Dr. Robert Englar (right) and student Scott Gregory are evaluating and improving the aerodynamic characteristics of unlimited-class hydroplane racing boats. Their findings might be applied to cargo craft of the future.
Developing methods of stabilizing high-speed racing boats will not just enhance a fast-paced sport -- senior research engineer Robert Englar says the findings and test methods established will benefit a whole new type of commercial shipping vehicle, as well as current commercial cargo or transport vehicles.
Dr. Robert Englar (right) and student Scott Gregory are evaluating and improving the aerodynamic characteristics of unlimited-class hydroplane racing boats. Their findings might be applied to cargo craft of the future.
Englar, who has evaluated and improved the aerodynamic characteristics of unlimited-class hydroplane racing boats since 1989, believes findings might be applied to cargo craft that would "fly" just above the ocean's surface at speeds considerably greater than those of current ships.
"Such vehicles could reduce the time needed by today's cargo ships to reach their destinations," said Englar, of the Georgia Tech Research Institute's (GTRI) Aerospace Sciences Lab. "The number of trips required by cargo aircraft to fly goods around the world also could be reduced, because of the large sizes possible for these advanced vehicles."
The hydroplane racing boats Engler and his team study for Douglas Ford Engineering of Golden, Col., travel one to eight inches above the surface of the water at speeds up to 225 miles per hour. Design changes the GTRI researchers recommended already have improved the stability and speed of the Miss Budweiser racing boat and those of other competitors. The changes greatly reduce the tendency of the boats' noses to pitch upward; as a result the boats are prevented from flipping end-to-end -- having a "blowover" -- in the face of strong wind, waves or wakes from other boats.
Most recently, the researchers have studied the tendency of the boats to flip sideways during turns. "There is no way to control the boat's turn if its rudder is out of the water," Englar explained. "We have identified a whole new phenomenon related to aerodynamic vortices, which must be understood and controlled to make the boats safer. We have installed and evaluated devices to counteract these phenomena."
The key to improving the racing boats -- and perhaps someday developing a cargo hydroplane -- is understanding and controlling ground effect. The closeness of a hydroplane boat's bottom surface to the water as it flies over it creates dynamics very different from those experienced by a conventional boat floating in water, or by an airplane flying at altitudes away from the ground.
"When you're close to the water but not in it, as you are in a hydroplane boat, the aerodynamic forces can be 10 to 15 times what they are away from the water," Englar explained. "The ground effect can lift a whole lot more weight off the water -- but it can also pitch the boat up, and roll or yaw it out of control."
The researchers perform experimental studies of ground effect using 1/8-scale models of the Miss Budweiser racer or other sponsors' boats in Georgia Tech's Model Test Facility, a subsonic research wind tunnel. They use a hydraulic actuator to lower the boat to the height it would normally be above the water, and use special techniques to have the floor of the test section properly simulate the water.
Since this project began the researchers also have applied their findings to smaller, limited-class racing boats, and their testing procedures to advanced automobiles. In addition to commercial cargo boats, the design modifications might be applied to the development of very fast luxury travel boats. These modifications, and the unique experimental test techniques and facilities used to test them, also are applicable to the study of conventional aircraft operating in ground effect, such as commercial airliners taking off or landing at airports.
Table of
Contents
Send all questions and comments to Webmaster@gtri.gatech.edu