We are endlessly fascinated by the largest, most powerful, or smallest and most infinitesimal of anything. Here we look at two extremes in electric propulsion. The Prodigious American Superconductor produces superconducting wires, and from those, winds a very large motor, that if not the biggest thing to power ships, is the most powerful for its size, and the most powerful to be used in a Navy ship. The company promotes the following benefits for its 36.5 MW (49,000 horsepower) HTS (high temperature superconductor) motor: high power density (compared to traditional copper-wound motors), high partial load efficiency, low noise, harmonic-free voltage, low synchronous reactance, cyclic load insensitivity, and low maintenance. The Petite Lad, living in St. Petersburg, Russia, has constructed the diametrical opposite of the HTS. His micro radio-controlled, electrically-powered model airplane weighs but 0.225 GRAMS – motor, R/C system, and battery. In an R/C forum, readers were blown away by this accomplishment, needless to say, and the general hub-bub prompted this …
Growing Your Own Battery
While Dr. Cui at Stanford works on perfecting his painted paper battery, reseachers in Sweden are growing algae that does well as a paper battery. Maria Stomme of the University of Uppsala says that the growth of Cladophora, an otherwise stinky beach slime, “Creates new possibilities for large-scale production of environmentally friendly, cost-effective, lightweight energy storage systems.” The algae, according to LiveScience.com, “makes an unusual kind of cellulose typified by a very large surface area, 100 times that of the cellulose found in paper. This allowed researchers to dramatically increase the amount of conducting polymer available for use in the new device, enabling it to better recharge, hold and discharge electricity. Despite the relative ease of making this rechargeable paper, researchers are not looking to replace lithium cells just yet. The battery is not anywhere near achieving the energy or power density of lithium batteries, and the suggested options for its use are fairly playful – light-up wrapping paper, for …
The Painted Battery
Dr. Yi Cui, assistant professor of materials science and engineering at Stanford University, is a battery scientist extraordinaire, and a presenter at last April’s Third Annual Electric Aircraft Symposium. His paper was well received, one in which he discussed how breakthroughs in his lab could lead to an 80-percent improvement in battery capacity for the same weight as current units. He has topped himself with an extraordinary approach to manufacturing batteries. Imagine painting an ordinary piece of paper with a coating of carbon nanotubes and silver nanowires, and ending up with a very thin battery or supercapacitor. This video, courtesy of Stanford University, shows that process, and includes Dr. Cui lighting an LED with a small square of paper. He and his colleagues have abused the battery, washing it with acid and crumbling it, but it still produces current. He notes that they haven’t tried burning it. Dr. Cui predicts that such batteries could be good for 40,000 cycles, a huge leap …
Largest-Battery Powered Airplane Takes Flight
Two weeks ahead of the 106th anniversary of controlled powered flight by the Wright Brothers, the Solar Impulse, HB-SIA broke its earthly bounds and flew 350 meters (about a quarter mile) at a height of about one meter. Because the airplane does not yet have its solar panels mounted, the flight was made on battery power. Graphic © Solar Impulse/EPFL Claudio Leonardi The project’s press release leaves no doubt as to the importance, and the thrill, of the flight. “The results of the ground tests conducted these last few weeks to verify numerous parameters (the prototype’s controllability, acceleration, braking paths and, engine power) had been overwhelming positive, thereby leading the team to give the go-ahead to Markus Scherdel, the test pilot, to take the prototype up to its take-off speed. “As the aircraft gently took up speed, the huge wing of the Solar Impulse gradually rose into the air under intense admiration of the project promoters, Bertrand Piccard and André Borschberg. After some 350 …
Isn’t It Ionic?
Only a few months after the first heavier-than-air hydrogen-fueled crossing of the English Channel (See Man of La Manche, October 29), the Naval Research Laboratory flew its hydrogen fuel cell-powered Ion Tiger for an endurance record of 26 hours and one minute. The flight took place on November 16th through November 17th. The Navy press release claims, “Fuel cells create an electrical current when they convert hydrogen and oxygen into water and heat. The 550 Watt (0.75 horsepower) fuel cell onboard the Ion Tiger has about four times the efficiency of a comparable internal combustion engine and the system provides seven times the energy in the equivalent weight of batteries. The Ion Tiger weighs approximately 37 pounds and carries a 4- to 5-pound payload.” This endurance record follows an October 9th and 10th unofficial record of 23 hours and 17 minutes. The NRL hopes to increase the power output of the fuel cell to 1.5 kW, or about 2 horsepower, …
Powerful Pancakes
AST, Automation Source Technologies, has a line of compact “pancake” motors that are of interest to those designing electric aircraft. Their CDS Series have power outputs ranging up to 21 kW, efficiencies up to 93.2 percent, and weights of no more than 21 kg. The CDS 150, largest in the line, can be either water or air-cooled, handles inputs from 24 to 96 Volts DC, and operates at 1,000 to 6,000 rpm. High torque peaks, and a three to four times overload capacity might make this eight-pole series worthy of consideration.
Sanyo Starting Mass Production of EV Batteries
Sanyo Electric Co., Ltd. has announced that mass production of its EVB-101 battery package will begin in 2010. This compact package – 366 × 213 × 66 mm – or 14.4 x 8.39 x 2.60 inches, wraps a group of 18650-size computer batteries in a water-resistant aluminum housing, complete with a standard communication plug for battery management and monitoring. The 14 in series, six in parallel package stores 10.8 Amp hours of energy and weighs about seven kilograms (15.4 pounds). It has a maximum discharge current of 120 Amps and a continuous output of 35 Amps. The batteries got a good workout in Yokohama Rubber’s E-V Buggy at Pike’s Peak on July 19, posting the second best time by an electric vehicle on the 20-kilometer (12.4 mile), 156-curve, 4,721 foot climb at 14 minutes 50 seconds – only 13 seconds off the all-time EV record. The specifications and demonstrated performance certainly seem to make this battery pack a contender in the …
A Tale of Three Pauls
Dr. Paul Robertson lectures at Cambridge University’s Engineering Department, and Paul Dewhurst serves as Director and Chief Flying Instructor at Flylight Airsports, Ltd. The two Pauls made simultaneous takeoffs March 1, 2009 in Britain’s first two electric aircraft. A third Paul, Welsh by name, acted as certification engineer for the effort. Dr. Robertson took to the skies in a Dragonfly hang glider powered by a Geiger/Eck 10kW motor/controller/propeller combination, while Dewhurst became skyborne in a Lazair ultralight propelled by a pair of Plettenberg Predator 12 kW (peak output) model airplane motors. This testbed in particular reflects Dr. Roberton’s studies toward the constuction of a sub-115 kg electric twin called Hummingbird. His PowerPoint presentation shows the mathematics of powering such a craft on model aircraft motors, the batteries required, and the anticipated and tested thrust for successful performance. The fact that practical outcomes matched mathematical projections attests to the care involved in his analysis. The presentation provides a good model for others who …
A Great Year and Gala Day for Yuneec
Last year, we knew Yuneec for its tidy power package for paramotors, the 10 kW EPac. We were awaiting developments on the EP200, a twin-motored, single-place ultralight that looked as though it would be powered by two EPac units. Springtime, 2009 brought the news that a two-seater was under development, and summer brought surprise after surprise. The 40 kW (54 horsepower) E430 made its first flights on June 12, 2009, followed by further testing on June 20. Test pilot Sun Xun managed two flights of 15 minutes, achieving a top speed of 150 kilometers per hour (93 mph) a climb rate of 7 meters per second (1,377 feet per minute), and a maximum altitude of 300 meters (960 feet). Sun commented on the quiet and smooth nature of motor operation. The prototype was quickly bundled up and shipped to Camarillo, California, where test pilot Dave Morss and members of EAA Chapter 723 gave the airplane a more stringent shakedown, in …
A Smart Electrical System for GA
Dr. Seeley made this available to Green Flight Challenge competitors. As a follow-on to your ideas for simplifying pilot licenses that I presented at Electric Aircraft Symposium III: Here is a link to a very encouraging development debuted at Sun & Fun: A comprehensive, integrated, smart electrical system for GA from Marc Ausman at Vertical Power Corporation ($1500 – $12,000). This looks like a very helpful reducer of pilot workload to help make flying simpler. The more up-scale versions offer redundancy and this technology should save weight and free up panel space as well. Also, the array of COTS eCFI/flight control options from MGL Avionics is very impressive too. Sure wish I had time to build a homebuilt aircraft with today’s technology!