ABSTRACT 
This report describes a radio-control system for free-running models of 
surface ships. The system is designed for use in models ranging from approxi- 
mately 15 to 30 feet in length and is arranged so that it may be used with single 
or multiscrew propulsion systems. A proportional rudder-control channel and 
two proportional propulsion-control channels are provided. Rudder position, 
rudder running time, and propulsion shaft rpm are indicated on the console to 
guide the operator in controlling the model. The system is powered by long-life 
rechargeable nickel-cadmium batteries. 
This report includes a brief review of the engineering study, and 
describes the complete system. Installation, operation and maintenance 
instructions, with photographs and schematic diagrams, are included. 
INTRODUCTION 
Free-running self-powered models of surface ships are used by the TMB Hydromechanics 
Laboratory for tests to determine and predict maneuverability characteristics of the ship. In 
the past these tests have been conducted in the J-shaped end of the main TMB towing tank. 
Power and control circuits to the model have been carried through a multiconductor cable or 
‘‘drop-cord,’’ supported by a movable boom which is manually operated to suspend the ‘‘drop- 
cord’’ more or less directly over the model during the test maneuver. 
During the course of design of the new TMB Maneuvering and Seakeeping Facility now 
nearing completion, work was initiated to develop requirements and specifications for a 
completely free-running self-powered radio-controlled model system. Since the maneuvering 
basin in this facility is about 240 by 360 feet, it was felt that a moving boom and drop-cord 
would be impractical over an area of this size. The functional requirements! for the radio- 
control system were developed by the Stability and Control Division of the Nydromechanics 
Laboratory. The Instrumentation Division and the Facilities Division of the Industrial 
Department jointly conducted a feasibility and preliminary design study? of a system to meet 
these requirements and subsequently designed and constructed the complete control and 
powering system. 
References are listed on page VI-1. 
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