How to make a real life size stuka siren

Discussion in 'Other Mechanical Systems Tech.' started by SA80, Jan 9, 2009.

  1. SA80

    SA80 New Member

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    Could any one help me does anyone know the workings of the stuka siren i know it was propeller driven and went under the wing not much else thow.
    How did it work? is it a simple design? does any one have blue prints? thanks very much for reading SA80
     
  2. Colin1

    Colin1 Active Member

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    Wasn't the 'Jericho Horn' simply a variation on the air raid siren theme?
    The air raid siren being hand-cranked and the variation in pitch provided by simply hand-cranking it faster?

    Mounted on the Ju87, the manual drive was replaced by a suitable alternative, a small propeller driving the unit instead; the variation in pitch here being provided by the Ju87's increase in speed as its dive progressed.

    I've an idea Doppler Effect would have been instrumental here, too, particularly if you were the position (or close to the position) being targetted.
     
  3. Colin1

    Colin1 Active Member

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    Hi
    home from work
    This is about the best I could find in my library, it names the parts but rather unhelpfully, it doesn't point the names at anything although it's mainly self-explanatory.

    Hope this helps
     

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  4. fly boy

    fly boy Member

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    thats what those are i thought it was to power lights
     
  5. GrauGeist

    GrauGeist Well-Known Member

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    There's a "brake" or more closely, a clutch, that keeps the siren mechanism from sounding until the drive brakes are released. As soon as the drive brakes are retracted, the Jerico Trumpet disengages.

    As I posted in another thread regarding this, sometimes the brake didn't reset, and the pilot had to listen to the thing all the way back to base...

    By the way, awesome detail image, Colin!
     
  6. Colin1

    Colin1 Active Member

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    Well, at least they'd know he was coming and could put the kettle on for a nice, soothing cup of tea...

    Stuka Ju87
    Alex Vanags-Baginskis
    Illustrations by Rikyu Watanabe
    Jane's Publishing Company Limited
    ISBN: 0 7106 0191 3

    I have to say I agree with you, Mr Watanabe is a master illustrator, as he is in the rest of the series.

    Sadly, as is the case with so many other aircraft book series (Ian Allen 'at war' series springs to mind), they're out of print; they do crop up here and there in online book communities and on eBay every now and again.
     
  7. Andy_the_Ace13

    Andy_the_Ace13 New Member

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    how do them sirens work? like what makes the noise?
     
  8. bobbysocks

    bobbysocks Well-Known Member

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    I'm going to say the slots on both sides of the prop. those would give it an old fire engine sound. i remember cranking one of those sirens ( more years ago than i wish to admit ) as a kid.
     
  9. Shortround6

    Shortround6 Well-Known Member

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    We still use mechanical sirens;

    Q-Siren | Sirens

    They seem to move people out of the way at least as good or better than any of the electronic sirens.:)
     
  10. Trebor

    Trebor Well-Known Member

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    I would have thought that once the stuka goes into a dive, the siren props would spin so fast that the tips of the blades would break the sound barrier, thereby giving it that wailing siren sound.
     
  11. GrauGeist

    GrauGeist Well-Known Member

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    The Jerico Trumpet was wind driven, and the Stuka in a dive didn't reach speeds that would allow the Trumpet's propellor tips reach that velocity.

    There's hollow cavities that interact with vanes driven by the prop, so that when the propellor spins, it creates a tone, much like a mechanical siren on an emergency vehicle or an Air Raid siren...
     
  12. Shinpachi

    Shinpachi Well-Known Member

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  13. jamal brickstone

    jamal brickstone New Member

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    Hi, would you mind reposting that file? I'm going to try and build a stuka siren
     
  14. fubar57

    fubar57 Well-Known Member

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    Colin1 hasn't been here for more than 5yrs.


    Geo
     
  15. jamal brickstone

    jamal brickstone New Member

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  16. A Pillow

    A Pillow New Member

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    #17 A Pillow, Jul 23, 2017
    Last edited: Jul 27, 2017
    Hello there. I don't know much about WW2 aircraft, but I believe I may be able to help you with the sirens. I am just dropping in here from google, and I hastily created an account so I could respond to this. Because of that, I haven't really gotten myself acquainted with the rules. Would anyone care to drop a link to them for me? Sorry if they are in plain sight, I am using a phone and it makes navigating the forum difficult. Thanks for putting up with me.

    Anyways, I'll do my best to help in this thread. The Jericho trumpet was a mechanical siren from what I can see. Mechanical sirens work by spinning a cylinder with holes cut in the sides inside of a bigger cylinder with the same amount of holes. As the smaller cylinder (the rotor) spins, it sucks air into it through the front of the siren. The centripetal force pushes the air against the walls of the rotor, forcing it out through the holes. The bigger cylinder (the stator) stays still, which means the air cannot escape all the time. As the holes open, air is forced out until the holes close. This causes an incredibly loud pulsing of air.

    Here is a .gif which shows a mechanical air raid siren in slow motion: https://www.thesirenboard.com/images/model2anim.gif

    Here is a video of a guy who built an electro-mechanical air raid siren:
    https://www.youtube.com/watch?v=XAfvOjdZpkg

    He explains how they work pretty well. Anyways, just like an air raid siren, the stuka's siren works the same way. Over at airraidsirens.com it seems that we are pretty confused about how the whole thing works, but we know the source of energy is the wind-driven propeller. Basically a siren's sound is a mixture of its port ratio and the speed that it spins at. The port ratio is basically how many holes are in the rotor and the stator. Like in the video and the gif, one ring of ports produces one tone and the other ring produces another. Some sirens are single tone, and only have one ring of ports. The problem is, I have no idea how many ports the stuka's siren has. It sounds unlike any siren I've ever heard, so you may have to do tons of digging to get any information. The siren sounds pretty low pitch to me, so I'd imagine it has a low speed or low ports. I'd imagine there is a combination of both because I kind of doubt the small propeller would get the siren to any of the speeds you'd see from sirens today.

    I've done some googling and I just can't find any good pictures of the siren. The closest image I have found is this one, (http://worldwarwings.com/wp-content/uploads/2017/03/Stuka-Siren.jpg) which I am skeptical of because the siren appears to be where a bomb would have been, and it is not on the landing gear. That propeller also doesn't seem like it'd do that great of a job driving the siren. If someone could get me better pics of the siren, that'd be great. Thanks.

    Anyways, from that picture it appears that that siren has 8 or 9 ports, and I have found a video of an 8 port siren. It sounds a tiny bit like the stuka's, it may need to be driven at a lower rpm to sound more like it.

    View: https://www.youtube.com/watch?v=e4OSpJtH_aQ



    View: https://www.youtube.com/watch?v=y7lHjJ0zOHk
    This is a 9 port siren.
    As you can tell the pitch is higher than the 8 port, but it still sounds similar.

    Basically if anyone could provide me with a good picture of the stuka's siren we might be able to get some clues as to how this siren functions. To make a similar sounding siren you could do something similar to what the guy in the video did, possibly. You would probably need to experiment a lot to the get the right sound. I think it may be possible that the stuka's main propeller "chops up" the sound as it's diving, similar to speaking into a fan. It sounds choppy while diving and then it gets clearer as the plane recovers from the dive.

    Anyways, that's just what I think regarding this topic. I'm sure the answer is somewhere but it just can't be found. Maybe you could contact a military history museum and ask what they know about it? That seems like the best course of action.

    I hope this doesn't go against any bumping rules, as I see the last reply was posted last year. Since I had some relevant information I think I may be in the clear. Please inform me if I am not. Anyways, I hope some of my information helped you, and if anyone could point me in the direction of the forum rules I would greatly appreciate it! Thank you.
     
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