PART | — ENGINEERING STUDY 
1. THE PROBLEM 
The functional requirements for a radio-control system! called for a system for use in 
10- to 30-foot models of surface ships. The total displacement for these models ranged from 
130 pounds for 10-foot models to approximately 2 tons for some of the large models. The 
control system was to provide two channels of step- or full-proportional control for propulsion 
motor drive, with capabilities of reversing either or both motors, and a third channel for step 
or proportional control of one or tworudders. The original propulsion requirement of 2 hp per 
channel was later revised to 3 hp per channel. Rudder torque requirements ranged from zero 
to 100 inch-pounds per rudder at velocities of from 4 to 40 degrees per second. It was desired 
that the overall accuracy and stability of the system be better then + 1 percent for each control 
function. The design of the system was to be flexible enough to permit the equipment to be 
used in as wide a range of hull types as possible and for a wide variety of model tests. 
The primary problems in the design of the system were: (1) the requirements for very 
high accuracy and stability in both steering and speed control, (2) the need for large amounts 
of propulsion power during 2- to 4-minute test runs, and (3) the limitations on weight of the 
equipment, to permit it to be used in small models. 
There were several minor requirements, such as having an indication of model-control 
behavior at the console, and providing a readout system which could be expanded to handle 
additional data channels. These did not constitute any serious problem, however. 
2. THE APPROACH 
2.1 CONTROL AND READOUT EQUIPMENT 
The first problem to be solved was the selection of suitable radio-control and data- 
handling equipment, and many types of radio-control and telemetering equipment were considered. 
It appeared at first that one of the military types of drone-control equipment would be suitable. 
Several types of these systems were investigated, ranging from the simple ‘‘beep’’ type to 
systems containing several proportional and on-off channels. A digital data-transmission 
system was also considered. This had been designed for the control of large drone boats and 
was of relatively high accuracy and stability. There were specially designed actuators for use 
with some of these systems; however, they were not available with suitable run-in rates and 
torque capabilities. None of these systems were considered to come near enough to the re- 
quirements of the TMB radio-control system. 
Attention was next focused on the use of standard telemetering equipment for both the 
control and readout equipment. There are a wide variety of telemetering methods such as 
I-1 
