Move Over Prius, Green Flight Challenge Aims High
2:02 AM on Sep 21, 2011
Aviation's richest prize is up for grabs on Sep 25-Oct 1 at Sonoma County Airport in California, where the CAFE (Comparative Aircraft Flight Efficiency) Foundation will stage NASA's Google-sponsored Green Flight Challenge.
The NASA-funded purse of $1.65 million includes a $1.3 million first prize for the aircraft with the best combination of speed and efficiency that meets or exceeds the Challenge's objective of achieving 200 passenger-miles per gallon with an average speed of at least 100mph over a range of 200 miles - that's twice the best fuel efficency achieved in past CAFE challenges.
To put that efficiency target in context, NASA design engineer Mark Moore provided me with some rough comparisons: 230 passenger-mpg for a hybrid car with five occupants; almost 140 for an Amtrak train carrying 300 passengers; and less than 75 for a 737 with 175 passengers. But he cautions that trains, like buses, often operate pretty empty, substantially increasing their actual fuel burn per passenger.
The 100mph speed and 200-mile distance minimums were set to ensure the competing aircraft are practical means of transport, with trip times faster than a car and a useful payload and range. Other constraints were put in place with the goal of attracting aircraft that could quickly move into production, says NASA engineer Doug* Wells in a paper analyzing the contestants that will be presented at an AIAA conference this week.
Thirteen teams registered to compete, but several did not complete their aircraft in time (mostly for lack of funding) and one - the electric-powered Yuneec E1000 - crashed, killing its pilot. That leaves five teams in the final running:
Embry-Riddle Aeronautical University - Eco Eagle, a Stemme S10 two-seat motor glider modified with a hybird power train. A 100hp Rotax 912 gasoline engine is used for take-off, switching over to a 40hp (30kW) electric motor for the cruise. A V-belt clutch system allows each powerplant to operate independently.
Czech Republic’s Phoenix Air - PhoEnix, a two-seat side-by-side motor glider with a modified wing, retractable landing gear and 44kW electric motor in place of the standard Rotax 912 gasoline engine.
Photo: Phoenix Air
Slovenia’s Pipistrel Aircraft - Taurus G4, a four-seater that is essentially two Electro Taurus G2 motor gliders joined by a wide-chord center-wing section mounting a 145kW electric motor.
Photo: Pipistrel Aircraft
Team Feuling - Green Flight Challenger, a single-seat Rutan Quickie modified with a 16kW electric motor.
University of Stuttgart - e-Genius, a two-seat sailplane configuration with a 60kW electric motor driving a large-diameter propeller mounted on top of the tail.
Photo: University of Stuttgart
*I originally said Dennis - sorry Doug!