Boeing B-29A-70-BN (S/N 44-62305). Note the streamlined top turret added on block 40 A models and later.
U.S. Air Force photo
circa 1940 <div style="display: none;">date QS:P,+1940-00-00T00:00:00Z/9,P1480,Q5727902</div>s
NMUSAF Photo: <a rel="nofollow" class="external free" href="http://www.nationalmuseum.af.mil/shared/media/photodb/photos/060712-F-1234S-029.jpg">http://www.nationalmuseum.af.mil/shared/media/photodb/photos/060712-F-1234S-029.jpg</a>