Question: Information: - Avro was a British aircraft manufacturer founded in 1910 whose designs include the Avro 504 used as a trainer in the First World War, the Avro Lancaster, one of the pre-eminent bombers of the Second World War, and the delta wing Avro Vulcan, a stalwart of the Cold War. - Heavy bombers are bomber aircraft with the greatest bomb load carrying capacity and longest range of their time. They have also typically been among the largest size aircraft in contemporary military or civil service. Delivery of the largest possible amount of air-to-ground weaponry over long distances to strike enemy targets is the heavy bomber's mission (see also strategic bomber). - A strategic bomber is a medium to long range penetration bomber designed to drop large amounts of air-to-ground weaponry onto a distant target for the purposes of debilitating the enemy's capacity to wage war. Unlike tactical bombers, penetrators, fighter-bombers, and attack aircraft, which are used in air interdiction operations to attack enemy combatants and military equipment, strategic bombers are designed to fly into enemy territory to destroy strategic targets (e.g., infrastructure, logistics, military installations, factories, and cities). In addition to strategic bombing, strategic bombers can be used for tactical missions. The United States, Russia, and China maintain strategic bombers. - The Avro 504 was a World War I biplane aircraft made by the Avro aircraft company and under licence by others. Production during the War totalled 8,970 and continued for almost 20 years, making it the most-produced aircraft of any kind that served in World War I, in any military capacity, during that conflict. Over 10,000 were built from 1913 to the time production ended in 1932. - Air-to-ground weaponry is aircraft ordnance used by combat aircraft to attack ground targets. The weapons include bombs, machine guns, autocannon, air-to-surface missiles, rockets, air-launched cruise missiles and grenade launchers. - The Avro 684 was a proposed British high altitude heavy bomber of the Second World War , based on Avro 's successful Lancaster . - The Avro Lancaster is a British four-engined Second World War heavy bomber designed and built by Avro for the Royal Air Force (RAF). It first saw active service with RAF Bomber Command in 1942 and, as the strategic bombing offensive over Europe gathered momentum, it was the central implement for the night-time bombing campaigns that followed. It became the main heavy bomber used by the RAF, the RCAF, and squadrons from other Commonwealth and European countries serving within the RAF, overshadowing its close contemporaries the Handley Page Halifax and Short Stirling. The "Lanc", as it was affectionately known, thus became one of the more famous and most successful of the Second World War night bombers, "delivering 608,612 long tons of bombs in 156,000 sorties." The Lancaster, an evolution of the troublesome Avro Manchester, was designed by Roy Chadwick and was powered by four Rolls-Royce Merlins, or, in one version, Bristol Hercules engines. - The Avro Vulcan (later Hawker Siddeley Vulcan from July 1963) is a jet-powered tailless delta wing high-altitude strategic bomber, which was operated by the Royal Air Force (RAF) from 1956 until 1984. Aircraft manufacturer A.V. Roe and Company (Avro) designed the Vulcan in response to Specification B.35/46. Of the three V bombers produced, the Vulcan was considered the most technically advanced and hence the riskiest option. Several scale aircraft, designated Avro 707, were produced to test and refine the delta wing design principles. - The Cold War was a state of political and military tension after World War II between powers in the Eastern Bloc (the Soviet Union and its satellite states) and powers in the Western Bloc (the United States, its NATO allies and others). Historians do not fully agree on the dates, but a common timeframe is the period (the second half of the 20th century) between 1947, the year the Truman Doctrine (a U.S. policy pledging to aid nations threatened by Soviet expansionism) was announced, and 1991, the year the Soviet Union collapsed. - A bomber is a combat aircraft designed to attack ground and sea targets by dropping air-to-ground weaponry, firing torpedoes or deploying air-launched cruise missiles. What entity does 'avro 684' has the relation 'subclass of' with?
Answer:
aircraft