Electric Aircraft Advances Showcased at CAFE SymposiumBy Peter S. Lert
April 29, 2010 — The CAFE Foundation’s fourth annual Electric Aircraft Symposium last weekend in Santa Rosa, California, showed evidence that electric propulsion continues evolve. Several hundred participants gathered for a series of discussions and presentations on issues surrounding electric aircraft (both fixed-wing and rotor). The gathering also addressed the overall role of electric-powered vehicles in the future energy picture which may have implications ranging far beyond those of aircraft alone.
In terms of electric aircraft technology, the impression was that progress during the last year has been incremental, rather than revolutionary. New electric motor designs offer significant improvements in efficiency and power-to-weight ratio. On the battery front, the possibility of using nanomaterials will allow better energy densities (the amount of power a battery can store for a given weight), although at present such materials remain very expensive. It may also be possible to use nanomaterials in aircraft structures, both to improve overall weight and strength and, possibly, to allow dual-use materials that could actually utilize structural elements as batteries. Even so, it would appear that for the next few years, pure electric aircraft - although entirely viable from a technological standpoint - will not be particularly practical for basic transportation. The fact remains that for pure electric power to replace the internal combustion engine, we still need an approximate 20-fold increase in battery energy density.
The picture remains considerably more promising, however, for the realm of recreational aviation. A light two-place aircraft with a range of, say, 100 nm is entirely feasible and even practical with current technology; given that much recreational flying occurs within 50 nm of the home airfield, this makes the electric airplane an attractive alternative. In addition, hybrid power begins to look quite attractive - possibly in an aircraft with an internal combustion engine for takeoff and climb and an electric motor for low-powered cruise flight. As can be expected, many such designs are at least somewhat sailplane-like, since cruise efficiency depends to a large extent on high-aspect ratio and low-span loading to minimize induced drag.
“Just a few years ago electric model aircraft were considered an impractical novelty, offered EAA’s Ron Wagner, manager of field relations and a symposium attendee. “Today, some say that about 90 percent of new model aircraft are electric powered. As new technologies develop, the same could happen within the full-scale aviation community. We live in exciting times.
“There is a “ground-swell of activity in the area of electric flight. Interest is high and EAA will play an important role by keeping its members informed about what is going on.”
Among the attendees were several of the entrants for next year’s CAFE Foundation Green Flight Challenge. This will be a flight efficiency competition for aircraft that can average at least 100 mph on a 200-mile flight while achieving greater than 200 passenger miles-per-gallon (or equivalent use of electricity). The prize for the aircraft with the best performance will be $1.5 million. This is the largest prize ever offered for a general aviation competition. A $150,000 prize for best score by a bio-fueled aircraft is also offered. Learn more here.
EAA will again highlight electronic aircraft advances at AirVenture this year with daily showcase flights; evening flight demos; and displays and forums in AirVenture's Aviation Learning Center. For more on electric aircraft innovation at AirVenture, click here.