Related by context. Frequent words. (Click for all words.) 56 rotating blades 54 soundwaves 53 helicopter rotors 53 whooshing 52 soundlessly 52 spinning blades 52 flapping wings 51 rooster tail 51 whirr 50 earthward 50 screeching noise 50 airfoils 50 rotors 50 piezo electric 50 whooshes 50 corkscrewing 49 vibrations 49 whirrs 48 yawing 48 whirling 48 helicopter rotor blades 48 juddering 48 counterclockwise direction 48 airstream 47 slewing 47 swooshing 47 inchworm 47 electrically powered 47 vortices 47 hydraulic rams 47 propeller blades 47 venturi 47 gliding 47 treadle 46 corrugations 46 propellers 46 thump thump 46 whir 46 noiselessly 46 chuffing 46 centrifugal force 46 jerkily 46 teardrop shape 46 ionize 46 compressed nitrogen 45 tank treads 45 jerky movements 45 rotor blades 45 boing 45 perpendicularly 45 unpowered 45 whirring sound 45 propeller 45 cambered 45 whirs 45 pneumatically 45 egg beater 45 thrum 44 centrifugal forces 44 infrared beam 44 electromagnets 44 whoosh 44 whizzing 44 hydraulically operated 44 jittering 44 rooster tails 44 twin turbochargers 44 turbine blades 44 thump thump thump 44 vibrating 44 screech 44 whooshing sound 43 tires squealing 43 snail shell 43 cone shaped 43 counter clockwise direction 43 electrohydraulic 43 ultrasonic waves 43 sickening thud 43 scramjet engine 43 clunks 43 raindrop 43 vibration 43 daddy longlegs 43 electromagnet 43 throaty roar 43 blowholes 42 magnetron 42 hissing sound 42 swinging pendulum 42 vertically 42 toroidal 42 pitched squeal 42 wavelike 42 spheroid 42 horizontally 42 hydraulically 42 clatter 42 droplets 42 clunk 42 clutch lever