"INTRODUCTION This Item provides simple semi-empirical methods for estimating the important in-plane forces and moments at low forward speeds on installed single-rotation and contra-rotating* propellers inclined at moderate angles (<20??say) to the local flow into the propeller. The data are presented in the form of force and moment coefficient derivatives with respect to the effective local flow angle at the propeller@ which requires a separate estimation@ see Item No. 90020 (Reference 12). The data are intended primarily for aircraft stability and control calculations at the project stage; more detailed methods will usually be required for load calculations@ such as propeller blade stresses and powerplant mounting loads. Section 3 gives a simple description of the origin of the in-plane forces and moments on an isolated inclined propeller and discusses the effects on the inclination angles of the installation of the propeller on an aircraft. Section 4 lists the equations for the important derivatives and discusses practical means whereby they can be made more amenable to graphical presentation. Section 5 provides a simple approximate relationship between the propeller effective solidity used as a parameter in the method and the total activity factor@ a quantity widely used at the project stage. Further@ Section 5 shows how the generalised@ dimensionless forms of the equations or graphs can be applied to provide the derivatives in terms of the dimensional parameters for the propeller commonly used in practical applications. Equations are also given for the conversion of the derivatives to ones based on free-stream kinetic pressure and aircraft reference area and length. Section 6 discusses the applicability and accuracy@ Section 7 gives the Derivation and References and Section 8 illustrates the practical application of the method by means of a detailed worked example. Appendix A provides details of a computer program for determining the propeller derivatives. A diskette containing the source code for the program and the input and output files of a number of examples@ in addition to that in Section 8@ is given in the Aerodynamics Software Volume. The software is also available on CD ROM. * Two rotors revolving in opposite directions on coaxial shafts. ""Contra-rotating"" propellers are also commonly known as ""counter-rotating"" or ""dual-rotation"" propellers."
ESDU 89047 B-1991 history
1991ESDU 89047 B-1991 IN-PLANE FORCES AND MOMENTS ON INSTALLED INCLINED PROPELLERS AT LOW FORWARD SPEEDS