Airships

Many people may know about the blazing crash of the Hindenburg in 1937 but are possibly unaware that it had made 62 flights before its final journey (including one transporting author Leslie Charteris, creator of The Saint). The disaster, however, did not end the airship era; blimps escorted convoys during World War II and were a part of air defense systems in the 1950s and 1960s. Airships still fly today, and new models are in the construction phase.
This book examines this branch of aviation history, delving into the science and engineering of airships and their design flaws, weather difficulties and operational errors. The chapters focus on function (lift, propulsion, materials, ground handling and so forth). The book concludes with speculations about future airship designs and missions.

Table of Contents

Preface
Abbreviations
Selected Airship Alphanumeric Designations
Chapter 1. Airships 101
What Is an Airship? 5; Airship Successes 6; The Forces on an Airship 9; Airship Design Goals 10; Airship Size 13; Airship Shape 15
Chapter 2. Buoyant (Aerostatic) Lift
Milestones in Airship (and Balloon) Lift 16; The Creation of Buoyancy 17; Specific Lift 18; Gross Aerostatic Lift 19; Hydrogen Versus Helium 20; Hydrogen Production and Purity 20; Helium Production and Purity 24; Inflating the Airship 25; Effect of Atmospheric Conditions on Specific Lift 25; Superheating and Supercooling 27; Superpressure 29; Maximum Gas Capacity 30; Altitude Effects 31; Thermal Airships: Hot Air 34; Rozier (Multigas) Airships 38; The Problem with Vacuum Lift 39
Chapter 3. Propulsion System
Milestones in Airship Propulsion 41; Propulsion System Components 42; Propulsors 42; Power Transmission 44; Propulsive Efficiency 44; Engines 47; Internal Combustion Engine Performance 49; Altitude Effects on Internal Combustion Engine Performance 50; Engine Efficiency, Overall Efficiency and Fuel Consumption 51; Sizing the Engine 52; Auxiliary Power Draw 53; Power and Weight 54; "Golden Age" Airship Engines 55; Later Airship Engines 57; Number of Engines 58; Propeller (and Engine) Location 58; Propulsion System Controls 60; Propulsion System Monitoring 60; Engine Reliability 61; Engine Cooling 61; Fuel Tanks 62
Chapter 4. Thrust and Drag
Dirigibility 63; Aerodynamic Drag 63; Power, Propulsive Efficiency, and Speed 66; Propulsion Scaling Rules 67; Airship Size and Power 68; Airspeed (Engine Power) Selection 69; The Drag Coefficient and the Reynolds Number 71; Drag Measurement 73; Prediction of Drag 74
Chapter 5. ­ ­ Non-Buoyant (Aerodynamic) Lift
Aerodynamic Lift Force 77; The Effect of Profile Shape 78; The Effect of Aspect Ratio 79; ­ ­ Lift-Induced Drag 80; Component Contributions to Lift and ­ ­ Lift-Induced Drag: Experimental Datä 80; Effect of Aerodynamic Lift and Drag on Airspeed (Engine Power) Selection 82; Aerodynamic Lift Measurements 84; ­ ­ Lift-Induced Drag Measurements 86
Chapter 6. Altitude (Net Total Lift) Control
The Problem of Altitude Control 88; Venting (or Burning) Lift Gas 89; Shipboard Production of Lift Gas (Hydrogen) 90; Dropping Ballast 91; ­ ­ Re-Ballasting 94; Drag Rope (Recoverable Ballast) 97; Temperature Manipulation 97; Dynamic Lift (Positive or Negative) 100; Directed Thrust 101; Burning Gaseous Fuels 103; Other Methods 103
Chapter 7. Orientation Stability and Control
Terminology 104; Pitching, Yawing and Rolling Moments 104; Stability and Control 105; Effect of Pitch 106; Effect of Yaw 108; Trim 108; Lift Gas Surge and Pitching Moment 109; Intrinsic Pitch Stability 109; Pitch and Yaw Stabilizing Surfaces 110; Longitudinal (Pitch) Control 110; Yaw (Directional) Control 111; Roll Stability 112; Reversing Speed 113
Chapter 8. Takeoff, Landing, and Ground Handling
Weighing Off 116; Unmoored Takeoff and Landing 117; Ground Crew 119; Forces on a "Walked" Airship 120; Wind Flow Near Hangars 123; Mechanical Aids 124; Miscellaneous Ground Handling Issues 125
Chapter 9. Hangars
Hangar Siting 128; Stationary Hangars 128; Hangar Entrances 132; Temporary (Demountable) Hangars 133; Rotating (Floating) Hangars 135; Floating, ­ ­ Non-Rotating Hangars 137; Rotating (Mechanical) Hangars 137; Circular or ­ ­ Many-Sided Hangars 139
Chapter 10. Mooring Systems
Stationary (Permanent) Mooring Systems 141; Temporary and Portable Masts 148; Mobile Masts 150; Auxiliary Mooring Equipment 156; Mooring Procedure 156; Mastless Mooring at Seä 158; Water Takeoffs and Landings 159; Miscellaneous ­ ­ Ship-Based Operations 160; Forest Clearing Havens 162; Emergency Field Expedients 162
Chapter 11. Flight Operations
Ascending and Descending 165; Cruising Altitude 166; Turning (Circling) 166; Route Planning 167; The Wind Triangle 168; Wind Speed and Altitude 171; Navigation 173; Pressure Pattern Flying 174; Other Weather Considerations 175; Flight Controls 176; Communications 177
Chapter 12. Structure
Envelope Construction 178; Superpressure 179; Simple Aerostat Envelope Accessories 180; Semirigid Airships: Keel Design 181; Multilobal Airships 183; Compound Aerostats 183; Rigid Airships 185; Car Suspension 191; Cars (Gondolas) and Internal Space 193; Empennage 194; Miscellaneous Structural Features 195; Airship Shapes 195
Chapter 13. Stresses on an Airship Hull
Simple Aerostats: The Need for Superpressure 199; Simple Aerostats: The Hull as a Pressure Vessel 200; Gas Pressure in a Rigid Airship 201; Transverse Forces on an Airship Hull 201; Resistance to Bending by Nonrigid Airship 202; Resistance to Bending by a Semirigid Airship 203; Resistance to Bending by Metalclad 204; Force Transfer in a Rigid Airship 204; The Hull as a Simple Beam 205; The Effect of Stresses on the ­ ­ Length-to-Diameter Ratio 208; Distortion of the Airship Cross Section 209; Temperature Stresses in Rigid Airships 210; Anticipated Aerodynamic Loads: Level Flight 210; Aerodynamic Loads from Flight Maneuvers 211; Aerodynamic Loads from Gusts 212; Water Models 213; Deflated (or Inflated) Gasbag Test 214; Finite Element Analysis 215; Safety Factors 216
Chapter 14. Materials
Flexible Materials 218; Environmental Protection Materials 219; High Specific Strength, Flexible Materials 221; Gas Containment Criteriä 225; Gas Containment Materials 227; Historical Laminates 230; Modern Laminates 234; Holes and Tears 235; Structural Materials 236
Chapter 15. Weight Estimation
Weight Classification 240; Surface Areä 240; Weight Efficiency 241; Detailed Empty Weight Breakdowns 243; Historical Attempts at Weight Estimation 246; Weight Estimation for Modern Nonrigid Airships 251; Operating Load 255
Chapter 16. Airship Failures and Accidents
Causative and Contributory Factors 256; Accident Contexts 267; Loss of the R101: Case Study 273; Loss of USS Macon: Case Study 274; Personal Injuries in Airship Accidents 274
Chapter 17. Fiery Deaths and Hydrogen Embrittlement
Fire and Explosion Risks from Lift Gases and Fuels 276; ­ ­ Non-Hydrogen Fires 277; Hydrogen Fires 277; The Hindenburg Disaster 280; Increasing Hydrogen Safety 282; Hydrogen Embrittlement 283
Chapter 18. The Future of Airships
Unmanned Airships 288; Hybrid (Semibuoyant) Lift 288; ­ ­ Solar-Electric Propulsion 291; Lift Gas Compression 292; Missions for Future Airships

Conclusion
Appendices:
A. Vacuum Lift
Failure by Crushing 305; Failure by Buckling 307; Akhmeteli's Layered Shell 308; Metlen's Reinforced Spheres 308; Barton Inflatable Vacuum Chamber (IVC) Design 308; Additional Vacuum Lift Proposals 309
B. Prediction of ­ ­ Zero-Lift Drag
Frictional Drag Coefficient, Flat Plate (Cf) 311; Reference Areä 312; Shape Factor 312; Beyond the Fineness Ratio 313; Complete Rigging Analysis 314; Rigging Factor 315; Accuracy of Drag Coefficient Predictions 317
C. Prediction of Lift and ­ ­ Lift-Induced Drag
Tail (Stabilizer) Contribution 319; Elevator Contribution 321; Hull Contribution 321; Car Contribution 323
D. Hot-Air Lift: Alternatives to Propane Burner Fuel
E. Thermal Airships: Steam Lift
F. Net Lift Control by Liquefaction of Lift Gas
Helium 328; Ammoniä 328; Water Vapor (Steam) 330
G. Net Lift Control by Liquefaction of Gaseous Fuel
H. Sizing the Empennage
I. Hydrogen Degradation of Polymers
J. Calculation of Maximum Bending Moment from Gusts
K. Additional Materials Data
Notes
Bibliography
Index