Engineering Design Handbook Automatic Weapons Guns

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Engineering Design Handbook Automatic Weapons Guns

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Open: Engineering Design Handbook Automatic Weapons Guns

This handbook presents and discusses procedures normally practiced for the design of automatic weapons, and explores the problems stemming from the functions of each weapon and its components. It is intended to assist and guide the designer of automatic weapons of the gun type, and to contain pertinent design information and references.

This handbook is one of a series on Guns. This handbook presents information on the fundamental operating principles and design of automatic weapons and applies specifically to automatic weapons of all types such as blowback, recoil-operated, gas-operated, and externally powered. These include single, double, multibarrel, and revolver-type machine guns and range from the simple blowback to the intricate M61A1 Vulcan and Navy 20 mm Aircraft Gun Mark II Mod 5 Machine Guns. Methods are advanced for preparing engineering design data on firing cycle, spring design, gas dynamics, magazines, loaders, firing pins, etc. All components are considered except tube design which appears in another handbook, AMCP 706-252, Gun Tubes.

This handbook was prepared by The Franklin Institute, Philadelphia, Pennsylvania, for the Engineering Handbook Office of Duke University, prime contractor to the U.S. Army, and was under the technical guidance and coordination of a special subcommittee with representation from Watervliet Arsenal, Rock Island Arsenal, and Springfield Armory.

LIST OF ILLUSTRATIONS
LIST OF TABLES
LIST OF SYMBOLS
PREFACE
CHAPTER 1. INTRODUCTION
SCOPE AND PURPOSE
GENERAL
DEFINITIONS
DESIGN PRINCIPLES FOR AUTOMATIC WEAPONS
CHAPTER 2. BLOWBACK WEAPONS
2-1 GENERAL 2-1
2-2 SIMPLE BLOWBACK 2-3
2-2.1 SPECIFIC REQUIREMENTS 2-3
2-2.2 TIMEOFCYCLE 2-4
2-2.2.1 Recoil Time 2-5
2—2.2.2 Counter recoil Time 2-6
2-2.2.3 Total Cycle Time 2-7
2-2.3 EXAMPLE OF SIMPLE BLOWBACK GUN 2-8
2-2.3.1 Specifications 2-8
2—2.3.2 Computed Design Data 2-8
2—2.3.3 Case Travel During Propellant Gas Period 2-10
2-2.3.4 Sample Problem of Case Travel 2-10
2—2.3.5 Driving Spring Design 2—11
2-3 ADVANCED PRIMER IGNITION BLOWBACK 2-12
2-3.1 SPECIFIC REQUIREMENTS 2-12
2-3.2 SAMPLE CALCULATIONS OF ADVANCED
PRIMER IGNITION 2-13
2-3.2.1 Firing Rate 2-13
2.3.2.2 Driving Spring Design 2—15
2.1 DELAYEDBLOWBACK 2-17
2-4.1 SPECIFIC REQUIREMENTS 2-17
2-4.2 DYNAMICS OF DELAYED BLOWBACK 2-18
2-4.3 SAMPLE PROBLEM FOR DELAYED
BLOWBACK ACTION 2-24
2-4.3.1 Specifications 2-24
2-4.3.2 Design Data 2-24
2-4.4 COMPUTER ROUTINE FOR COUNTERRECOILING
BARREL DYNAMICS 2-33
2-4.5 SPRINGS 2-37
2-4.5.1 Driving Spring 2-37
2-4.5.2 Barrel Spring 2-39
2-4.5.3 Buffer Spring 2-39
2-5 RETARDEDBLOWBACK 2-40
2-5.1 SPECIFIC REQUIREMENTS 2-40
2-5.2 DYNAMICS OF RETARDED BLOWBACK 2-40
2—5.2.1 Kinematics of the Linkage 2—40
2-5.2.2 Equations of Dynamic Equilibrium 2—43
2—5.2.3 Digital Computer Program for
the Dynamic Analysis 2—44
2-6 RATING OF BLOWBACK WEAPONS 2-47
CHAPTER 3. RECOIL-OPERATED WEAPONS
3-1 GENERAL 3-1
3-2 LONG RECOIL DYNAMICS 3_i
3-3 SAMPLE PROBLEM LONG RECOIL MACHINE GUN .. 3-1
3-3.1 SPECIFICATIONS 3_1
3-3.2 DESIGNDATA 3-1
3-4 SHORT RECOIL DYNAMICS 3_9
3-5 SAMPLE PROBLEM SHORT RECOIL MACHINE GUN . . 3-9
3-5.1 SPECIFICATIONS 3_9
3-5.2 DESIGNDATA 3-9
3-6 ACCELERATORS 3_15
3-7 SAMPLE PROBLEM ACCELERATOR 3-17
3-7.1 SPECIFICATIONS 3-17
3-7.2 DESIGNDATA 3-17
3-8 RATING OF RECOIL-OPERATED GUNS 3-21
CHAPTER 4. GAS-OPERATED WEAPONS
4-1 GENERALREQUIREMENTS 4-1
4-2 TYPES OF GAS SYSTEMS 4-1
4-3 CUTOFF EXPANSION SYSTEM 4-1
4-3.1 MECHANICS OF THE SYSTEM 4_i
4—3.1.1 Gas Filling Period 4_g
4-3.1.2 Bolt Locking Cam 4_9
4—3.1.3 Cam Curve 4—15
4-3.2 SAMPLE PROBLEM FOR CUTOFF EXPANSION
SYSTEM 4-17
4—3.2.1 Specifications 4—17
4—3.2.2 Design Data, Computed 4—17
4—3.2.3 Counter recoil Computed Data 4—19
4-3.2.4 Counter recoil Time 4_20
4-3.2.5 Recoil Time 4-23
4-3.2.5.1 Recoil Time, Decelerating 4—23
4-3.2.5.2 Recoil Time, Accelerating 4—24
4-3.3 DIGITAL COMPUTER ROUTINE FOR CUTOFF
EXPANSION 4-28
4-3.3.1 Gas Dynamics Before Cutoff 4-28
4—3.3.2 Gas Dynamics After Cutoff 4—29
4-3.3.2.1 Bolt Unlocking During Helix Traverse 4-29
4-3.3.2.2 Bolt Unlocking During Parabola Traverse 4-29
4-3.3.2.3 Bolt Unlocked, Bolt Traveling With
Operating Rod 4—31
4—3.3.3 Dynamics After Gas Cylinder Operations 4-32
4-3.3.3.1 Recoil Dynamics 4-32
4-3.3.3.2 Counter recoil Dynamics 4-35
4-3.3.3.3 Bolt Locking Dynamics 4-36
4-3.3.3.4 Firing Rate 4-37
4-3.4 SPRINGS 4-37
4-3.4.1 Driving Spring 4-37
4-3.4.2 Buffer Spring 4-37
4-4 THE TAPPET SYSTEM 4-38
4-4.1 SAMPLEPROBLEM 4-38
4-4.1.1 Specifications 4-38
4-4.1.2 Preliminary Design Data 4-38
4-4.1.3 Design Data. Computed 4-38
4-4.1.4 Spring Design Data 4-45
CHAPTER 5. REVOLVER-TYPE MACHINE GUNS
5-1 SINGLE BARREL TYPE 5-1
5-1.1 PRELIMINARY DYNAMICS OF FIRING CYCLE 5-2
5—1.1.1 Sample Problem of Preliminary Firing Rate Estimate . . . 5-7
5-1.1.2 Analysis of Cam Action 5-8
5-1.1.2.1 Sample Calculation of Cam Action 5-14
5-1.1.2.2 Driving Spring 5-18
5_1.2 FINAL ESTIMATE OF THE COMPLETE FIRING CYCLE 5-18
5—1.2.1 Control of Recoil Travel During Propellant Gas Period . . 5-20
5-1.2.2 Operating Cylinder Design 5-23
5—1.2.3 Dynamics of Simultaneous Adapter-operating
Cylinder Action 5-31
5 — 1.2.4 Sample Calculation for Complete Firing Cycle 5-32
5-1.2.4.1 Counter recoil Time of Recoiling Parts 5-33
5-1.2.4.2 Digital Computer Analyses of Barrel drum Dynamics . . . 5-37
5-1.2.4.3 Firing Rate Computation 5-39
5-2 DOUBLE BARREL TYPE 5-46
5-2.1 FIRINGCYCLE 5-46
5-2.1.1 Cam Function 5-46
5-2.1.2 Loading and Ejecting 5-48
5-2.1.3 Ammunition Feed System 5—48
5-2.2 DYNAMICS OF FIRING CYCLE 5-49
5-2.2.1 Cam Analysis 5-50
5-2.2.2 Energy Concept 5-52
5-2.2.3 Digital Computer Program for Firing Cycle 5-52
CHAPTER 6. MULTIBARREL MACHINE GUN
6-1 GENERAL 6-1
6-2 BOLT OPERATING CAM DEVELOPMENT 6-1
6-2.1 CAMACTION 6-1
6—2.1.1 Cam Kinematics 6-3
6-2.1.2 Definition of Symbols 6-4
6—2.1.3 Cam Forces 6—5
6—2.1.4 Locking Angle 6-6
6-2.2 ROTOR KINEMATICS 6-7
6-2.3 ILLUSTRATIVE PROBLEM 6-9
6-2.3.1 Cam Analysis During Feed, Rotor at Constant Velocity .. 6-9
6-2.3.2 Cam Analysis During Ejection, Rotor at Constant
Velocity 6-11
6—2.3.3 Cam Analysis During Rotor Acceleration 6—12
6-2.3.4 Digital Computer Program for Gun Operating Power .... 6-13
6-3 RATING OF GAS-OPERATED AND EXTERNALLY
POWEREDGUNS 6-14
CHAPTER 7. COMPONENT DESIGN
7-1 GENERAL 7-1
7_2 FEED MECHANISM DESIGN 7-1
7-2.1 MAGAZINES 7-2
7—2.1.1 Box Magazines 7-2
7-2.1.2 Box Feed System 7-4
7-2.1.2.1 Flat Tape Spring 7-5
7-2.1.2.2 Rectangular Coil Spring 7-6
7—2.1.3 Example Problems 7-6
7-2.1.3.1 Flat Tape Spring 7-7
7-2.1.3.2 Rectangular Coil Spring 7-8
7-2.2 BOLT-OPERATED FEED SYSTEM ?-9
7_2.3 ROTATING FEED MECHANISM 7-10
7-2.3.1 Recoil-operated Feed Mechanism 7-10
7-2.3.2 Electrically Driven Feed Mechanism 7-12
7_2.4 LINKLESSFEED SYSTEM 7-14
7—2.4.1 Power Required 7-19
7-2.4.2 Example Problem for Power Required 7-21
7-3 EXTRACTORS, EJECTORS, AND BOLT LOCKS 1~24
7-3.1 EXTRACTORS 7~24
7_3.2 EJECTORS 7-27
7_3 2.1 Ejector Dynamics 7-27
7-3.2.2 Sample Problem of Ejector Dynamics 7-27
7-3.3 BOLTLOCKS 7-30
7_4 FIRING MECHANISM 7-32
7_4.1 COMPONENTS, TYPES, AND ACTION 7-32
7-4.1.1 Trigger Pull 7-37
7_4 12 Firing Pin Design 7-39
7_5 ' LINKS •. . . . 7-39
7_5 i TYPES OF LINK 7-40
7_s'.2 DESIGN REQUIREMENTS 7-40
7-6 MOUNTS 7-44
7_6.1 GEOMETRY AND RESOLUTION OF FORCES 7-44
7-6.2 SAMPLEPROBLEM 7-48
CHAPTER 8. LUBRICATION OF MACHINE GUNS
3-1 GENERALCONCEPT 3-1
3-2 EXAMPLES OF LUBRICANTS 8-1
8-3 CASELUBRICANT 8-2
A-1 Flow Chart for Delayed Blowback A-1
A—2 Listing for Delayed Blowback Program A—4
A-3 Flow Chart for Retarded Blowback A-6
A-l Listing for Retarded Blowback Program A—9
A5 Flow Chart for Cutoff Expansion A—12
A-6 Listing for Cutoff Expansion Program A—15
A-7 Flow Chart for Operating Cylinder A-20
A-8 Listing for Operating Cylinder Program A—22
A—9 Flow Chart for Cam and Drum Dynamics During Recoil . . A—26
A—10 Listing for Cam and Drum Dynamics During Recoil A—30
A—1 1 Flow Chart for Cam and Drum Dynamics During Counterrecoil A—35
A—12 Listing for Cam and Drum Dynamics During Counterrecoil A—38
A—13 Flow Chart for Double Barrel Machine Gun A—43
A—14 Program Listing for Double Barrel Machine Gun A—46
A-15 Flow Chart for Multibarrel Power A-52
A—16 Program Listing for Multibarrel Power A—59
B Automatic Control of Rounds in a Burst for
Weapon Effectiveness B— 1
GLOSSARY G-l
REFERENCES R-1