tailieunhanh - Aircraft Design Projects Episode 10

Tham khảo tài liệu 'aircraft design projects episode 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Project study advanced deep interdiction aircraft 251 Altitude ft Fig. Engine performance at where x H 36089 H altitude ft For our aircraft the reference area is 1430 sq. ft 133 sq. m . As we are unaware of the fuel burnt in each segment at this stage in the design process it will be necessary to make some assumptions regarding the weight of the aircraft at the start of each stage as shown below a Outbound supercruise MTOW b Outbound dash MTOW c Return dash MTOM d Return supercruise MTOW And if the return stages follow the release of munitions e Return dash MTOM - 8000 lb f Return supercruise MTOW - 8000 lb where from section MTOM 114 082lb 51 739kg . The aircraft weight defines the CL which in turn defines the CD from which the aircraft drag is calculated. This is multiplied by the engine sfc to obtain the fuel used per hour. This procedure is easily performed using a spreadsheet method. The results are shown in Figure . This clearly shows an optimum altitude for each stage. The optimum heights are cross-plotted against aircraft weight in Figure . The associated fuel consumption is also plotted on this graph. At this point it is possible to use the fuel consumption results to determine the overall fuel burnt on the mission assuming that the fuel consumption in each stage is the average between the start and end values . The time spent on each stage is the stage distance divided by the aircraft speed. As the speed is constant kt the 252 Aircraft Design Projects Cruise altitude ft Fig. Aircraft fuel burn versus altitude Altitute ft Best alt Fuel burn lb hr Aircraft weight lb Fig. Optimum cruise versus aircraft weight supercruise stages of 1000 nm take hr and the dash stages of 750 nm take hr. The analysis is shown in Table . This is much larger than originally estimated due to the lower lift to drag ratio compared to assumed earlier . This would mean that the aircraft MTOW