The Application of Established Automatic Control Methods to the Study of Basic Flight Problems

Abstract

The use of automatic controls in flight testing inspires a new approach to the study of the basic flight problems. Their use makes it possible to record data heretofore unobtainable. The controls themselves improve the performance characteristics of the aircraft. They also ensure ability to repeat test data, thereby making possible truly scientific results. Actual flight testing is the final measure of aeronautical development progress. Precise results are difficult to obtain because of the number and type of variables influencing the data. Testing is usually divided into three major categories: performance, stability and control, and structural tests. These categories are interdependent. Definition of the operating characteristics of the aircraft requires a study of the basic flight problems. Such a study also outlines the requirements of automatic controls for satisfactory operation. These controls as applied to aircraft are discussed under two headings—power plant and stability. Since automatic control parameters are based on flight performance, they are an invaluable flight-test tool. Their use in flight testing results in several advantages: crew relief; stable, dynamic, and integrated control of variables; evaluation of automatic control; and economy. Specific examples of their use in actual tests demonstrate the results that are possible, including the promise of data for the determination of the dynamic constants in the equations of flight.