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150 AFDD Weight Models Table 19-1. Parameters for tiltrotor-wing weight. parameter definition units Wbox, Wspar wing torque box and spar weights slug or kg WSD structural design gross weight lb (CT /σ)jump rotor maximum thrust capability (jump takeoff) njump Nrotor bw ℓw = bw − wfus cw wtb ctb = wtbcw load factor at WSD (jump takeoff) number of rotors wing span (length of torque box) wing length (span less fuselage width) wing chord torque box chord to wing chord ratio torque box chord wing airfoil thickness-to-chord ratio ft or m ft or m ft or m ft or m τw tw = τwcw wing thickness ft or m rpylon pylon radius of gyration (pitch inertia = r 2 pylon Mtip) ft orm Ω rotor speed for wing weight design condition rad/sec ωT wing torsion mode frequency (fraction rotor speed) per rev ωB wing beam bending mode frequency (fraction rotor speed) per rev ωC wing chord bending mode frequency (fraction rotor speed) per rev ρtb density of torque box material slug/ft 3 or kg/m 3 ρsp density of spar cap material slug/ft 3 or kg/m 3 Gtb torque box shear modulus lb/ft 2 or N/m 2 Etb torque box modulus lb/ft 2 or N/m 2 Esp spar modulus lb/ft 2 or N/m 2 ɛU Ct Cj Cm etb esp ultimate strain allowable (minimum of spar and torque box) weight correction for spar taper (equivalent stiffness) weight correction for spar taper (equivalent strength) strength correction for spar taper (equivalent stiffness) structural efficiency factor, torque box structural efficiency factor, spars Ufair unit weight of leading and trailing edge fairings lb/ft 2 or kg/m 2 Uflap unit weight of control surfaces lb/ft 2 or kg/m 2 Sfair area of leading and trailing edge fairings ft 2 or m 2 Sflap area of control surfaces ft 2 or m 2 ffit wing fittings and brackets (fraction total weight excluding fold) wing fold/tilt (fraction total weight excluding fold, including weight on tips) ffold wattach width of wing structural attachments to body ft or m Uext unit weight of wing extension lb/ft2 or kg/m2 Sext area of wing extensions (span bext times mean chord cext) ft 2 or m 2 fefold wing extension fold/tilt (fraction extension weight)
AFDD Weight Models 151 19-1.2 Aircraft Wing There are two models intended for the wing of a compound helicopter: area method and parametric method. For the area method (based on weight per unit area), the total wing weight excluding folding is: wwing = SwUw fprim =1− ffair − fflap − ffit Typically Uw =5to 9 lb/ft2 . For the parametric method (AFDD93), the total wing weight including folding is: wwing =5.66411fLGloc WSD 1000 cos Λw 0.847 n 0.39579 z S 0.21754 w A 0.50016 w ((1 + λw)/τw) 0.09359 (1 − bfold) −0.14356 fprim =1− ffair − fflap − ffit − ffold where fLGloc =1.7247 if the landing gear is on the wing, and 1.0 otherwise. Based on 25 fixed-wing aircraft, the average error of the aircraft-wing equation is 3.4% (fig. 19-1). Then the primary structure, secondary structure, and control surface weights are: The wing extension weight is: wext = SextUext Wprim = χprimfprimwwing Wfair = χfairffairwwing Wflap = χflapfflapwwing Wfit = χfitffitwwing Wfold = χfoldffoldwwing Wext = χextwext wefold = fefoldWext Wefold = χefoldwefold and these terms are added to Wprim and Wfold. Parameters are defined in table 19-2, including units as used in these equations. Table 19-2. Parameters for aircraft-wing weight. parameter definition units Sw wing planform area (theoretical) ft 2 Uw unit weight of wing planform lb/ft 2 WSD structural design gross weight lb nz design ultimate flight load factor at WSD g Λw wing sweep angle deg Aw λw τw bfold ffair fflap ffit wing aspect ratio wing taper ratio (tip chord/root chord) wing airfoil thickness-to-chord ratio fraction wing span that folds (0 to 1) fairings (fraction total wing weight) control surfaces (fraction total wing weight) fittings (fraction total wing weight) fold/tilt (fraction total wing weight) ffold Uext unit weight of wing extension lb/ft2 Sext area of wing extensions (span bext times mean chord cext) ft 2 fefold wing extension fold/tilt (fraction extension weight)
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NASA/TP-2009-215402 NDARC NASA Desi
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NASA/TP-2009-215402 NDARC NASA Desi
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TABLE OF CONTENTS CHAPTER 1 - INTRO
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TABLE OF CONTENTS (cont.) CHAPTER 1
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viii LIST OF FIGURES (cont.) Figure
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Chapter 1 Introduction The NASA Des
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Introduction 3 of rotorcraft config
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Introduction 5 previous case DESIGN
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Introduction 7 4) Scully, M.; and F
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Chapter 2 Nomenclature The nomencla
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Nomenclature 11 Fuel Tanks Power Na
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Nomenclature 13 Motion aF AC aircra
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Chapter 3 Tasks The NDARC code perf
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Tasks 17 engine group is found (inc
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Tasks 19 3-4 Maps 3-4.1 Engine Perf
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Chapter 4 Operation 4-1 Flight Cond
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Operation 23 e) Input payload weigh
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Operation 25 Table 4-1. Mission seg
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Operation 27 horizontal ground dist
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Operation 29 climb for zero power m
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Operation 31 a) Horizontal velocity
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Operation 33 From the pressure p =
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Chapter 5 Solution Procedures The N
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Solution Procedures 37 Sizing Task
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Solution Procedures 39 relaxation i
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Solution Procedures 41 Table 5-4. T
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Solution Procedures 43 successive s
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Solution Procedures 45 initialize e
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Chapter 6 Cost Costs are estimated
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Cost 49 Table 6-1. DoD and CPI infl
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Cost 51 predicted base price (1994$
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Chapter 7 Aircraft The aircraft con
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Aircraft 55 The tilt control variab
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Aircraft 57 forward axes for descri
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Aircraft 59 For steady-state flight
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Aircraft 61 where Δz F = z F − z
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Aircraft 63 disk area); or the drag
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Aircraft 65 7-10 Performance Indice
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Aircraft 67 WEIGHT EMPTY STRUCTURE
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Chapter 8 Systems The systems compo
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Chapter 9 Fuselage There is one fus
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Fuselage 73 αe = αfus − αzl, w
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Chapter 10 Landing Gear There is on
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Chapter 11 Rotor The aircraft can h
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Rotor 79 propulsion group. The driv
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Rotor 81 plane command. The collect
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Rotor 83 or just CSF = WCHF with no
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Rotor 85 If μ is zero, the equatio
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Rotor 87 The velocity ratio is fW =
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Rotor 89 T/T ∞ 1.3 1.2 1.1 1.0 Ha
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Rotor 91 TPP tilt / cyclic magnitud
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Rotor 93 with an average over the r
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Rotor 95 (all equal to 1 for μz =0
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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 and 160: Chapter 19 AFDD Weight Models This
Page 161: AFDD Weight Models 149 The spar-cap
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
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