All photos this article courtesy NASA
Orange plastic barrier fences and blue tent tops shiver in the light breeze. Competition team members, pilots, event staff and media move with purpose under the bright, clear September sun. Holding the focus is a clutch of white composite electric, hybrid and gasoline-powered aircraft, lining the taxiway at Sonoma County Airport in Northern California. They've come here to win some big prize money, and make history in the process.
In time, we may well look back on the event as a Wright/Lindberghian moment: as the first time aircraft conclusively demonstrated electric flight has moved beyond prototype demonstrations of future technology. The event is the Green Flight Challenge (GFC), conceived and hosted by the bright folks of the CAFE Foundation and cosponsored by NASA, and no less an icon of global change than Google.
CAFE stands for Comparative Aircraft Flight Efficiency. The group of aviation hobbyists-turned-aeronautical scientists grew its flight-test acumen into a globally respected proving ground for aerodynamic data. In the process, the sky above Santa Rosa, Calif., has become a kind of outdoor wind tunnel.
Electric Bridges Too Far?
In the past, the GFC had tasked itself with stimulating, quantifying and qualifying ever-increasing flight efficiency. This year, its intent was to raise the bar for electric flight—as in asking a high jumper to pull off a 20 footer!
The GFC threw down a prodigious gauntlet: Each aircraft had to fly 200 miles, at an average speed no less than 100 mph, while burning the fuel equivalent of—get this—no more than one gallon of fuel per passenger!
To add stick-and-carrot incentive, NASA and Google tossed in a mighty big carrot indeed: $1.65 million in total prize money. As the Orteig Prize for flight across the Atlantic demonstrated in 1927, if you wave the greenbacks, they will come.
But perhaps evocative of the growing pains of all new movements, after a promising response of 13 original entrants, only five aircraft teams felt equal enough to the task to even show up. One disappointment was the absence of the radical double-box-tail Synergy, a truly futuristic-looking concept electric.
Team members of the e-Genius aircraft prepare their plane prior to the Green Flight Challenge at the Sonoma County Airport in Santa Rosa, Calif., on Monday, Sept. 26.
Before long, four remained: the all-electric eGenius from Stuttgart University and Pipistrel's Taurus Electro G4; the gas/electric hybrid Eco Eagle from Embry-Riddle Aeronautical University; and the production Rotax-powered Phoenix motorglider.
And then there were three: Eco Eagle was disqualified on technicalities, leaving just three aircraft to compete for prize money.
Competition tasks included takeoff noise qualifications (clear 50-foot obstacle in 2,000 feet, sound level no higher than 78 dB), efficiency flight to measure pMPG (passenger miles per gallon) and the "main event": fastest speed through the course while maintaining a 200 pMPG efficiency ceiling.
Energy consumption (1 pMPG = 33.69 kWh of energy) couldn't exceed one gallon per passenger for the 200 miles, and oh yes: a 30-minute "fuel" reserve also was required.
In a strategic move designed to increase its chances of winning, Pipistrel conjoined two of its Taurus G2 production motorgliders with one large wing, added a central power pod for the single electric motor and batteries, and thus gained the benefit of the electrical equivalent of four gallons of gas, because the G4— weighing 3,300 pounds at gross, one-third of which is batteries!—carries four people.
The CAFE Foundation Hangar Boss Mike Fenn waves the speed competition checkered flag for the PhoEnix aircraft.
Still, think of it: The equivalent of four gallons had to fly four adults at 100 mph for 200 miles.
Competing electrode to electrode with the G4 was eGenius. It went with a less-radical two-place motorglider design, but added a stroke of aerodynamic wizardry: the 80 hp electric motor mounted in the tail, allowing a larger, more efficient propeller. Adding drama to the race, eGenius had already broken the electric two-place world record for speed and endurance by flying, not coincidentally, more than 200 miles at more than 100 mph, with plenty energy left over.
But which strategy would carry its team to victory on the last day's task? It promised to be quite a showdown.
2011: Advances...And Setbacks
In terms of participation, the GFC wasn't the only big splash that didn't quite cannon-ball into the electric flight pool this year. After Europe's annual Aero Friedrichshafen convention last spring, the e-Flight Expo's Berblinger Flight Competition promised a high-profile demonstration of electric prototypes. Alas, 36 teams signed up, 24 made it to the Expo, 13 launched, but only eight finished the 115-mile course. Lack of funds, technical challenges, transportation obstacles and regulatory problems such as incomplete license paperwork short-circuited many efforts.
And yet, eight electric aircraft did finish, demonstrating that respectable distances could be flown—and setting the stage for the GFC. The Berblinger's €100,000 prize money went to three pilots: €45,000 each to Eric Raymond, renowned designer/pilot of the globe-girdling Sunseeker series of solar-powered aircraft; and Axel Lange, flying his Antares 20 electric motorglider, the world's first certified production electric airplane and winner of last year's Lindbergh LEAP award. Manfred Ruehmer, a European champion hang-glider pilot and electric flight pioneer, won €10,000 with his electric Swift flying wing.
"We raced 115 miles from Friedrichshafen to Ulm and back," Raymond recounted later. A strong northeast wind made it hard work to reach the turn, but the return was easy. I was so stressed by the headwind and turbulence, I forgot to retract my landing gear and fought my way there despite the extra drag."
Raymond continues to push the envelope—there must be avian strands in his DNA. "This year, I hope to finish my two-seat solar plane, based on the Stemme S-10 (sailplane). In late 2012, my wife and I plan to fly it from Europe to Australia, spend the winter there, then fly back, hopefully with the BBC documenting the entire adventure."
Team members applaud as aircraft return from the speed competition. NASA and the CAFE Foundation hosted the challenge with the goal to advance technologies in fuel efficiency and reduced emissions with cleaner renewable fuels and electric aircraft.
One other big electric event, EAA AirVenture's $60,000 Electric Flight Prize, was postponed until 2012. The stumbling block was the failure by most entrants to fly off enough hours to qualify for FAA's Phase I flight certification. Although there's no aviation electric powerplant standard yet, ASTM passed its version this year, and FAA is reviewing it for possible rule making by the end of 2012.
Regardless, as Tom Poberezny, recently retired head of EAA, stated, "Let's be clear that the era of electric flight is drawing closer every day, and it will be showcased at Oshkosh."
The World Is Watching...And Building!
In that spirit, Oshkosh 2011 went forward with its second annual eVenture World Symposium on Electric Aircraft, with scheduled talks and forums from luminaries such as Burt Rutan, Sergei Sikorsky of Sikorsky Aircraft, and Dennis Bushnell of NASA Langley Research Center.
Erik Lindbergh, grandson of Charles Lindbergh, presented the LEAP (Lindbergh Electric Aircraft Prize) Vision award to Dr. Calin Gologan's Elektra One, acknowledging its flight and supporting infrastructure accomplishments. Dr. Gologan, a Romanian engineer, has big plans for the near future, including the two-seat Electra Two and four-seat Electra Four.
Electra One, slated for market in 2012, will join a stable of electrics already in production: Pipistrel's Taurus Electro G2, the Lange Antares 20E and Alatus-ME self-launching sailplanes, Icaro's Elektro Swift flying wing and Pit-trike hang glider, and U.S. pioneer Randall Fishman's ElectraFlyer Trike.
Fishman is busy on a number of projects. A new electric trike with a folding prop and three-axis keel mount, and a single-seat composite motorglider, dubbed ElectraFlyer ULS (Part 103 ultralight legal), are nearing completion.
The company that bolted out of the gate two years ago, Yuneec Aviation, continues its electric flight development along several fronts. Flight Design USA head and e-Spyder electric ultralight designer Tom Peghiny updated with this report: "Yuneec is reworking the E-430 for certification in Germany, finishing the second electric E-Viva two-seat motorglider and finishing preparation for production of the e-Spyder. They are way ahead in development of their electric power systems with hardware and controlling software tested to commercial standards."
The e-Spyder finished load testing and has a new, larger-diameter, high-aspect-ratio, three-blade prop from Helix of Germany, which improves climb, duration and "makes the e-Spyder incredibly quiet—so quiet you can hear dogs barking and car doors closing from 1,000 feet!" says Tom.
Beyond Aviation (formerly Bye Energy), partnering with Cessna, began taxi tests last July of its electric C-172. The "e-Skylane" will use a 168 hp all-electric or hybrid pro-pulsion system, which could retrofit the huge existing fleet. First flight date is reportedly imminent.
Sikorsky's Firefly electric helicopter project was trumped by a solo project: Pascal Chretien of France built and successfully hovered an ultralight e-chopper, taking the design to flying prototype in just 12 months! He's the first in history to fly an electric helicopter.
Another French pioneer, Hugues Duval, set a world speed record for electric aircraft in his miniscule twin engine Cri-Cri, christened "E-Cristaline." His speed: 175 mph! Endurance? That's another story, but still, wow!
And then there's Flynano, another joined-wing...uh...flying jetski? The small single seater is already in high-speed water-taxi testing. The first version will be gas powered, with an electric version to come afterward.
Everybody's getting into the act. Luxembourg Special Aerotechnics announced first flights of its model MC30E Firefly electric airplane, sporting an electric propulsion system from Electravia, which has electric aircraft projects of its own. The converted kit plane, from the original designer of the Cri-Cri, uses a 26-hp E-Motor and 4.7 kWh Kokam battery pack. Initial flights brought 1,181 fpm of climb and 119-knot level cruise.
Back on the home front, Dale Kramer, designer of a beloved '80s ultralight, the elegant, butterfly-light Lazair, converted it to electric power with 90% of the components coming directly from the radio-controlled modeling world, slapped it all on a monofloat, and flew it off a lake! He's getting 75-minute flights out of his 100-pound battery pack.
Growing The Grid
Before long, electric infrastructure will require the same push that electric airframe and propulsion design is getting now. Pipistrel sells a Solar Trailer to go with its Taurus Electro G2. And PC Aero's Calin Gologan updated me on the Electra line—which also includes a charging trailer.
"We are installing newer, lighter batteries on the One," he said, "with enough energy density for a 300-mile flight. Our goal is to get German certification and produce the Electra One in 2012."
He expects improvements in battery energy density of 11% per year. "In about five years, we will have very, very good batteries. We will apply solar cells to the wings to bring 15% charging capacity to the airplane. Next year, we hope to extend our range to 600 miles on a single charge."
PC Aero's solar panel-bedecked trailer completely charges the airplane in a few hours. "We only need 200 square feet of panels to supply 300 hours of flying per year. That's a normal flying club's yearly amount. Electric flight can be successful only if we fight for low weight, good aerodynamics, and find the best compromise. This is the secret. Electra One was designed as a cruiser, but came out with a glide ratio of 34:1 and is very sensitive in thermals. The battery life is about 1,000 cycles."
And The Winner Is
On the final day of the Green Flight Challenge, the tightly guarded tabulations of all the flight data were released and the winners announced.
The largest aviation prize ever given, $1.35 million, went to Pipistrel's Taurus G4, with the second place award of $120,000 going to eGenius. Surprising numbers confirmed both the aircraft achieved almost twice the fuel efficiency required for the competition! That means each flew the 200 mile-course using just over a half gallon of fuel equivalent per passenger.
"Ultraefficient aviation is within our grasp," said Joe Parrish, NASA's acting chief technologist. "Today, we've shown that electric aircraft have moved beyond science fiction."
Running With The Vision
Erik Lindbergh made a prediction: "The first company to produce a certified two-seat electric aircraft with a 1.5-hour range will dominate the aviation training market." It now appears several such aircraft could be available within two or three years.
This year's electrifying events have another winner: everyone who has dreamed of practical electric flight. Only a year ago, electro-pundits online bemoaned their certainty that a two-hour, 100 mph electric flight was still years away.
Berblinger and the GFC alone demonstrated the movement is accelerating. Yes, only 10 electric aircraft finished in two major contests, but 49 entered! Forty-nine separate groups put in the time, energy, work and brain power to field a flying electric aircraft. It speaks volumes about the enthusiasm and commitment out there.
It's a thrilling time to be watching the skies, and watch we should: We won't be hearing these e-birds coming!