How to make a real life size stuka siren

[Monarch140]

I am new here, and just today I started looking at the stuka siren, but I have a theory. I think that the stuka siren could have 8 internal ports and 9 or 7 external ports (or vice versa), I don't know if this would even make sound (although I think so), but it could be a solution for the uniqueness of the stuka siren sound (apart from having irregular sized ports (which could be enough to solve the problem))

 

[Blixie]

Hey everyone, I know I'm late to the chat, but I've got a picture of a real life Stuka siren that may help with our questions.View attachment 552327 View attachment 552328Please note that these are NOT my pictures, the photography is from a video from the "Fight to Fly Photography" Youtube channel. There's a museum in Washington state that is doing a Stuka restoration. The museum is called "Flying Heritage & Combat Armor Museum". They have a Youtube channel as well; I suggest looking into it for more information on the Stuka's build. Anyway, as you can see from my images above, it appears that the propeller has open slots on the side of it, which I'm assuming played a key role in causing the siren sound. As the plane dove, wind would drive the propellers, and while this was happening, the siren system would sound inside of the propellers. The sirens were obviously driven by the wind powered propellers. What I don't know is what exactly happened inside of the propellers that caused the Jericho trumpets to sound. The previous post that mentioned the different ports of an air raid siren is a pretty possible scenario as to how the Stuka sirens worked. Anyway, I hoped this helped, and I hope someone replies, because this is an incredibly fascinating subject that shouldn't be abandoned.

This prop went for over 6900 Euro on ebay 3 years ago. It was sold by a woman who found it on an Austrian vintage car swap.
She was very kind to provide me with all possibly measures and photos. As I recently had bought an original Ju 87 Flugzeug-Handbuch Teil 12 D Sondereinbauten Heft 1 Lärmgerät for 400 Euro learning really everything about these sirens BUT how the sound was emitted, I hoped that the bottom of the vanes on this piece was moving freely from the prop showing other inner vanes but no. However, she sent me a Stuka photo where the vanes was covered with metal sheets and that must be taken as a proof for where the sound came from. The vanes on the real propellers had also square ends while they are rounded on the Kopiermuster and there can't me any other reason to make them square. The length of the vanes should, if they worked as whistles, produce a sound with the same pitch as the 32rd note above middle c on a piano and that seems too high compared with the wartime recordings I have heard but, I heard a Texan in a long free dive and as it sounded exactly as the movie Stukas so I might be listening for the wrong note. I'm sorry that I cant solve our problem but, at least, you know how much you have to cash up for a prop

 

[Hoplias]

This prop went for over 6900 Euro on ebay 3 years ago. It was sold by a woman who found it on an Austrian vintage car swap.
She was very kind to provide me with all possibly measures and photos. As I recently had bought an original Ju 87 Flugzeug-Handbuch Teil 12 D Sondereinbauten Heft 1 Lärmgerät for 400 Euro learning really everything about these sirens BUT how the sound was emitted, I hoped that the bottom of the vanes on this piece was moving freely from the prop showing other inner vanes but no. However, she sent me a Stuka photo where the vanes was covered with metal sheets and that must be taken as a proof for where the sound came from. The vanes on the real propellers had also square ends while they are rounded on the Kopiermuster and there can't me any other reason to make them square. The length of the vanes should, if they worked as whistles, produce a sound with the same pitch as the 32rd note above middle c on a piano and that seems too high compared with the wartime recordings I have heard but, I heard a Texan in a long free dive and as it sounded exactly as the movie Stukas so I might be listening for the wrong note. I'm sorry that I cant solve our problem but, at least, you know how much you have to cash up for a prop

Interesting. Do you have any pictures you can share?

 

[Blixie]

Interesting. Do you have any pictures you can share?

I believe so but I have to find them.. The vanes are 85 mm long, 20 mm wide and 8 mm deep. The spinner is 120 mm cross over. A test spinner could be made from that

 

[Hoplias]

I believe so but I have to find them.. The vanes are 85 mm long, 20 mm wide and 8 mm deep. The spinner is 120 mm cross over. A test spinner could be made from that

Thanks for the info. Those are for the two slots on either side of the propeller, correct? That definitely plays a part in making the siren, but I'm curious as to what's inside of the propellor that we can't see, because I doubt that it's only the vanes that create the siren sound.

 

[Blixie]

Thanks for the info. Those are for the two slots on either side of the propeller, correct? That definitely plays a part in making the siren, but I'm curious as to what's inside of the propellor that we can't see, because I doubt that it's only the vanes that create the siren sound.

Yes, it is the two slots. The seller said that the bottom of these are stiff and not movable, that would have been fine.

 

[Hoplias]

Yes, it is the two slots. The seller said that the bottom of these are stiff and not movable, that would have been fine.

Ok. So I've considered that the siren gets its sound from air passing through the two vanes on the sides of the propellor, with the siren's pitch increasing as the propellor speeds up. If you look at the picture I posted of the siren fairings on the wrecked stuka, you can see that they are hollow and split down the middle. Do you think that's what makes the sound? The propellor vanes interacting with the inside of the trumpet mountings? Thank you for the info once again.

 

[Jake0405]

This prop went for over 6900 Euro on ebay 3 years ago. It was sold by a woman who found it on an Austrian vintage car swap.
She was very kind to provide me with all possibly measures and photos. As I recently had bought an original Ju 87 Flugzeug-Handbuch Teil 12 D Sondereinbauten Heft 1 Lärmgerät for 400 Euro learning really everything about these sirens BUT how the sound was emitted, I hoped that the bottom of the vanes on this piece was moving freely from the prop showing other inner vanes but no. However, she sent me a Stuka photo where the vanes was covered with metal sheets and that must be taken as a proof for where the sound came from. The vanes on the real propellers had also square ends while they are rounded on the Kopiermuster and there can't me any other reason to make them square. The length of the vanes should, if they worked as whistles, produce a sound with the same pitch as the 32rd note above middle c on a piano and that seems too high compared with the wartime recordings I have heard but, I heard a Texan in a long free dive and as it sounded exactly as the movie Stukas so I might be listening for the wrong note. I'm sorry that I cant solve our problem but, at least, you know how much you have to cash up for a prop

Do you have the pictures?

 

[Blixie]

Do you have the pictures?

Yes, now I found the ones presented on ebay

 

[Hoplias]

Yes, now I found the ones presented on ebayView attachment 581734View attachment 581735View attachment 581736View attachment 581737

Thx bro

 

[Jake0405]

Yes, now I found the ones presented on ebayView attachment 581734View attachment 581735View attachment 581736View attachment 581737

Thank you very much!

 

[FlyMachine]

In my work as an aeronautics illustrator, cutaway artist I too, have been searching and researching the enigmatic Stuka Siren workings and I must say it is a bit of a mystery even among the most studied enthusiasts. The recent photos posted here by Blixie are the most compelling and illuminating I have come across in more than 2 years of research, my assumption was always that the propellor hub slots were key but I was sure the sound was being produced inside the mount just behind the props and the slots were just outlets for the sound but it seems (typically) far more simple and deviant than that, from what I can see in these pics the slots in the prop hub are slotted in such a way that when they pass over slots or ports in the fixed inner hub (not visible here) we get the same effect as the Carter and other sirens with pulsing air being forced out, I am certain that oncoming airflow from the dive would help amplify the sound but it seems a certainty now that this is how the Stuka got its trumpet. The housing on which the prop/siren was mounted seems just for the infamously unreliable clutch which would give some control of the siren to the pilot and in earlier marks was coupled to the dive brakes. I wonder if the fact that the alloy prop fitted to a dissimilar metal hub is why so few of these sirens remain intact today?

Attached is the crudest of crude drawings illustrating what I now believe to be the workings of the siren. I will fabricate something similar in scale to test the theory but I suspect this is the answer after all. Thank you for this amazing thread.

 

[FlyMachine]

Fascinating reading, seems the CIA endeavored to use a similar psychological weapon developed by Chrysler, with a drawing of the basic concept. CIA Tracked Down A Nazi, Scoured Museums To Build An Aircraft Siren To Scare The Hell Out Of People

 

[Blixie]

Interesting 2 posts!
According to the text on my manual, they planned to mount sirens on the 87 D too. The pictures I provide here are the most explaining from the book. Due to health issues I will sell it on ebay.com in about 1 month and want to warn you for buying it for finding any more clues about the sound emitting device than this thread and these pictures gives.
All the best!

 

[Dare_Furor]

Something to consider: Was the Port siren a different pitch from the Starboard siren? There are two sirens, and this could explain the single cylinder/two-tone sound.

 

[Davidmacalister]

Interesting 2 posts!
According to the text on my manual, they planned to mount sirens on the 87 D too. The pictures I provide here are the most explaining from the book. Due to health issues I will sell it on ebay.com in about 1 month and want to warn you for buying it for finding any more clues about the sound emitting device than this thread and these pictures gives.
All the best!
View attachment 653074View attachment 653075View attachment 653076View attachment 653077

I found the full diagram of the Stuka siren mechanisms on another Stuka thread @
Post in thread 'eBay: Junkers Ju87'
eBay: Junkers Ju87

 

[Rlpor]

As shown in the attached image, the early versions of the siren did not have this slit, so it is probably not essential for generating sound.

It is also likely that the slit does not move.

The reason for adding this slit in later models was likely to enhance the siren sound through aerodynamic effects or to adjust the pitch and tone quality.

It is also interesting to note that the models without the slit have a hole in the center.