This combination of power plant and propeller allowed the Dragonfly to climb 235 feet per minute at sea level. The extra weight of the engine, plus the drag from the widened fuselage, gave the Dragonfly a mediocre lift-to-drag ratio. The self-launch capability cost too much performance to appeal to most prospective motorglider owners and Bowlus and Nelson only sold seven Dragonflys. Nelson attempted to design another self-launching glider in 1949 but this time, he teamed with Harry Perl. Don Mitchell also helped on the new airplane. Nelson and Perl called this new design the Hummingbird (see NASM collection). Nelson mounted a more powerful Nelson engine on a retractable pylon behind a two-seat, tandem cockpit. This arrangement improved the soaring performance but the aircraft cost much more than a conventional, two-seat glider and Nelson and Perl built only six Hummingbirds.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/28567825@N03">Cliff</a> from I now live in Arlington, VA (Outside Washington DC), USA
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<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/28567825@N03/2973029411/">Nelson BB-1 Dragonfly</a>