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| Armstrong Whitworth Albemarle prototype (note the yellow "P" on a disc thinly outlined in yellow identifying it as a prototype). |
The Armstrong Whitworth A.W.41 Albemarle was a twin-engine
transport aircraft developed by the British aircraft manufacturer Armstrong
Whitworth and primarily produced by A.W. Hawksley Ltd, a subsidiary of the
Gloster Aircraft Company. It was one of many aircraft which entered service
with the Royal Air Force (RAF) during the Second World War.
The Albemarle had been originally designed as a medium
bomber to fulfill Specification B.9/38 for an aircraft that could be built of
wood and metal without using any light alloys; however, military planners
decided to deemphasize the bomber role in favor of aerial reconnaissance and
transport missions, leading to the aircraft being extensively redesigned
mid-development. Performing its maiden flight on 20 March 1940, its entry to
service was delayed by the redesign effort, thus the first RAF squadron to
operate the Albemarle, No. 295 at RAF Harwell, did not receive the type in
quantity until January 1943. As superior bombers, such as the Vickers
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, paratroop transport and glider
towing, in addition to other secondary duties. Albemarle squadrons participated
in Normandy landings and the assault on Arnhem during Operation 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examples in RAF service were withdrawn less than a year after the war's end.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, the Soviet Air Force also 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 favor of procuring the American Douglas C-47 Skytrain instead.
Development
Background
The origins of the Albemarle can be
traced back to the mid-1930s and the issuing of Specification B.9/38 by the
British Air Ministry. This sought a twin-engine medium bomber of wood and metal
construction, without the use of any light alloys, 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 standard Queen Mary trailer to facilitate the
adoption of a dispersed manufacturing strategy. 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.
Several aircraft manufacturing
firms, including Armstrong Whitworth, Bristol and de Havilland, were approached
to produce designs to meet the specification. 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 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. The AW.41 was designed with
Rolls-Royce Merlin engines in mind, but also with provisions for the use of
Bristol Hercules as an alternative powerplant.
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. 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.
Into Production
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. Furthermore,
according to aviation author Oliver Tapper, the brief was a relatively
difficult one for any company to fulfill. Initially, physical work centered
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 number P1360, was assembled at Hamble Aerodrome by Air
Service Training; the aircraft performed its maiden flight on 20 March 1940.
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. Months later, P1360 was damaged after a forced landing during the test
flight program, but was promptly repaired. Early flights of the type by test
pilots typically described it as being relatively average and being free of
flaws. 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. 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 the rudder's trailing edge to 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.
The Albemarle's production run was
principally undertaken by A.W. Hawksley Ltd of Gloucester, a subsidiary of the
Gloster Aircraft Company, which was specifically formed to construct the
Albemarle. Originally, Gloster was to have undertaken this work itself at its
Brockworth facility. Both Gloster and Armstrong Whitworth were member companies
of the Hawker Siddeley group, one of the largest aircraft manufacturing
interests in Britain. Individual parts and sub-assemblies for the Albemarle
were produced by in excess of 1,000 subcontractors. Amongst the companies that
were subcontracted were MG Motor, to produce the forward fuselage, Rover, which
constructed the wing centre section, and Harris Lebus, which built the
tailplane units. Production of the Albemarle was terminated during December
1944, by which point 602 aircraft had been completed.
Design
The Armstrong Whitworth Albemarle was a mid-wing cantilever
monoplane with twin fins and rudders. The fuselage was built in three primary
sections; the structure being composed of unstressed plywood over a steel tube
frame, including four circular steel longerons; most elements were bolted
together via gusset plates. 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 center 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.
Aside from a portion of the leading edge that used light alloys, the majority
of the wing was covered in plywood. The extension wings were almost entirely
made of wood, save for the bracing of the two spars by steel tubing; the
Frise-type ailerons and tailplane were also composed of wood. The structure of
the forward section used stainless steel tubing as to reduce interference with
magnetic compasses.
The Albemarle featured a Lockheed-designed
hydraulically-operated, retractable tricycle 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 the Royal Air Force. Power was provided by a pair of Bristol
Hercules XI air-cooled radial engines, each capable of 1,590 hp and driving a
three-blade de Havilland Hydromatic propeller unit. Fuel was typically stored
in four tanks, two in the center fuselage and two within the wings center
section; in circumstances where extended range would be required, a maximum of
additional auxiliary tanks could be installed within the aircraft's bomb bay.
This sizable bomb bay was equipped with hydraulically-operated doors and
spanned from just aft of the cockpit to roughly halfway between the wings and
the tail.
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 a
Boulton-Paul design, which was electrically operated and originally armed with
four Browning machine guns. A fairing forward of the turret automatically retracted
as the turret rotated to fire forwards. 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, the Mk I Series I, were produced in such a
configuration.
As a bomber, the Albemarle was commonly considered to be
inferior to several other aircraft already in RAF service, such as the Vickers
Wellington; according to aviation author Ray Williams, the type was only used
ever used as a bomber on two occasions. 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 of gliders. 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.
Operational History
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 the Vickers
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.
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, in which a 296 Squadron Albemarle 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 favor of abundant
American Douglas C-47 Skytrains. The Soviet camp at Errol Field continued until
April 1944: apparently the Soviet government had hoped to secure de Havilland
Mosquitos. Tapper speculated that a major reason for the Soviet's interest in
the Albemarle had been its Bristol Hercules engines, which were reverse
engineered and subsequently copied by Soviet industries.
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 final RAF unit to operate the Albemarle was the Heavy
Glider Conversion Unit, which replaced its examples with Handley Page Halifaxes
during February 1946, at which point the type was formally retired from all
operational units.
Type: Transport, glider tug
National origin: United Kingdom
Manufacturer: Armstrong Whitworth Aircraft
Built by: A W Hawksley Ltd
Primary users:
Royal Air Force (RAF)
Soviet Air Force
Number built: 602
Manufactured: 1941–1944
Introduction date: January 1943
First flight: 20 March 1940
Retired: February 1946
Variants
Over the course of its production life, a number of variants
of the Albemarle were built:
ST Mk I: 99 aircraft
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)
Maximum 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 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)
Guns:
Four × .303 in (7.7 mm) Browning
machine guns in dorsal turret.
Two × .303 in (7.7 mm) machine
guns in ventral turret (first prototype only)
Bombs: Internal bomb bay for 4,500 lb (2,000 kg) of bombs
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 ten 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.
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 – 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.
Bibliography
Air Transport Auxiliary Ferry
Pilots Notes. Elvington, Yorkshire, UK: Yorkshire Air Museum, Reproduction ed.
1996.
Bowyer, Michael J.F. Aircraft for
the Royal Air Force: The "Griffon" Spitfire, The Albemarle Bomber and
the Shetland Flying-Boat. London, UK: Faber & Faber, 1980.
Buttler, Tony. British Secret
Projects: Fighters and Bombers 1935–1950. Hinckley, UK: Midland Publishing,
2004. I
Mason, Francis K. The British
Bomber since 1914. London, UK: Putnam Aeronautical Books. 1994.
Morgan, Eric B.
"Albemarle". Twentyfirst Profile, Volume 1, No. 11. New Milton,
Hants, UK: 21st Profile Ltd.
Tapper, Oliver. Armstrong Whitworth
Aircraft since 1913. London: Putnam, 1988.
Williams, Ray. "The Unloved
Albemarle". Air Enthusiast, Thirty-nine, May–August 1989, pp. 29–42.
"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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| Armstrong Whitworth Albemarle prototype. |
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| Armstrong Whitworth Albemarle of No. 296 or 297 Squadron RAF, taking off from Brize Norton, Oxfordshire, with an Airspeed Horsa Mark I in tow. 1944. |
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| Airspeed Horsa glider is towed into the air by an RAF Albemarle, part of the second airborne drop on the night of 6th June 1944. |
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| Airspeed Horsa towed by an Armstrong Whitworth Albemarle. |
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| Armstrong Whitworth Albemarle P5-S. |
