A radio control and powering system for free-running models of surface ships / by C.W. Hoffman.

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 approximately 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 "dropcord" 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 1 for the radiocontrol system were developed by the Stability and Control Division of the Hydromechanics Laboratory. The Instrumentation Division and the Facilities Division of the Industrial Department jointly conducted a feasibility and preliminary design study 2 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.

Keeping the Serpin Machine Running Smoothly: Figure 1.

“…Subsequent conformational change, involving major reorganization of a large, exposed proteinaserecognition loop and one of the three ␤ sheets, is fundamental to the normal functioning of many serpins as suicide inhibitors of serine and cysteine proteinases. Other properties of serpins, such as antiangiogenic activity (O'Reilly et al 1999), chemotactic response (Potempa et al 1991;Banda et al 1988;Hoffman et al 1989), or ability to regulate cell migration (Stefansson and Lawrence 1996) also appear to depend on the serpin's ability to undergo conformational change. The primary structure of a serpin must therefore ensure not only that a folding pathway leading to the metastable conformation be followed but that, under appropriate circumstances, structural rearrangement to the most stable state can occur rapidly and smoothly enough to carry out the physiological function of the serpin.…”