A Twin-Motored Ultralight Flying Wing – It’s the New Millennium

Dean Sigler Electric Powerplants, Sustainable Aviation Leave a Comment

Richard Glassock, an Australian now living and working in Hungary, sent the links to YouTube videos of a Millennium hang glider, neatly electrified and flown at this year’s Santa Cruz Salt Flats Race.  Richard has been a speaker at the Electric Aircraft Symposium with a talk on his efforts with small hybrid electric power systems for large-scale models and small aircraft.

Steve Morris, co-designer of the Millennium along with Ilan Kroo, Brian Porter, Brian Robbins, and Erik Beckman helped develop this rigid-wing hang glider to offer a lighter, more portable version of Swift.  Steve reported on his electric-powered Swift at the 2010 Electric Aircraft Symposium.

Ilan Kroo reflected on the idea of practical, powered ultralight sailplanes in his American Institute of Aeronautics and Astronautics paper on the design of the Swift.  “With refinements in aerodynamic control and composite structures, hang gliders will continue to evolve toward more soarable foot-launched sailplanes. If one does not constrain the designs to be able to be launched like hang gliders, much higher performance ultralight sailplanes are possible. If an acceptably reliable, convenient, and quiet propulsion technology becomes more practical, a self-launching very light sailplane may finally make Lilienthal’s vision of routinely soaring like birds a reality.”

Steve Morris performed an early test of this idea with his Millennium, mounting a Zenoah 20-horsepower two-stroke engine to his aircraft.  As can be seen in the video, the machine has a tight turning radius, allowing one to “core” even a small-diameter thermal.

Since then, Steve has mounted a pair of tractor Turnigy RotoMax motors, Turnigy controllers and Hobby King battery packs.  He reports a cost of $3,000 to $3,600 for the complete power setup.

He explains, in the notes accompanying the first YouTube video, “This video shows 2 flights made during the 2015 Santa Cruz Flats Race in my electric powered Millennium hang glider. I only used the motors to gain initial altitude and then the remainder of each flight was thermal soaring. I used nearly maximum power for the first 200 feet of climb and then minimal power for climbing while trying to stay in lift until I stopped the motors. Both flights were made using the same 2KW battery pack without any recharging between flights.”

He provides links to the Turnigy motors, controllers, and Zippy batteries.  Taking the list prices from Hobby King’s web site, the breakdown shows that battery pack is 14S – cells in series (51.8 Volts and 40 Amp-hours; approximately two kilowatt Hours, according to Steve) comprise a large part of even a budget electric airplane’s costs.

As people find neglected or partially completed hang gliders or ultralights (although Steve’s is a one-original owner model), perhaps the desire to see what they would look and fly like with electric power might grow some new aircraft and nourish some new experiences for budget flyers.  Let’s all look for opportunities.

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