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158 AFDD Weight Models where fcw =1.3131 for ballistically survivable (UTTAS/AAH level) and 1.0 otherwise. The ballistic tolerance factor fbt =1.0 to 2.5. The fuel flow rate F is calculated for the takeoff power rating at static SLS conditions; typically K0plumb = 120 and K1plumb =3. Based on 15 aircraft, the average error of the fuel tank equation is 4.6% (fig. 19-16). Parameters are defined in table 19-11, including units as used in these equations. Table 19-11. Parameters for fuel-system weight. parameter definition units Nint number of internal fuel tanks Cint internal fuel tank capacity gallons fbt ballistic tolerance factor Nplumb total number of fuel tanks (internal and auxiliary) for plumbing Neng number of main engines K0plumb,K1plumb plumbing weight, constants F fuel flow rate lb/hr 19-7.4 Drive System The drive system consists of gear boxes and rotor shafts, drive shafts, and rotor brake. This distribution of drive-system weights is based on the following functional definitions. Gearboxes are parts of the drive system that transmit power by gear trains, and the structure that encloses them. Rotor shafts are the structure (typically a shaft) that transmits power to the rotor. Drive shafts are the structure (typically a shaft) that transmits power in the propulsion system, but not directly to the rotor or by a gear train. The rotor brake weight encompasses components that can prevent the rotor from freely turning. The gear-box and rotor-shaft weights for the AFDD83 model are: wgbrs =57.72P 0.8195 DSlimitf 0.0680 Q N 0.0663 gb (Ωeng/1000) 0.0369 /Ω 0.6379 rotor Wgb = χgb(1 − frs)wgbrs Wrs = χrsfrswgbrs Based on 30 aircraft, the average error of the gear-box and rotor-shaft equation is 7.7% (fig. 19-17). The gear-box and rotor-shaft weights for the AFDD00 model are: wgbrs =95.7634N 0.38553 rotor P 0.78137 Wgb = χgb(1 − frs)wgbrs Wrs = χrsfrswgbrs DSlimitΩ 0.09899 eng /Ω 0.80686 rotor Based on 52 aircraft, the average error of the gear-box and rotor-shaft equation is 8.6% (fig. 19-18). Typically frs =0.13 (range 0.06 to 0.20). Parameters are defined in table 19-12, including units as used in these equations. The drive-shaft (AFDD82 model) and rotor-brake weights are: Wds = χds1.166Q 0.3828 DSlimitx 1.0455 hub N 0.3909 ds Wrb = χrb0.000871Wblade(0.01Vtip) 2 (0.01fP ) 0.2693
AFDD Weight Models 159 where fP = fQΩother/Ωmain. Based on 28 aircraft, the average error of the drive-shaft equation is 16.0% (fig. 19-19). Based on 23 aircraft, the average error of the rotor-brake equation is 25.1% (fig. 19-20). The clutch weight in the weight statement is associated with an auxiliary power unit, and is a fixed input value. The conventional rotor drive-system clutch and free-wheeling device weights are included in the gear-box and rotor-shaft weight equations. Parameters are defined in table 19-13, including units as used in these equations. Typically fP = fQ = 60% for twin main rotors (tandem, coaxial, and tiltrotor); for a single main rotor and tail rotor, fQ =3%and fP = 15% (18% for 2-bladed rotors). Table 19-12. Parameters for drive-system weight. parameter definition units PDSlimit drive system rated power hp Nrotor number of main rotors number of gear boxes Ngb Ωrotor main rotor rotation speed rpm Ωeng engine output speed rpm fQ second (main or tail) rotor rated torque % frs (fraction of total drive system rated torque) rotor shaft weight (fraction gear box and rotor shaft) Table 19-13. Parameters for drive shaft and rotor brake weight. parameter definition units QDSlimit PDSlimit/Ωrotor hp/rpm number of intermediate drive shafts Nds xhub length of drive shaft between rotors ft fP second (main or tail) rotor rated power (fraction of total drive system rated power) % Vtip main rotor tip speed ft/sec 19–8 Flight Controls Group The flight controls group consists of cockpit controls, automatic flight control system, and system controls. Wcc and Wafcs weights are fixed (input). System controls consist of fixed-wing flight controls, rotary-wing flight controls, and conversion (rotor tilt) flight controls. The weight equations model separately non-boosted controls (which do not see aerodynamic surface or rotor loads), boost mechanisms (actuators), and boosted controls (which are affected by aerodynamic surface or rotor loads). The load path goes from pilot, to cockpit controls, to non-boosted controls, to boost mechanisms, to boosted controls, and finally to the component. Fixed-wing flight controls consist of non-boosted flight controls and flight-control boost mechanisms. The weights are: full controls w =0.91000W 0.6 MTO only stabilizer controls w =0.01735W 0.64345 MTO S 0.40952 ht
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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
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Rotor 101 11-5.1.3 Twin Rotors For
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Rotor 103 The wake is a skewed cyli
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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 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: AFDD Weight Models 157 Table 19-9.
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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