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154 AFDD Weight Models where Tat is at maximum speed, design gross weight, and SLS conditions, calculated or input. Parameters are defined in table 19-5, including units as used in these equations. Table 19-5. Parameters for tail weight. parameter definition units Sht horizontal tail planform area ft 2 Svt vertical tail planform area ft 2 Aht horizontal tail aspect ratio Avt vertical tail aspect ratio Vdive design dive speed at sea level kts Rtr tail rotor radius ft PDSlimit drive system rated power hp R main rotor radius in hover ft Vtip main rotor hover tip velocity number of auxiliary thrusters ft/sec Nat Tat thrust per propeller lb Aat auxiliary thruster disk area ft2 19–4 Fuselage Group The fuselage group consists of: basic structure; wing and rotor fold/retraction; tail fold/tilt; and marinization, pressurization, and crashworthiness structure. The AFDD84 model is a universal bodyweight equation, used for tiltrotor and tiltwing as well as for helicopter configurations. The AFDD82 model is a helicopter body-weight equation, not used for tiltrotor or tiltwing configuration. For the AFDD84 (UNIV) model, the basic structure weight is wbasic =25.41fLGlocfLGretframp Wbasic = χbasicwbasic WMTO 1000 0.4879 0.2075 nzWSD S 1000 0.1676 body ℓ 0.1512 where fLGloc =1.1627 if the landing gear is located on the fuselage, and 1.0 otherwise; fLGret =1.1437 if the landing gear is on the fuselage and retractable, and 1.0 otherwise; framp =1.2749 if there is a cargo ramp, and 1.0 otherwise. Based on 35 aircraft, the average error of the body equation is 6.5% (fig. 19-9). The tail fold, wing and rotor fold, marinization, pressurization, and crashworthiness weights are: wtfold = ftfoldWtail wwfold = fwfold(Wwing + Wtip) wmar = fmarWbasic wpress = fpressWbasic wcw = fcw(Wbasic + Wtfold + Wwfold + Wmar + Wpress) Wtfold = χtfoldwtfold Wwfold = χwfoldwwfold Wmar = χmarwmar Wpress = χpresswpress Wcw = χcwwcw Typically ftfold =0.30 for a folding tail, and fcw =0.06. For wing folding the weight on the wing tip (Wtip) is required (calculated as for the wing group). Parameters are defined in table 19-6, including
AFDD Weight Models 155 units as used in these equations. Table 19-6. Parameters for fuselage weight (AFDD84 model). parameter definition units WMTO maximum takeoff weight lb WSD structural design gross weight lb Sbody wetted area of body ft2 R main rotor radius ft nz ℓ design ultimate flight load factor at WSD length of fuselage g ft ftfold tail fold weight (fraction tail weight) fwfold wing and rotor fold weight (fraction wing/tip weight) Wtail tail group weight Wwing + Wtip wing group weight plus weight on wing tip fmar marinization weight (fraction basic body weight) fpress pressurization (fraction basic body weight) crashworthiness weight (fraction fuselage weight) fcw For the AFDD82 (HELO) model, the basic structure weight is 0.4908 WMTO wbasic =5.896framp 1000 n 0.1323 z S 0.2544 body ℓ 0.6100 Wbasic = χbasicwbasic where framp =1.3939 if there is a cargo ramp, and 1.0 otherwise. Based on 30 aircraft, the average error of the body equation is 8.7% (fig. 19-10). The tail fold, wing and rotor fold, marinization, pressurization, and crashworthiness weights are: wtfold = ftfoldWbasic wwfold = fwfold(Wbasic + Wtfold) wmar = fmarWbasic wpress = fpressWbasic Wtfold = χtfoldwtfold Wwfold = χwfoldwwfold Wmar = χmarwmar Wpress = χpresswpress wcw = fcw(Wbasic + Wtfold + Wwfold + Wmar + Wpress) Wcw = χcwwcw Typically ftfold =0.05 for a folding tail, and fcw =0.06. Parameters are defined in table 19-7, including units as used in these equations. Table 19-7. Parameters for fuselage weight (AFDD82 model). parameter definition units WMTO maximum takeoff weight lb Sbody wetted area of body ft2 R main rotor radius ft nz ℓ design ultimate flight load factor at WSD length of fuselage g ft ftfold tail fold weight (fraction basic structure) fwfold wing and rotor fold weight (fraction basic structure and tail fold) fmar marinization weight (fraction basic body weight) fpress pressurization (fraction basic body weight) crashworthiness weight (fraction fuselage weight) fcw
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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
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 and 164: AFDD Weight Models 151 19-1.2 Aircr
Page 165: AFDD Weight Models 153 where w = nz
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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