Đây là cuốn sách hoàn hảo cho các ước tính trọng lượng thành phần trong quá trình thiết kế ban đầu. Nó được viết bằng một ngôn ngữ mà có thể được hiểu bởi bất kỳ người kỹ thuật và đó là nội dung có giá trị hành nghề kỹ sư hàng không vũ trụ. Cuốn sách này theo phong cách giống như tất cả các cuốn sách của Roskam. | For easy reference the airplane will be referred to as the Selene the name of the Greek Moon Goddess. Step Ĩ Tables and contain component weight data for airplanes in the same category as the Selene. Specifically the following airplanes have comparable sizes and missions Cessna 310C Beech 65 Queen Air Cessna 404-3 and Cessna 414A. Step 3 For reasons of brevity only the following component weights are considered Wing Empennage Landing Gear Power Plant Fuselage Nacelles Fixed Eqpmt Step 4 The following table lists the pertinent weight fractions and their averaged values. Because the intent is to apply conventional metal construction methods to the Selene there is no reason to alter the averaged weight fractions. Beech 65 QA Cessna 310C Cessna 404-3 Cessna 414A Selene Average Pwr Plt GW Fix Eqp GW 0. 123 0. 103 0. 134 0. 132 Empty Wht GW 0. 638 0. 628 0. 665 0. 631 Wing Grp GW 0. 095 Emp. Grp GW Fus. Grp GW 0. 066 0. 0 80 Nac. Grp GW 0. 034 Gear Grp GW 0. 054 0. 049 Note that the ratio of w. GW which follows from the preliminary sizing is 4 900 7 900 . This is close to the average value of in the above tabulation. Step 5 Using the averaged weight fractions from Step 4 the following preliminary component weight summary can be determined Part V Chapter 2 Page 8 Component First weight estimate lbs Adjustment lbs Selene Class I weight alum. lbs Class I weight compos. lbs Wing 751 -13 738 627 Empennage 182 - 3 179 152 Fuselage 632 -11 621 528 Nacelles 253 - 4 249 212 Landing Gear 3 87 - 7 3 80 3 80 Power Plant 1 738 -30 1 708 1 708 Fixed Eqp. 1 043 -18 1 025 1 025 Empty Wht 4 9 86 -86 4 900 4 632 Payload 1 250 1 250 Fuel 1 706 1 706 Trapped fuel and oil 44 44 Take-off Gross Weight 7 900 7 632 When the numbers in the first column are added they yield an empty weight of 4 986 lbs instead of the desired
