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NORDEN.THE INTERACTIVE MANUAL

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Parts & componentsPage size3D experience ↗

LOWRY FIELD · 1943

The Norden
Bomb Sight

Maintenance & Calibration

IN THIS EDITION 01—252

01Cover 02Title page 03The M-series bombsight 04Blank verso 05Foreword 06Foreword, continued 07Sections I–II 08Sections III–IV 09Section V 10Sections VI–VIII 11Sections VIII–IX 12Sections IX–X 13Sections X–XI 14Section XI continued 15Illustrations 16Illustrations continued 17Introduction 18Introduction, continued 19Stabilizer rear view 20Stabilizer front view 21Operation and nomenclature: stabilizer 22Bomb sight clutch assembly 23P.D.I. and drift clutch assemblies 24Stabilizer assemblies, continued 25Stabilizer gyro 26Directional gyro, ring gear and torque motor 27Torque (servo) motor assembly 28Torque motor and precession motor 29Precession motor and PDI system 30M-3 stabilizer wiring diagram 31M-3 stabilizer circuits and isolated sector 32M-6 stabilizer wiring without Honeywell modification 33Isolated sector operation and M-6 wiring 34M-6 stabilizer wiring with Honeywell modification 35M-6 stabilizer modification C. L. I. 42-6 36Stabilizer assemblies “M” series 37Disassembly and reassembly, stabilizer 38Stabilizer disassembly (continued)39Stabilizer reassembly 40Stabilizer reassembly (continued)41Inspection and overnight settings 42Bomb sight clutch disassembly 43Disassembly and reassembly of assemblies, stabilizer 44Auto-pilot and drift clutch disassembly 45Auto-pilot and drift clutch disassembly and reassembly 46Torque motor disassembly 47Torque motor disassembly and reassembly 48Torque motor disassembly, continued 49Torque motor reassembly, continued 50Gyro and cardan disassembly 51Stabilizer gyro and cardan 52Stabilizer gyro and cardan 53Gyro from cardan disassembly 54Gyro and cardan reassembly 55Maintenance, general 56Bombsight log books 57Overnight settings and pre-flight inspection 58Pre-flight inspection, continued 59Daily inspection 60Fifteen-day and fifty-hour inspection 61Stabilizer maintenance chart 62Electrical continuity checks 63Stabilizer inspection procedures 64Clutch tensions 65Clutch adjustment 66Rotor bearing lubrication 67Rotor bearing maintenance 68Stabilizer gyro and cardan care 69Commutator maintenance 70Brush maintenance 71Torque motor maintenance 72Cleaning torque-motor clutches 73Cleaning the torque-motor commutator 74Torque motor disassembly 75Torque motor disassembly, continued 76Torque motor disassembly, continued 77Bomb sight and stabilizer M-series 78Bombsight nomenclature 79Operation and nomenclature of the sight 80Sight operation, continued 81Sight assemblies 82Course knob assembly 83Stabilized sector and altitude knob 84Altitude knob assembly 85Altitude-knob adjustment 86Rate-end cutaway 87Telescope motor assembly 88Rate and displacement mechanism 89Disc and search-knob assemblies 90Rate of drive 91Automatic release mechanism 92Telescope and cable operation 93Installation of telescope cable 94Cross-trail mechanism 95Cradle differential lever 96Cross-trail operation 97Cradle differential action 98Bombsight wiring 99Sight cardan and wiring 100Telescope cradle assembly 101Telescope motor circuit 102M-6 sight changes 103Mechanical solution of cross-trail problem 104Twenty-degree forward-view mechanism 105M-6 later-model forward view 106Sight wiring diagram 107M-6 sight wiring explanation 108Blank leaf 109The bombing problem 110Trajectory and range 111Effect of increased speed 112Air resistance 113Bomb trajectory 114Point of release and impact 115Wind and ground speed 116Bombing problem, continued 117Bomb path in a moving air mass 118Drift angle and cross trail 119Definitions 120Definitions, continued 121Velocity of closure 122Synchronous sight 123Trajectory triangle 124Whole range and actual time of fall 125Dropping angle 126Transition of the bombing problem to the sight 127Technical solution of the bombing problem 128Solution by rate end 129Rate-end solution, continued 130Simplified cross-trail mechanism 131Cross-trail solution 132Eccentric disc and dove tail 133Gyroscope 134Apparent easterly precession and north hook 135Precession of gyros 136Linear mil and north hook 137Precession run 138Cardinal heading and static balance 139Static balance, continued 140Blank leaf 141Sight disassembly and reassembly 142Bomb sight assemblies 143Housing and rate-end disassembly 144Cardan and end-cover disassembly 145Sight reassembly 146Blank leaf 147Rate-end motor-half disassembly and reassembly 148Motor-half rate-end disassembly 149Altitude-knob disassembly 150Rate and displacement pinion-shaft blocks 151Rate-end computer-half reassembly 152Cross-trail carriage 153Cross-trail operating mechanism 154Leveling knobs and gyro removal 155Gyro removal from cardan 156Cradle removal from cardan 157Gyro locking knob and telescope cross-hair light 158Course knobs 159Maintenance, sight 160Bombsight log 161Storage and shipment 162Daily inspection 163Daily inspection, continued 164Corrosion prevention 165Brushes and commutator 166Cleaning gears 167Electrical maintenance checks 168Cleaning bearings 169Telescope motor brushes 170Checking disc speed 171Governor points 172Disc speed adjustment 173Telescope governor maintenance 174Installation of telescope cable 175Automatic release mechanism 176Zeroing the roller 177Telescope cable installation 178Zeroing the roller with the rate mechanism 179Rate quadrant adjustment 180Gyro maintenance 181Gyro bearing precautions 182Commutator maintenance 183Brush pigtails 184Precession leveling knobs 185Cardan maintenance 186Bail magnet circuit 187Course knobs adjustment 188M-6 sight without A.E.S.189A.E.S. changes 190Bomb sight and stabilizer M-9 191Telescope calibration checks 192Bombsight electrical diagram 193Telescope return spring 194Torque motor circuits 195Thirty-day inspection 196Section IX closing leaf 197Calibration introduction 198Pedestal reference index 199Calibration 200Grid line on true heading 201Alignment of vertical hair 202Synchronize trail arm 203Trail arm synchronization 204Level head of stand 205Precision level 206Level stabilizer 207Leveling procedure 208Gyro erected to vertical 209Gyro erection procedure 210Erection of optics to vertical 211Precession check 212Precession check of stabilizer gyro 213Review and reference information 214Confidential letters of instruction 215Calibration tools 216Tachometer 217Reasons for calibration steps 218Pedestal reference index rationale 219Precision level rationale 220Wedge the gyro 221Erect transverse hair 222Erect fore-and-aft hair 223Deflection and range errors 224Stabilizer alignment errors 225Dovetail alignment 226Drift and optics tilt 227Reticle alignment 228Quadrants driving toward release 229Time of bomb release 230Release errors 231Telescope quadrant drive 232Telescope quadrant error 233Beam and tape 234Beam and tape calculations 235Beam and tape procedure 236Publications and instruction 237Low altitude attachment 238Rate end parts 239Defects and malfunctions 240Troubleshooting bombsight errors 241Troubleshooting, continued 242Common sight errors 243Common sight errors, continued 244Wind error causes 245Electrical fault checks 246Calibration inspection checklist 247Substitutes for calibration equipment 248Heater element circuit 249Heater element circuit, continued 250Bombsight calibration outfit inventory 251M-series comparison chart 252Ball bearing chart

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252 RECREATED PAGES

Original words. Interactive illustrations.

Source & transcription

Pages 1–25 are recreated from references/NORDEN.pdf, dated September 1, 1943. Added pages use references/norden2.pdf, whose wording, date and pagination differ. Original spelling and contents references are retained. The newly added pages are a first transcription pass: text follows source positions, while faint or damaged characters still need proofreading. The body text is newly typeset in Courier; the scanner’s footer is omitted.

The comparison slider reveals a direct scan of each page’s source PDF. Circuit diagrams retain their source images. The 3D diagrams reconstruct visible parts; dimensions not established by the source remain approximate.

THE M-SERIES MANUALAN INTERACTIVE EDITION

The Norden Bomb Sight manual

Torque motor disassembly

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Torque motor disassembly

PAGE 46 / Torque motor disassembly

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TORQUE MOTOR DISASSEMBLY

Interactive drawing

FIG. 15

28

Original scan: norden2.pdf, PDF page 46

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Explore this mechanismTorque motor and magnetic clutches ↗