2018/3/11 C.G.Locations 图上声大学 Typical Landing Gear Geometry Parameters 国上清大坐 >C.G.locations are important for positioning of the landing ” gear CG Six main geometry >Can be estimated from component weights parameters ground angle-p(停机角) b一前，主轮距 tip back angle-Y(防倒位角) wheel base-B(住轮距) tail clearance angle-8( 地角) Height一高度 Ref:land_3 o r nd 0171 Soor an0 Ground Angle- 国上活大峰 Tip Clearance Angle- 国上道大坐 Definition:the angle between level base line of Definition:the angle between runway surface and a aircraft and runway surface plane passing through main gear touchdown point and To reduce takeoff field length tangent to the bottom of aft fuselage ·Typical values0°w4 Influence on aft fuselage flow characteristics Determined from AOA for landing a Takeolf=a incidence alanding a incidence y=a Takeoff-aincidence =C landing-V-mnctdence rAer 8oa6o0e四k-a88 Tipback Angle -Y 图上洋大峰 前，主轮距-b和主起落架高度-H 园上海发大坐 Tipback angle is the maximum aircraft nose-up angle ·When deciding b with the tail touching the ground and strut fully -To make sure nose gear doesn't carry too much or too extended little load 防倒立角should be max(tail clearance angle,15) b =(0.3-0.4)L fuselage Or -85%-92%of weight supported by main gear ·防倒立角should be max(tail clearance angle+(1°~2°)， When deciding H 15) -Constrained by where the main gear is retracted into ·r Sufficient ground clearance ·max(tail clearance angle-+(1°w2°)[former Soviet Union] 32018/3/11 3 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 C.G. Locations  C.G. locations are important for positioning of the landing gear  Can be estimated from component weights Ref: land_3 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Typical Landing Gear Geometry Parameters C.G. B Six main geometry parameters ground angle－ψ (停机角) b－前，主轮距 tip back angle－γ (防倒立角) wheel base－ B(主轮距 ) tail clearance angle－δ (着 地角) Height－高度 b ψ γ δ H © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Ground Angle－ψ • Definition: the angle between level base line of aircraft and runway surface • To reduce takeoff field length • Typical values 0°~ 4°  Takeoff     incidence    Takeoff   incidence © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Tip Clearance Angle－δ • Definition: the angle between runway surface and a plane passing through main gear touchdown point and tangent to the bottom of aft fuselage • Influence on aft fuselage flow characteristics • Determined from AOA for landing  landing      incidence    landing    incidence © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Tipback Angle －γ • Tipback angle is the maximum aircraft nose-up angle with the tail touching the ground and strut fully extended • 防倒立角 should be max(tail clearance angle, 15) • Or • 防倒立角 should be max(tail clearance angle+(1°~2°), 15) • Or • max(tail clearance angle+(1°~2°) [former Soviet Union] © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 前，主轮距－b 和主起落架高度－H • When deciding b – To make sure nose gear doesn’t carry too much or too little load – b = (0.3-0.4)L fuselage – 85%-92% of weight supported by main gear • When deciding H – Constrained by where the main gear is retracted into – Sufficient ground clearance