Green Flight Challenge Final Results

Dean Sigler Electric Powerplants, GFC, Sustainable Aviation 15 Comments

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 …

A Useful Spreadsheet and GFC Handicapping Tool

Dean Sigler Electric Powerplants, GFC, Sustainable Aviation 1 Comment

For analyzing the greatest economy from an aircraft’s design, Howard Handelman, a highly-engaged reader of this blog, provides a link to his web site, which includes a downloadable spreadsheet he has devised that will give the inquiring reader hours of enjoyment. Handelman, self-described as, “just a retired IT guy,” with “weak math skills,” but a “compulsively curious” nature, has devised a tool for analyzing any airplane’s performance based on a few known variables, and which he has applied to many of the Green Flight Challenge’s aircraft. The basis for his analyses is his “triangle tool,” a wedge that can be used to help design propellers, “test [the] truth” of claimed aircraft performance, and estimate brake horsepower in real life circumstances (at least within the parameters of the triangle tool).  Handelman notes that some aircraft, including those with laminar flow, will “not fit the model very well because they don’t fit the V-squared curve.  Synergy won’t look anything like the model.” His findings …