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Sentry 20V2T Size Comparison Pic
Posted: Mon Oct 06, 2014 5:46 am
by CDV777-1
I'm in the process of overhauling my site's siren section and came across this pic while digging through the archives.
Just thought it would be of interest. I don't think I ever posted on the board before.

Re: Sentry 20V2T Size Comparison Pic
Posted: Mon Oct 06, 2014 6:36 am
by Stormsetter4
Sheesh, that sentry is pretty big. Where were those sirens originally from?
Re: Sentry 20V2T Size Comparison Pic
Posted: Mon Oct 06, 2014 10:52 am
by Chicagosiren-hunters
Now THAT is a monstrous size!
Re: Sentry 20V2T Size Comparison Pic
Posted: Mon Oct 06, 2014 12:49 pm
by Brendan W
stormsetter4 wrote:Sheesh, that sentry is pretty big. Where were those sirens originally from?
Allen, Texas if I remember correctly.
Re: Sentry 20V2T Size Comparison Pic
Posted: Mon Oct 06, 2014 1:31 pm
by CDV777-1
Yeah it was Allen. I took this before they took down the two T-135s.
Allen originally had 2-Thunderbolts, 2-2T22s, 1-Model 5 and the 20V2T.
In the Mid 1990s they took down 1-Thunderbolt, 1-2T22 and the Model 5 and put up the two T-135s.
That was such a cool system. It was a collection of classics.
The only way that original system could have been any better is if it had an Allertor or Hurricane or two in the mix.
Here's a pic of the original bunch that were removed in the 90s.

Re: Sentry 20V2T Size Comparison Pic
Posted: Mon Oct 06, 2014 3:01 pm
by TboltTX1
Awesome pictures, thanks for sharing. Allen sure seems to have changed alot since then, I'd imagine there was nothing but fields northwest of I-75 since most of the developments in that area are fairly new.
Where was the second T-135 installed on the west side of town?
Re: Sentry 20V2T Size Comparison Pic
Posted: Mon Oct 27, 2014 5:35 am
by CDV777-1
Here's a relevant bump. I found a photo of all the old Allen sirens together. I thought everyone would like to see it.

Re: Sentry 20V2T Size Comparison Pic
Posted: Mon Oct 27, 2014 5:53 am
by Stormsetter4
Those T-135's are huge. It looks like they use the same chopper intake as my P-15.
Re: Sentry 20V2T Size Comparison Pic
Posted: Mon Oct 27, 2014 7:40 am
by Travis
stormsetter4 wrote:Those T-135's are huge. It looks like they use the same chopper intake as my P-15.
I think they are a little bigger than the ones on the smaller Penetrators. I never understood why they used the stator from the Cyclone 120, and not the 125. Seems kind of redundant to make two differently shaped ones that--from a noise production aspect--are the exact same thing.
Re: Sentry 20V2T Size Comparison Pic
Posted: Mon Oct 27, 2014 12:27 pm
by DJ2226
My guess would be that the change in the stator would allow the sound to be fired straight out. With the older design it would have fired out straight from the 8 port side and out and downward on the 12 port side, which happens to be the loudest side. Firing both components out straight is probably the reason the later model gets five more dB.
A guy could fit inside of that intake.
