In February of 1942 the Avro Lancaster four-engined heavy bomber was introduced for service with the Royal Air Force (RAF). Its participation in World War 2 (1939-1945) proved to be ultra-critical to the bombing campaign - and overall success - of the Allied war effort. Over 7,000 were produced and the last was not retired until 1963 by Canadian forces. While the Lancaster was developed from the Avro Manchester, it too served as the basis for several other large aircraft cousins all its own - the Avro Lincoln Heavy Bomber and the Avro York four-engined transports were two of its offspring.
Avro proceeded with the design of a new four-engined transport based on its Lancaster under the "Type 685" designation. To expedite its development, the new aircraft retained the wing sections, tail unit and undercarriage of the original and had an all-new slab-sided fuselage added for improved internal volume. A double-finned rudder arrangement was seated at the extreme aft-end of the aircraft (just as in the Lancaster) and the cockpit flight deck was fitted at the extreme front end of the aircraft with good views over the nose. The operating crew numbered four.
Power stemmed from 4 x Rolls-Royce Merlin 24 series liquid-cooled inline piston engines developing 1,280 horsepower each. Performance specs went on to include a maximum speed of 300 miles per hour, a range out to 3,000 miles, a service ceiling of 23,000 feet and a rate-of-climb of 820 feet-per-minute.
In 1942, the Air Ministry laid out Specification C.1/42 calling for a transport-minded aircraft and this led to interest in the Avro project of which three prototypes were ordered (four were eventually built). LV626 was the first to fly on July 5th, 1942 but, due to the revised aerodynamics of the new aircraft (when compared to the Lancaster), there proved issues with stability and control which led to the adoption of a triple-finned tail unit. Satisfied, the RAF took the transport into service and the series eventually stocked the inventories of over twenty of its squadrons. Several special groups also operated the type and some were even modified to serve in the VIP role. Beyond the RAF, the aircraft was also used by allies in Australia, France and South Africa. Total production reached 259 units (including prototype examples).
Initial military production models were the York C.I of which 208 examples were manufactured by Avro with a single unit being built by Victory Aircraft of Canada. The Canadian company ramped up for larger-scale production but the war ended after just one was completed and parts for a further five were made. The York C.II became a "one-off" prototype fitting 4 x Bristol Hercules XVI air-cooled radial piston engines - this form was not adopted for service.
The York found gainful employment in the civilian market even during the war years - delivered to British Overseas Airways Corporation (BOAC) during February of 1944 for overseas routes. The series endured into the post-war years as well, taking part in the Berlin Airlift (1948-1949) and in airliner and cargo-hauling service ventures. At least forty-four were operated as civilian-market-minded York Mk.Is and these served the nations of Australia, Argentina, Canada, Iran, Lebanon, South Africa and the United Kingdom.
The RAF Museum at Cosford holds an Avro 685 in its collection.