Automobiles 4.094 Design and construction 1.727 Maintenance and repair 1.051 Motors 823 Motor vehicles 785 Airplanes 678 Aerodynamics 581 Springs and suspension 417 Brakes 346 Electronic equipment 316 Automatic control 283 Aeronautics 274 Dynamics 263 Safety measures 242 Performance 238 Steering-gear 233 Materials 226 Electric equipment 225 Air conditioning 213 Electric vehicles 175 History 168 Bodies 167 Testing 165 Hybrid electric vehicles 161 Heating and ventilation 160 Automobiles, Racing 149 Data processing 148 Control systems 147 Space vehicles 146 Chassis 139