Hello. I was wondering if someone could explain to me how Nerf Whistler darts work. These are the darts that are orange with black, rubber tips. In the top of the dart, there is a tiny 4mm wide by 2mm tall. This tiny opening leads to a cylindrical cavern inside of the top of the dart. It is approx. 12mm in diameter and 7mm tall. When you shoot the dart, It produces a high pitched whistling noise. I am wanting to scale up the tips of these darts and make them out of balsa wood and I want the wood to produce a whistle sound too. Should I just scale up the dimensions of the top of the dart or are there some ideal proportions to produce the best whistle? How do the darts themselves actually make the whistle sound? Thank you.