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2.3 Typical Design Process

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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.

2.3.2 Typical Resources Deployment

All phases do not work under uniform manpower-loading; naturally, Phase 1 starts with light manpower during the conceptual study and reaches peak manpower (100%) at Phase 3; it decreases again when flight testing starts, by which stage the design work is virtually done and support work continues. Figure 2.2a is a typical distribution of cost and manpower loading (an average percentage is shown); the manpower-loading forecast must be finalized during the Phase 1 study. Figure 2.2b shows the cumulative deployment. At the end of a project, it is expected that the actual figure should be close to the projected figure. Project costs consist primarily of salaries (most of the cost), bought-out items, and relatively smaller miscellaneous amounts (e.g., advertising, travel, and logistics). Chain lines in Figure 2.2 illustrate the cost-frame outlay.

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