Specifications (Avro 683 Lancaster B.Mk I & III)
Type: Seven or Eight Seat Heavy Bomber
Accommodation/Crew: A crew of seven consisting of the Pilot, Flight Engineer, Observer/Nose Gunner/Bomb-aimer, Navigator, Radio/Wireless Operator, Mid-Upper Gunner, and Tail Gunner. The Bomb-aimer was in the nose position below the front turret. Above and behind and to the port is the Pilot’s position in a raised canopy with good all-round vision and armour plating on the back of the seat and armour protection behind his head. Inside the canopy immediately aft of the pilot’s seat is the Fighting Controller’s position and is provided with special bullet-proof glass. Slightly aft of this position is the Navigator’s position, with table, chart stowage and astral done in the roof. At the rear end of the navigator’s table and just forward of the front spar is the Radio Operator’s station. Within the centre-section is a restroom with a bed. Aft of the rear spar is the mid-upper and mid-lower turrets, together with various equipment stowage for flares, emergency rations, etc. A dinghy is carried in the centre-section trailing-edge portion of the wing and is automatically deployed and inflated upon impact with water. It can also be operated by hand. In the extreme tail is the rear turret. A walkway is provided along the entire length of the fuselage and the main entrance door is situated on the starboard side just forward of the tailplane.
Design: Chief Designer Roy Chadwick and Managing Director Roy Dobson of A. V. Roe Aircraft Company Limited based on the Avro 679 Manchester design.
Manufacturer: Alexander V. Roe (Avro) Aircraft Company Limited based in Greengate, Middleton (Chadderton), Manchester with another production facility located at Yeadon. 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. In order to further expand production capability, Metropolitan Vickers Limited of Trafford Park (Manchester), Armstrong Whitworth Limited of Baginton and Bitteswell (Coventry), Austin Motors of Longbridge (Birmingham), Vickers Armstrong of Chester and Castle Bromwich and Victory Aircraft of Canada (Malton, Ontario) also built the aircraft. A large number of sub-contractors were also involved in component manufacture.
Powerplant: (B.Mk I) Initially four Rolls-Royce Merlin XX or 22 Vee 12-cylinder liquid-cooled inline engines each rated at 1,280 hp (955 kW) for take-off and 1,240 hp (925 kW) at 2,850 rpm at 10,000 ft (3050 m) with a maximum power rating of 1,480 hp (1104 kW) at 3,000 rpm at 6,000 ft (1830 m). Late production B.Mk I aircraft being equipped with four Rolls-Royce Merlin 24 Vee 12-cylinder liquid-cooled inline engines rated at 1,620 hp (1209 kW) for take-off and 1,240 hp (925 kW) at 2,850 rpm at 10,000 ft (3050 m) with a maximum power rating of 1,640 hp (1223 kW) at 3,000 rpm at 2,000 ft (610 m). (B.Mk II) Four Bristol Hercules VI 14-cylinder two-row air-cooled radial engines rated at 1,615 hp (1205 kW) for take-off and 1,675 hp (1250 kW) at 2,900 rpm at 4,500 ft (1370 m) with a maximum power rating of 1,675 hp (1250 kW) at 2,900 rpm at 4,500 ft (1450 m). The radial engined Lancasters had a higher top speed but also had a higher fuel consumption. (B.Mk III) Four American-built Packard Merlin 28 Vee 12-cylinder liquid-cooled inline engines each rated at 1,300 hp (970 kW) for take-off, or four American-built Packard Merlin 38 (Merlin 22) Vee 12-cylinder liquid-cooled inline engines each rated at 1,390 hp (1037 kW) for take-off. Some later B.Mk III aircraft had the American-built Packard Merlin 224 (Merlin 24) Vee 12-cylinder liquid-cooled inline engines each rated at 1,620 hp (1209 kW) for take-off. All Merlin engines used a mechanically driven, two-speed, single stage, centrifugal supercharger. Note: Rolls-Royce engine marks up to XX (twenty) are distinguished by Roman numbers, while marks above that were distinguished by Arabic numericals.
Propellers: Hamilton-Standard or Rotol propellers. In later aircraft paddle-bladed Nash-Kelvinator propellers were used increasing the cruising speed by 8 mph (12.9 km/h) and the service ceiling by 1,500 ft (457 m). The airscrew shaft was a SBAC No. 5 type with a reduction gear ratio of 0.42:1.
Performance: (Early B.Mk I) Maximum speed 275 mph (443 km/h) at 15,000 ft (4572 m). (Late B.Mk I) Maximum speed 287 mph (462 km/h) at 11,500 ft (3505 m), 275 mph (443 km/h) at 15,000 ft (4572 m), 260 mph (419 km/h) at 19,400 ft (5913 m); cruising speed 234 mph (377 km/h) at 21,000 ft (6401 m), 200 mph (322 km/h) at 15,000 ft (4572 m); stalling speed (clean) 95 mph (153 km/h) at 60,000 lbs (27211 kg); normal service ceiling 23,000 ft (7010 m), nominal service ceiling 24,500 ft (7468 m); absolute service ceiling 24,671 ft (7500 m); climb to 20,000 ft (6096 m) in 41 minutes and 40 seconds; initial rate of climb 250 ft (76 m) per minute with full bombload. In a hard dive the prototype aircraft achieved speeds reaching almost 400 mph (644 km/h) with production aircraft (operational loadout) being limited to 360 mph (578 km/h).
Carburetion (Merlin): SU float carburettor, type AVT 40 / 241 / 216 / 224 / 227. American built Packard Merlins had the Bendix Stromberg pressure-injected type.
Ignition (Merlin): Two BTH C.5 SE12-S or Rotax NSE12-4 magnetos.
Fuel Capacity / Specification: A total of six fuel tanks consisting of two 580 Imperial gallon (703 US gallon or 2637 litre) inboard tanks, two 383 Imperial gallon (464 US gallon or 1740 litre) intermediate tanks and two 114 Imperial gallon (138 US gallon or 518 litre) outboard tanks giving the aircraft a total fuel capacity of 2,154 Imperial gallons (2,610.6 US gallons or 9790 litres). Provisions for one or two overload fuel tanks of 400 Imperial gallons (485 US gallons or 1818 litres) each could be carried in the bomb bay. Fuel specification 100 / 130 Grade DED 2475 (AN-F-28).
Coolant Capacity / Specification: 5 Imperial gallons (6 US gallons or 22.7 litres) per engine made up of 70 percent water + 30 percent ethylene glycol to specification DTD 344 A.
Oil Capacity / Specification: Each engine had its own oil tank in the nacelle with a capacity of 37.5 Imperial gallons (45.4 US gallons or 170.25 litres) for a total of 150 Imperial gallons (181.6 US gallons or 681 litres). Oil specification DED 2472 / B / O.
Range (typical): 2,530 miles (4072 km) with a bombload of 7,000 lbs (1795 kg); 1,730 miles (2786 km) with a bombload of 12,000 lbs (5442 km); 1,550 miles with a bombload of 22,000 lbs (9977 kg).
Weights & Loadings: Empty (clean) 39,600 lbs (16740 kg), empty (equipped) 53,300 lbs (24040 kg) with a maximum take-off weight of 65,000 lbs (29480 kg). The B.Mk I Special had a maximum take-off weight of 70,000 lbs (31751 kg) while carrying a 22,000 lbs (9980 kg) Grand Slam bomb. Wing loading 52.7 lbs/sq ft (258 kg/sq m); power loading 13.3 lbs/hp (6.35 kg/hp).
Dimensions: Span 102 ft 0 in (31.09 m); length 69 ft 6 in (21.18 m); height 20 ft 6 in (6.25 m); wing area 1,297.0 sq ft (120.49 sq m); tailplane area: 237.0 sq.ft (22.0 sq m); tail fin and rudder area: 111.40 sq ft (10.35 sq m); aileron span 17 ft 3 in (5.3 m).
Gunsights: The main gunsight used in Lancaster turrets was the Barr & Stroud G Mk Ill reflector sight. In use the screen was mounted at a 45 degree angle showed an illuminated orange circle with a central dot, both focused at infinity. A brightness control adjusted it according to conditions; bright in sunlight, dim at night. The radius of the circle was approximately equal to the wingspan of a single-engined fighter at a range of 1,200 ft (365 m), while the radius of the circle gave the deflection (the amount of aiming ahead) needed to hit a target with a relative crossing speed of 50 mph (80 km/h). In 1944, the Mk llc gyroscopic sight entered service as a turret sight. This could actually predict the point of aim, if the approaching fighter could be tracked for a short while, and its wingspan set on a dial.
Defensive Armament: A total of ten 7.7 mm (0.303 in) Browning machine-guns in a nose, mid-upper, tail and ventral position. The ventral position was soon deleted on most RAF Lancasters as it was thought unnecessary and took the same position as the H2S radome. Where possible, and unofficially, many crews installed a single 7.7 mm (0.303 in) or 12.7 mm (0.50 in) Browning machine-gun on aircraft lacking the ventral turret in order to deal with the ever increasing ‘behind and below’ attacks of German night fighters using Schräge Musik, which interesting, did not use tracer ammunition. These were hastily installed configurations usually consisting of the gunner sitting on a bicycle type seat with the ammunition box being bolted to the floor and the gun mounted in a hole cut into the floor. The British would eventually re-introduce the F.N.64 turret on aircraft equipped with G-H radar (an improved version of Gee) since that type of radar did not have the large radome as the H2S required. During 1943/1944 when the use of Schräge Musik on german Nachtjagd (night fighters) became widespread, the new twin-gun F.N.64 power-operated turrets became the most important gun position on the bomber. On aircraft that were modified to carry the “Tall Boy” or “Grand Slam” bombs, most had the nose and mid-upper turrets were removed and the tail turret reduced to a single pair of 7.7 mm (0.303 in) Browning machine-guns in order to reduce weight. The 7.7 mm (0.303 in) ammo consisted of Ball, Tracer, Armour Piercing and Incendiary.
2 × 7.7 mm (0.303 in) Browning Mk II trainable forward-firing machine-guns in the power-operated Frazer-Nash F.N.5A nose turret with 1,000 rounds per gun using a Barr & Stroud G Mk III reflector sight.
2 × 7.7 mm (0.303 in) Browning Mk II trainable machine-guns in the power-operated Frazer-Nash F.N.50 (Boulton-Paul) dorsal turret with 1,000 rounds per gun using a Barr & Stroud G Mk IIIA reflector sight.
4 × 7.7 mm (0.303 in) Browning Mk II trainable rearward-firing machine-guns in the power-operated Frazer-Nash F.N.20A tail turret with 2,500 rounds per gun using a Barr & Stroud G Mk III reflector or Gyro Mk IIc sight.
2 x 7.7 mm (0.303 in) Browning Mk II trainable rearward firing machine-guns in a power-operated Frazer-Nash F.N.64 ventral turret with 500 rounds per gun using a periscopic sight. (This position did not have a dedicated gunner).
Offensive Ordnance: Up to 8,000 lbs (3629 kg) of bombs carried in a 33 ft (10.0 m) long under fuselage internal bomb bay. While capable of carrying much more weight, early aircraft were limited to 8 x 1,000 lbs (454 kg) GP/MC (General Purpose Medium Capacity) bombs due to the physical restrictions of the bomb bay, but continued improvements enabled later production aircraft to carry up to 14,000 lbs (6350 kg) of bombs normally, including 2,000 lbs (907 kg) AP (Armour Piercing) or HE/SAP (High Explosive Semi-Armour Piercing) bombs, 4,000 lbs (1814 kg) HE/HC (High Explosive High Capacity) ‘Block Buster’ (also called a “Cookie”) and a single 8,000 lbs (3628 kg) HE/HC (High Explosive High Capacity) bomb. Some aircraft underwent special modifications to allow them to carry the 12,000 lbs (5443 kg) HE/DP (High Explosive Deep Penetration) ‘Tall Boy’, the 12,000 lbs (5443 kg) HE/HC (High Explosive High Capacity) ‘Factory Buster’ and the 22,000 lbs (9979 kg) HE/DP (High Explosive Deep Penetration) ‘Grand Slam’ bombs. The 12,000 lbs (5443 kg) HE/HC ‘Factory Buster’ was actually three 4,000 lbs (1800 kg) HC High Explosive “Cookies” bolted together given the bomb a total of 5,200 lbs (2358.7 kg) of Torpex ‘cemented’ within a 1 inch (25.4 mm) jacket of TNT. Aircraft capable of carrying the larger 4,000 lbs (1800 kg) and 8,000 lbs (3629 kg) bombs can easily be identified by the use of a bulged bomb bay door. Standard loadouts were as follows:
Blast & Demolition – 1 x 8,000 lbs (3628 kg) HE plus up to 6 x 500 lbs (227 kg) HE bombs.
Blast & Demolition – 14 x 1,000 lbs (454 kg) bombs.
Blast, Demolition & Fire – 1 x 4,000 lbs (1814 kg) HE ‘Cookie’ plus 3 x 1,000 lbs (454 kg) HE bombs plus up to 6 SBC (Small Bomb Cannisters) each holding either 236 x 4 lbs (1.8 kg) or 24 x 30 lbs (13.6 kg) incendiaries.
Blast, Demolition & Fire – 1 x 4,000 lbs (1814 kg) HE ‘Cookie’ plus up to 12 SBC (Small Bomb Cannisters) each holding either 236 x 4 lbs (1.8 kg) or 24 x 30 lbs (13.6 kg) incendiaries.
Maximum incendiary – 14 SBC (Small Bomb Cannisters) each holding either 236 x 4 lbs (1.8 kg) or 24 x 30 lbs (13.6 kg) incendiaries.
Deployed Tactical Target – 1 x 4,000 lbs (1814 kg) HE ‘Cookie’ plus up to 18 x 500 lbs (227 kg) HE bombs.
Low Level Attack – 6 x 1,000 lbs (454 kg) HE bombs with delayed action fuses.
Hardened Targets & Ships – 6 x 2,000 lbs (907 kg) AP bombs with very short fuses.
Mine Laying – Up to 6 x 1,500 lbs (680 kg) or 1,850 lbs (839 kg) parachute sea mines which could be either acoustic or magnetic. First used on the night of 3/4 March 1942.
Variants: BT308 (first prototype), DG595 (second prototype), B.Mk I, B.Mk I Special (Grand Slam), B.Mk I FE (Far East), B.Mk II (Hercules engines), B.Mk III, B.Mk III Type 464 Special (Dambuster), B.Mk IV (renamed Lincoln Mk I), B.Mk V (renamed Lincoln Mk II), B.Mk VI, B.Mk VII, B.Mk VIII FE (Far East), B.Mk X (Canadian Built).
Equipment/Avionics: The Mark IXA Course-Setting Bomb Sight (CSBS) and the Mark XIV Computing Bomb Sight (CBS) were standard. The Radio section is complete with a Marconi Transmitter T.1154 and Receiver R.1155 with a Morse key on the right of the wireless operators table. The operator was also provided with a switching gear to connect crew positions to the receiver or transmitter if required. H2S “Fishpond” Indicator 182 aircraft detection display plus all the auxiliary equipment. The Navigators section contains the Gee & Oboe radio guidance navigation equipment, H2S main blind bombing/mapping radar with the PPI (Plan Position Indicator) plus all the navigation aids used prior to the introduction of the Gee, Oboe & H2S radars. An improved H2X radar would replace the older H2S radar after German FuG 350 Naxos Z radar equipped night fighters could home in on the H2S radar transmissions. Some aircraft used the “Monica” tail mounted early warning radar which was effective to a range of about 1,000 yards, but had no IFF (Identification Friend or Foe) capability. Monica was discontinued in use when it was discovered that German FuG 227 Flensburg radar equipped night fighters could actually home in on the transmission signal given out by the Monica radar. Rebecca navigation radar was also used on small numbers of aircraft. Boozer early warning radar (ground and air) was also used and considered better than Monica. Tinsel was an electronic warfare jamming device which in its early use was successful, but German response to the device limited later effectiveness. An automatic gun-laying apparatus (A.G.L.T) code-named ‘Village Inn’ was fitted to the F.N.121 tail turret to allow radar guided beyond visual range firing. The device although potentially devastating, it originally lacked the ability to distinguish between Friend or Foe. The aircraft is also fully equipped for night flying. An F.24 camera was standard equipment for vertical photography to confirm bombing accuracy.
Wings/Fuselage/Tail Unit: The wings are of a mid-wing cantilever monoplane type. The wing is made up of five main sections, comprising a centre-section of parallel chord and thickness which is integral with the fuselage centre-section, two tapering outer sections and two semi-circular wing-tips. Subsidiary wing units consist of detachable leading and trailing-edge sections of outer wings and centre-section, flaps and ailerons. All units are built up individually with all fittings and equipment before assembly. Two-spar wing structure, each spar consisting of a top and bottom extruded boom bolted on to a single thick gauge webplate. Ribs are aluminium-alloy pressings suitably flanged and swaged for stiffness. The entire wing is covered with a smooth aluminium-alloy skin. Ailerons on outer wing sections have metal noses and are fabric covered aft of the hinges. Trimming tabs in ailerons. Split trailing-edge flaps between ailerons and fuselage. The fuselage in an oval all-metal structure in five separately assembled main sections. The fuselage backbone is formed by pairs of extruded longerons located halfway down the cross-section of the three middle sections. Cross beams between these longerons support the floor and form the roof of the bomb compartment. “U”-frames and formers bolted to the longerons carry the smooth skin plating. The remaining sections are built up of oval frames and formers and longitudinal stringers, covered with flush riveted metal skin. All equipment and fittings are installed before final assembly of the separate units. The tail unit is a cantilever monoplane type with twin oval fins and rudders. Tailplane in two sections built up in similar manner to the wings, the tailplane spars being joined together within the fuselage on the centreline. Tailplane, fins and rudders are metal covered with the elevators covered in fabric. Trimming tabs in elevators and rudders.
Landing Gear: The main landing gear was retractable with a fixed tailwheel. Main wheels are hydraulically retracted into the inboard engine nacelles and hinged doors connected to the retracting gear close the apertures when the wheels are raised. The main landing wheels have a track of 23 ft 9 in (7.24 m).
History: First flight (prototype BT308) 9 January 1941; first flight (prototype DG595) 13 May 1941; first flight (Mk II prototype BT310) 26 November 1941; first flight (Canadian B.Mk X) 6 August 1943; last new delivery (Mk I (FE) serial TW910) 2 February 1946; last aircraft retired from RAF service (MR.Mk III) February 1954.
Operators: United Kingdom (RAF & BOAC), Canada (RCAF), Australia (RAAF), New Zealand (RNZAF), Poland (Free Polish Squadron serving with the RAF). Post-war operators included Argentina, France (Aéronavale), Egypt and Sweden.
Units: The Lancaster equipped Nos. 7, 9, 12, 15, 35 (Madras Presidency), 44 (Rhodesia), 49, 50, 57, 61, 83, 90, 97 (Straits Settlements), 100, 101, 103, 106, 109, 115, 138, 149 (East India), 150, 153, 156, 166, 170, 186, 189, 195, 207, 218 (Gold Coast), 227, 514, 550, 576, 582, 617 (Dambuster), 619, 622, 625, 626, 630 & 635 RAF Bomber Command Squadrons. The Lancaster initially entered service with No. 44 (Rhodesia) Squadron based at Waddington followed by No. 97 Squadron and then No. 207 Squadron. No. 300 (Masovian) was an all Polish Squadron serving with the RAF. Squadron No. 101 was a special unit whose aircraft could be distinguished externally by three large aerials on top of the fuselage. They carried the top-secret ABC (Air-Borne Cigar) from October 1943 onwards. ABC was a jammer working on the German night fighter frequency and required an additional member of the crew to operate it. Lancasters of No. 101 Squadron carried a full load of bombs and scattered throughout the bomber streams, accompanied the Main Force on nearly every raid. In the later stage of the war, with multi-pronged raids becoming the norm, 101 Squadron would become the largest Lancaster squadron of all, with a final complement of 42 aircraft.
Royal Canadian Air Force Squadrons No. 405 (Vancouver), 408 (Goose), 419 (Moose), 424 (Tiger), 426 (Thunderbird), 427 (Lion), 428 (Ghost), 429 (Bison), 431 (Iroquois), 432 (Leaside), 433 (Porcupine), 434 (Bluenose) Squadrons all equipped the Lancaster. The Royal Australian Air Force equipped three squadrons Nos. 460, 463 & 467 and the Royal New Zealand Air Force equipped No. 75 Squadron with Lancasters.
Number Built: 7,366
