Basic Helicopter Aerodynamics, 3rd Edition

Appendix

Performance and Mission Calculation¹

A.1 Introduction

In the main body of the book, methods have been described which enable the calculation of the power necessary to allow a helicopter to operate at a given weight and at a given speed. The results of these calculations, when combined with appropriate engine data, enable the fuel consumption to be determined and a mission can then be ‘flown’ in a computer. The ability to perform these calculations now enables a project study to be carried out on a proposed helicopter design. The purpose of this appendix is to collate the various theories of the momentum/actuator disc into an overarching calculation scheme. Earlier chapters highlighted the fact that momentum theories are the simplest available and, in order to make the results more realistic, a scheme of factoring will be required. The simplicity of these methods makes them easy to implement but, in addition, prevents them from being used for calculations where the rotor is operating close to any limitations of the flight envelope. For normal operations, this limitation should not be necessary and the simplicity of these methods will permit parametric studies to be performed with speed and economy. The modern personal computer, and the software available, make these methods, described in this appendix, readily implementable. In this way, an overall picture of the proposed helicopter configuration and its ability to complete a given mission can be readily assessed.

The ...