The Problems of Speed Measurement: The Difficulty of Arriving at Accurate Knowledge

MOST readers of AIRCRAFT ENGINEERING, and all who have at any time been associated with performance tests, will know that the arrival at a decision as to what is the real maximum speed of any aeroplane is by no means a simple matter. There arc so many variables and possibilities of error that elaborate arrangements must be made for tests if a correct figure is to be obtained. The position has in recent years become complicated by a lack of precision and uniformity in the terms used to denote the various speeds—or, rather, the speeds obtained by various methods of measurement.