East Farmingdale Fire Company HQ Thunderbolt 1003

[Jim Z]

Wow! That's one slow wind-down! It sounds like the blower is forcing air into the back of the chopper instead of the front.

I don't think that's physically possible.

edit: I mean, I don't think it's physically possible for it to work any differently than every other thunderbolt out there.

[500 AT fan]

It could be the BLOWER TYPE, too, you know. Maybe it has the older (huge) A series blower? Good video, anyways.

[murrfarms]

It could be the BLOWER TYPE, too, you know. Maybe it has the older (huge) A series blower?

That could be true, but why would a B-series Thunderbolt have an old A-series blower? I think I'm with 3t22 on the C-faced motor theory, because a lot of the C-faced motors I've ever seen took a while to stop as well when there was very little resistance on what it was driving. Good, well greased bearings in a motor play a big role in the how fast the motor stops as well.

[Daniel]

Whatever blower style it is, it is surprising how loud the blower is over the siren.

[JasonC]

It's a modern style blower (the 3600rpm type). Those rotary-lobe blowers are loud. You can hear them many times at sewage treatment plants. The blower type shouldn't have anything to do with the way it winds down since its all the same air.

[ver tum]

Here's another Thunderbolt that winds down the same speed whether or not the blower is on. It's been posted here before I'm sure.

http://www.youtube.com/watch?v=rCLdEC8-S44

It's not high pitched, but all the abnormally high ones I've heard also have the slow wind-down.

BTW that Conway Middle School Thunderbolt sounds like it is on chopper setting 8 (if that existed). So if the 4 semitones thing holds true it's probably on level 6 like you said in the comments.

The reason I said level 6 was because that's the pitch it would sound at without the blower running if it was on level 6. Since the chopper doesn't appear to be effected by the blower on the Conway TBolt, it's probably set to level 6. I could ask my contact with the city to check it the next time he inspects it. I'd love to be able to post some pics of the inside of that Thunderbolt, just to see if my blower pipe theory is right. It's not normal for TBolts to have slow wind-downs like this, so the subject has really peaked my curiosity. Jason is right, the blower should normally slow down the chopper, making the wind-down faster, but on these slow wind-down TBolts, that doesn't appear to be the case.

Also, notice how in that video from Ben1003, the overall tone of that siren is different from most TBolts. I've noticed that a lot of these slow wind-down TBolts have that tone, including the Conway TBolt. The harmonics are different than a normal TBolt.

I posted a topic a while back on the Main Outdoor Warning Sirens Board about these unusual TBolts.
http://airraidsirens.com/forums/viewtop ... 4193#44193

[Banshee_DUDE]

Wow! That's one slow wind-down! It sounds like the blower is forcing air into the back of the chopper instead of the front. I wish someone could post pictures of the inner workings of one of these TBolts with slow wind-downs, so we can compare it to a normal TBolt. I'm particularly interested in the way that the blower pipe is configured.

Here is a video I found on youtube of the chopper solenoids on a T-Bolt 1003.
http://www.youtube.com/watch?v=CbnqeiIZcjg