ROUNDED ThunderBolts?!

[500AT]

This (yes, I will call it B.S.) B.S. about there being a Thunderbolt made for the Trinity test has popped up on this board before. I would like to see some believable source of this info. There's no way in he11 that this ever happened. You mean to tell me that in all the preparation, research, engineering etc etc that went into the Manhattan project that there was also some urgent effort to put some siren out there in the desert when the bomb went off for the first time? The idea is just so goofy and far-fetched that it's laughable.

I have actually seen the photo of the prototype Thunderbolt, when I visited Federal's factory in 1992. Art Johannes, explained to me that this was the first ever Thunderbolt developed for the test site in New Mexico. Apparently, a lot of research went into the development of the siren, and placing it the area of the Atomic Bomb site where the employees were at.

The photo clearly showed the Thunderbolt in the foreground, and behind it was many dignitaries, and representatives from Federal. Among the more important people that come to mind in the photo are:

Henry Stimson
Leslie Groves
Tom Farrell
Art Compton

All of the Federal employees were dressed in very nice suits with Fedoras, and Homburg dress hats.

[JasonC]

So are you saying the Thunderbolt was placed there to be blown up, or to alert the scientists of the impending blast? BTW, what did it look like?

[500AT]

So are you saying the Thunderbolt was placed there to be blown up, or to alert the scientists of the impending blast? BTW, what did it look like?

It was to alert the scientists, and others that an air raid, or blast was imminent. From what I was told, the U.S. War Dept., wanted an outdoor warning siren that could cover a larger area than a Model 5 or 7. Apparently, Federal decided to introduce a rotating beam siren, which used an air compressor to increase the sound output over a longer distance.

The prototype Thunderbolt's projection horn was actually larger than the later production models, and each section of the horn was welded together. Likewise, the rotator mechanism and blower housing were more streamlined. From what I could tell of the photo, the siren was painted a very dark color.

Art Johannes and Dan Bierovic told me, the siren survived the blast, but was damaged and they could not inspect it for a long-time after the test. However, they did build a few more experimental editions of the Thunderbolt before it went into regular production in 1952. Sadly, none of them are known to survive today.

[SirenMadness]

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.

True, per siren, it would be easier to make one, larger square horn than many smaller square horns. Then again, when Sentry switched to making round horns, they did not make trumpet-style horns either, but rather straight ones, which shows their simplicity. Also, while a round horn with the same diameter as a square one projects sound better than the square one, ACA was the company that continued making it, because ACA had the technique and the machines to mold fiberglass, while Federal Signal didn't, so they found it easier and more profitable to just make a horn out of metal sections.

[CDV777-1]

It was to alert the scientists, and others that an air raid, or blast was imminent. From what I was told, the U.S. War Dept., wanted an outdoor warning siren that could cover a larger area than a Model 5 or 7.

Didn't the Chrysler already exist at the time? Seems like the Chrysler would completely blow away a 5 or a 7. Why would they have to go to Federal for a siren when they could just use a Chrysler?

Apparently, a lot of research went into the development of the siren, and placing it the area of the Atomic Bomb site where the employees were at.

How much "research" could have really gone into the Thunderbolt? It's a model 2 in a can with a horn sticking out and a water treatment plant aerator to pump air through it.
At the Trinity site there were 3 shelters 10,000 yards from Ground Zero. That's over 5 miles. They were about that far apart too. The only VIP viewing area was at Compania Hill 20 miles away. Base camp was about 5 miles south of the south 10,000 yard shelter putting Base Camp about 10 miles from Ground Zero. In Richard Rhodes' book The Making Of The Atomic Bomb it does mention "at the two minute warning a long wail of the siren at base camp." They also fired signal rockets as warning too. The mention of the siren at base camp in the book is good enough for me to confirm that there was indeed a siren there. Though why the Los Alamos guys would need to contract with Federal to build a Thunderbolt just for the occasion isn't very believable to me. Base Camp was far to distant from the other shelters for a siren to be of any use and the camp surely wouldn't have been so large at to need a specially built large siren for warning.

Art Johannes and Dan Bierovic told me, the siren survived the blast, but was damaged and they could not inspect it for a long-time after the test.

If the siren was in "it the area of the Atomic Bomb site where the employees were at" where the employess damaged by the blast too?

What's hard for me to believe about the photo you mentioned is that in the midst of the culmination of the entire Manhattan Project, which was the Trinity Test, that these big-shots of the program took the time to pose with the signal siren at base camp. The siren at base camp wouldn't have had any more importance to them than a generator or a workshop. Another thing that's not believable is the Federal guys being at the Trinity test just because they supplied the base camp siren.
Sounds to me like these guys "Art Johannes and Dan Bierovic" (whoever they are) were as they say "pulling your leg." I'll be convinced when I see the photo you mentioned.

Another thing I just thought of....
If Federal HAD made a specially built Thunderbolt for the Trinity Test they would have had that ALL OVER their advertising in the 1950s. That would have been at the top of EVERY Thunderbolt advertisement "The Siren Specially Made For The Trinity Atomic Bomb Test." Wonder why if they had a Thunderbolt at the Trinity Test they never mentioned it in any advertising. Hmmmmmmm......... Maybe they had the worst advertising department in history????

[Robert Gift]

Once perfecting a round exponential form on which to fabricate fiberglass projectors, I would think they would be much easier and cheaper to produce than the square metal Thunderbolt horns.

Round exponential horns are also more efficient than square horns, produce less sound cancelation and present less wind load.

Why would they have more icing problems?

How sad that some dolts at Federal Signal lacked the sense and foresight to retain valuable and historic records.
They could have found a place to store them.
Same with the morons who discarded films of the Tonight Show with Johnny Carson.
They were too stupid to offer them to a library or university.
They just threw them in the trash.

[SirenMadness]

Yes, round horns are generally more efficient than square horns, but you have to take a look at the priorities that existed in terms of manufacturing.

[JasonC]

Sentry's horns are sheet metal and are easily rolled into a calendar and pressed into place. The Thunderbolt's horns are made of thick 1/8 plate steel and thus, those horns are much easier to be pressed into a square shape and welded.

[Robert Gift]

Sentry's horns are sheet metal and are easily rolled into a calendar and pressed into place. The Thunderbolt's horns are made of thick 1/8 plate steel and thus, those horns are much easier to be pressed into a square shape and welded.

Wouldn't round fibreglass horns be better? Easier to make, lighter weight, easier to stack?

[SirenMadness]

Fiberglass horns are not always easier to make, as casting or spraying of the material on or into the mold are more complicated processes than simply bending sheet metal into a horn. Also, ACA used fiberglass extensively back then, so Federal Signal did not want to go down the same road after the Thunderbolt-and-Hurricane issue.