Some of the most significant engineering and technological breakthroughs of the last century centered on the development of piston aero engines from the 1920s through to the 1950s when they began to be supplanted by jet engines. This book explains in detailed, well illustrated, and easy-to-understand terms how these piston-powered radial engine airliners developed throughout this long era.Many magnificent aircraft took to the skies from the early small single-engine airliners carrying a handful of passengers of the 1920s to large long-range, four-engine aircraft carrying many passengers and linking all the world’s continents by air in the 1950s.This book not only traces the technical evolution of every radial-engine power plant used over that time span but also includes interesting and fact-filled sidebars that detail what it was like flying aboard each generation of these aircraft. In 1948, the largest radial piston engine ever produced entered airline service, the mighty 3,500-hp 28-cylinder Pratt & Whitney R-4360. This is one of 12 different radial engines covered in-depth by the authors of this book.Colourfully illustrated stories of flying aboard the world’s greatest piston-powered airliners are interwoven with detailed yet comprehensible descriptions and graphics showing the intricacies of high-performance piston radial engines. The advancement and success of America’s air transportation system can be linked directly to the concurrent growth of long-range, high-speed airliners and their revolutionary power plants. This book tells the compelling story of this aspect of the development of aviation for the very first time.