Boeing Y1B-17, front view.
U.S. Air Force
circa 1937 <div style="display: none;">date QS:P,+1937-00-00T00:00:00Z/9,P1480,Q5727902</div>
<a rel="nofollow" class="external free" href="https://media.defense.gov/2006/Jun/01/2000554890/-1/-1/0/060512-F-1234S-002.JPG">https://media.defense.gov/2006/Jun/01/2000554890/-1/-1/0/060512-F-1234S-002.JPG</a>, from <a rel="nofollow" class="external text" href="https://www.nationalmuseum.af.mil/Upcoming/Photos/igphoto/2000554890/">gallery page</a>.