2018/3/11 Historical Trend Line for WE 国上活大坐 Trapped Fuel 国上清大学 What we know:historical data from similar aircrafts can be used Trapped fuel is typically small,as percentage of aircraft take off What we also know:the new aircraft should be better weight And can be estimated using Can als be 3.1) Mre =0227MLWTo Soor an0 the First Weight Estimate 圆上清文大些 Estimation of SFC 国上道大坐 Mission SFC:is the fuel mass required to provide specific net thrust for a requirement given period,[lb/hr/Ibf]or [g/(kN-s)] Typical values for SFC Concept Sketeh Initial Sizing Aspect Ratio L/D TypicalJet SFCs:1/hr(mg/Ns]Cruise Loiter Estimates ww。 Pure turbojet 0.92551 0.822.71 selection Low-bypass turbofan 0.822.7刀 0.719.8 High-bypass turbofan 05f141 0.411.3到 ww。 equation iterate Wa -1-Mrm-Me1 Calculated w。and (.6) 8oa6o0e四k-a88 Estimation of L/D 图上洋大峰 Weight Estimation Iteration 园上海发大坐 Reflects the overall aerodynamic efficiency At subsonic speed,mostly affected Wing span -Wetted area In level flight,L=G,L/D depends on D Drag is composed of -Induced drag,caused by the generation of lift -Zero-lift drag,primarily skin-friction drag and directly related to the total exposed surface area of the aircraft Historical data of similar aircraft are often used -- -初时” 42018/3/11 4 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Historical Trend Line for WE • What we know: historical data from similar aircrafts can be used • What we also know: the new aircraft should be better 19 B707-320C B717-200B727-200Adv B737-200 B737-300 B737-400 B737-500 B737-600 B737-700 B737-800 B747-100B747-200 B747-400 B757-200 B757-300 B767-200B767-200ER B767-300 B767-300ER B777-200B777-200IGW B777-300 A300-600R A310-300 A319-100 A320-200 A321-200 A330-300 A330-200 A340-200 A340-300 A340-500 A340-600 A3XX-100 0.4 50000.4 100000.4 150000.4 200000.4 250000.4 300000.4 0 100000 200000 300000 400000 500000 600000 Operating Empty Weight (kg) Maximum Takeoff Weight (kg) 0.079 1000 0.82         MTOW MTOW OE W W W MTOW MTOW OE W W W  0.5* © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Trapped Fuel • Trapped fuel is typically small, as percentage of aircraft take off weight • And can be estimated using • Can also be ignored at this stage 20 0.001  MTF  0.005 2 / 3 1/ 3 0.227  MTF  MFUELWTO (3.11) © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 the First Weight Estimate 21 Mission requirement Concept Sketch Initial Sizing Swet/Sref Aspect Ratio Estimates L/D SFC We /W0 Wf/W0 W0 guess W0 equation Calculated W0 and Wf Engine selection iterate Equation (3.6) TO E TO FUEL PLC FUEL E PLC TO W W W W W M M W W       1 1 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Estimation of SFC • SFC: is the fuel mass required to provide specific net thrust for a given period, [lb/hr/lbf] or [g/(kN∙s)] • Typical values for SFC • 22 Typical Jet SFCs: 1/hr[mg/Ns] Cruise Loiter Pure turbojet 0.9[25.5] 0.8[22.7] Low-bypass turbofan 0.8[22.7] 0.7[19.8] High-bypass turbofan 0.5[14.1] 0.4[11.3] © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Estimation of L/D • Reflects the overall aerodynamic efficiency • At subsonic speed, mostly affected – Wing span – Wetted area • In level flight, L=G, L/D depends on D • Drag is composed of – Induced drag, caused by the generation of lift – Zero-lift drag, primarily skin-friction drag and directly related to the total exposed surface area of the aircraft • Historical data of similar aircraft are often used 23 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Weight Estimation Iteration 24