Their most productive period was during World War Two. A graceful, twin engined trainer-cum-light transport aircraft known as the AS10 Oxford had a production run exceeding 8,500. Almost 3,800 AS51 and AS58 Horsa gliders were built for the Royal Air Force and its allies. Many of these made one-way journeys into occupied France as part of the D-Day landings, towed from England by Commandos, Dakotass and other piston-engined aircraft.
In 1940 de Havilland bought the Airspeed company and, besides adapting some surplus Oxford aircraft as AS65 Consuls for the commercial market, they went on to produce a superbly streamlined twin-engined piston airliner called the AS57 Ambassador. This aircraft offered seating for 47 passengers and with a nosewheel undercarriage looked far more modern than the Commandos, Dakotas, Lancastrians and Vikings that were common on Europe's shorter airline routes. With three low fins it shared something of the character of the larger trans-continental Lockheed Constellation. It first flew on July 10th 1947. British European Airways operated up to twenty of them between 1952 and 1958, calling them "Elizabethans" in honour of the newly crowned Queen, it also helped the growth of Dan-Air an important airline in the development of package holidays. The popularity of this splendid aircraft was soon eclipsed however by the arrival of faster turboprops such as the Lockheed 188 Electra and the Vickers Viscount. Airspeed Ambassador 2 aircraft unfortunately made the headlines in a disastrous take off from Munich air disaster, West Germany on 6 February 1958 (also a tragedy for English football) and a spectacular fatal crash landing at London Heathrow Airport, England on 3rd July 1968 by a BKS AS57 Ambassador in which several horses on board died and a parked HS121 Trident was written-off just before the airliner hit terminal buildings. One has been preserved by the Imperial War Museum at Duxford, Cambridgeshire in eastern England.
Airspeed also refers to the speed of an aircraft in relation to the air which may be different from groundspeed which is the speed of the aircraft in relation to the ground. The difference between airspeed and groundspeed is a function of the velocity and direction of the wind. Airspeed is important because it determines the aerodynamic characteristics of the aircraft.