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152 AFDD Weight Models 19–2 Rotor Group The rotor group consists of: blades, hub and hinge, spinner, and blade fold structure. The blade and hub-hinge weights for the AFDD82 model are: wblade =0.02606NrotorN 0.6592 blade R 1.3371 c 0.9959 V 0.6682 tip ν 2.5279 blade whub =0.003722NrotorN 0.2807 blade R 1.5377 V 0.4290 tip ν 2.1414 hub (Wblade/Nrotor) 0.5505 Wblade = χbladewblade Whub = χhubwhub Based on 37 aircraft, the average error of the blade equation is 7.7% (fig. 19-2). Based on 35 aircraft, the average error of the hub equation is 10.2% (fig. 19-3). The blade and hub-hinge weights for the AFDD00 model are: wblade =0.0024419ftiltNrotorN 0.53479 blade R 1.74231 c 0.77291 V 0.87562 tip ν 2.51048 blade whub =0.18370NrotorN 0.16383 blade R 0.19937 V 0.06171 tip ν 0.46203 hub (Wblade/Nrotor) 1.02958 Wblade = χbladewblade Whub = χhubwhub where ftilt =1.17940 for tilting rotors; 1.0 otherwise. Based on 51 aircraft, the average error of the blade equation is 7.9% (fig. 19-4). Based on 51 aircraft, the average error of the hub equation is 9.2% (fig. 19-5). For teetering and gimballed rotors, the flap frequency ν should be the coning frequency. The fairing/spinner and blade fold weights are: Wspin = χspin 7.386NrotorD 2 spin Wfold = χfold ffoldWblade The blade weight is for all blades of the rotors. If the weight is evaluated separately for each rotor, then Nrotor =1should be used in the equations. Typically ffold =0.04 for manual fold, and ffold =0.28 for automatic fold. Parameters are defined in table 19-3, including units as used in these equations. Table 19-3. Parameters for rotor weight. parameter definition units Nrotor number of rotors Nblade number of blades per rotor R rotor radius in hover ft c rotor mean geometric blade chord ft Vtip rotor hover tip velocity ft/sec νblade,νhub flap natural frequency (for weight estimate) per rev Dspin spinner diameter blade fold weight (fraction total blade weight) ft ffold For lift-offset rotors, the blade and hub weights can be calculated based on the methodology of reference 3. The blade and hub-hinge weights are: wblade = Nrotor 0.000041466 wR 3 /(2ht 2 .2R) whub = Nrotor 0.17153 wRNblade +0.000010543(Wblade/Nrotor)V 2 +0.081304 wR 2 2hL/t.2R tipt.2R/R Wblade = χbladewblade Whub = χhubwhub
AFDD Weight Models 153 where w = nzWSD/1000, and t.2R = τ.2Rc 0.8+0.2λ 0.5+0.5λ is the blade thickness at 20%R. These equations were developed for the coaxial rotor configuration (Nrotor =2). The blade-weight estimate is based on the stiffness required for tip clearance of the two rotors. The first two terms in the hub-weight equation account for the structure required to react the hub moment and the centrifugal force; the last term accounts for the weight of the main-rotor upper shaft. Parameters are defined in table 19-4, including units as used in these equations. Table 19-4. Parameters for lift-offset rotor weight. parameter definition units number of rotors Nrotor WSD structural design gross weight lb nz design ultimate flight load factor at WSD g λ blade taper ratio (tip chord/root chord) τ.2R blade airfoil thickness-to-chord ratio (at 20%R) c blade mean chord number of blades per rotor Nblade h coaxial rotor separation (fraction rotor diameter) L Vtip lift offset (Mroll/T R) rotor hover tip velocity ft/sec 19–3 Empennage Group The empennage group consists of: horizontal tail, vertical tail, tail rotor, and auxiliary thruster. The weight model depends on the aircraft configuration. The helicopter or compound model is AFDD82. The horizontal tail weight is: tiltrotor or tiltwing Wht = χhtSht(0.00395S 0.2 ht Vdive − 0.4885) helicopter or compound Wht = χht0.7176S 1.1881 ht A 0.3173 ht Based on 13 aircraft, the average error of the helicopter horizontal tail equation is 22.4% (fig. 19-6). The vertical tail weight is: tiltrotor or tiltwing Wvt = χvtSvt(0.00395S 0.2 vt Vdive − 0.4885) helicopter or compound Wvt = χvt1.0460ftrS 0.9441 vt A 0.5332 vt where ftr =1.6311 if the tail rotor is located on the vertical tail; 1.0 otherwise. Based on 12 aircraft, the average error of the helicopter vertical tail equation is 23.3% (fig. 19-7). Vdive is the design dive speed, calculated or input; Vdive =1.25Vmax, where Vmax is the maximum speed at design gross weight and SLS conditions. The tail rotor weight is: Wtr = χtr1.3778R 0.0897 tr (PDSlimitR/Vtip) 0.8951 Based on 19 aircraft, the average error of the helicopter tail rotor equation is 16.7% (fig. 19-8). The auxiliary propulsion weight (as a propeller) is: compound, propeller Wat = χat0.0809484NatT 1.04771 at (Tat/Aat) −0.07821
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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
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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 and 162: AFDD Weight Models 149 The spar-cap
Page 163: AFDD Weight Models 151 19-1.2 Aircr
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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