<p>Martin MB-2 (NBS-1) reproduction, viewed from above, at the National Museum of the United States Air Force in Dayton, Ohio.
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(Unfortunately this photo was digitized poorly; a higher-quality scan would be much preferred.)
USAF
U.S. Air Force photo <a rel="nofollow" class="external autonumber" href="https://media.defense.gov/2007/Nov/07/2000432712/-1/-1/0/071107-F-1234S-003.JPG">[1]</a> from the <a rel="nofollow" class="external text" href="http://www.nationalmuseum.af.mil/Visit/Museum-Exhibits/Fact-Sheets/Display/Article/197395/martin-mb-2-nbs-1/">fact sheet</a> on the museum website.