This book may not contain everything you want to know about the 'Rainbow' project, but it certainly contains every scrap that is available. Author Machat has wrung every conceivable source dry for material, most of which now presides in the archives of the Cradle of Aviation Museum on Long Island. An admirable effort has also been made to present a thorough picture of the XF-12/XR-12 - including the attempts to gain a foothold in the commercial airline market - even going so far as to document the 'what-if' variants possible, had the project really survived to full production. In beautifully rendered color profiles, Machat explores the possibilities running from aerial tanker for the Air Force's early jet bomber fleet (no more 'tobogganing' behind a lumbering KC-97) to electronic warfare platforms - all certainly within the realm of believability, and worth consideration.
I enjoyed the inclusion as well of Howard Hughes' XF-11, making a good balance in fleshing out the whole postwar USAF high-speed reconnaissance competition.
It is a shame to see Specialty Press closing its doors, but they couldn't ask for a grander 'farewell' to the publishing arena than this volume. I recommend it highly.