THE DTMB PLANAR-MOTION-MECHANISM SYSTEM
Test and evaluation rept.
DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD DEPT OF HYDROMECHANICS
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The paper describes and discusses the underlying principles of a planar-motion-mechanism system which incorporates in one device a means for experimentally determining all of the hydrodynamic-stability coefficients required in the equations of motion for a submerged body in six degrees of freedom. These include coefficients usually classified into the three categories of static-stability, rotary-stability, and acceleration derivatives. The most unique feature of the system is the method used to impart hydrodynamically pure pitching and heaving motions to a given submerged body. This enables the explicit and accurate determination of individual derivatives without resort to the solution of simultaneous equations as is necessary when other types of oscillation devices are used. Other combinations of pitching and heaving motions can also be produced by the mechanism, if so desired. The balance system used to measure the forces and moments also differs distinctly from the multi-component dynamometers used by most other model-basin or wind-tunnel facilities. It is composed of modular flexural gages employing a variable-reluctance transducer which individually measure a single force in either the X-, Y-, or Z-direction depending upon orientation.
- Marine Engineering
- Test Facilities, Equipment and Methods
- Fluid Mechanics