. Four Phases of Aircraft Design

Aircraft manufacturers conduct year-round exploratory work on research, design, and technology development as well as market analysis to search for a product. A new project is formally initiated in the four phases shown in Chart 2.2, which is applicable for both civil and military projects. (A new employee should be able to sense the pulse of organizational strategies as soon joining a company.)

Among organizations, the terminology of the phases varies. Chart 2.2 offers a typical, generic pattern prevailing in the industry. The differences among ter­minologies are trivial because the task breakdown covered in various phases is

approximately the same. For example, some may call the market study and specifi­cations and requirements Phase 1, with the conceptual study as Phase 2; others may define the project definition phase (Phase 2) and detailed design phase (Phase 3) as the preliminary design and full-scale development phases, respectively. Some pre­fer to invest early in the risk analysis in Phase 1; however, it could be accomplished in Phase 2 when the design is better defined, thereby saving the Phase 1 budgetary provisions in case the project fails to obtain the go-ahead. A military program may require early risk analysis because it would be incorporating technologies not yet proven in operation. Some may define disposal of aircraft at the end as a design phase of a project. Some companies may delay the go-ahead until more informa­tion is available, and some Phase 2 tasks (e. g., risk analysis) may be carried out as a Phase 1 task to obtain the go-ahead.

Company management establishes a DBT to meet at regular intervals to con­duct design reviews and make decisions on the best compromises through multidis­ciplinary analysis (MDA) and MDO, as shown in Chart 2.3; this is what is meant by an IPPD (i. e., concurrent engineering) environment.

Specialist areas may optimize design goals, but in an IPPD environment, com­promise must be sought. It is emphasized frequently that optimization of individual goals through separate design considerations may prove counterproductive and usu­ally prevents the overall (i. e., global) optimization of ownership cost. MDO offers

Manpower

Cost Frame

100% deployment

Customer

Support

a. Phase-wise deployment

Figure 2.2. Resource deployments (manpower and finance) good potential but it is not easy to obtain global optimization; it is still evolving. In a way, global MDO involving many variables is still an academic pursuit. Indus­tries are in a position to use sophisticated algorithms in some proven areas. An example is reducing manufacturing costs by reshaping component geometry as a compromise – such as minimizing complex component curvature. The compromises are evident in offering a family of variant aircraft because none of the individuals in the family is optimized, whereas together, they offer the best value.

When an aircraft has been delivered to the operators (i. e., customers), a manu­facturer is not free from obligation. Manufacturers continue to provide support with maintenance, design improvements, and attention to operational queries until the end of an aircraft’s life. Modern designs are expected to last for three to four decades of operation. Manufacturers may even face litigation if customers find cause to sue. Compensation payments have crippled some well-known general aviation compa­nies. Fortunately, the 1990s saw a relaxation of litigation laws in general aviation – for a certain period after a design is established, a manufacturer’s liabilities are reduced – which resulted in a revitalization of the general aviation market. Military programs involve support from “cradle to grave” (see Section 1.7.)

This emphasizes that the product must be done right the first time. Midcourse changes add unnecessary costs that could be detrimental to a project – a major change may not prove sustainable. Procedural methodologies such as the Six Sigma approach have been devised to ensure that changes are minimized.