An Encyclopedia of the History of Technology part 66. This one of a kind encyclopedia presents the entire field of technology from rudimentary agricultural tools to communication satellites in this first of its kind reference source. Following an introduction that discusses basic tools, devices, and mechanisms, the chapters are grouped into five parts that provide detailed information on materials, power and engineering, transportation, communication and calculation, and technology and society, revealing how different technologies have together evolved to produce enormous changes in the course of history | PART THREE TRANSPORT Figure A Supermarine Spitfire VII of 1942 typical of the high-performance fighter of its time with all-metal structure and thin cantilever wings. The engine is a 1120kW 1500hp Rolls-Royce Merlin 61 with two-speed supercharger and the cabin was pressurized to allow operation up to 12 000m 40 000ft altitude. other types of similar configuration notably in the USA by the 14-seat Douglas DC-2 and 21-seat DC-3 Figure . With these aircraft the American airlines were able to provide regular reliable and safe passenger services. Safety and reliability were enhanced by effective de-icing measures blind-flying instruments air-toground radio communications meteorological forecasting services and the provision of hard-surfaced runways at airports. The pattern was followed in Europe and eventually world-wide. THE SECOND WORLD WAR The new technologies were applied also to military aircraft albeit somewhat hesitantly. New designs of fabric-covered biplane fighters with fixed undercarriages were still being introduced into Royal Air Force squadron service as late as February 1937 but by the outbreak of the Second World War in 1939 the front line fighter and bomber units of all the major air forces had been equipped with cantilever monoplanes with enclosed cockpits and retractable undercarriages. Engines of around 750kW 1000hp supercharged to maintain power at altitudes around 6000m 20 000ft became the norm. The Supermarine Spitfire may be taken as typical in 1939 the original Mark 1 version with a Merlin engine of 738kW 990hp driving a two-bladed wooden airscrew had a maximum speed of 588kph at 6150m 353mph at 20 000ft . Wartime development of the basic design produced the final operational version Mark 22 with a 1530kW 2050hp Griffon engine and five-bladed airscrew this achieved 735kph at 8000m 457mph at 25 000ft see Figure . 632 AERONAUTICS Progress in bomber design was rather less impressive but the twin-engined Vickers Wellington 1 bomber
