With Boeing facing financial doldrums because of its ongoing grounding and resulting slump in sales of the 787 Dreamliner, the stakes are high for the company. That makes today’s Reuters’ report that the manufacturing giant may have found a “way to fix battery problems on its grounded 787 Dreamliner jets” good news for not only Boeing, but for electric aircraft in general. Readers should read these findings with some caution, though, since another report from Japan gives a different possible cause for the problems. That said, the two reports might not be mutually exclusive. Many electric light aircraft developers use spacing between cells and some method to circulate cooling air over them. In Boeing’s two 787 lithium battery packs, eight large cells fill a fairly tight housing. Reuters quotes an anonymous source, “’The gaps between cells will be bigger. I think that’s why there was overheating,’ said the source, who declined to be identified because the plans are private. “A …
Early Warning for Li-Pos
Nobody wants an airplane fire. You’re way up in the air, can’t pull over to the curb, and have limited means of quelling the flames. The most energy-dense batteries, based on lithium chemistries, are subject to failure from physical and electrical abuse. Most cells run through their promised cycle life without giving a hint of trouble, but sometimes fate or mischance leads to disaster. Battery alternatives with lower risk usually possess lower energy and/or power density, crucial to use in aircraft, since weight is usually a primary consideration in vehicle design. Lithium fires are quite often spectacular, probably a consideration that prompts Dale Kramer to recharge his 100 pounds of cells in his fireplace – with the flue wide open. Even small cells found in laptop computers and cell phones have caused injury and death to their users. For all lithium battery users, some reassurance may be found in news from the Johns Hopkins University Applied Physics Laboratory (APL) in …
Embry Riddle Begins GFC Test Flights
On August 23, 2011, the Embry Riddle Aeronautical University’s Green Flight Challenge hybrid-powered modified Stemme S10, the Eco-Eagle, began its ground tests on the Daytona Beach International taxiways, “Getting ATC used to us!” The next day saw several ground-skimming “flights,” starting at 2-feet, and rising to 10 and 50-feet high runs, all with the gear down. The day’s flights ended with a trip around the pattern for the airport’s longest runway. August 25 saw a morning excursion of 45 minutes, with the airplane flying in the face of the approaching Hurricane Irene. Test pilot Mikhael Ponso reported beautiful clouds and no high winds during the seven laps around the field. As he tested the gear retraction and various flap settings, he was able to sort things out for the upcoming GFC flights in Santa Rosa, California during the last week in September. The school’s Eco-Eagle has a Rotax hybrid-power system originally developed for Flight Design, a German firm that builds …
Electric Gull Flies at Arlington
The annual fly in at Arlington, Washington was an electric landing zone for Mark Beierle’s Gull 2000, powered by his own design 20-kilowatt motor. The 36-coil, 42 magnet disk, weighing 16 pounds, is mounted on a truss arrangement behind the airplane’s high wing, and drives a ground-adjustable pusher propeller. Flying five half-hour demonstration flights during the half-week event accounted for almost half the six hours total time on the airplane so far. The airplane has a 74-Volt Rhino Lithium-polymer battery pack made up to 11 packs in a parallel/series arrangement. Beierle says this array, and taking voltage from the ends of each 3.7-Volt series pack, allows balancing of all 210 cells. Power is run through a 500-Amp Kelly controller, which weighs about 12 pounds: Beierle hopes to try a new Kelly unit which will be half that weight and less expensive. Battery protection is provided by circuits in the charger, which will be the same Kelly unit Beierle uses in recharging his …