OK, here’s the deal.
I figured if I take the pea out of a known functional whistle and scale it to a ping pong ball, then build a to scale whistle around it, I should be able to stick it out the car window while my partner in crime drives 55-60 MPH and make a cool whistle noise.
No such luck. I did create an extended funnel on the input end, about 4"x5" trying to get the ping pong ball to float but no go.
What part of physics or areodynamics don’t I understand?
Thanks
IANAPhysicist, but pitch is directly related to size. My guess is that your scaled up whistle may have been infrasonic, i.e. below the range of human hearing. Either that or you weren’t able to scale up the pressure adequately. 50-60 mph may not be a high enough multiple of the air velocity you can generate with your mouth, and I’d wager that either the pressure and velocity (or both) needed for larger whistle have to increase geometrically, not linearly.
But congrats for doing the experiment. Keep it up.
The best way to understand building whistles is to go where people are building whistles. I’d like to recommend my other favourite forum: the Musical Instrument Maker’s Forum. . Nothing there for giant whistles to hang on your car window, I’m afraid, but there is lots of information. You’ll have to register to search thier archives, and be aware the policies are strict, but the people there are outstanding and range from beginners to masters.
I guess what you’re really trying to build is a closed organ pipe with a rattle. The air must be directed very carefully across the edge, in both the proper direction and speed. And you’ll need a lot of it.
Could you link us to a picture or a drawing of what you have, that we may better direct you?
The problem you’re going to have in scaling up car mounted whistle from a smaller whistle is if you make the resonant cavity too big it will require too much air pressure (via the car speed) to generate a resonating wave. A wide air intake aperture that narrows down (like a funnel) might help solve this problem.
Cool link Astro. I’m going to work on the bevel part mentioned and will post my sucesss/failure. I am hoping volume is not exponential to size.
Ahhhh summertime madness 