A Report On POWER EFFECTS ON THE LONGITUDINAL CHARACTERISTICS OF SINGLE-ENGINE PROPELLER-DRIVEN AIRCRAFT
SUMMARY
The effects of power on the longitudinal flying qualities of a single-engine propeller driven aircraft have been investigated. The net effective developed as the resultant of six major contributions which, in this study, ,,vr-bwestimatcd from the USAF Stability and Control Datcom. These contributions are no Independent and In general are non, linear functions of both incidence and speed. It is shown that the effect on stability of S, ,the incidence-dependent terms is conveniently described by the neutral point t,),While the combined Inciderce and speed terms can be described by the static stability limit.4.z. The effects of each power contribution on the longitudinal static and dynamic characteriics of a basic aircraft layoutrmior~d-a4h.'utandard cue!!0have 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 bndependent of c.g. position. The power effects for an aircraft layout typical of modern drsgns 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. The sources of many of the estimation m'ethods in Datcom are identified and discussed From the survey and from the Information presented in this Report it is concluded that "[here exists a need for more robust theoretical and numerical design methods for most of 'the power effects considered and also for more comprehensive wind tunnel and flight test data regarding the effect .if slipstream on tail-plane lift.
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