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128 Propulsion tiltrotor configurations). For the single-main-rotor and tail-rotor configuration, typically fQ =0.03 and fP =0.15 (0.18 with a two-bladed teetering main rotor).
Chapter 17 Engine Group The engine group consists of one or more engines of a specific type. For each engine type an engine model is defined. The Referred Parameter Turboshaft Engine Model (RPTEM) is implemented. The engine size is described by the power Peng, which is the sea-level static power available per engine at a specified takeoff rating. The number of engines Neng is specified for each engine group. If the sizing task determines the engine power for a propulsion group, the power Peng of at least one engine group is found (including the first engine group). The total power required is PPG = r NengPeng, where r = max(PreqPG/PavP G). The sized power is Psized = PPG − fixed NengPeng. Then the sized engine power is Peng = fnPsized/Neng for the n-th engine group (with f1 = n=1,sized fn for the first group). 17–1 Engine Performance 17-1.1 Power Available Given the flight condition and engine rating, the power available Pa is calculated (from the specific power SPa and mass flow ˙ma). The flight-condition information includes the altitude, temperature, flight speed, and primary rotor speed; a power fraction fP ; and the states of the engine, drive system, and IR suppressor. The engine turbine speed is N = (60/2π)rengΩprim, where Ωprim is the current rotor speed and reng is the gear ratio (depending on the drive-system state). If the reference primary rotor speed Ωprim corresponds to the specification turbine speed Nspec, then reng =Ωspec/Ωprim; alternatively, the engine gear ratio can be a fixed input. In the engine model, installation losses Ploss are subtracted from Pa (Pav = Pa − Ploss), and then the mechanical limit applied: Pav = min(Pav,PmechR). The engine model gives the performance of a single engine. The power available of the engine group is obtained by multiplying the single-engine power by the number of engines operational (total number of engines less inoperable engines): PavEG =(Neng − Ninop)Pav The propulsion group power available is obtained from the sum over the engine groups: PavP G = fP PavEG, including a specified power fraction fP . The drive-system rating at the flight condition is rPDSlimit, where r =Ωprim/Ωref. Optionally this limit is applied to the propulsion group power: PavP G = min(PavP G,rPDSlimit). Similarly the engine-shaft limit at the flight condition is optionally applied to the engine group power.
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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
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 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: Propulsion 127 If the sum of the fi
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
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