Whistling blades on wind direction weather vane Answered
I have a propeller with four blades that acts as a wind direction weather vane. What I would like is for the propeller to make a whistling noise when it is rotated by the wind. Someone told me if I put a small hole or a slit in each of the blades it will make a whistling noisy which should change with wind speed. Can anyone tell me what size hole/slit I would need? Also at what angle would the slit have to be? Or can you tell me any other way to get a whistle from the blades when the wind is blowing? The blades are metal and about 200mm long (400mm overall diameter).