515-2.
  • Buttler, Tony.British Secret Projects: Fighters and Bombers 1935–1950.Hinckley, UK: Midland Publishing, 2004.ISBN1-85780-179-2.
  • Mason, Francis K.The British Bomber since 1914.London: Putnam Aeronautical Books. 1994.ISBN0-85177-861-5.
  • 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.ISBN0-85177-826-7.
  • 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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