Avro 691 Lancastrian
British four-engine transport/airliner

Archive Photos ^1,21

Airplane Card: Avro 691 Lancastrian, Barbers Teas, UK, 1956, Card 10 of 25. (The Skytamer Archive copyright © 2013 Skytamer Images) ²

Overview ²

• Avro 688 Lancastrian
• Role: Passenger and mail transport
• Manufacturer: Avro
• Designer: Roy Chadwick
• First flight: 1943
• Introduction: 1945 (BOAC)
• Retired: 1960
• Primary users: BOAC; Trans Canada Airlines; Alitalia; Royal Air Force; Rolls-Royce (engine test-beds)
• Produced: 1943-1945
• Number built: 91 (including conversions)
• Developed from: Avro Lancaster

The Avro 691 Lancastrian was a Canadian and British passenger and mail transport aircraft of the 1940s and 1950s developed from the Avro Lancaster heavy bomber. The Lancaster was named after Lancaster, Lancashire; a Lancastrian is an inhabitant of Lancashire.

The Lancastrian was basically a modified Lancaster bomber without armor or armament and with the gun turrets replaced by streamlined metal fairings, including a new nose section. The initial batch was converted directly from Lancasters; later batches were new builds.

Design and Development ²

In 1943, Canada’s Victory Aircraft converted a Lancaster × bomber for civil transport duties with Trans-Canada Airlines (TCA). (After the war Victory Aircraft was purchased by what became Avro Canada). This conversion was a success resulting in eight additional Lancaster Xs being converted. The "specials" were powered by Packard-built Merlin 38 engines and featured a lengthened, streamlined nose and tail cone. Range was increased by two 400 gal (1,818 L) Lancaster long-range fuel tanks fitted as standard in the bomb bay. These Lancastrians were used by TCA on its Montreal-Prestwick route.

The modification of abundant military aircraft into desperately needed civil transports was common in the United Kingdom in the immediate post-war period: the Handley Page Halton was a similar conversion of the Halifax heavy bomber.

Operational History ²

In 1945, deliveries commenced of 30 British-built Lancastrians for BOAC. On a demonstration flight on 23 April 1945 (G-AGLF) flew 13,500 mi (21,700 km) from England to Auckland, New Zealand in three days, 14 hours at an average speed of 220 mph (354 km/h).

The Lancastrian was fast, had a long range, and was capable of carrying a heavy load, but space inside was very limited as the Lancaster had been designed with space for its 7 crew dispersed through the fuselage, and the 33 ft (10.05 m) long bomb bay. Consequently it was not suited to carry large numbers of passengers, but for mail and a small number of VIP passengers. BOAC used it for flights between England and Australia from 31 May 1945. It also served with the RAF; RAF Lancaster I (PD328) was converted to a Lancastrian and renamed Aries, as well as serving with QANTAS and Flota Aérea Mercante Argentina.

Lancastrians were used during the Berlin Airlift to transport petrol; 15 aircraft made over 5,000 trips. In 1946 a Lancastrian operated by BSAA was the first aircraft to make a scheduled flight from the then-newly opened London Heathrow Airport.

Lancastrian Engine Test-beds ²

With the advent of gas turbine engines there emerged a need to test the new engines in a controlled flight environment in well instrumented installations. An ideal candidate emerged as the Avro Lancastrian which could easily accommodate the test instrumentation as well as fly on the power of two piston engines if required. Several Lancastrians were allocated for engine test-bed work with turbojet engines replacing the outer Merlin engines or test piston engines in the inner nacelles. Fuel arrangements varied but could include Kerosene jet fuel in outer wing tanks or fuselage tanks, with AVGAS carried in remaining fuel tanks.

The B.S.A.A Lancastrian 3, Star Dust ²

On 2 August 1947 Lancastrian Star Dust (G-AGWH) of British South American Airways was lost in the Argentine Andes, whilst en route from Buenos Aires, Argentina, to Santiago, Chile. The probable cause of the crash was a navigation error due to the then-unknown effect of the fast-moving jetstream.

Variants ²

• Lancaster XPP: Nine built by converting Lancasters at Victory Aircraft Ltd. Canada.
• Lancastrian C.1: Nine-seat transport aircraft for BOAC and Qantas. Royal Air Force designation Lancastrian C.1 to Specification 16/44. A total of 23 built by Avro.
• Lancastrian C.2: Nine-seat military transport aircraft for the RAF. A total of 33 built by Avro.
• Lancastrian 3: 13-seat transport aircraft for British South American Airways. A total of 18 built by Avro.
• Lancastrian C.4: Ten to 13-seat military transport aircraft for the RAF. Eight built by Avro.

Operators ²

Civil Operators

• Argentina: Flota Aérea Mercante Argentina
• Australia: Qantas
• Canada: Trans Canada Airlines
• Italy: Alitalia - six Lancastrians operated circa 1948
• United Kingdom: British European Airways; British Overseas Airways Corporation (BOAC); British South American Airways; Flight Refuelling Ltd.; Silver City; Skyways Limited

Military Operators

• Argentina: Argentine Air Force
• United Kingdom: Royal Air Force

Avro 691 Lancastrian Specifications ⁴

Type

• Four-engined long-range mail, freight and passenger transport.

Manufactures

• A. V. Roe and Co Ltd

Wings

• Mid-wing cantilever monoplane.
• Wing in five main sections, comprising a center-section of parallel chord and thickness which is integral with the fuselage center-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 center-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 web-plate.
• Ribs are aluminum-alloy pressings suitably flanged and swaged for stiffness.
• The entire wing is covered with a smooth aluminum-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.

Fuselage

• 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.
• Same as Lancaster but with new nose and tail fairings

Tail Unit

• Cantilever monoplane type with twin oval fins and rudders.
• Tail-plane in two sections built up in similar manner to the wings, the tail-plane spars being joined together within the fuselage on the center-line.
• Tailplane, fins and rudder, are metal-covered, elevators covered with fabric.
• Trimming-tabs in elevators and rudders.

Landing Gear

• Retractable main wheels and fixed tail-wheel.
• 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.
• Track: 23 ft 9 in (7.24 m).

Powerplants

• Four 1,280-hp Rolls-Royce Merlin 24 twelve-cylinder Vee liquid-cooled engines with two-speed superchargers.
• Three-blade de Havilland constant-speed full-feathering airscrews.
• Fuel tanks in wings (2,154 Imp. gallons) and in fuselage beneath cabin floor (1,020 Imp. gallons).

Accommodation

• Crew of five and nine passengers.
• Two pilots side-by-side with dual controls.
• Navigator and radio-operator behind pilots.
• Passenger cabin with seats for nine on portside facing inwards.
• These seats may be converted into three sleeping bunks by lowering seat backs.
• Three further bunks pull down from the roof above the seats.
• Sound proofing, ventilation and oxygen equipment.
• Toilets and gallery.
• Mail and freight carried in nose compartment and beneath floor of cabin.
• Storage aft of passenger accommodation for life-saving dinghies.

Dimensions

• Span: 102 ft 0 in
• Length: 76 ft 10 in
• Height: 19 ft 6 in
• Net wing area: 1,205 ft²
• Gross wing area: 1,297 ft²

Weights and Loadings

• Tare weight: 3,426 lbs
• Fixed and removable equipment (including electrical, instruments, auto-controls, radio, de-icing, dinghies, heating and ventilation, and oxygen): 4,160 lbs
• Furnishings (including bunks, mattresses, settees, toilets, upholstery, carpets, sound-proofing, galley, food and water): 1,564 lbs
• Weight fully equipped and furnished: 36,150 lbs
• Fuel (3,174 Imp. gallons): 22,853 lbs
• Oil (150 Imp. gallons): 1,350 lbs
• Crew (5 at 170 lbs): 850 lbs
• Crew baggage: 200 lbs
• Passengers (9 at 170 lbs each): 1,530 lbs
• Passenger’s baggage: 495 lbs
• Mail or freight: 1,572 lbs
• Payload (passengers, baggage and cargo): 3,597 lbs
• Maximum payload (with corresponding reduction in fuel): 4,845 lbs
• Weight loaded: 65,000 lbs.
• Wing loading: 50.10 lbs/ft²
• Power loading: 12.7 lbs/hp

Performance

• Maximum speed at 3,500 ft with a mean weight of 53,000 lbs: 295 mph; at 12,000 ft: 310 mph
• Maximum weak mixture cruising speed at 11,000 feet: 275 mph; at 17,500 ft: 285 mph
• Rate of climb at 9,500 ft with a weight of 65,000 lbs: 750 ft/min; at 16,000 feet: 550 ft/min
• Service ceiling: 23,000 feet

Ranges
Under still air conditions with no allowance for take-off and climb and using 3,174 Imp. gallons of fuel and caring 3,597 lbs payload at 15,000 ft).

• At maximum weak mixture cruising speed of 265 mph: 3,570 miles
• At speed between most economical and maximum weak mixture cruising speed of 232 mph: 3,950 miles
• At most economical speed of 200 mph: 4,501 miles

References

1. Shupek, John. Avro 691 Lancastrian 3-view drawing via The Skytamer Archive (3-view drawing by John Shupek copyright © 2013 Skytamer Images. All Rights Reserved)
2. Barbers Teas, Airplanes, Airplane Trade Cards, 1956, UK
3. Wikipedia, the free encyclopedia. Avro Lancastrian
4. Bridgman, Leonard, Avro: The Avro 688 Tudor I (Avro XX). Jane’s All the World’s Aircraft 1945/1946. Sampson Low, Marston & Company Limited, London, 1946. pp. 13c-14c