2018/3/11 国上清庆大坐 Overview of Lectures 国上清大学 0.Overview 14/15 Performance(a,b) 16.Aircraft certification 2.Overall configuration 17.Aviation economics weight estimation 18.System integration and d weight estimation configuration management Aircraft Design Fuselage design 19.Multidisciplinary design 6/7/8 Aerodynamic design(a,b,c) ootimization (飞行器设计) .hat and ing 20.Military aircraft design-overview 21.Environmental issues 10.Landing gear and Aircraft systems 22.Design skills 11.Power plant Wenbin Song 12.Stability and control School of Aeronautics and Astronautics 13.Loads,materials and structures Shangy o r nd 0171 Soor an0 Aircraft Sizing 圈上活大坐 Definitions of T/W and Wing Loading 国上大峰 Sizing procedure used to determine the major parameters of the 。Definitions aircraft during conceptual study -Thrust-to-Weight Ratio (T/W):Engine Thrust to Aircraft Weight Ratio T/W and wing loading are the two important parameters affecting Or Power-to-Thrust Ratio (Propeler Engines) the aircraft performance Wing Loading:Aircraft Weight to Wing Reference Area Ratio -Methods to determine T/W Methods to determine W/S el,static thrust, Used along with mission weight calculations settings eagaea2-w58 8oa6o0e四k-a88 T/W and Wing Loading are 图上洋大峰 Thrust Loading vs Wing Loading Interconnected Design Space 国上清大学 Two parameters are interconnected This is our objective from W/S and T/W analysis Both affect the performance of the aircraft 1.6 Small wing loading High wing loading ar母in四 [small wing). Short takeoff cistance Small engine Large engine (High T/W) T/w Wing loading can be determined by stall speed during approach for landing T/W is usually determined first 1
2018/3/11 1 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Wenbin Song School of Aeronautics and Astronautics Shanghai Jiao Tong University swb@sjtu.edu.cn Aircraft Design （飞行器设计） © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Overview of Lectures 0. Overview 1. Introduction 2. Overall configuration 3. Preliminary weight estimation 4. Refined weight estimation 5. Fuselage design 6/7/8 Aerodynamic design(a, b, c) 9. Thrust/Weight ratio and wing loading 10.Landing gear and Aircraft systems 11.Power plant 12.Stability and control 13.Loads, materials and structures 14/15 Performance(a, b) 16.Aircraft certification 17.Aviation economics 18.System integration and configuration management 19.Multidisciplinary design optimization 20.Military aircraft design – overview 21.Environmental issues 22.Design skills © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Aircraft Sizing • Sizing procedure used to determine the major parameters of the aircraft during conceptual study • T/W and wing loading are the two important parameters affecting the aircraft performance – Methods to determine T/W – Methods to determine W/S • Used along with mission weight calculations © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Definitions of T/W and Wing Loading • Definitions – Thrust-to-Weight Ratio (T/W): Engine Thrust to Aircraft Weight Ratio • Or Power-to-Thrust Ratio (Propeller Engines) – Wing Loading: Aircraft Weight to Wing Reference Area Ratio • T/W is typically defined using sea-level, static thrust, standardday conditions at design takeoff weight and maximum throttle settings © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 T/W and Wing Loading are Interconnected • Two parameters are interconnected • Both affect the performance of the aircraft • Wing loading can be determined by stall speed during approach for landing • T/W is usually determined first Small wing loading (large wing) Small engine Short takeoff distance High wing loading (small wing) Large engine (High T/W) © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Thrust Loading vs Wing Loading Design Space • This is our objective from W/S and T/W analysis
2018/3/11 Thrust Loading vs Wing Loading 圈上声克大学 Thrust-to-Weight Ratio 国上清大学 For cargo and passenger transport Performance implications of T/W parameter ®的厂 ration imum speed Turn rate For fighter jet aircraft T/W varies during flight as Weight variation (as fuel is burned) -Engine thrust varies with altitude,speed and throttle settings T/W used in design often refers to the value for take-off 4。 (sea-leve 0M7 vsaic,standard-day condtion,design takeoff weigh setting) 1 bf/=4.882427636kgym2- Soor an0 Thrust-to-Weight Ratio 国上注道大坐 Empirical Estimation of T/W 圆上洋文廷大蜂 Typical T/W Values for jet powered aircraft For jet powered aircraft,the T/W can be estimated based on Mmax m。=aMx 0254 Table3.3:喷气飞机的典型指重比T/W)与/m,的经验径值系数 Power loading for propeller powered aireraft 设气机英型 defined as weight/house power(W/hp) 0488 008 -Typically ranges from 10-15 0.64s 0.594 -Relations with T/W 0.514 0141 -00 军用运输机/轰炸机 0.244 0341 民用喷气客机/运输机 0.267 0363 wherep is propeller efficiency,V is speed in ft. rAer 8oa6o0e四k-a88 Estimation of T/W from Cruise Conditions 国上清大学 Cruise with Minimum Thrust 图上活大坐 For steady level flight,the speed is a function of wing loading,air ·For jet engine density( ude),and lift coefficient Lift and drag coefficient for minimum drag cruise T=D=gS(CDo KCi) L =W=gSCL =-背-0 av 忌周 医 T/W for cruise can be defined as 安原 品而器+() ”asc+k√受月 =qS(Co。+CpJ 2
2018/3/11 2 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Thrust Loading vs Wing Loading • For cargo and passenger transport lbf/lbm 1lbf/ft2=4.882427636kg/m2 For fighter jet aircraft © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Thrust-to-Weight Ratio • Performance implications of T/W parameter – Acceleration – Climb – Maximum speed – Turn rate • T/W varies during flight as – Weight variation (as fuel is burned) – Engine thrust varies with altitude, speed and throttle settings • T/W used in design often refers to the value for take-off conditions (sea-level, static, standard-day condition, design take-off weight, maximum throttle setting) © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Thrust-to-Weight Ratio • © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Empirical Estimation of T/W • For jet powered aircraft, the T/W can be estimated based on Mmax C aM W T max 0 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Estimation of T/W from Cruise Conditions • For steady level flight, the speed is a function of wing loading, air density (altitude), and lift coefficient • T/W for cruise can be defined as © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Cruise with Minimum Thrust • For jet engine • Lift and drag coefficient for minimum drag cruise
2018/3/11 Cruise with Minimum Power 图上唐大学 Conversion of T/W from Cruise to Take-off Condition 国上活大学 For turboprop engines Minimum powered required for level flight dtobe cmverted o take/orengine P-DV -gS(Cos KCi)Y oV'S(Coo+KCi) P=nc+器 Lift and drag coefficient for minimum power cruise (T/Wtakoyy=(T/W)rue WT/Toru 部-}p9cw-0 0.956 层展 1/(2o-%)for typical high BPR turbofan engine DsCon+ICp ege-0滑 Soor an0 Estimation of(L/D)max 圈上活大坐 Other Estimation Methods of T/W 圆上洋廷大蜂 ·From climb rate From takeoff field length From maximum cruise speed Notes:the last two criteria will also involve wing loading therefore it is necessary to re-check T/W after wing loading is estimated orrs 8oa6o0e四k-a88 Wing Loading 图上洋大峰 Wing Loadings of Typical Aircrafts 园上洋天大坐 ·Wing loading -Refers to the value at take-off condition Aircraft type N/m -Affected by aerodynamics,structure and propulsion Medium jets 3000 -Can be estimated by a number of methods Large executive jets 400 ·From stall speed Milaty jet trainers 25003000 From takeoff field length From landing distance Tubopropeller transports 3000-4000 Naval srkeinercepor aircraft 35004000 Land based srike/inerceptor aircraf 4000.5000 Supersoec long range beenber and transpor aircra 500 Subsonic long range bomber aireraft 500m.6000 5500-6500+ 3
2018/3/11 3 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Cruise with Minimum Power • For turboprop engines • Minimum powered required for level flight • Lift and drag coefficient for minimum power cruise © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Conversion of T/W from Cruise to Take-off Condition • (T/W)cruise needs to be converted to takeoff T/W for engine selection 0.956 1/(20-25%) for typical high BPR turbofan engine © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Estimation of (L/D)max © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Other Estimation Methods of T/W • From climb rate • From takeoff field length • From maximum cruise speed • Notes: the last two criteria will also involve wing loading, therefore it is necessary to re-check T/W after wing loading is estimated V V W L D T vertical climb climb 1 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Wing Loading • Wing loading – Refers to the value at take-off condition – Affected by aerodynamics, structure and propulsion – Can be estimated by a number of methods • From stall speed • From takeoff field length • From landing distance © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Wing Loadings of Typical Aircrafts Aircraft type N/m2
2018/3/11 Historical Trend of Wing Loadings for Transport Aircraft 园上声哀通大学 Wing Loading of Some Civil Jet Aircraft 国上清大学 A reflection of wing aerodynamic efficiency 60 装e 2 50 9 5 and Wing Loading from Stall Speed 圆上清文大些 CLmax for different high lift devices 园上活道大整 Level flight,stall speed Landing requirements most demanding,takeoff condition is 20% less Therefore W-1-qaoSC=pVauSCL Decision factor for HLD choices ·How to calculate W/S Table 21 C for high lift devices Relationship bet en stall speed and approach speed High lift device Typical flap angle,deg CLma/cOs(AcH) Vpm =(1.2-1.3V for civil jet Trailing edge Leading edge Takeoff Landing Takeoff Landing Plain 20 60 14→1.61.7+2.0 -The approach speed is normally given as one of design criteria Single skot 15→17 18→22 Foler 15 20,2.2 2.5→29 Double sltd. 17→2.0 23→27 W/S-VrCm 26 000 2.8→32 32→35 eagaea2-w58 Ret Arcraft Engine Design.AIAA educaon seres Crude Estimation of CLmax 国上清大学 CLmax of some civil aircraft 图上活大坐 For clean wing CLma=0.9CIm COS A025e For flapped wing m品品 品已m S. Flapped wing section max lif coeeiet(stal AOA=) 女 lift coefficient at a Cfor take off condition Cfor landing condition 4
2018/3/11 4 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Historical Trend of Wing Loadings for Transport Aircraft • A reflection of wing aerodynamic efficiency Ref: A Wing for Airbus.pdf © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Wing Loading of Some Civil Jet Aircraft © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Wing Loading from Stall Speed • Level flight, stall speed • Therefore • How to calculate W/S – Relationship between stall speed and approach speed – The approach speed is normally given as one of design criteria (1.2 ~ 1.3) V V approach stall for civil jet © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 CLmax for different high lift devices • Landing requirements most demanding, takeoff condition is 20% less • Decision factor for HLD choices Ref: Aircraft Engine Design, AIAA education series © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Crude Estimation of CLmax • For clean wing • For flapped wing CLmax Cl max 0.25c 0.9 cos Flapped wing section max lift coefficient (stall AOA= α) unflapped wing section lift coefficient at α © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 CLmax of some civil aircraft CLmax for take off condition CLmax for landing condition
2018/3/11 Wing Loading from Takeoff Field Takeoff Field Length Requirements Length 图上活大学 周上洋文大学 Takeoff distance the the All Engines and tah-出r. ed) Operating ired from brake release until the aircraft has reached some specified aititude(S_h)(35ft for commercial aircraft) 产流的 One engine inoperative (OEI)before tart ta Vland continus the ac deasion V=Vrot R speed (V1) V-OL hm 630420404234004300423004430060400200008764 One engine s_g inoperative sh-sb after decision speed Other Factors Affecting the Takeoff Field Length 圈上活大坐 Wing Loading from Landing Distance 圈上活大整 Aerodynamic drag 部 ·Landing distance caused early roll -Landing ground roll:distance travelled from the time the wheel first Rolling resistance touch to the time the aircraft comes to a complete stop vay surface -FAR25 landing field length:50ft obstacle clearance at approach speed, plus 2/3 margin for safety reasons arrangement of tyres approach stall spced R touchdown specd-115stall speed V=9 For given takeoff distance,wing loading can be determined for jet aireraft by '-GCo(W）Density ratio 8oa6o0e四k-a88 Estimation of Landing Distance 国上清大学 Wing Loading from Cruise 国上清大学 First approximation To maximize range during cruise,the wing loading is selected to Estimated from approach speed in knots 0.3V providea highL/D A better approximation Range is optimized using "cruise climb"technique For jet aircraft,the following wing loading provides the maximum 一=得以之」=传以之网 range -Sa=1000ft {305m)for airliner,3 degree glide slope W/S=q\CDo/3k =qzeCDo/3 Note:this wing loading must be converted to takeoff condition mission calculated value 5
2018/3/11 5 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Wing Loading from Takeoff Field Length • Takeoff distance – Ground roll: the actual distance travelled before the wheels leave the ground (S_g) at liftoff speed (1.1 stall speed) – Obstacle clearance distance: distance required from brake release until the aircraft has reached some specified altitude (S_h) (35ft for commercial aircraft) – Balanced field length: the distanced required to clear the obstacle when one engine fails at “decision speed (V1)” (S_b) [FAR takeoff field length] V = 0 V = Vroll hto R gt-o S_g S_h S_b © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Takeoff Field Length Requirements • There are three difference cases All Engines Operating JAR 25.113 Take-off distance and take-off run (a) Take-off distance is the greater of - (1) The horizontal distance along the take-off path from the start of the take-off to the point at which the aeroplane is 35 ft above the take-off surface, determined under JAR 25.111; or (2) 115% of the horizontal distance along the take-off path, with all engines operating, from the start of the take-off to the point at which the aeroplane is 35 ft above the take-off surface, as determined by a procedure consistent with JAR 25.111. One engine inoperative (OEI) before decision speed (V1) JAR 25.109 Accelerate-stop distance. (a) The accelerate-stop distance (...) is the greater of the following distances: (2) The sum of the distances necessary to - (i) Accelerate the aeroplane from a standing start to V1 and continue the acceleration for 2·0 seconds after V1 is reached with all engines operating; and (ii) Come to a full stop from the point reached at the end of the acceleration period prescribed in sub- paragraph (a)(2)(i) of this paragraph, assuming that the pilot does not apply any means of retarding the aeroplane until that point is reached and that all engines are still operating. One engine inoperative after decision speed JAR 25.111 Take-off path. (2) The aeroplane must be accelerated on the ground to VEF, at which point the critical engine must be made inoperative and remain inoperative for the rest of the take-off; and (3) After reaching VEF, the aeroplane must be accelerated to V2. (b) During the acceleration to speed V2, the nose gear may be raised off the ground at a speed not less than VR. However, landing gear retraction may not be begun until the aeroplane is airborne. (c) During the take-off path determination in accordance with sub-paragraphs (a) and (b) of this paragraph - (2) The aeroplane must reach V2 before it is 35 ft above the take-off surface © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Other Factors Affecting the Takeoff Field Length • Aerodynamic drag caused early roll • Rolling resistance – Runway surface – Type, number, inflation pressure, and arrangement of tyres For given takeoff distance, wing loading can be determined for jet aircraft by TOP C T W S W LTO Density ratio © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Wing Loading from Landing Distance • Landing distance – Landing ground roll: distance travelled from the time the wheel first touch to the time the aircraft comes to a complete stop – FAR25 landing field length: 50ft obstacle clearance at approach speed, plus 2/3 margin for safety reasons V = Vroll V = 0 hto R g=3 ° S_g S_h approach speed=1.3 stall speed touchdown speed=1.15stall speed © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Estimation of Landing Distance • First approximation – Estimated from approach speed in knots 0.3𝑉 ଶ • A better approximation – Sa=1000ft {305m}for airliner, 3 degree glide slope – For FAR25 aircraft, Slanding increased by two thirds – Wing loading obtained must be converted to takeoff conditions, and for jet liners, the weight ratio can be taken as 0.85 instead of using mission calculated value [ ] 1 [ ] 5 1 80 max max S m S C W S ft S C W S a L a L landing © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Wing Loading from Cruise • To maximize range during cruise, the wing loading is selected to provide a high L/D • Range is optimized using “cruise climb” technique • For jet aircraft, the following wing loading provides the maximum range • Note: this wing loading must be converted to takeoff condition W S q CD0 3k q AeCD0 3
2018/3/11 Wing Loading from Loiter Endurance 圈上声克大学 Use of Wing-Loading and Thrust- Weight Ratio 国上清大学 beoreandinrethe For jet aircraft,best loiter occurs at maximum L/D,therefore W/S=qCpo/k=qAeCDo IT W Wing loading determined from conditions such as turns are more relevant to fighter jets 设计 催e Fiue4.11:翼载和推重比的约束空间 o r nd 0171 Soor an0 Summary 国上注道大峰 国上清道大坐 Thrust-to-Weight Ratio (T/W)and Wing Loading (W/S)are two of the most important parameters that affects -Takeoff/Landing field length -aimb performance -Tumning performance -Cruise/Loiter performance are interrelate nee to be cross checked after i using a numbe different criteria Backup slides rAer 8oa6o0e四k-a88 More realistic example 国圆上清发大坐 Cruise at Different Speed 园上海发大坐 的乙#设计日都可用批木推地 深用复合材料 Min thrust cruise(min drag) Max endurance cruise(min 二 气动减阻：提高发动机油耗 power,min fuel used) 着场长 Optimum cruise(best range cruise) 低速性 Shanghal Jao Tong Unkversty-Dr.Wer 6
2018/3/11 6 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Wing Loading from Loiter Endurance • Typically, 20min of loiter before landing is required in the mission design of most aircraft • For jet aircraft, best loiter occurs at maximum L/D, therefore • Wing loading determined from conditions such as turns are more relevant to fighter jets D0 AeCD0 W S q C k q © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Use of Wing-Loading and ThrustWeight Ratio © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Summary • Thrust-to-Weight Ratio (T/W) and Wing Loading (W/S) are two of the most important parameters that affects – Takeoff/Landing field length – Climb performance – Turning performance – Cruise/Loiter performance • T/W and W/S are interrelated and need to be cross checked after determined using a number of different criteria © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Backup slides © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 More realistic example 约束条件或设计目标 可用技术措施 TOGW最小 采用复合材料 DOC最小 平衡售价和使用成本 轮档燃油最小 气动减阻；提高发动机油耗 Vapproach 着陆场长 起飞场长 起飞要求 单发失效高度 低速特性 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics, 2017-2018 Cruise at Different Speed • Min thrust cruise (min drag) • Max endurance cruise (min power, min fuel used) • Optimum cruise (best range cruise)
