From the Syphus-Bunker Papers (MS-00169). The folder contains an original handwritten letter, an envelope, a typed transcription of the same letter, and a copy of original letter attached.
Transcribed from back of photo: "Howard Hughes (in cockpit) warms up the XF-11 for its initial test flight. It is one of the world's fastest long-range photographic planes, July 7, 1946."