An illustrated guide to three of the most important piston-engined airliners of the postwar era. With his hugely successful commercial aircraft, including the legendary DC-3, founder Donald W. Douglas led his company to the forefront of aircraft manufacturers starting in the 1930s. "Depend on Douglas" was the company motto, and the company founder stood behind it with his name. Between 1945 and 1960, the DC-4, DC-6, and DC-7 four-engine "Big Prop" models were flown by many of the world's most famous commercial airlines of the era, including Pan Am, United, American, Eastern, Delta, KLM, BOAC, Swissair, SAS, Air France, Alitalia, and Japan Air Lines. This is the history of the design, development, and operational use of the Douglas Big Props, including technical specifications and details of military variants. Period photographs bring to life the fascinating history of these early, and influential, commercial airliners, some of which still fly today. AUTHOR: Wolfgang Borgmann's enthusiasm for aviation was passed on to him by his parents, who were active in the aviation field. In his early years, he began building up an aviation historical collection that provides numerous rare photos and documents, as well as exciting background information, for his books. Since April 2000, Borgmann has been active as an author and freelance aviation journalist. Since February 2022, he works as editor for the leading German civil aviation magazine Aero International. He lives in Oerlinghausen, Germany. His website is www.aerojournalist.de. SELLING POINTS: . The DC-4 is famous largely through its military versions, the C-54 and R5D, both of which played major roles in both WWII and the Berlin Airlift . Commercial variants of Douglas "Big Props" flew with Pan Am, United, American, Eastern, Delta, KLM, BOAC, Swissair, SAS, Air France, Alitalia, Japan Air Lines, and many others . Originally developed for a military contract as an improved version of the DC-4, the DC-6 project led to a highly successful commercial airliner, some of which are still operating today 160 colour and b/w photographs