ASME-Landmark:Rotating-Arm Model-Test Facility

Built at the Stevens Institute of Technology thanks to the pioneering efforts of Professor Kenneth S.M. Davidson (1898-1958), the Davidson Laboratory Rotating-Arm Model-Test Facility was the first in the world to conduct experiments for obtaining comprehensive measurements of those forces and moments necessary to define the maneuverability and control of surface ships, submersibles, and airships.

The facility consists of a 75-foot square, oblique sea basin, having a water depth of 5 feet, and a central, vertical shaft. The horizontal, radial structure, called the Rotating-Arm, is driven by the vertical shaft at prescribed turning rates, or angular velocities. The test model is mounted on a force and moment measuring apparatus, which is secured at various radial positions along this horizontal arm. Data are obtained over a range of angles of attack, angular velocities and turning radii. The facility can determine the distinct dependence of force and moment coefficients on each separate motion variable, while all other variables are held fixed. It provides data at large magnitudes of the motion variables, allowing non-linear effects to be measured and identified.

During its first three years of existence, the new basin was the test site for many free-running models of Navy combatants. The models were tested to determine their trajectories under action of rudders whose forces were measured by an on-board dynamometer. In the years since, this and subsequent facilities throughout the world have been essential in the design of more responsive vessels through calculations derived from the performances of precision models in laboratory water tanks. See ASME website for more information