Steve Williams, CAFE Foundation board member and e-totalizer guru, released the final results for the NASA Green Flight Challenge sponsored by Google, held at the Charles M. Schulz Sonoma County Airport from September 25 through October 1, 2011. Figures show a profound difference between the two electric winners and the two gas-powered and hybrid runners-up.
All competitors flew extremely clean motorgliders with demonstrated lift-to-drag ratios between 25:1 and 35:1. Possible explanations for the large differences in energy use include low cooling drag for electric aircraft and the efficiency of electric motors – but the differences are still surprising.
Note that a little over 11 US gallons of gasoline (energy equivalent) were used to fly seven people (Embry Riddle’s Eco-Eagle flew with only one pilot) over a total of 725.5 miles (Embry Riddle flew a shorter total distance on both “runs”). This is an enormous achievement for all concerned and a significant increase in efficiency over even the best general aviation craft available today.
Congratulations are in order for everyone who participated in making this event a grand success.
| Efficiency Competition | |||||
| Pipistrel | e-Genius | Phoenix | Eco-Eagle | ||
| Fuel used | 3.82 | 3.82 | gallons 100LL | ||
| Energy used | 65.4 | 34.7 | 3.8 | kWh | |
| Equivalent fuel used | 1.94 | 1.03 | 3.98 | 4.10 | gallons (auto fuel) |
| Flight time (for speed) | 1:47:16 | 1:48:27 | 2:25:01 | 2:00:48 | |
| Flight time (for mileage) | 1:49:37 | 1:50:23 | 2:25:43 | 2:04:07 | |
| Distance (for speed) | 192.0 | 191.0 | 186.7 | 142.5 | |
| Distance (for mileage) | 195.9 | 193.7 | 187.8 | 148.1 | |
| Mileage | 403.5 | 375.7 | 94.3 | 72.2 | ePMPG |
| Speed | 107.4 | 105.7 | 77.3 | 70.7 | MPH |
| Speed Competition | |||||
| Fuel used | 6.61 | 4.19 | gallons 100LL | ||
| Energy used | 68.3 | 37.5 | 3.0 | kWh | |
| Equivalent fuel used | 2.03 | 1.11 | 6.90 | 4.47 | gallons (auto fuel) |
| Flight time (for speed ) | 1:41:55 | 1:47:45 | 1:22:11 | 1:43:21 | |
| Flight time (for mileage) | 1:44:10 | 1:50:24 | 1:22:57 | 1:44:53 | |
| Distance (for speed) | 193.0 | 192.7 | 188.4 | 143.9 | |
| Distance (for mileage) | 196.8 | 196.2 | 189.5 | 146.2 | |
| Mileage | 388.4 | 352.4 | 55.0 | 65.5 | ePMPG |
| Speed | 113.6 | 107.3 | 137.5 | 83.5 | MPH |
| Score | 72.7 | 68.3 | 35.1 | 25.2 | |
| Score = 1/( 1/Speed + 2/Mileage ) | |||||