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18 Tasks specified as an increment d plus a fraction f of a weight W : WSD = dSDGW + fSDGWW = WMTO = dWMTO + fWMTOW = dSDGW + fSDGWWD dSDGW + fSDGW(WD − Wfuel + ffuelWfuel−cap) dWMTO + fWMTOWD dWMTO + fWMTO(WD − Wfuel + Wfuel−cap) This convention allows the weights to be input directly (f =0), or scaled with WD. ForWSD, W is the design gross weight WD, orWD adjusted for a specified fuel state (input fraction of fuel capacity). For WMTO, W is the design gross weight WD, orWD adjusted for maximum fuel capacity. Alternatively, WMTO can be calculated as the maximum gross weight possible at a designated sizing flight condition. 3-1.2.7 Drive-System Rating The drive-system rating is defined as a power limit, PDSlimit. The rating is properly a torque limit, QDSlimit = PDSlimit/Ω, but is expressed as a power limit for clarity. The drive-system rating can be specified as follows: a) Input PDSlimit. b) From the engine takeoff power rating, PDSlimit = flimit NengPeng (summed over all engine groups). c) From the power available at the transmission sizing flight conditions, PDSlimit = flimit(Ωref/Ωprim) NengPav (largest of all conditions). d) From the power required at the transmission sizing flight conditions, PDSlimit = flimit(Ωref/Ωprim) NengPreq (largest of all conditions). with flimit an input factor. The drive-system rating is a limit on the entire propulsion system. To account for differences in the distribution of power through the drive system, limits are also used for the torque of each rotor shaft (PRSlimit) and of each engine group (PESlimit). The engine-shaft rating is calculated as for the drive-system rating, without the sum over engine groups. The rotor-shaft rating is either input or calculated from the rotor power required at the transmission sizing flight conditions. The power limit is associated with a reference rotational speed, and when applied it is scaled with the rotational speed of the flight state. The rotation speed for the drive-system rating PDSlimit is the hover speed of the primary rotor of the propulsion group (for the first drive state). The rotation speed for the engine-shaft rating PESlimit is the corresponding engine turbine speed. The rotation speed for the rotor-shaft rating PRSlimit is the corresponding speed of that rotor. 3–2 Mission Analysis For the mission analysis, the fuel weight or payload weight is calculated. Power required, torque (drive system, engine shaft, and rotor shaft), and fuel weight are then verified to be within limits. Missions can be fixed or adjustable. 3–3 Flight Performance Analysis For each performance flight condition, the power required is calculated or maximum gross weight is calculated. Power required, torque (drive system, engine shaft, and rotor shaft), and fuel weight are then verified to be within limits.
Tasks 19 3–4 Maps 3-4.1 Engine Performance The engine performance can be calculated for a specified range of power, altitude, and speed. 3-4.2 Airframe Aerodynamics The airframe aerodynamic loads can be calculated for a specified range of angle of attack, sideslip angle, and control angles. The aerodynamic analysis evaluates the component lift, drag, and moments given the velocity. The aircraft velocity is here v F AC = CFA (v 00) T ; interference velocity from the rotors is not considered. From the angle of attack α and sideslip angle β, the transformation from wind axes to airframe axes is C FA = YαZ−β (optionally C FA = Z−βYα can be used, for better behavior in sideward flight). The loads are summed in the airframe axes (with and without tail loads), and then the wind axis loads are: F A ⎛ = ⎝ −D ⎞ Y ⎠ = C −L AF F F M A = ⎛ ⎝ Mx My Mz ⎞ ⎠ = C AF M F The center of action for the total loads is the fuselage location zfuse. The ratio of the loads to dynamic pressure is required, so a nominal velocity v = 100 (ft/sec or m/sec) and sea-level standard density are used.
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 and 26: Nomenclature 13 Motion aF AC aircra
Page 27 and 28: Chapter 3 Tasks The NDARC code perf
Page 29: Tasks 17 engine group is found (inc
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
Page 77 and 78: 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
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Chapter 9 Fuselage There is one fus
Page 85 and 86:
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
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
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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
Page 125 and 126:
Wing 113 13-3.1 Lift The wing lift
Page 127 and 128:
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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Page 157 and 158:
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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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