I originally thought that It could have been for wind resistance but I don’t think wind would be an issue.
I honestly have no idea why some have fins & some don’t either: is it for aesthetic reasons I wonder?
My dad was thinking that it could be used to equilize the pressure of the wind to prevent the siren from being pushed by the wind. That’s just his guess though.
Doesn’t seem like there’s much logic in that considering outdoor warning sirens are very well fixed in place by what they’re attached to: if anything the fin would give the wind more surface area to blow on/against the siren with.
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That is true. Though, I guess it is just the way some of them are built. I think it would be better if you ask Whelen themselves.
That’s correct. It was only used on ones with slab rotators though. They didn’t use the fin on the new rotator design
What’s correct? (a previously-stated reason for the fins? If so which one?)
I’ve heard many years ago that the fin was to make it so the siren would get rotated by the wind in the event that the rotator would fail.
Although I think this is more an urban legend, I can definitely see that fin causing the wind to work against the rotator motor and cause unnecessary strain on it.
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Yeah that would make no sense, especially since wind isn’t constant (& on top of that it would probably take quite a strong gust to turn the heavy siren).
Not only that but also possibly giving the wind enough surface area to blow the siren down while stationary if the wind is strong enough.
Early finned Vortexes (or as they’re affectionately referred to as “finback”) getting knocked loose definitely happened apparently.
Even though it’s not fully understood why the earlier Vortexes had a fin: What is the difference between Whelen WPS-4004 and Whelen Vortex R4? - Page 2 - The Siren Board
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Huh, would you look at that.
According to “uncommonsense” a few posts below that one:
“My understanding is the first gen Vortex rotators are belt driven as opposed to later gear driven models (it’s obvious from looking at the boxes the first gen Vortex uses a very different type of rotator). The fins better handled the wind load so as to reduce the chance of damage to the rotation mechanism under high winds.”
No idea how a fin of all things would stop damage to the rotator but there you are.