Category I: Technology-Driven Design Considerations

Design for Performance: Classical aircraft design entails aerodynamics, struc­tures, propulsion, and systems to minimize fuel consumption. Aeronautical engineers strive to make an aircraft light, with low drag and matched engine, low sfc, and bought-out items (e. g., engine, avionics, and actuators) that offer the best value for the money. It is a proven technology for generic, subsonic, commercial aircraft design, with diminishing returns on investment to incor­porate advancements.

Design for Safety: Crashworthiness, emergency exits, and so forth are also proven considerations.

Design for Component Commonality: The family concept of derivative air­craft design offers considerable benefits of cost reduction by maintaining sev­eral component commonalities within the variants. Derivative designs cover a wider market at a much lower unit cost beacuse amortization of NRC is distributed over larger numbers of units sold. Some of the variant aircraft designs may not be sized for the least fuel burned, but the lower unit cost offsets to a lower DOC. This consideration at the conceptual design stage is crucial to the success of the product range.

Design for Reliability and Maintenance: Currently, significant maintenance resources are planned after the design and then acquired to fit the require­ments. This is due to the difficulty of translating statistical feedback from the operational arena, which can be quite abstract. Design attributes – which can make maintenance difficult by demanding additional time and training for highly skilled technicians – must have more detailed considerations to reduce maintenance costs. Cost trade-off studies with the attributes of reli­ability, repairability, and fault detection and isolation must be investigated more stringently at the conceptual design stage. Reliability issues are most important for improving the support environment – in generic terminology, this is a robust design.

Design for Ecology: Since the 1970s, environmental issues (e. g., antipollution) have been enforced through government legislation on noise and emissions at additional cost. The use of alternative fuels for sustainability is also an issue. The growing stringency of existing requirements as well as additional issues only increase the product cost. This is approaching a matured technology with diminishing returns on investment for improvement.

Design for Recycling: Aerospace technology cannot ignore the emphasis on recyclability, a concern that is gaining strength, as evidenced by the topical agenda of “sustainable development” in recent United Nations summit meet­ings. The design for stripping is an integral part of the Design for Recycling to minimize the costs of disassembly. New materials (i. e., composites and metals) result in additional disposal considerations. Cost trade-off studies on

LCC versus material selection for recycling may infringe on marginal gains in weight reduction or fabrication costs.

Design for Anti-terrorism: In the offing is a newer demand for Design for Anti-terrorism. In-flight safety features for protection against terrorist activ­ities include an explosion-absorbing airframe and compartmentalization of the cabin for isolation, which incur additional cost.

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