INTRODUCTION
This book has attempted to give an introduction to most aspects of aircraft design, with emphasis on giving the reasons for the shapes of aircraft, and descriptions of their constituent parts. The preface clearly stated that it was not intended to produce a book about aircraft conceptual design, as many good texts are currently available. Some of these are referred to in the previous chapter, and they should be used, with help, to produce aircraft conceptual designs. Conceptual designs, however, are not usually end-products, but merely important steps in the whole design–manufacture–operation cycle.
Conceptual designs must be objectively assessed to see if they warrant the significantly increased expenditure that would be required to perform preliminary and detailed design. A vital precursor to this decision-making process is a clear definition of the characteristics of the conceptual design, and this is discussed in Section 10.2. Section 10.3 shows the options that are available following a conceptual design process and Section 10.4 describes simple decision-making techniques. The final section of this chapter gives an example of a conceptual-design definition, and describes the decisions that were made about its future.
CONCEPTUAL DESIGN DEFINITION
It is important to summarize clearly the results of the conceptual design process by providing the following types of information:
(i) Configuration description – This will be defined by means of conventional engineering drawings, tabular data, computer models, physical models or a combination of these methods, together with a brief description of the rationale of the design.
(ii) Mass estimates – These will include gross and empty masses, together with component mass estimates to be used as targets for subsequent work.
(iii) Performance estimates – Drag and lift predictions will be produced, together with powerplant data to give payload-range curves, field-performance, and direct operating cost targets for commercial aircraft. Military aircraft will also require predictions to be made of sortie performance, and point performance criteria such as attained turn rate, sustained turn rate and specific excess power.
(iv) Reliability and maintainability targets – The direct operating cost targets, mentioned above, imply estimates of acquisition costs as well as reliability and maintainability (R and M) characteristics. These may be used to set R and M targets for subsequent design stages (Appendix C).
Review the options below to login to check your access.
Log in with your Cambridge Aspire website account to check access.
If you believe you should have access to this content, please contact your institutional librarian or consult our FAQ page for further information about accessing our content.