How low(cost) can you go and still fly? That question forms one of the pursuits of the Minimalist Airplane Study Group, hosted by William Rich on Yahoo Groups. He may have found an answer that leads to several intriguing alternative uses for the type of electric powerplant described below. Use of model aircraft components leads to a low-cost build, and judicious use of off-the-shelf parts from other hobbies keeps costs low and speeds up the development process.
He points to a hack from Laserhacker.com, which uses a motor, controller, propeller batteries and connectors one might find at the local hobby shop. This assemblage manages to fly a paramotor despite the small size of the motor and the relatively small size of the propeller.
The Laserhacker link shows not only several videos (this has to be the most fun per dollar flying machine), but includes the parts list and pricing for everything but the final battery pack. Components include 3D-printed items from Thingiverse.com.
Weighing things out, this would be a remarkably light system. Batteries, for instance, calculated from packs comparable to the listed Zippy’s, would be around 10 pounds. The Turnigy Rotomax motor weighs 7.8 pounds and the Biela carbon fiber propeller a mere 0.6 pound. Even with the backpack frame and “Carp Buster” prop ring and net (clever repurposing of off-the-shelf parts) the system should not be over 25 pounds. This is less of a landing hazard and backache than the up-to-80 pounds of more powerful units.
Such innovations, starting with Csaba Lemak’s first flights with a powered paramotor in 2007, convinced your editor that lightweight electric flight was a practical and economic reality with rigid-wing machines. After all, Eric Raymond had flown across the United States in 2009 with his model-motor-powered Sunseeker, and others had demonstrated limited hops before that. But the draggy nature of the powered parasail showed that excellent performance might be possible with the units pushing or pulling ultralight aircraft skyward. Imagine a series of designs that use off-the-shelf model gear (including hybrids) to allow low-budget flying.
January 12 Followup
William Rich included the following in his Minimalist Airplane Study Group discussion yesterday. It has a link that helps one understand the basic design needs for powered paragliders.