Nelson BB-1 Dragonfly

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    Nelson BB-1 Dragonfly

    High-wing, semi-monocoque wooden motorglider; seats two side-by-side, powered by pusher engine mounted on aft end of fuselage pod, between twin tail booms; retractable tricycle landing gear.

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This object is on display in the Boeing Aviation Hangar at the Steven F. Udvar-Hazy Center in Chantilly, VA.

Boeing Aviation Hangar

In 1945, William H. Bowlus and Ted Nelson formed the Nelson Aircraft Corporation to build a two-seat, motor glider version of the popular Bowlus BA-100 Baby Albatross. The designers nicknamed this design the Bumblebee but they sold the powered glider under the official moniker, Dragonfly. The men retained the basic Baby Albatross design but significantly widened the cockpit and added side-by-side seating and flight controls for each occupant. Other improvements included tricycle landing gear and a steerable nose landing gear, additional vertical fins mounted on the ends of the horizontal stabilizer, and a hinged canopy. A handle to pull-start the engine was also available inside the cockpit. The aft section of the fuselage pod on the Baby Albatross was an ideal place to install a pusher engine and propeller. Bowlus and Nelson first selected a Ryder four-cylinder, two-cycle power plant but this engine only managed to produce about 16 horsepower. This was not enough power for flight so Nelson decided to build a suitable engine from scratch. His new motor generated 25 horsepower, barely enough to takeoff and slowly climb.

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.

Gift of Charles R. Rhoades.