Helicopters look odd when the blades are fully static whilst flying. The same is true of most rotary aircraft because we never see them flying with the blades still, our eyes only see the blur of motion so we expect to see it. It's why aviation of rotary aircraft is one were where people often use shutter priority mode - setting the shutter speed just fast enough to catch the action whilst panning, but slow enough to let the blades blurr.