When I read this, I wonder if this is an example of the Coanda effect. If the leading edge could ever be covered with a super sonic laminar flow of air, the incoming air flow would adhere almost perfectly to the wings surface and maximize lift while sharply reducing drag.
A small jet would certainly cover part of the wing in that manner and this is certainly a good start in that direction. Drag would definitely reduce. My own thoughts along those lines were toward developing a somewhat more elegant solution which may be simply impractical. On a very large wing, you have the flexibility to apply a much less elegant method like dedicating a few small jet engines.
It may be possible to enclose a three to six inch pressure tube along the leading edge with exit slots initiating laminar flow just before the leading edge that is fed by the dedicated jet engine. The laminar flow must leave the slot under a hundred psi pressure drive for the layer to adhere to the wing’s surface.
In the event, it is on the big birds that this technology can be made to work in the first instance. It just never occurred to me that such new research of this nature could be conducted on the big birds already in service.
May 22, 2009 04:27 PM
Not a drag: High-tech airplane wings could cut fuel costs by 20 percent
By Larry Greenemeier
A new study says that within three years jumbo jet–makers could be testing a new type of wing that reduces midair drag and cuts fuel costs by an estimated 20 percent. The wing would do this using small, built in jets that redirect air around the wing during flight.
"This has come as a bit of a surprise to all of us in the aerodynamics community," Duncan Lockerby, an associate professor of fluid-solid mechanics at the University of Warwick in the U.K. and head of the research project funded by the Engineering and Physical Sciences Research Council (EPSRC) and aircraft maker Airbus, said in a statement. "It was discovered, essentially, by waggling a piece of wing from side to side in a wind tunnel."
Lockerby acknowledged that he and his team weren't sure exactly how the small jets actually reduce drag, but they're building prototypes they hope will be ready for testing as early as 2012 and will eventually reduce surface friction drag by up to 40 percent.
Part of this learn-as-they-go approach stems from the Advisory Council for Aeronautical Research in Europe's (ACARE) goal of cutting carbon dioxide emissions from passenger aircraft in half by 2020, Lockerby notes on Warwick's Web site.
Airlines and aircraft makers are already experimenting with biofuels to cut the amount of greenhouse gases their aircraft emit high in the atmosphere. Virgin Atlantic Airlines, the U.S. Air Force, Airbus, and Florida-based Green Flight International are testing coconut and babassu oils mixed with regular petroleum-based jet fuel as well as "synfuel" liquid jet fuel made from coal or natural gas.
Cargo ships are also turning to new technology in an attempt to reduce drag and cut fuel costs, including an experimental approach that pumps air about 25 feet (less than 10 meters) below the waterline into subsurface cavities—broad, shallow recesses built into the underside of the ship's hull—creating buoyant pockets that help ships slip more easily through the sea surface.
