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14 Nomenclature Rotor A disk area cdmean profile power mean drag coefficient, CPo =(σ/8)cdmeanFP CT /σ thrust coefficient divided by solidity, T/ρA(ΩR) 2 σ CW /σ design blade loading, W/ρAV 2 tip σ (Vtip = hover tip speed) H, Y , T drag, side, thrust force on hub (shaft axes) L/De rotor effective lift-to-drag ratio, VL/(Pi + Po) M rotor hover figure of merit, TfDv/P Mat advancing tip Mach number Mx, My roll, pitch moment on hub Pi, Po, Pp induced, profile, parasite power Q shaft torque R blade radius r direction of rotation (1 for counter-clockwise, −1 for clockwise) r blade span coordinate Tdesign design thrust of antitorque or auxiliary thrust rotor W/A disk loading, W = fW WD βc, βs longitudinal, lateral flapping (tip-path plane tilt relative shaft) γ blade Lock number η propulsive efficiency, TV/P κ induced power factor, Pi = κPideal λ inflow ratio μ advance ratio ν blade flap frequency (per-rev) θ0.75 blade collective pitch angle (at 75% radius) θc, θs lateral, longitudinal blade pitch angle) σ solidity (ratio blade area to disk area) ψ blade azimuth coordinate Wing AR aspect ratio, b 2 /S b span c chord, S/b S area W/S wing loading, W = fW WD
Chapter 3 Tasks The NDARC code performs design and analysis tasks. The design task involves sizing the rotorcraft to satisfy specified design conditions and missions. The analysis tasks can include mission performance analysis, flight performance calculation for point operating conditions, and generation of subsystem or component performance maps. 3–1 Size Aircraft for Design Conditions and Missions 3-1.1 Sizing Method The sizing task determines the dimensions, power, and weight of a rotorcraft that can perform a specified set of design conditions and missions. The aircraft size is characterized by parameters such as design gross weight (WD) or weight empty (WE), rotor radius (R), and engine power available (Peng). The relationships between dimensions, power, and weight generally require an iterative solution. From the design flight conditions and missions, the task can determine the total engine power or the rotor radius (or both power and radius can be fixed), as well as the design gross weight, maximum takeoff weight, drive-system torque limit, and fuel-tank capacity. For each propulsion group, the engine power or the rotor radius can be sized. a) Engine power: Determine Peng, for fixed R. The engine power is the maximum of the power required for all sizing flight conditions and sizing missions (typically including vertical flight, forward flight, and one-engine inoperative). Hence the engine power is changed by the ratio max(PreqPG/PavP G) (excluding flight states for which zero power margin is calculated, such as maximum gross weight or maximum effort). This approach is the one most commonly used for the sizing task. b) Rotor radius: Determine R for input Peng. The maximum power required for all sizing flight conditions and sizing missions is calculated, and then the rotor radius determined such that the power required equals the input power available. The change in radius is estimated as R = Rold PreqPG/PavP G (excluding flight states for which zero power margin is calculated, such as maximum gross weight or maximum effort). For multi-rotor aircraft, the radius can be fixed rather than sized for some rotors. Alternatively, Peng and R can be input rather than sized. Aircraft parameters can be determined by a subset of the design conditions and missions. a) Design gross weight WD: maximum gross weight from designated conditions and missions (for which gross weight is not fixed).
Page 1 and 2: NASA/TP-2009-215402 NDARC NASA Desi
Page 3 and 4: NASA/TP-2009-215402 NDARC NASA Desi
Page 5 and 6: TABLE OF CONTENTS CHAPTER 1 - INTRO
Page 7: TABLE OF CONTENTS (cont.) CHAPTER 1
Page 10 and 11: viii LIST OF FIGURES (cont.) Figure
Page 13 and 14: Chapter 1 Introduction The NASA Des
Page 15 and 16: Introduction 3 of rotorcraft config
Page 17 and 18: Introduction 5 previous case DESIGN
Page 19 and 20: Introduction 7 4) Scully, M.; and F
Page 21 and 22: Chapter 2 Nomenclature The nomencla
Page 23 and 24: Nomenclature 11 Fuel Tanks Power Na
Page 25: Nomenclature 13 Motion aF AC aircra
Page 29 and 30: Tasks 17 engine group is found (inc
Page 31 and 32: Tasks 19 3-4 Maps 3-4.1 Engine Perf
Page 33 and 34: Chapter 4 Operation 4-1 Flight Cond
Page 35 and 36: Operation 23 e) Input payload weigh
Page 37 and 38: Operation 25 Table 4-1. Mission seg
Page 39 and 40: Operation 27 horizontal ground dist
Page 41 and 42: Operation 29 climb for zero power m
Page 43 and 44: Operation 31 a) Horizontal velocity
Page 45 and 46: Operation 33 From the pressure p =
Page 47 and 48: Chapter 5 Solution Procedures The N
Page 49 and 50: Solution Procedures 37 Sizing Task
Page 51 and 52: Solution Procedures 39 relaxation i
Page 53 and 54: Solution Procedures 41 Table 5-4. T
Page 55 and 56: Solution Procedures 43 successive s
Page 57 and 58: Solution Procedures 45 initialize e
Page 59 and 60: Chapter 6 Cost Costs are estimated
Page 61 and 62: Cost 49 Table 6-1. DoD and CPI infl
Page 63 and 64: Cost 51 predicted base price (1994$
Page 65 and 66: Chapter 7 Aircraft The aircraft con
Page 67 and 68: Aircraft 55 The tilt control variab
Page 69 and 70: Aircraft 57 forward axes for descri
Page 71 and 72: Aircraft 59 For steady-state flight
Page 73 and 74: Aircraft 61 where Δz F = z F − z
Page 75 and 76: 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;
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Chapter 12 Force The force componen
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Chapter 13 Wing The aircraft can ha
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Wing 111 denotes outboard edge, sub
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Wing 113 13-3.1 Lift The wing lift
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Wing 115 The wing interference at t
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Chapter 14 Empennage The aircraft c
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Empennage 119 14-4 Weights The tail
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Chapter 15 Fuel Tank 15-1 Fuel Capa
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Fuel Tank 123 if Wfuel >Wfuel−max
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Chapter 16 Propulsion The propulsio
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Propulsion 127 If the sum of the fi
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Chapter 17 Engine Group The engine
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Engine Group 131 The engine group p
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Engine Group 133 specific fuel cons
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Chapter 18 Referred Parameter Turbo
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Referred Parameter Turboshaft Engin
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Chapter 19 AFDD Weight Models This
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AFDD Weight Models 149 The spar-cap
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AFDD Weight Models 151 19-1.2 Aircr
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AFDD Weight Models 153 where w = nz
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AFDD Weight Models 155 units as use
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AFDD Weight Models 157 Table 19-9.
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AFDD Weight Models 159 where fP = f
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AFDD Weight Models 161 The conversi
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AFDD Weight Models 163 19-12 Foldin
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AFDD Weight Models 165 error (%) er
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