Conceptual Aircraft Design

14Aircraft Sizing, Engine Matching and Variant Derivatives

14.1 Overview

Chapter 8 configured a preliminary geometry of a new aircraft based on the laid out specifications. It started with the estimated maximum takeoff mass (MTOM), wing reference area, S_W, and engine size from the available statistics of past designs for the class of aircraft. The fuselage geometry was determined to accommodate what it has to house, for example, in case of civilian aircraft, the number of passengers and in the case of military designs, the engine, fuel volume, equipment and so on. Chapter 9 laid out the undercarriage based on an estimated aircraft aft centre of gravity (CG) position. Empennage size is linked with wing S_W and where it is placed in relation to it. With these preliminary aircraft component geometries, a proper estimate of aircraft MTOM and CG position was evaluated in Chapter 10. At this point, if the estimated MTOM differed (very likely) from the guessed MTOM, the first iteration is required to reconfigure the aircraft primarily affecting the S_W. Together, this presented a ‘concept definition’ of the new aircraft project at the Phase I stage of conceptual design study.

The next step in the conceptual design study is the size of the aircraft with the proper reference wing area S_W with a matched engine to be more precise than a guesstimate taken from statistics.

The aircraft sizing and engine matching routine is a necessary procedure for a new aircraft project starting early at the ...