TABLE OF CONTENTS In most scientific endeavors, we must deal with errors or uncertainty in the data we collect. Flight testing is no exception. In fact, many of our error sources are unique to our field and require special attention. The purpose of this chapter is to examine the sources of error related to flight testing, to discuss some methods of eliminating or minimizing these errors, and to determine how to deal with the remaining uncertainty when we present our data. Flight testing is a complicated experimental technique. As a result, it combines most of the types of errors found in experimental methods. For instance, fixed, or systematic, errors are found in the instruments from which we collect our data. Random errors come from the atmosphere, from pilot technique, and from errors in taking readings. Gross blunder errors can come from poor test planning, pilot technique, and several other sources.
Although most flight tests can be performed as multisample experiments with considerable improvement in accuracy, the cost of performing the test normally limits us to a single sample experiment. This being the case, we must understand where the sources of our uncertainty lie, take steps to avoid or minimize that uncertainty, and then present the data in a manner that recognizes the remaining uncertainty.
Before we can find the sources and magnitudes of errors we must first define errors. An error can be defined as the difference between the true value and the measured value.
