Early example of a flat twin aircraft engine, on display in the National Air &amp; Space Museum in Washington, D.C. It is suitable only for single seat aircraft and was used in a quadraplane in approximately 1913.
<a href="//commons.wikimedia.org/wiki/User:Fletcher6" title="User:Fletcher6">Fletcher6</a>
<span class="int-own-work" lang="en">Own work</span>