Một cách tuyệt vời cho các đội thiết kế để bắt đầu quá trình của sự hiểu biết các vấn đề thiết kế này là việc sử dụng quá trình được gọi là "động não". Điều này được thảo luận chi tiết hơn trong phần . Động não là cơ bản là một quá trình mà trong đó tất cả các thành viên của một đội có thể mang lại cho tất cả các ý tưởng về dự án để bàn với | Project study scheduled long-range business jet 91 21 - 20 19- 18- 17- 16- Fig. Trade-off study cruise L D ratio 1000 kg 46- 44- 42 - 40 38- 36 34 32 - Fig. Trade-off study stage fuel mass Economic analysis The results from the studies above can be used together with operational data to assess the economic viability and sensitivity to the aircraft geometrical changes. The aircraft price is related to the aircraft empty mass and engine size. The cost of fuel is proportional to fuel mass. Other operational costs are related to aircraft take-off mass. Hence changes to the aircraft configuration will affect both aircraft selling price and operating costs. For civil aircraft designs these two cost parameters are often selected as the principal design drivers optimising criteria . Although the aircraft configuration 92 Aircraft Design Projects 1000 kg 127- 123 - 119 115- 111 107- 103 - Fig. Trade-off study aircraft max. TO mass sq. m 320 q 300 280 260 240 220 200 180- Fig. 4 .23 Trade-off study wing area may not be selected at the optimum configuration for these parameters the design team will need to know what penalty they are incurring for designs of different configuration. All of the cost calculations have been normalised to year 2005 dollars by applying an inflation index based on consumer prices. Several separate cost studies have been performed as described below. Project study scheduled long-range business jet 93 m 2005 88- 86848280 7876 74 72 70 68- 66 64 Fig. Trade-off study aircraft price Aircraft price Aircraft price is one component in the evaluation of total investment. This includes the cost of airframe and engine spares. For this aircraft the total investment is about 12 per cent higher than the aircraft price. Figure shows the variation of aircraft price for the geometrical changes considered previously. At the design point the price is estimated to be m. The carpet plot shows that this price would fall by about 5 per
