Download - NASA

More documents

Recommendations

Info

148 AFDD Weight Models fold/tilt weights are: wfair = SfairUfair wflap = SflapUflap wfit = ffit (wprim + wfair + wflap) 1 − ffit wfold = ffold (Wprim + Wfair + Wflap + Wfit + Wtip) Wfair = χfairwfair Wflap = χflapwflap Wfit = χfitwfit Wfold = χfoldwfold The control surface area Sflap for a tiltrotor wing is the sum of the flap and flaperon areas. The fairing area is The wing extension weight is: Sfair =(bw − wattach) cw (1 − wtb) − Sflap wext = SextUext wefold = fefoldWext Wext = χextwext Wefold = χefoldwefold and these terms are added to Wprim and Wfold. The tiltrotor-wing weight (and wing folding weight in fuselage group) depends on the weight on the wing tips, Wtip, which is the sum of rotor group, engine section or nacelle group, air induction group, engine system, drive system (except drive shaft), rotary wing and conversion flight controls, hydraulic group, trapped fluids, and wing extensions. The weight on wing tip is used as the fraction ftip = Wtip/WSD; the mass on the wing tip is Mtip (slug or kg). To estimate the wing weights, the required stiffness is scaled with input frequencies (per rev) of the wing primary bending and torsion modes. First the torque box is sized to meet the torsional stiffness (frequency) requirement. Next spar-cap area is added as required to meet the chord and beam bendingfrequency requirements. Finally spar-cap area is added if necessary for a jump takeoff condition. Wing section form factors, relating typical airfoil and torque-box geometry to ideal shapes, are input or calculated from the thickness-to-chord ratio and the torque-box-chord to wing-chord ratio: FB =0.073 sin(2π(τw − 0.151)/0.1365) + 0.14598τw +0.610 sin(2π(wtb +0.080)/2.1560) − (0.4126 − 1.6309τw)(wtb − 0.131) + 0.0081 FC =0.640424w 2 tb − 0.89717wtb +0.4615τw +0.655317 FT = ((0.27 − τw)/0.12)0.12739 − 2.7545w 2 tb +5.1799wtb − 0.2683 FVH =0.25 sin(5.236wtb)+0.325 −0.96 + 3.32+94.6788wtb − (wtb/0.08344) 2 for beam bending, chord bending, torsion, and spar cap vertical/horizontal bending. The ideal shape for torsional stiffness is a tube of radius tw, so the torsional stiffness J = FT Atbt2 w/4. The ideal shape for chord bending is two caps ctb apart, so ICtb = FCAtbc2 tb /4. The ideal shape for beam bending is two caps tw apart, so IBsp = FVHAspt 2 w/4 and IBtb = FBAtbt 2 w/4. The torque-box cross-sectional area is obtained from the wing-torsion frequency; 2 1 GJ =(ωTΩ) 2 bw 1 2 Mtipr 2 pylon Atb =4GJ/(GtbFT t 2 w)
AFDD Weight Models 149 The spar-cap cross-sectional area (in addition to torque-box material) is obtained from beam and chord bending frequencies: 2 1 EIC =(ωCΩ) 24 b3 1 w 2 Mtipfmode 2 1 EIB =(ωBΩ) 24 b3w EICtb = EtbFCAtbc 2 tb/4 EICsp = EIC − EICtb ACsp = EICsp/(Espc 2 tb/4) EIBtb = EtbFBAtbt 2 w/4 EIVH = EspFVHACspt 2 w/4 1 2 Mtipfmode EIBsp = EIB − EIBtb − EIVH ABsp = EIBsp/(Espt 2 w/4) EIsp = EIVH + EIBsp Asp = ACsp + ABsp where EICsp and EIBsp are replaced by zero if negative (no additional spar material required). The factor fmode =1− ftip is a mode-shape correction for fuselage motion. Next the primary structure, fairing, flap, and fitting weights are calculated as before; and the sum Wwing = Wprim + Wfair + Wflap + Wfit. Additional spar-cap material for a jump takeoff condition is obtained from the ultimate applied bending moment at the wing root: MU = Tcapℓw 0.75(1 − ftip) − 0.375(ℓw/bw)(Wwing/WSD) where Tcap is the maximum thrust capability of one rotor, equal to the greater of njumpWSD/Nrotor or (CT /σ)ρAbV 2 tip (from an input CT /σ at the jump takeoff condition, SLS and hover rotor speed). The bending-moment capacity of the wing is Mtb =2EIBtbɛU /tw Msp =2CmEIspɛU /tw Then the additional cross-section area is obtained from the moment deficit: ΔM = MU − (Mtb + Msp) ΔAsp =2ΔM/(ɛU Esptw) ΔWspar = CjΔAspρspbw/esp where ΔM is replaced by zero if negative (no additional spar material required). If ΔWspar is positive, it is added to Wspar, and the primary structure, fairing, flap, and fitting weights are recalculated. Parameters are defined in table 19-1, including units as used in these equations. Here a consistent mass-length-time system is used, producing Wbox and Wspar in slug or kilogram. Typically the input uses conventional English units for density (pound/inch 3 ) and modulus (pound/inch 2 ).
Page 1 and 2:
NASA/TP-2009-215402 NDARC NASA Desi
Page 3 and 4:
NASA/TP-2009-215402 NDARC NASA Desi
Page 5 and 6:
TABLE OF CONTENTS CHAPTER 1 - INTRO
Page 7:
TABLE OF CONTENTS (cont.) CHAPTER 1
Page 10 and 11:
viii LIST OF FIGURES (cont.) Figure
Page 13 and 14:
Chapter 1 Introduction The NASA Des
Page 15 and 16:
Introduction 3 of rotorcraft config
Page 17 and 18:
Introduction 5 previous case DESIGN
Page 19 and 20:
Introduction 7 4) Scully, M.; and F
Page 21 and 22:
Chapter 2 Nomenclature The nomencla
Page 23 and 24:
Nomenclature 11 Fuel Tanks Power Na
Page 25 and 26:
Nomenclature 13 Motion aF AC aircra
Page 27 and 28:
Chapter 3 Tasks The NDARC code perf
Page 29 and 30:
Tasks 17 engine group is found (inc
Page 31 and 32:
Tasks 19 3-4 Maps 3-4.1 Engine Perf
Page 33 and 34:
Chapter 4 Operation 4-1 Flight Cond
Page 35 and 36:
Operation 23 e) Input payload weigh
Page 37 and 38:
Operation 25 Table 4-1. Mission seg
Page 39 and 40:
Operation 27 horizontal ground dist
Page 41 and 42:
Operation 29 climb for zero power m
Page 43 and 44:
Operation 31 a) Horizontal velocity
Page 45 and 46:
Operation 33 From the pressure p =
Page 47 and 48:
Chapter 5 Solution Procedures The N
Page 49 and 50:
Solution Procedures 37 Sizing Task
Page 51 and 52:
Solution Procedures 39 relaxation i
Page 53 and 54:
Solution Procedures 41 Table 5-4. T
Page 55 and 56:
Solution Procedures 43 successive s
Page 57 and 58:
Solution Procedures 45 initialize e
Page 59 and 60:
Chapter 6 Cost Costs are estimated
Page 61 and 62:
Cost 49 Table 6-1. DoD and CPI infl
Page 63 and 64:
Cost 51 predicted base price (1994$
Page 65 and 66:
Chapter 7 Aircraft The aircraft con
Page 67 and 68:
Aircraft 55 The tilt control variab
Page 69 and 70:
Aircraft 57 forward axes for descri
Page 71 and 72:
Aircraft 59 For steady-state flight
Page 73 and 74:
Aircraft 61 where Δz F = z F − z
Page 75 and 76:
Aircraft 63 disk area); or the drag
Page 77 and 78:
Aircraft 65 7-10 Performance Indice
Page 79 and 80:
Aircraft 67 WEIGHT EMPTY STRUCTURE
Page 81 and 82:
Chapter 8 Systems The systems compo
Page 83 and 84:
Chapter 9 Fuselage There is one fus
Page 85 and 86:
Fuselage 73 αe = αfus − αzl, w
Page 87 and 88:
Chapter 10 Landing Gear There is on
Page 89 and 90:
Chapter 11 Rotor The aircraft can h
Page 91 and 92:
Rotor 79 propulsion group. The driv
Page 93 and 94:
Rotor 81 plane command. The collect
Page 95 and 96:
Rotor 83 or just CSF = WCHF with no
Page 97 and 98:
Rotor 85 If μ is zero, the equatio
Page 99 and 100:
Rotor 87 The velocity ratio is fW =
Page 101 and 102:
Rotor 89 T/T ∞ 1.3 1.2 1.1 1.0 Ha
Page 103 and 104:
Rotor 91 TPP tilt / cyclic magnitud
Page 105 and 106:
Rotor 93 with an average over the r
Page 107 and 108:
Rotor 95 (all equal to 1 for μz =0
Page 109 and 110: Rotor 97 κ 1.30 1.25 1.20 1.15 1.1
Page 111 and 112: Rotor 99 (C T /σ) s c d mean 0.20
Page 113 and 114: Rotor 101 11-5.1.3 Twin Rotors For
Page 115 and 116: Rotor 103 The wake is a skewed cyli
Page 117 and 118: Rotor 105 weight per lifting rotor;
Page 119 and 120: Chapter 12 Force The force componen
Page 121 and 122: Chapter 13 Wing The aircraft can ha
Page 123 and 124: Wing 111 denotes outboard edge, sub
Page 125 and 126: Wing 113 13-3.1 Lift The wing lift
Page 127 and 128: Wing 115 The wing interference at t
Page 129 and 130: Chapter 14 Empennage The aircraft c
Page 131 and 132: Empennage 119 14-4 Weights The tail
Page 133 and 134: Chapter 15 Fuel Tank 15-1 Fuel Capa
Page 135 and 136: Fuel Tank 123 if Wfuel >Wfuel−max
Page 137 and 138: Chapter 16 Propulsion The propulsio
Page 139 and 140: Propulsion 127 If the sum of the fi
Page 141 and 142: Chapter 17 Engine Group The engine
Page 143 and 144: Engine Group 131 The engine group p
Page 145 and 146: Engine Group 133 specific fuel cons
Page 147 and 148: Chapter 18 Referred Parameter Turbo
Page 149 and 150: Referred Parameter Turboshaft Engin
Page 159: Chapter 19 AFDD Weight Models This
Page 163 and 164: AFDD Weight Models 151 19-1.2 Aircr
Page 165 and 166: AFDD Weight Models 153 where w = nz
Page 167 and 168: AFDD Weight Models 155 units as use
Page 169 and 170: AFDD Weight Models 157 Table 19-9.
Page 171 and 172: AFDD Weight Models 159 where fP = f
Page 173 and 174: AFDD Weight Models 161 The conversi
Page 175 and 176: AFDD Weight Models 163 19-12 Foldin
Page 177 and 178: AFDD Weight Models 165 error (%) er
show all

Download - NASA

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?