A SIMPLE TOTAL ENERGY SENSOR

Abstract

A sailplane owes its performance to the utilization of energy supplied frorn external sources. Sensitive rate of climb instruments (variometers) connected to static pressure sources are comonnly used to indicate rising or sinking of the sailplane. Several methods have been used to provide dynamic pressure conpensation for rate of climb when zooming or...diving, so that the variometer indicates rate of change in total energy instead of rate of change in potential energy. The most widely used compensators have been of two types; diaphragm-volume systems and venturi systems. This research concerns a study of a simple technique for total energy compensation having the prirnary requirement of good compensation with a low cost, easy to make, sensor. A comprehensive library search and a srnall wind tunnel were used to explore fundamentals and to develop a number of probes which were flight tested with satisfactory results. Simple probe configurations were tested using the characteristics of laminar flow separation around a small cylinder to produce a sensor pressure having the desired relationship between static and dynamic pressures. Wind tunnel and flight tests confirmed the concepts for a wide range of speeds, altitudes, and flow directions encountered in soaring. Data and findings are presented, along with a discussion of factors important to total energy compensation.