Among the makers of these unusual aircraft were Focke-Wulf, Flettner and Wiener-Naustädter.[AuthorName]By (author) Heinz J. Nowarra[/AuthorName][AuthorBio][/AuthorBio][NumIllustration]b/w photographs, line drawings[/NumIllustration][CoAuthor][/CoAuthor][SubTitle][/SubTitle][ColorPattern]b/w photographs, line drawings[/ColorPattern]