NIAR Aerodynamics Lab tests Raytheon's SDB II
The Aerodynamics Laboratory at the National Institute for Aviation Research (NIAR) recently performed wind tunnel tests for the Raytheon Small Diameter Bomb (SDB) II. In April, Raytheon was awarded a $144 million (USD) contract from the U.S. Air Force Air Armament Center (Eglin Air Force Base, Fla.) to conduct risk reduction work for the SDB II. Raytheon will be competing for selection in 42 months as the prime contractor for the SDB II program, which has a potential value of more than $1.3 billion.
The SDB II is a netted weapon with an all-weather, tri-mode seeker that provides warfighters with advanced capability to attack moving targets. This results in a robust weapon system compatible with a wide variety of global positioning system (GPS)-based targeting systems that can acquire and recognize moving targets.
According to Raytheon test engineers, the wind tunnel data collected during this test may be the most comprehensive database for base and boattail pressures in the presence of deflected and undeflected control surfaces that has ever been acquired by any organization. Raytheon engineers spent more than 120 hours in the 7 ft by 10 ft (2.1m by 3m) Walter H. Beech Wind Tunnel facility, testing the aerodynamic effects and perfecting the design of the SDB II.
Mounting the SDB II in the tunnel proposed a challenge because it was necessary to see the aerodynamic effects on the fuselage without skewing the results where the teste article attaches to a mounting device. To solve this problem, endplates were attached to the wind section in order to mount the model. The aerodynamics effects of the endplates were then subtracted from the final result.
”This approach allowed us to measure 52 pressures on the afterbodies and the bases over a wide range of angle of attack, with negligible effects from the model-support system,“ said Raytheon Missile Systems Engineering Fellow David R. Carlson.
NIAR’s Aerodynamics Lab centers around the recently modernized Walter H. Beech Memorial Wind Tunnel, a premier low-speed, closed return wind tunnel. The lab also includes a flow visualization tunnel, and has access to the nearby Wichita State University College of Engineering’s 3-ft by 4-ft (0.9m by 1.2m) subsonic wind tunnel and two supersonic wind tunnels.
To learn more, visit the NIAR Aerodynamics Lab's Web site: www.aero-labs.org.
