Avro 679 Manchester


 

In May 1936 Group Captain R.D. Oxland, Director of the Air Ministry's Operational Requirements, issued specification P.13/36 for a six seat twin engine bomber with cruising speed of 275 mph (443 km/h), achieving this by means of a high wing loading. It was also to be capable of carrying internally a 12,000 lbs (5442 kg) maximum bomb load, or a single 8,000 lbs (3628 kg) bomb, or a pair of torpedoes. The bomber was to have a range of 3,000 miles (4831 km) carrying a load of around 4,000 lbs (1814 kg). It was also to be capable of carrying out dive bombing attacks from an angle of 30 degrees. A major innovation was to be the use of power operated gun turrets which had just been perfected.

Two firms were invited to build prototypes of their design submissions. Handley Page submitted their H.P.56 design and Avro submitted the Avro 679 Manchester (Contract No. 624973/37/C4(c) of 30 april 1937. Avro Works Order No. 5667). Both prototypes were to use the new Roll-Royce Vulture "X" Type 24-cylinder engine then under development, with an expected rating of around 2,000 hp (1492 kW) per unit. Handley Page had doubts that the Vulture engine would emerge as a reliable production powerplant, and in 1937 set about the task of redesigning the H.P.56 to take four Bristol Taurus engines, (soon changed to incorporate Rolls-Royce Merlins instead), effectively withdrawing from the competition. A fateful decision on the part of Handley Page, as the redesigned Handley Page H.P.56 would lead to the development of the four engined H.P.57 Halifax, itself to become a rival to the Lancaster when the latter eventually replaced the Manchester.

The Vulture was a very complex engine, effectively two Rolls-Royce Peregrine (Kestrel) 12-cylinder engine blocks joined together (one inverted on top of the other) with the lower pair being inverted to give an X-type arrangement driving a single crankshaft and with an intricate lubricating system. In reality the engines only produced between 1,480 - 1,500 hp (1104 - 1119 kW) and suffered from chronic overheating. Early hydraulic system failures were also common but this was eventually traced to an oil leak which fouled the undercarriage microswitches and was corrected.

The first of two Manchester prototypes (L7246) flew on 25 July 1939 from Ringway Airport piloted by Group Captain H.A. Brown. While only airborne for 17 minutes It was long enough to realize that the Vulture engines were turning out much less power than anticipated and wing loading made the aircraft extremely difficult to fly. It was followed by the second (L7247) on 26 May 1940 (armed with a two-gun nose, tail and a ventral turret). On 1 July 1937 a production contract No. 648770/37/C4(c) was placed for 200 aircraft to meet another Air Ministry specification, P.19/37. This was later increased to 400 aircraft, but in the end only 200 were built before being replaced on production lines by the Lancaster.

Following flight trials take-off's were found to be longer than excepted, and in order to correct the problem the wing span was increased from 82 ft 2" (25.04 m) to 90 ft 1 in (27.46 m). A lack of directional stability, which indicated that the area of the tail fins was insufficient, was also discovered and a central fin was added to supplement the small twin fins and rudders. Later, after a number of Manchesters had been delivered as Mk Is, the central fin was deleted and the twin fins increased in area and in this form it became the Mk IA. The prototype and first two production aircraft were delivered to the Armament Experimental Establishment, Boscombe Down, for tests, while the second prototype went to the Royal Aircraft Establishment, Farnborough.

Even with the prototype flying and flight trails proceeding, development of the aircraft was far from complete. The Vulture engines continued to prove unreliable averaging only 76 flying hours between engine failures, and in flight ran extremely hot requiring the pilot to continuously nurse them. Engine bearing failures, caused mainly from lack of oil circulation, were also causing major problems. And much to the dismay of the Avro Engineers, it was found that the aircraft was unable to maintain height when flying on one engine while at heavier loaded weights. Prototype L4246 having to make emergency landings in a convenient field on more than one occasion during the trails. The Air Ministry too, were not helping things, as they continued to revise to requirements of the aircraft from those originally specified. Although, in most cases these changes actually deleted requirements from the aircraft, most of these initial requirements were already built into the aircraft and could not be easily "designed out" again.

The first squadron delivery was to No. 207 on 6 November 1940, which had reformed at Waddington on 1 November 1940. The first operational sortie of the type was made by six Manchesters (18 were on squadron strength) against German Capital ships in Brest, on the night of 24/25 February 1941 when they attacked the German cruiser Admiral Hipper with 500 lbs (227 kg) armour-piercing bombs (12 per aircraft). Flak was moderate and all the aircraft returned safely but L7284 crash landed at Waddington when the hydraulic system failed. During this raid it was revealed that the bomb-aimer did not have a good enough field of view to see where his bombs hit.

By April, a second squadron had formed on Manchesters, No. 97, and aircraft from both units joined Bomber Command raids in the coming months, but continued problems with the engines meant further groundings, and during one such time, in April 1941, when all 40 aircraft were to have engine bearings replaced, it was discovered that repeated overheating of the Vultures was causing the oil to lose its viscosity in one-fifth of the expected time. Other modifications were made to aircraft to allow carriage of the new 4,000lb bombs.

During the summer of 1941, No. 61 Squadron became the third Manchester squadron, and the first to receive a revised version featuring larger fins which cured the poor handing of the earlier aircraft. As deliveries built up, other squadrons became equipped with the new bomber, these included Nos. 49, 50, 57, 83, 106, 408 and 420, while No. 144 Squadron of RAF Coastal Command received enough aircraft to form one flight.

The Manchester proved to be a failure mainly because of the unreliability of the Vulture engines and the inability of these powerplants to deliver their designed power. Hydraulic system problems also plagued the aircraft. There were also a number of airframe defects and it was with great relief that squadrons began to relinquish their Manchesters from mid-1942 as Lancasters began to replace them.

The last Bomber Command Manchester operation took place on 25/26 June 1942 against Bremen, and in the final tally it was found that the type had flown 1,269 sorties, dropping 1885 tonnes (1,826 tons) of high explosive (HE), plus incendiaries. Some 202 aircraft were built, of which about 77 aircraft were lost on operations and 20 aircraft were written off in crashes, with another 24 aircraft being lost on training flights with non-operational units. At least 33 of the aircraft lost were due directly to engine failures. However, on the credit side, the Manchester paved the way for the Lancaster, and without the earlier aircraft one must conjecture whether or not the RAF's finest bomber would have seen the light of day. One Victoria Cross was awarded to Flying Officer L. T. Manser, a Manchester pilot assigned to No. 50 Squadron for his actions on 30 May 1942.

Manchester's were to continue in service with the RAF until June 24, 1942, when the last squadron finally traded their aircraft in for a newer type. The aircraft was then relegated to training purposes, where they remained for a short period. Finally being totally removed from the RAF's requirements before the war's end.

Variants

Manchester B.Mk I - Two 1,760 hp (1312 kW) Rolls-Royce Vulture I 24-cylinder X-form inline piston engines.

Manchester B.Mk IA - Two 1,760 hp (1312 kW) Rolls-Royce Vulture I 24-cylinder X-form inline piston engines. The central fin was deleted and the twin fins were enlarged to correct a problem with tail flutter.

Manchester B.Mk II - The Rolls-Royce Vulture engines were proving wholly inadequate and unreliable, resulting in three projects in order to correct the problem. This was the first of the projected versions using two 2,240 hp (1671 kW) Napier Sabre "I" Type horizontal 24-cylinder four-stroke sleeve-valve liquid-cooled piston engines with two-speed superchargers. Not built.

Manchester B.Mk IIA - A projected version using two 2,520 hp (1880 kW) Bristol Centaurus XI 18-cylinder two-row sleeve-valve air-cooled radial engines with two-speed superchargers. Not built.

Manchester B.Mk III - A projected version using four Rolls-Royce Merlin X 12-cylinder liquid-cooled engines each rated at 1,075 hp (802 kW) for take-off and 1,130 hp (843 kW) at 5,250 ft (1525 m) at 3,000 rpm. This was the first of the projects completed. Using a Manchester B.Mk I airframe (Serial BT308) and fitted with a new wing centre section of 102 ft (31.09 m), into which the new engines were installed. The aircraft first flew on 9 January 1941 and it didn't take the designers long to see that they created a truly remarkable aircraft. This four engine aircraft was so successful that the twin-engined projects (Manchester B.Mk II & IIA) were dropped. Later given the new designation Lancaster Prototype BT308, the new "Lancaster" was ordered into production (using unfinished Manchester airframes) as soon as the 200th Manchester aircraft had been completed.

Specifications (Avro 679 Manchester B.Mk IA)

Type: Six or Seven Seat Medium Bomber

Accommodation/Crew: Pilot, Co-Pilot/Navigator, Bombardier/Nose Gunner, Wireless/Radio Operator and 2 Gunners. A third dedicated gunner could be carried depending on equipment and loadout.

Design: Chief Designer Roy Chadwick and Managing Director Roy Dobson of A. V. Roe Aircraft Company Limited

Manufacturer: Alexander V. Roe (Avro) Aircraft Company Limited based in Greengate, Middleton (Chadderton), Manchester with plants in Newton Heath, Manchester and Ivy Works, Failsworth, Lancashire. Prior to 1938, the main plant was located in Newton Heath, but in the spring of 1939 the company moved its main office to the new, much larger facility in Greengate (157 aircraft built). In order to further expand production capability, Metropolitan Vickers Limited of Trafford Park (contract No. B108750/40/C4(a) January 1941 for 43 aircraft), Fairey Aviation Limited of Hayes (Contract No. B108750/40 - none built) and Armstrong Whitworth Limited of Coventry (Contract No. B108750/40 - none built) were also contracted to build the Manchester.

Powerplant: Two 1,760 hp (1312 kW) Rolls-Royce Vulture "I" 24-cylinder X-form inline piston engines driving metal three-bladed de Havilland propellers. The engine was actually created by joining two Rolls-Royce Peregrine (Kestrel) 12-cylinder engine blocks together on a single crankcase with the lower pair being inverted to give an X-type arrangement. In reality the engines only produced between 1,480 - 1,500 hp (1104 - 1119 kW).

Performance: Maximum speed 265 mph (426 km/h) at 17,000 ft (5180 m); cruising speed of 185 mph (298 km/h) at 15,000 ft (4570 m); service ceiling 19,200 ft (5850 m).

Fuel Capacity: 1,700 Imperial gallons (2060.26 US gallons or 7726 litres).

Range: 1,630 miles (2623 km) on internal fuel with a bombload of 8,100 lbs (3674 kg) or 1,200 miles (1930 km) with maximum bombload of 10,350 lbs (4695 kg).

Weights & Loadings: Empty 29,432 lbs (13350 kg) with a maximum designed take-off weight of 56,000 lbs (25401 kg). In use the maximum take-off weight never exceeded 50,000 lbs (22680 kg).

Dimensions: Span 90 ft 1 in (27.46 m); length 69 ft 4 in (21.13 m); height 19 ft 6 in (5.94 m); wing area 1,137 sq ft (105.63 sq m).

Defensive Armament: A total of eight 7.7 mm (0.303 in) Browning machine-guns in nose, dorsal and tail turrets. Early B.Mk I aircraft had a Frazer-Nash (Nash and Thompson) F.N.25A belly "dustbin" turret or Frazer-Nash F.N.21A ventral turret instead of a dorsal turret.

  • 2 7.7 mm (0.303 in) Browning trainable forward-firing machine-guns in the power-operated Frazer-Nash F.N.5 nose turret with 1,000 rpg and a Mk III Reflector gunsight.
     

  • 2 7.7 mm (0.303 in) Browning trainable machine-guns in the power-operated Frazer-Nash F.N.7 dorsal turret with 1,000 rpg and a Mk III Reflector gunsight.
     

  • 4 7.7 mm (0.303 in) Browning trainable rearward-firing machine-guns in the power-operated Frazer-Nash F.N.20A tail turret with 2,500 rpg and a Mk III Reflector gunsight.

Disposable Ordnance: Up to 10,350 lbs (4695 kg) of bombs and/or incendiaries.

  • 2 18 in (457 mm) torpedoes, or
     

  • 4 sea mines, or
     

  • 4 2,000 lbs (907 kg) bombs, or
     

  • 12 500 lbs (227 kg) bombs, or
     

  • 2 4,000 lbs (1814 kg) bombs, or
     

  • 1 4,000 lbs (1814 kg) bomb and 6 x 1,000 lbs (454 kg) bombs.
     

Variants: Manchester B.Mk I, B.Mk 1A, B.Mk II, B.Mk IIA, B.Mk III (Lancaster prototype).

Equipment/Avionics: Standard communications and navigation equipment.

History: First flight (prototype L7246) 25 July 1939; first flight (prototype L7247) 26 May 1940; first service delivery (No. 207 Squadron RAF) 6 November 1940; end production November 1941; retired from service 24 June 1942.

Operators: United Kingdom (RAF), Canada (RCAF).

Units: RAF Squadron Nos. 9 (training only), 44, 49, 50, 57, 61, 83, 97, 106, 144 (one flight only) & 207. The RAF also operated two training units (No. 25 Operational Training Unit (Finningley) & No. 1485 Bombing & Gunnery School). The Royal Canadian Air Force (RCAF) operated two squadrons Nos. 408 & 420.