sirendude2012 wrote:Liquid_Pooterbear wrote:So the pitch of the 10/12 siren would be an octave higher, but would the volume be the same?
My theory was that the faster a chopper spins, the more air it pumps through it. I got this theory from the way a chopper spinning at 30 RPM makes very little noise (or none at all) compared to the full volume of full RPM. I'd go with Holler and make sure the RPM doesn't exceed 4000.
A higher number of ports will increase the pitch, but the air will have less time to pressurize. When the air can pressurize properly, the sound is nice and crisp. An example is how a Model 2 sounds more crisp than an HOR Siro-Drone, though the chopper design is exactly the same. The Model 2 has larger ports, so the air has more time to pressurize before being depressurized and chopped. The Thunderbolt has tons of time to pressurize because of the single stator slot, however the air does not have enough time to fully depressurize before it is chopped because the stator slot is thinner than the ports of the rotor.
If you were to make a 5/6 port 3450RPM siren, it would sound louder than the 10/12 port though the volume would increase just slightly, if at all.
Thx, since I like lower pitched sirens better I'm going with 5/6.
Just one last thing before I get started with this project: In the youtube video I posted in the original post, the rotor has ports and solids between them of the same size. Meaning if the circle had a circumference of 10, and it was a 5 port siren, it would be a 1 inch wide port, then 1 inch of solid, then 1 inch of port, etc. Then the holes on the stator are the same size as the solids on the rotor, making the ports on the stator a bit smaller than the solids. Is this the best way to make the siren, or could it be better? If you don't understand, you can find the video on how he made the wooden siren here:
http://www.youtube.com/watch?v=XAfvOjdZpkg.
Basically i'm wondering how big I should make the ports on both the rotor and stator.
It makes sense, because if the rotor solids are smaller than the stator ports, it won't completely block the air
EDIT: I watched this homemade air raid siren video where the stator ports were REALLY big and it still worked, so it seems that sirens aren't as picky as I thought