812. A Parametric Approach to Estimating Weights of Surface Control Systems of Combat and Transport Aircraft

Paper

Abstract

This paper presents methods for estimating the weights of surface control systems for two major categories of aircraft: modern transonic and supersonic combat-type designs, and subsonic transport-type designs having hydraulically powered lateral, longitudinal, and directional controls. The methods are parametric in nature and are intended for use primarily during preliminary design. While they must be considered to have only ‘ballpark’ accuracy, it is felt that they will make it possible to avoid the large errors in Surface Controls Group estimates that have sometimes occurred in the past. The approach taken in developing the methods is to define a separate method, or group of methods, for each different type of control system – one group for the maneuvering systems controls (aileron controls, elevator controls, etc.), one for the trailing edge flap controls, etc. Moreover, each method takes into account the characteristics of the particular system as well as those of the overall aircraft. Application of the methods is illustrated by a sample calculation performed on an existing aircraft design, and the results are compared with the corresponding actual weights. An appendix to the paper defines some approximate relationships between the nature of several maneuvering controls system design characteristics and such overall aircraft parameters as design gross weight and maximum speed; these relationships will be useful to the weight engineer in making estimates during the preliminary phases of aircraft design.