I wish I knew how. I have tried and tried to post some Pic, with no luck. If you can tell me how I will be glad too. I put the whistles where I4C noted. Just put the whistles on the bottom where they will get the most air on the wings near the tips. This will give you a constant sound with the greatest loudness. I used a drop of CA to hold them in place. I just wish I knew how the smaller ones done in the prop wash. I went to a club near by my club just to be friendly. I grab my Patriot 40 with some of my fellow members. I took off and they set puzzled to see a prop jet with that sound. Later I told them the secret.
Hey, I4C, why want you send me a set of the smaller whistles to test in the prop wash. It will not cost you a thing for me to test them.
Freebird