Power Effects on the Longitudinal Characteristics of Single-Engine Propeller-Driven Aircraft

摘要

The effects of power on the longitudinal flying qualities of a single-engine propeller-driven aircraft were investigated. The net effect is developed as the resultant of six major contributions which, in this study, were estimated from the USAF Stability and Control Datcom. These contributions are not independent and in general are nonlinear functions of both incidence and speed. It is shown that the effect on stability of the incidence-dependent terms is conveniently described by the neutral point while the combined incidence and speed terms can be described by the static stability limit. The effects of each power contribution on the longitudinal static and dynamic characteristics of a basic aircraft layout have been illustrated both individually and collectively. The influence of aircraft layout and configuration has also been demonstrated with both power-off and power-on. It is shown that net power effects are sensitive to aircraft layout and can change appreciably when flaps are deflected. An instability is demonstrated which is due to power and flap effects and which is almost independent of c.g. position. The power effects for an aircraft layout typical of modern designs are also illustrated. The study is completed by a survey of research on propeller power effects which draws attention to the large amount of wind tunnel research which has been carried out from the early days of powered flight. Sources of many of the estimation methods in Datcom are identified and discussed.