| Submit your comments on this article |
| Home Front: Tech |
| Sound Improves Aerodynamic Lift By 22% |
| 2005-09-28 |
| The distinctive growl of a light plane may soon be accompanied by an eerie hum, thanks to Australian research that shows the effectiveness of aircraft wings is dramatically increased when sound is applied to them. Qantas engineer Ian Salmon tested wing sections covered with a piezoelectric material that vibrates when a current is applied to it. When the tone of the sound was at its most effective pitch, Salmon's wing panel achieved 22 percent more lift than it would have without the piezoelectric hum... Vibrating wings could be used to make planes safer, reduce wing size and provide another element of control for pilots, Salmon said. But don't expect the wings on commercial jets to start humming away any time soon. The technique only works well on smaller planes such as light aircraft and military-style unmanned aerial vehicles like the Predator. Larger aircraft are equipped with advanced sensors and sophisticated trailing-edge flaps, which are used to change the shape of the wing during takeoff and landing. Vibrations could improve these conventional controls, but likely not replace them completely. For example, the greater a wing's angle to the horizontal, the slower the plane can fly and thus the safer it can land. Vibrations could also eventually help engineers design planes more efficiently. Professor Russell Cummings of the U.S. Air Force Academy Department of Aeronautics said he is unfamiliar with Salmon's research, but believes the theory is sound (no pun intended). "If it works, it could mean use of smaller wings and engines," he said. It's all about changing the air flow from an unstable laminar flow to a turbulent flow that increases lift, Cummings said. The vibrations change the way the air behaves when it starts to break away from the wing's surface, sucking it closer. Salmon works for Qantas, but his research was a part of an undergraduate degree in aerospace engineering at the University of New South Wales in Sydney. His supervisor, associate professor Noor-E-Alam Ahmed, had previously experimented with "external excitation": bombarding a wing section with large speakers. "The noise level was such that people were complaining in different parts of the lab," Ahmed said. He passed the idea of internal acoustic excitation to Salmon. With promising results now behind them, Ahmed is seeking to extend the research, spinning off the work into both postgraduate and undergraduate research. Ahmed doesn't have any immediate plans to test the technology in flight. Instead, he'll use the university's leased planes to test a new stall-onset sensor. Predicting the onset of stall would give a pilot more time to react, greatly reducing the chances of a stall-related accident. "We may be able to increase lift at any angle of incidence," he said. |
| Posted by:Anonymoose |
| #8 LOL Dar! |
| Posted by: Red Dog 2005-09-28 20:06 |
| #7 It's just busting up the laminar flow. Nothing new. By the way, at the very least the reporter got it all wrong (and possibly Mr. Engineer too) by talking about "lift". There is no such thing as "lift" or negative pressure on the top of the wing "sucking" the wing upward. Airplanes (and helicopters) fly by pushing air DOWN. Remember Newton and his Actions and Reactions? http://www.aa.washington.edu/faculty/eberhardt/lift.htm |
| Posted by: Parabellum 2005-09-28 18:26 |
| #6 Great--now they'll expect all of us in coach to hum for the entire flight. |
| Posted by: Dar 2005-09-28 15:34 |
| #5 Buzzing like a bumblebee's wings? |
| Posted by: eLarson 2005-09-28 15:22 |
| #4 Sound Improves Aerodynamic Lift By 22% I knew that. |
| Posted by: Ella Fitzgerald 2005-09-28 15:13 |
| #3 nothin by lynard skynard |
| Posted by: Chuper Whegum3442 2005-09-28 13:21 |
| #2 3 miles high |
| Posted by: Chuper Whegum3442 2005-09-28 13:20 |
| #1 white rabbit |
| Posted by: Chuper Whegum3442 2005-09-28 13:19 |