The book, X-Plans: Research Aircraft 1891 - 1970 (Aviation Pioneers # 1) represents a unique pictorial study of flying prototypes, their designers and the pilots who flew them.  "X-Planes: Research Aircraft 1891 - 1970 (Aviation Pioneers # 1)" focuses on both the aviation breakthroughs and failures to tell the story of experimental aircraft between 1891 and 1970.  The author's lifelong professional involvement with aviation as both a pilot and research analyst lends a degree of authority as he explains why a particular design was shaped as it was or why another suffered a catastrophic in-flight failure.  "X-Planes: Research Aircraft 1891 - 1970 (Aviation Pioneers # 1)" benefits tremendously from the wealth of archival photographs many of which have never been previously published.  The major sections of "X-Planes: Research Aircraft 1891 - 1970 (Aviation Pioneers # 1)" are as follows: 1) Preface; 2) Chapter 1 - Early Essays, 1891 - 1912; 3) Chapter 2 - Helicopter Hopefuls, 1907-1957; 4) Chapter 3 - Evolving the Species, 1909-1955; 5) Chapter 4 - The Tailless Option, 1906-1952; 6) Chapter 5 - The Jet, The War And Big Problems, 1939-1945; 7) Chapter 6 Prototypes in Profusion, 1947-1964; 8) Chapter 7 - Faster, Higher, Further, 1946-1970; 9) Chapter 8 - Vertical Flight Without Rotors, 1954-1967 and 10) Index.  In addition to an informative narrative, this book includes approximately 185 black and white photographs many never previously published.  This book is 96 pages and is in very good condition.  The author is Hugh W. Cowin.  Edition published in 1999.