Alpaero, a small firm in the southern French alps (hence its name?) created an ultralight sailplane/motorglider about 10 years ago that was originally powered by a two-stroke engine. Recently, though, it’s gone green with a four-stroke, Briggs & Stratton engine and even greener with an electric motor version. Claude Noin, the designer, wanted to answer the request for a “light autonomous sailplane at a reasonable cost,” able to meet ULM (ultralight) qualifications. The fixed engine behind the cockpit configuration avoids the complexity of the retractable engine configuration, which Alpaero says can increase drag two or even three times over that of the “clean” sailplane when the engine or motor is extended. As Dick Van Grunsven has pointed out, the need for motor extension usually occurs at some low point in the flight, when other options have been exhausted. Even the clean design of his Antares motor system produces a noticeable drop in gliding performance, he notes. The large cockpit has …
Big Birds Flying Green Economy Class (Part Two): Inspire and Aspire
Strategy was almost as important as design in the recent Green Flight Challenge, with near flawless planning and execution of carefully-crafted flight paths by the winning teams. This same precision and use of resources will become more important in a future constrained by increasingly precious fuels. According to Greenaironline.com, “The Indian Ocean Strategic Partnership to Reduce Emissions (Inspire) partnership achieved fuel savings of 3,482kilograms (29,723lb) and carbon dioxide savings of 42,469kg on five flights operated between Australia and the Middle East and South Africa.” These green demonstration flights, according to Greenair, show, “what is what is possible when air navigation service providers (ANSP), airlines and airports work together to remove operational constraints.” Begun in 2010 to “develop gate-to-gate procedures, practice and services” with the goal of reducing fuel use and emissions “across all phases of flight,” Inspire follows Aspire – the Asia and Pacific Initiative to Reduce Emissions – established in February 2008 by Airservices Australia, Airways New Zealand and the U. …
Small car, Small motor, Big Launch
This recent video from FES (Front Electric Sustainer) in Slovenia shows a relatively low-budget way to launch and sustain a sailplane in flight. This was uploaded to YouTube by Lumakaja on September 27, with the following commentary. “This way of sailplane start, can make gliding much cheaper! Idea is simple: Use of FES after being airborne with help of auto-tow. Only a few sailplanes have high enough landing gear, so that propeller clearance on grass is not too small for safe self-launch. With minimal help of auto-tow than all FES equipped sailplanes would not need towing plane or winch any more to become airborne. All you need is FES equipped sailplane, usual car and about 120 meters (384 feet) of Dyneema rope. Such start could be used also on relatively short, let say 750 meter (2,460 feet) long airfields, which are otherwise too short for usual winch or car launch! If only short runway is available, then more powerful car is needed for …
Big Birds Flying Green Economy Class (Part One)
While the world waits for the 10X battery, a safe, long-range source of flight for our post-Green Flight Challenge fliers, we will probably have to go aloft powered by some bio-fuel derivative or combination of “traditional” fossil fuels and biofuel. Major players in the airline industry are responding to the probability that things will get a bit thin in finding ready, cheap sources of sweet crude, and are taking on not only the issue of using green energy, but of flying more efficiently – ala Green Flight Challenge practices and Voyager-type voyages. This interest by the big players in the industry will probably be good for continuing fuel sources for general aviation, too. With more activity than can be imagined in this arena, your editor turns to two excellent sources for background: Flightglobal.com and Greenair Online.com. Recent reports from both show several major successes, but also much political discord between national interest groups that slow progress. We’ll look at a …
A Weighty Matter
Several readers have asked for the weights of the Green Flight Challenge competitors. Here they are, pound for pound, among the most efficient flying machines on the planet. Those who wish can calculate different takes on that efficiency, including overall glide ratios for the course, ton-miles per gallon energy equivalent, or more exotic parameters. Empty Weight Takeoff Weight in Competition Pounds Pounds e-Genius 1670.2 2070.2 Pipistrel G4 2491.0 3294.1 Embry-Riddle 1970.0 2370.0 Phoenix 754.0 1199.7
How Green was GFC Electricity?
The blog received several comments about the relative energy use of electric aircraft, and how NASA and the CAFE Foundation might have overstated the efficiency and low emissions for the electric aircraft in the competition. Reader Robert Swanson thought the conversion between kilowatt hours and gasoline created a discrepancy. “The discrepancy in performance of gasoline and electric powered aircraft is due to an absurd conversion factor between kWh and gallons of gasoline. The conversion should be calculated from the number of gallons of gasoline consumed by the engine driving the generator used to charge the batteries.” Steven Crow added this objection. “Even after reading the relevant pdf’s, it is far from clear to me how CAFE computed ‘mileage’ for the electric aircraft. The right way of doing it is clear enough: base the mileage on the fossil fuel used to charge the batteries. Electric motors and batteries are not subject to Carnot efficiency limitations. They can seem to be nearly …
Dipping and Coating for Better Batteries
Could dipping electrodes in a secret sauce improve supercapacitor and battery endurance and power? Could coating cell internals be the flavor of the month? These recipes for better batteries may improve things at a better than normal rate, if California researchers have anything to say about it. Working with his compatriot Dr. Jaephil Cho in South Korean, Dr. Cui of Stanford University has been a leader in developing improved battery technology, even developing a painted paper battery. In an appearance at the 2009 Electric Aircraft Symposium, Cui explained a basic truth of battery development – that improvements generally created about eight percent greater power or endurance in cells every year, leading to a doubling of battery capabilities every seven and one-half years. He aims to improve that rate of change in batteries and ultracapacitors. Although ultracapacitors are able to charge and discharge rapidly, they are only about one-tenth as energy dense as batteries of equivalent mass. Cui and colleague Zhenan Bao …
Green Flight Challenge Final Results
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 …
NASA Adds Some Numbers to Green Flight Challenge
NASA’s Mark Moore sends this link to NASA’s press release on the recent NASA Centennial Challenge Green Flight Challenge sponsored by Google. The CAFE Foundation organized and managed the event. “Today we’ve shown that electric aircraft have moved beyond science fiction and are now in the realm of practice.” – Chief technologist at NASA Joe Parrish. The lead quote is informative, as are some figures from the release. “The competition resulted in the world’s most efficient aircraft, beating the state of the art of approximately 100 pmpg (passenger miles per gallon) which is achieved by the newly released Boeing 787 airliner. Essentially this contest showed the ability of small aircraft to achieve twice the efficiency of the most efficient production automobiles today, while traveling at over twice the speed.” Part of this efficiency came about because of inspired design. NASA explains, “The Taurus G4 used a multi-body concept (reminiscent of the twin Mustang, or an inverse P-38); this accomplished a 61% useful …
AVweb Readers Weigh In on Electric Aircraft, Green Flight Challenge
Mary Grady of AVweb started an expanding dialogue with her recent opinion piece on NASA and the CAFE Foundation’s Green Flight Challenge sponsored by Google. The stimulating and varied points of view reflect what is probably floating around in the general public’s perception of “green aviation,” ranging from total ignorance of what has been done already, to confusion about what it all means, to well-honed, technically aware arguments on both sides of the issue. Her thought that electrification is, “the first step down a long and bumpy road that could take general aviation in new directions,” was reinforced with the following reflections that might be similar to those that readers of this blog often experience. “For people who fly for fun — presuming there are many of those left, it seems to be one of the fastest-shrinking segments of GA — electric airplanes are sure to appeal. They are easier to deal with, and quieter, with less vibration. A few …