The Siren Board

Hello everyone,



While looking around in the forums, I found mention of a ROUNDED Projector for a ThunderBolt siren. Does ANYONE have any information about it? Maybe a picture or two? That's all.


:)500ATfan:)

In the late 1950s, Federal experimented with a round projector for their Thunderbolt sirens. This concept was designed to test whether their was any advantage in sound projection, especially in high-wind, Hurricane conditions. Sadly, the costs were too high to produce this design. Moreover, water tended to collect inside and freeze in the colder climates. Curiously, ACA went with the rounded projector for their Hurricane series. Nonetheless, Federal decided that it was easier to stay with the square design that we all know today.

500AT wrote:In the late 1950s, Federal experimented with a round projector for their Thunderbolt sirens. This concept was designed to test whether their was any advantage in sound projection, especially in high-wind, Hurricane conditions. Sadly, the costs were too high to produce this design. Moreover, water tended to collect inside and freeze in the colder climates. Curiously, ACA went with the rounded projector for their Hurricane series. Nonetheless, Federal decided that it was easier to stay with the square design that we all know today.

That's interesting as Sentry claimed it was trouble-some to make squared projectors and decided to go with rounded projectors for easier manufacture and shipping purposes. Though to be fair the Thunderbolt only has one large projector while the Sentry's had anywhere from 8 to 16 or so.

so not to sound totally stupid, but I want to make sure I have this right.
Federal made the square-horned Thudnerbolt (duh!), but experimented with a round-horned Thunderbolt. ACA made the rounded Hurricane, but experimented with a square-horned type.

That to me is pretty ironic considering the similarities between the two sirens.

I thought the Square Hurricanes came first!



Anyways, does anyone have any pictures/photographs of this Rounded ThunderBolt siren Projector? Was it just like the Rounded Hurricanes, or not?


Keep in mind, that, the MOUNTING systems for the Hurricane and the T-Bolts were VERY Different. Seriously. The Hurricanes use a miniature Sator/Rotor assembly. The ThunderBolta use a miniature CHOPPER of COMPLETLY different shape and size!

500 AT fan wrote:


Anyways, does anyone have any pictures/photographs of this Rounded ThunderBolt siren Projector? Was it just like the Rounded Hurricanes, or not?

No, one of the members here was told by a retired engineer of federal that they made them no documented proof or photo. It may be worth sending federal a e-mail asking if they have any info.

CABLEVision wrote:

500 AT fan wrote:


Anyways, does anyone have any pictures/photographs of this Rounded ThunderBolt siren Projector? Was it just like the Rounded Hurricanes, or not?

No, one of the members here was told by a retired engineer of federal that they made them no documented proof or photo. It may be worth sending federal a e-mail asking if they have any info.

Federal has no old records of their products from years ago, it was all thrown out in the move from Blue Island.

The last time I saw a picture of a Thunderbolt, with a rounded projector was in the early 1990s, when I visited their factory in University Park, Illinois. Sadly, most of their historical archives were tossed into the trash, but ironically, now they have decided, or at least their current thinking is to develop a company museum. Nonetheless, the siren in the photo was located somewhere along the Atlantic Seaboard.

According to Art Johannes, who was the head of Midwestern sales when I visited there, "Most of the Hurricane projectors were removed and replaced with standard projection horns." Moreover, from what I remember being told about the Thunderbolts with the rounded "Hurricane" projectors, was they looked just like the square design, but weighed a lot more, and this factor also presented a problem to the rotator mechanism. Likewise, they tended to freeze-up in the winter months in the colder climates, making them much less desirable in this climate.

Federal replaced the projectors on these special units, with standard square projectors within 2-3 years. However, ACA must have made some rather special modifications to their design when it was introduced with the round projector.

500 AT fan wrote:I thought the Square Hurricanes came first!

The prototype Thunderbolt that was designed for use at the Trinity Site, was constructed in 1945. This siren had a square projection horn, but the blower and rotation mechanisms looked more streamlined. However, it would take a while to examine the original Thunderbolt, so that modifications could be made in subsequent experimental units. This research all culminated in the 1952 commercial release.

Heres the photo of a square horned hurricane for anyone interested. Which is all of us I guess.