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118 Empennage 14-3.1 Lift The tail lift is defined in terms of lift-curve slope CLα and maximum lift coefficient CLmax (based on tail planform area). The three-dimensional lift-curve slope is input directly or calculated from the two-dimensional lift-curve slope: CLα = cℓα 1+cℓα(1 + τ)/(πAR) where τ accounts for non-elliptical loading. The effective angle-of-attack is αe = αtail + i − αzl, where αzl is the angle of zero lift; in reverse flow (|αe| > 90), αe ← αe − 180 signαe. Let αmax = CLmax/CLα be the angle-of-attack increment (above or below zero lift angle) for maximum lift. Including the change of maximum lift angle caused by control deflection, Amax = αmax +Δαmaxf and Amin = −αmax +Δαmaxf. Then ⎧ CLααe +ΔCLf Amin ≤ αe ≤ Amax ⎪⎨ π/2 −|αe| (CLαAmax +ΔCLf ) αe >Amax CL = π/2 −|Amax| ⎪⎩ π/2 −|αe| (CLαAmin +ΔCLf ) αe 90), αe ← αe −180 signαe. For angles of attack less than a transition angle αt, the drag coefficient equals the forward-flight (minimum) drag CD0, plus an angle-of-attack term and the control increment. Thus if |αe| ≤αt, the profile drag is and otherwise CDp = CD0 (1 + Kd|αe| Xd )+ΔCDf CDt = CD0 (1 + Kd|αt| Xd )+ΔCDf CDp = CDt +(CDV − CDt) sin π 2 |αe|−αt π/2 − αt Optionally there might be no angle-of-attack variation at low angles (Kd =0), or quadratic variation (Xd =2). In sideward flight (defined by (v B x ) 2 +(v B z ) 2 < (0.05|v B |) 2 ), the drag is obtained using φv = tan −1 (−v B z /v B y ) to interpolate the vertical coefficient: CDp = CD0 cos 2 φv + CDV sin 2 φv. The induced drag is obtained from the lift coefficient, aspect ratio, and Oswald efficiency e: CDi = (CL − CL0) 2 πeAR Conventionally the Oswald efficiency e can represent the tail parasite-drag variation with lift, as well as the induced drag (hence the use of CL0). Then D = qSCD = qS is the drag force. The other forces and moments are zero. CDp + CDi
Empennage 119 14–4 Weights The tail weight (empennage group) model depends on the configuration: helicopters and compounds, or tiltrotors and tiltwings. Separate weight models are available for horizontal and vertical tails. The AFDD tail weight model depends on the design dive speed at sea level (input or calculated). The calculated dive speed is Vdive =1.25Vmax, from the maximum speed at the design gross weight and sea-level standard conditions.
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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
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: Chapter 14 Empennage The aircraft c
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 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
Page 179 and 180: AFDD Weight Models 167 error (%) er
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AFDD Weight Models 169 error (%) er
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