Here are a few I just came across today: American Aerospace Archive
Secret Aerospace Projects of the US Navy, Volume 1: The Incredible Attack Aircraft of the USS United States, 1948-1949
The American Aerospace Archive is a new journal exploring the history of aerospace research and development in the United States, with special emphasis on lesser known prototypes and unrealized projects. Based on extensive research in government and corporate archives, the magazine covers aircraft, missiles, helicopters, and other flying machines from the 1920s through the 1950s. Each issue features num