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4 Introduction 1–3 Overview 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 off-design mission performance analysis, flight performance calculation for point operating conditions, and generation of subsystem or component performance maps. Figure 1-1 illustrates the tasks. The principal tasks (sizing, mission analysis, and flight performance analysis) are shown in the figure as boxes with heavy borders. Heavy arrows show control of subordinate tasks. The aircraft description (fig. 1-1) consists of all the information, input and derived, that defines the aircraft. The aircraft consists of a set of components, including fuselage, rotors, wings, tails, and propulsion. This information can be the result of the sizing task; can come entirely from input, for a fixed model; or can come from the sizing task in a previous case or previous job. The aircraft description information is available to all tasks and all solutions (indicated by light arrows). 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, weight empty, rotor radius, and engine power available. 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. Missions are defined for the sizing task and for the mission performance analysis. A mission consists of a number of mission segments, for which time, distance, and fuel burn are evaluated. For the sizing task, certain missions are designated to be used for design gross-weight calculations; for transmission sizing; and for fuel-tank sizing. The mission parameters include mission takeoff gross weight and useful load. For specified takeoff fuel weight with adjustable segments, the mission time or distance is adjusted so the fuel required for the mission (burned plus reserve) equals the takeoff fuel weight. The mission iteration is on fuel weight. Flight conditions are specified for the sizing task and for the flight performance analysis. For the sizing task, certain flight conditions are designated to be used for design gross-weight calculations; for transmission sizing; for maximum takeoff-weight calculations; and for antitorque or auxiliary-thrust rotor sizing. The flight-condition parameters include gross weight and useful load. For flight conditions and mission takeoff, the gross weight can be maximized, such that the power required equals the power available. A flight state is defined for each mission segment and each flight condition. The aircraft performance can be analyzed for the specified state, or a maximum effort performance can be identified. The maximum effort is specified in terms of a quantity such as best endurance or best range, and a variable such as speed, rate of climb, or altitude. The aircraft must be trimmed, by solving for the controls and motion that produce equilibrium in the specified flight state. Different trim-solution definitions are required for various flight states. Evaluating the rotor-hub forces may require solution of the blade-flap equations of motion. 1–4 Terminology The following terminology is introduced as part of the development of the NDARC theory and
Introduction 5 previous case DESIGN ANALYZE Sizing Task size iteration design conditions design missions Flight Condition max GW fixed model or previous job or Aircraft Description Flight State max effort / trim aircraft / flap equations Airframe Aerodynamics Map Engine Performance Map Mission Analysis Flight Performance Analysis Mission adjust & fuel wt iteration max takeoff GW each segment Figure 1-1. Outline of NDARC tasks. software. Relationships among these terms are reflected in figure 1-1. a) Job: An NDARC job consists of one or more cases. b) Case: Each case performs design and/or analysis tasks. The analysis tasks can include off-design mission performance calculation, flight performance calculation for point operating conditions, and generation of airframe aerodynamics or engine performance maps. c) Design Task: Size rotorcraft to satisfy specified set of design flight conditions and/or design missions. Key aircraft design variables are adjusted until all criteria are met. The resulting aircraft description can be the basis for mission analysis and flight performance analysis tasks. d) Mission Analysis Task: Calculate aircraft performance for one off-design mission. e) Flight Performance Analysis Task: Calculate aircraft performance for point operating condition. f) Mission: Ordered set of mission segments, for which time, distance, and fuel burn are evaluated.
Page 1 and 2: NASA/TP-2009-215402 NDARC NASA Desi
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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: Introduction 3 of rotorcraft config
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 and 26: Nomenclature 13 Motion aF AC aircra
Page 27 and 28: Chapter 3 Tasks The NDARC code perf
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
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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;
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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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