<a href="https://en.wikipedia.org/wiki/Douglas_C-1" class="extiw" title="w:Douglas C-1">Douglas C-1C</a> (S/N 26-424) on Dec. 15, 1931. Aircraft is on a tow carriage used to move the plane around the airfield on the ground. (U.S. Air Force photo)
U.S. Air Force
1931-12-15
National Museum of the U.S. Air Force, <a rel="nofollow" class="external text" href="http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=3236">Factsheets : Douglas C-1C</a> (<a rel="nofollow" class="external text" href="http://www.nationalmuseum.af.mil/shared/media/photodb/photos/051127-F-1234P-015.jpg">image link</a>)