The Art of the Helicopter John Watkinson - Karatunov.net

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Introduction to rotorcraft 21 a rotor tachometer. The response of a helicopter to control inputs depends on rotor speed, and this needs to be controlled to close limits. The rotor tachometer and enginerelated instruments are detailed in Chapter 6, whereas flight instruments are covered in Chapter 7. References 1 Spenser, J.P., Whirlybirds, University of Washington Press, Seattle, ISBN 0-295-97699-3 (1998) 2 Spenser, J.P., Vertical Challenge, University of Washington Press, Seattle, ISBN 0-295-97203-3 (1998) 3 Coates, S., Helicopters of the Third Reich, Classic Publications, Hersham, ISBN 1-903223-24-5 (2002) 4 Boulet, J., L’Histoire de l’Hélicoptère, Editions France-Empire, Paris, ISBN 2-7048-0040-5 (1982) 5 DuMoulin, A., Les Hélicoptères Florine 1920–1950, Fonds National Alfred Renard, Brussels (1999) 6 Everett-Heath, J., British Military Helicopters, Arms and Armour Press, London, ISBN 0-85368-805-2 (1986) 7 Nowarra, H.J., German Helicopters, Schiffer, West Chester, ISBN 0-88740-289-5 (1990) 8 Dowling, J., RAF Helicopters: the first twenty years, HMSO, London, ISBN 0-11-772725-3 (1992)
2 Technical background This chapter provides an introduction to concepts that will be needed to follow the technical explanations in the rest of the book. 2.1 Introduction to mechanics Mechanics is the study of how objects interact with the forces applied to them. Designers are concerned with resisting the forces generated in flight so that the machine stays intact. Using the controls of a helicopter the pilot changes the forces applied to it and thereby determines the path it takes. It is important for a pilot to understand some mechanics so that he can predict what control movements will be necessary to make the machine do what is wanted. When this happens, the pilot is said to be in control. Any other situation is not recommended. 2.2 Mass and density The amount of matter in a body is specified by its mass, measured in pounds (lb) or kilograms (kg). Since the amount of matter in a body cannot readily change, the mass is the same wherever the body is and however it moves. The density of a substance is the mass of unit volume. In the old imperial units, density was expressed as pounds per cubic foot. In the SI system, the term ‘relative density’ is used, where water has a relative density of one. 2.3 Force and acceleration Weight is the force a body exerts on its supports. In orbit, objects have no supports: they are weightless. Back on earth the gravitational field pulls them down and they have weight. Weight is equal to mass multiplied by the strength of the gravitational field. This is why astronauts can bounce around on the moon; gravity is much weaker there. Since the strength of gravity doesn’t change much from one place on earth to another, earthlings tend to buy things by weight not by mass, and often confuse the two. All real objects, helicopters included, have their mass distributed over their dimensions. Whilst each part has its own mass, for some purposes this can be replaced by a single mass located at the centre of mass (CM) (Figure 2.1(a)). The older term centre
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Page 4 and 5: The Art of the Helicopter John Watk
Page 6 and 7: Contents Preface xi Acknowledgement
Page 8 and 9: 4.12 Feathering 134 4.13 Pitch cont
Page 10: 8.5 Power management 326 8.6 Flying
Page 13 and 14: xii Preface reader to make sense of
Page 16 and 17: 1 Introduction to rotorcraft 1.1 Ap
Page 18 and 19: Introduction to rotorcraft 3 Fig. 1
Page 24 and 25: Introduction to rotorcraft 9 for th
Page 26 and 27: Introduction to rotorcraft 11 Fig.
Page 28 and 29: (a) (b) (c) (d) Introduction to rot
Page 30 and 31: Fig. 1.18 The contra-rotating coaxi
Page 32 and 33: Fig. 1.20 The structure of a light
Page 34 and 35: Introduction to rotorcraft 19 wings
Page 38 and 39: Technical background 23 Fig. 2.1 At
Page 40 and 41: Fig. 2.3 Effect of force on velocit
Page 42 and 43: C Force A E Resultant (a) Force B (
Page 44 and 45: (a) (b) Technical background 29 Fig
Page 46 and 47: Technical background 31 Fig. 2.11 A
Page 48 and 49: Technical background 33 Fig. 2.12 (
Page 50 and 51: Technical background 35 If the volu
Page 52 and 53: Fig. 2.16 The definition of a radia
Page 54 and 55: Technical background 39 force would
Page 56 and 57: Technical background 41 Figure 2.20
Page 58 and 59: Technical background 43 force where
Page 60 and 61: Technical background 45 the cosine
Page 62 and 63: Technical background 47 Fig. 2.28 F
Page 64 and 65: Technical background 49 Fig. 2.30 T
Page 66 and 67: Technical background 51 centripetal
Page 68 and 69: 2.17 The gyroscope Technical backgr
Page 70 and 71: Technical background 55 of oscillat
Page 72 and 73: Technical background 57 the inertia
Page 74 and 75: Technical background 59 shut down a
Page 76 and 77: 3 Introduction to helicopter dynami
Page 78 and 79: Introduction to helicopter dynamics
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Introduction to helicopter dynamics
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(a) (c) (b) Introduction to helicop
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(a) (b) (c) (d) Introduction to hel
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Fig. 3.23 Conditions for hover and
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(a) (b) Introduction to helicopter
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(a) (b) Introduction to helicopter
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4.1 Introduction 4 Rotors in practi
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(a) (b) Rotors in practice 119 Fig.
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Rotors in practice 121 Designers of
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Rotors in practice 123 opposite occ
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Rotors in practice 125 Fig. 4.6 (a)
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Rotors in practice 127 assembly tha
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Rotors in practice 129 Pitch change
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× T=c× D Rotors in practice 131 F
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Rotors in practice 133 In a real he
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Rotors in practice 135 Fig. 4.15 Va
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(a) (b) Rotors in practice 137 Fig.
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Rotors in practice 139 Fig. 4.18 Th
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Rotors in practice 141 swashplate a
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Fig. 4.23 A fixed-pitch tilting hea
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Rotors in practice 145 Fig. 4.25 Bl
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Rotors in practice 147 Fig. 4.27 Ef
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Rotors in practice 149 Fig. 4.29 (a
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Rotors in practice 151 concerned ar
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Rotors in practice 153 and lag damp
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Rotors in practice 155 disappears a
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(d) (e) (f) Rotors in practice 157
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Rotors in practice 159 hull and a v
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Rotors in practice 161 Fig. 4.35 (C
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Rotors in practice 163 Abrasion is
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Rotors in practice 165 There are so
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eing more visible to ground personn
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otates the rod in the screw thread.
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In the case of a rotor having offse
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The tail rotor designer is faced wi
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Fig. 5.5 A right-side wrong-directi
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centre of mass. The solution was to
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safe to start the rotors. However,
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Fig. 5.10 Tail plane locations: (a)
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Fig. 5.12 (a) A top-mounted fin is
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Fig. 5.14 (a) Main rotor lateral ro
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long. The cross-section of the duct
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drag. However, the slots are emitti
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6 Engines and transmissions The pow
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Engines and transmissions 193 the D
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(a) (b) Engines and transmissions 1
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(a) (b) (c) Engines and transmissio
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Fig. 6.5 A typical horizontally opp
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Engines and transmissions 201 the v
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Engines and transmissions 203 The c
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6.9 The oil system Engines and tran
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Engines and transmissions 207 (non-
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(a) (b) Engines and transmissions 2
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Engines and transmissions 211 a hot
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Engines and transmissions 213 Fig.
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Engines and transmissions 215 In wa
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Engines and transmissions 217 is a
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Engines and transmissions 221 own t
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Fig. 6.16 The complex fuel system o
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Engines and transmissions 233 and c
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Engines and transmissions 237 Sensi
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Engines and transmissions 243 the A
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Fig. 6.37 Displays which may be see
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Engines and transmissions 251 slipr
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Engines and transmissions 253 a fau
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Engines and transmissions 255 resul
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Engines and transmissions 257 The p
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Fig. 7.1 (a) A minimal control loop
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Fig. 7.2 (a) When attitude conditio
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fixed point in the hover despite ex
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(a) (b) Fig. 7.4 (a) The earth beha
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7.4 Compass errors A magnetic compa
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In most cases the machine will have
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Fig. 7.7 The remote indicator for a
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is set by the use of a control knob
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Fig. 7.11 The VSI (vertical speed i
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Fig. 7.13 A chaser system which all
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e modified if the gyro is in a movi
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must be in steady flight when the D
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arranged on opposite sides of the p
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Fig. 7.19 The turn indicator is spr
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7.17 Airflow-sensing devices The he
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Fig. 7.24 Using RADAR signals. At (
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Fig. 7.27 Transducers used in signa
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Fig. 7.28 In PCM or digital signall
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(a) Fig. 7.30 Using slicing and rec
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Fig. 7.33 The false codes created i
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Fig. 7.35 In a pure binary system,
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Fig. 7.38 Producing two’s complem
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Fig. 7.40 A power-assisted hydrauli
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Fig. 7.42 An electro-hydraulic valv
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path axis and the flybar axis diver
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and autostabilization, it also prov
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Fig. 7.47 The Lockheed gyrobar syst
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Fig. 7.49 In the Lockheed AMCS, the
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Fig. 7.50 With the autopilot diseng
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or without the AFCS. Systems of thi
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Thus if a VOR receiver detected a 9
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7.29 Fault tolerance In feedback sy
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8 Helicopter performance 8.1 Introd
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Helicopter performance 325 column i
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Helicopter performance 327 Fig. 8.1
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Helicopter performance 329 to skid
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(a) (b) Helicopter performance 331
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Helicopter performance 333 Fig. 8.7
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8.7 Climbingand descending Helicopt
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Helicopter performance 337 In the c
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Helicopter performance 339 of its c
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8.10 Stability Helicopter performan
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Fig. 8.13 The origin of pitchup ins
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Helicopter performance 345 moment f
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9 Other types of rotorcraft Althoug
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Other types of rotorcraft 349 De la
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Other types of rotorcraft 351 Fig.
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Other types of rotorcraft 353 incre
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Other types of rotorcraft 355 and c
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Fig. 9.7 The Bell-Boeing Osprey til
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(a) (b) Other types of rotorcraft 3
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Other types of rotorcraft 365 a low
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Other types of rotorcraft 367 the y
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Other types of rotorcraft 371 the r
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Other types of rotorcraft 373 For e
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Acceleration: and force, 22-5 and v
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Convertiplane, 11-12, 355-8 Bell-Bo
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tanks, 219-20 turbine engines, 237-
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Lockheed flybar system, 309-13 AMCS
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centrifugal stiffening, 71, 100 and
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tail/main rotor interaction, 173 te
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