Out of curiosity, what's the meaning of a "veined" rotor and stator? I can understand how the modern "flower pattern" designs would get more out of a given chopper setup than the old single-port vertical or single-horn horizontal choppers would, but I've got NO clue what "veining" would be.
ETA: Also, seeing as I'm an old fart (almost 37!) who grew up in the waning days of the Civil Defense era, in a town with, when I was born, a system of 4/5-port 1000Ts and SD-10s, I personally feel that single-tone sirens don't have the same sort of "YOU ARE ABOUT TO DIE!" factor as the dual-tone units, and the siren manufacturers should seriously consider returning to dual-tone designs, even if it gives up a tiny bit of SPL efficiency--that way, they can have their high-pitched tone to get good penetration, *and* a low-pitched tone for good propogation, helping to fill potential coverage gaps with less overlap between sirens. (Heck, I came up with a three-tone that was kindly synthed for me by Sirendude2012 that adds a tone more than an octave *below* that of an STL-10, because I believe that much in the value of a low tone... I won't link the synth here, it's in the Siren Synth Requests thread, but I'll mention that a friend of mine argued that, rather than being a "tornado siren," it was a "Cthulhu siren"...)
rdfox wrote:Out of curiosity, what's the meaning of a "veined" rotor and stator? I can understand how the modern "flower pattern" designs would get more out of a given chopper setup than the old single-port vertical or single-horn horizontal choppers would, but I've got NO clue what "veining" would be.
Lets see if I can diagram this pictorially. And hope I don't botch this explanation--which I fear I may well. If anyone has experience, please chime in! I'm going to give this my best shot:
A typical siren assembly features a rotor and a stator. Simply put, when the rapid opening and closing of the ports are what cause noise to be made. There's nothing fancy here. Just ports opening and closing. Note this in Eric Green's photograph of the Thunderbolt chopper:
chop2.jpg (24 KiB) Viewed 4510 times
Now, instead, lets look at the rotor/stator assembly on an ACA Allertor from Jeb:
images.jpg (7.77 KiB) Viewed 4510 times
Also visible on the T-128 (same base is used for the T-112 and T-121), thanks to mixerbd for the photo:
ASC_T-128's_motor.jpeg (7.75 KiB) Viewed 4510 times
And on the 508 (same base used for the Eclipse-NH and Eclipse-8), straight from Federal:
Note the veins on the rotor, curved in a particular manner. The difference is also notable on the ACA Cyclone, as there is visible evidence of the veined rotor in its stator assembly. This image from a YouTube video Dillon uploaded:
mqdefault.jpg (5.49 KiB) Viewed 4510 times
You'll notice how the rotor curves and, in this case, the design of the siren accommodates a stator that also matches that curvature.
The point of the veins is to increase the efficiency of the siren unit by focusing how the air is moved through it/channeling the air. In a way (and this is my understanding so please someone correct me if I'm botching this) the veins on the rotor help form, direct, and amplify the sound as it comes out of the rotor/stator assembly. The assembly can only be run in one direction. If the rotor is turning the wrong way, it dramatically decreases the output of the siren given that the way the air is moved through the siren is incorrect.
You can really see the effect well on this walkthrough video of a P-15:
It's basically a Model 3 rotor with the projector "horns" attached. The motor is in the front and the air is pulled in from the back. The rotor is 14 inches in diameter, just like a 2t22/3t22 or Model 3.
Here is a picture of a 2001 we worked on a while back. The front nose cone has been removed, exposing the motor. I'm sliding the guard off the brush band so I can inspect the condition of the brushes and commutator. You can clearly see the 12 individual discharge ports.
As for the veins on a rotor, they help to "scoop" in more air. The more air you move through those ports the more noise you make.
holler wrote:It's basically a Model 3 rotor with the projector "horns" attached. The motor is in the front and the air is pulled in from the back. The rotor is 14 inches in diameter, just like a 2t22/3t22 or Model 3.
Here is a picture of a 2001 we worked on a while back. The front nose cone has been removed, exposing the motor. I'm sliding the guard off the brush band so I can inspect the condition of the brushes and commutator. You can clearly see the 12 individual discharge ports.
As for the veins on a rotor, they help to "scoop" in more air. The more air you move through those ports the more noise you make.
I'll post some pictures of my model 3 rotor once I get back to my apartment.
Owner/Operator of SirenTex LLC
Proud of a Federal Signal Thunderbolt 1000T, 2t22A, Model 2t, Model 3 Model 5, SD-10, STH-10, American Signal Corp. T-128, Whelen WPS-2750 and too many Whelen Lights
Could Model 3s be ordered with 8 ports? If this is the case then it would have been just an easy swap of rotors and making a new stator for the chopper in the Equinox. How big is the chopper in the 508/T-128?
DJ2226 wrote:How big is the chopper in the 508/T-128?
Oddly enough, it seems both of those sirens run the same chopper; their choppers seem practically identical to one-another. I think it has been said on here that Federal obtains certain parts from the same supplier as ASC does. Is there any more info on that?
OH, I see, a VANED chopper, as in it uses vanes to act as a fan (or more precisely, a centrifugal pump) to force more air through. OK, that makes more sense. (I was thinking "vein" as in the blood vessel, and that left me wondering how the hell having lots of little air passages inside the walls of the chopper would make it more efficient...)
Clear as crystal now; I just hadn't heard that exact term used before.
who grew up in the waning days of the Civil Defense era, in a town with, when I was born, a system of 4/5-port 1000Ts and SD-10s, I personally feel that single-tone sirens don't have the same sort of "YOU ARE ABOUT TO DIE!" factor as the dual-tone units, and the siren manufacturers should seriously consider returning to dual-tone designs, even if it gives up a tiny bit of SPL efficiency--that way, they can have their high-pitched tone to get good penetration, *and* a low-pitched tone for good propogation, helping to fill potential coverage gaps with less overlap between sirens. (Heck, I came up with a three-tone that was kindly synthed for me by Sirendude2012 that adds a tone more than an octave *below* that of an STL-10, because I believe that much in the value of a low tone... I won't link the synth here, it's in the Siren Synth Requests thread, but I'll mention that a friend of mine argued that, rather than being a "tornado siren," it was a "Cthulhu siren"...)
