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PostPosted: Mon Jul 26, 2021 12:10 pm 
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Tom Dougherty wrote:
As I mentioned above, it is the 1966 “as built” USS Sturgeon in the kit. In order to do a late model, you will need to lengthen the hull, add a dome aft (I believe this is the WLR-9A) and a towed array hull fairing, tube, tube support structure and deployment tube on the port side. I have never seen a vortex attenuators hub on a 637 class screw.

As far as lengthening the MikroMir 1/144 Sturgeon hull, it is about 1/8 inch thick glass reinforced resin (GRP), not polystyrene. Not impossible, but a tougher job to lengthen than if it were polystyrene.


My bad, when I said “late model” I really meant late period, i.e. ‘90s 637s, but didn’t realize it until it was 1am and I was on a train in the middle of nowhere and no way to edit the post.
As for doing a stretch, nope, most I will do is add the necessaries like towed array, etc. The 1/350 can represent my stretch.

As for attenuators (we called it “the device” cuz hush-hush at the time), we had them on Aspro and Tunny, probably on the other boats too but I can only vouch for those two. A semi-interesting story about Aspro’s device, during availability when the torpedo-damaged screw was replaced (a story for another time and place, perhaps), shipyard lost it! It was going to be a big deal with NIS coming down with charges of sabotage, etc, and putting out to sea with a dunce cap instead. We had to get a talk about it since technically it was our equipment (Machinery division), but hey we didn’t take it offf, ask the crane operators! Anyway it turned up somewhere and all was right with the world once more.

Scott

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PostPosted: Mon Jul 26, 2021 1:56 pm 
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Grandahi wrote:
As for attenuators (we called it “the device” cuz hush-hush at the time), we had them on Aspro and Tunny, probably on the other boats too but I can only vouch for those two. A semi-interesting story about Aspro’s device, during availability when the torpedo-damaged screw was replaced (a story for another time and place, perhaps), shipyard lost it! It was going to be a big deal with NIS coming down with charges of sabotage, etc, and putting out to sea with a dunce cap instead. We had to get a talk about it since technically it was our equipment (Machinery division), but hey we didn’t take it offf, ask the crane operators! Anyway it turned up somewhere and all was right with the world once more.

Scott


Was that similar to the hub vortex diffuser on the 688s (a boss with a number of blades), or the propeller boss with a straight taper (see drawing)?

Image

Jacob

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PostPosted: Mon Jul 26, 2021 2:40 pm 
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Vepr157 wrote:


Was that similar to the hub vortex diffuser on the 688s (a boss with a number of blades), or the propeller boss with a straight taper (see drawing)?


Jacob


We had 11 blades on the device, (a question I asked of the nubs when they came for a propulsion train checkout), similar to what the internet shows on the 688s. As far as any other details, I didn't have a tape measure or a protractor with me, alas, so I am useless for providing any other details. The straight taper was the dunce cap we were going to be saddled with otherwise, if I am interpreting your question/drawing correctly.
Scott

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PostPosted: Mon Jul 26, 2021 5:02 pm 
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Great, thanks for the info! The 688 one has 11 blades as well. Funnily enough you can look its naval stock no. up online:

https://www.parttarget.com/2010-00-106- ... B35ACCC521

One thing that's always mystified me is why the 585s and 637s had that unusual straight-taper boss, but the 594s had a regular conical boss.

Jacob

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PostPosted: Mon Jul 26, 2021 9:11 pm 
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Grandahi wrote:
Vepr157 wrote:


Was that similar to the hub vortex diffuser on the 688s (a boss with a number of blades), or the propeller boss with a straight taper (see drawing)?


Jacob


We had 11 blades on the device, (a question I asked of the nubs when they came for a propulsion train checkout), similar to what the internet shows on the 688s. As far as any other details, I didn't have a tape measure or a protractor with me, alas, so I am useless for providing any other details. The straight taper was the dunce cap we were going to be saddled with otherwise, if I am interpreting your question/drawing correctly.
Scott


Well this is extraordinarily interesting!


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PostPosted: Mon Jul 26, 2021 9:19 pm 
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This isn't going to get me a visit from the goon squad is it?


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PostPosted: Tue Jul 27, 2021 7:07 am 
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That’s an interesting factoid! I have never seen a J screw with the 11 blade attenuator on it. How widespread was it employed? What time era (1990’s?) was the attenuator added to the 637’s? Any idea on the effectiveness?

My understanding is it was a response to the Russian installation of the SOKS wake detection system. The attenuator seemed to come and go in a short period. I was never clear on whether the 688I ring screw was to control tip vortices or to protect the prop tips under ice. Or both.

Build Report on the 1/144 Sturgeon
As far as the MikroMir Sturgeon kit, I joined the two halves of the bow cap. I ran small amounts of microweld along the interior of the cap to join the pieces. Unfortunately, although the two pieces are close matches, but you end up with a slight, “overbite” lip at the very front. So, out came the 400, 600 & 1000 wet sand paper to make the two pieces meet smoothly. I was very careful to frequently change sanding directions so as not to end up with a flat spot. I also had to use Tamiya putty to hide the seam. I placed tape very close on either side of the seam to limit the putty spread. So that simple process took two hours to get to a decent result.

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PostPosted: Tue Jul 27, 2021 11:05 am 
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Woodstock74 wrote:
This isn't going to get me a visit from the goon squad is it?

Jethro Gibbs is on his way!

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"Project Azorian: The CIA and the Raising of the K-129" Book
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PostPosted: Wed Jul 28, 2021 5:24 am 
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The Los Angeles made their homeport in Pearl in '78. Soon after their arrival, I attended a class with the lead sonarman who gave us a tour of the boat. I remember him mentioning they had an 18-bladed screw - a standard 7 blade model with an 11-bladed vortex dissipater, so it was installed very early on. He said they experimented with a five-bladed screw and while the speed was significantly greater, it was a lot noisier, so the 18 bladed screw was adopted.

Compared to the 637's on the waterfront, the LA was like the starship Enterprise.


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PostPosted: Wed Jul 28, 2021 12:12 pm 
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Folks, I am on the "slightly uninformed" list as to propellers.

Are these examples of the "stuff" being talked about?
( Top Pic a Type 212 prop)
( Middle Pic: 3D printing. Thank You Mike.)
(Bottom pic a 688 class prop example)

Nino.

P.S. Top photo I will attribute to J Gibbs. (Ya know, In case)

And take a look here if building 1/350 Subs: http://www.steelnavy.net/FullerPropelle ... herty.html


Attachments:
Prop of type 212 vortex attenuatror.jpg
Prop of type 212 vortex attenuatror.jpg [ 328.26 KiB | Viewed 3847 times ]
prop for Skipjack class  7-blade vortex attenuator.png
prop for Skipjack class 7-blade vortex attenuator.png [ 57.38 KiB | Viewed 3847 times ]
688 class attenuator.jpg
688 class attenuator.jpg [ 17.83 KiB | Viewed 3845 times ]
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PostPosted: Wed Jul 28, 2021 2:08 pm 
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Tom Dougherty wrote:
That’s an interesting factoid! I have never seen a J screw with the 11 blade attenuator on it. How widespread was it employed? What time era (1990’s?) was the attenuator added to the 637’s? Any idea on the effectiveness?

My understanding is it was a response to the Russian installation of the SOKS wake detection system. The attenuator seemed to come and go in a short period. I was never clear on whether the 688I ring screw was to control tip vortices or to protect the prop tips under ice. Or both.



Unfortunately I cannot comment on how widespread the employment was, only physically seeing it on two different boats, Aspro and Tunny. I was on board and decommissioned Aspro from 1992-1995, and Tunny from '95-'96. This was in Pearl Harbor btw. Other boats that were there at the time besides the usual 637s and 688s, were USS Kamehameha (SSBN/SSN-642), undergoing conversion to SSN (and the reason we never carried the DDS on Tunny during my time on her), and USS Haddock (SSN-621), which came to Pearl for inactivation and decommissioning. Fun factoid, ex-USS Aspro and ex-USS Haddock were towed together in 1995 back to Washington for recycling.
I always figured the device was installed as part of Aspro's overhaul at Mare Island ca. 1989-90, which I believe is when she got SHT, sonar and fire control upgrades, etc. With those upgrades we could do all and more than 688s, except go as fast.
For the most part we were too busy keeping her (Aspro) in a state of readiness to really delve into when which equipment got put on. Tunny was in MUCH better shape, even for being just a few years younger . . .

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PostPosted: Wed Jul 28, 2021 4:48 pm 
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Woodstock Mike had a mockup of an example, looks like the post has since been deleted. Anyway I was unable to chime in at the time, but it looked like reality to me. Although I think it should have more pitch on the attenuator blades, as in the upper left of the attached pic. But otherwise who is going to rivet-count it?
We had the tech manual with profile and pitch drawings for the screw, and it indicated it was the same on a slew of different classes of boats, as we all know now. Of course the 688s had a bigger and newer design, to account for their larger power-plant. No books on the device.
Cheers.


Attachments:
File_000.jpeg
File_000.jpeg [ 43.88 KiB | Viewed 3825 times ]

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PostPosted: Wed Jul 28, 2021 7:34 pm 
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Based on Grandahi's description:

Attachment:
Screenshot 2021-07-28 193909 Sturgeon_w_the_device.jpg
Screenshot 2021-07-28 193909 Sturgeon_w_the_device.jpg [ 19.15 KiB | Viewed 3815 times ]


Attachment:
Screenshot 2021-07-28 193834 Sturgeon_w_the_device.jpg
Screenshot 2021-07-28 193834 Sturgeon_w_the_device.jpg [ 30.19 KiB | Viewed 3815 times ]


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PostPosted: Thu Jul 29, 2021 6:33 pm 
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Woodstock74 wrote:
Based on Grandahi's description:

Attachment:
Screenshot 2021-07-28 193909 Sturgeon_w_the_device.jpg


Attachment:
Screenshot 2021-07-28 193834 Sturgeon_w_the_device.jpg


Looks as good as anything out there! Two thumbs up.

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USS Tunny (SSN-682)
"Give me heaven or a 637"


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PostPosted: Fri Jul 30, 2021 2:39 pm 
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Wish we had some photo evidence. There are precious few images of Sturgeon screws. And zero of this.


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PostPosted: Fri Jul 30, 2021 5:41 pm 
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Woodstock74 wrote:
Wish we had some photo evidence. There are precious few images of Sturgeon screws. And zero of this.

Agreed! But in the meantime here are some pics that you may or may not have already, they are handy for seeing the variable pitch (twist) if nothing else .


Attachments:
File comment: USS Barb
BARBSCRE.JPG
BARBSCRE.JPG [ 22.17 KiB | Viewed 3755 times ]
File comment: Boomer of some variety
prop.jpg
prop.jpg [ 170.33 KiB | Viewed 3755 times ]
File comment: Tech manual illustration
navymanual_full.gif
navymanual_full.gif [ 24 KiB | Viewed 3755 times ]
protected_prop_full.jpg
protected_prop_full.jpg [ 24.03 KiB | Viewed 3755 times ]

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USS Tunny (SSN-682)
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PostPosted: Mon Aug 02, 2021 6:38 pm 
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Grandahi wrote:
Tom Dougherty wrote:
That’s an interesting factoid! I have never seen a J screw with the 11 blade attenuator on it. How widespread was it employed? What time era (1990’s?) was the attenuator added to the 637’s? Any idea on the effectiveness?

My understanding is it was a response to the Russian installation of the SOKS wake detection system. The attenuator seemed to come and go in a short period. I was never clear on whether the 688I ring screw was to control tip vortices or to protect the prop tips under ice. Or both.



Unfortunately I cannot comment on how widespread the employment was, only physically seeing it on two different boats, Aspro and Tunny. I was on board and decommissioned Aspro from 1992-1995, and Tunny from '95-'96. This was in Pearl Harbor btw. Other boats that were there at the time besides the usual 637s and 688s, were USS Kamehameha (SSBN/SSN-642), undergoing conversion to SSN (and the reason we never carried the DDS on Tunny during my time on her), and USS Haddock (SSN-621), which came to Pearl for inactivation and decommissioning. Fun factoid, ex-USS Aspro and ex-USS Haddock were towed together in 1995 back to Washington for recycling.
I always figured the device was installed as part of Aspro's overhaul at Mare Island ca. 1989-90, which I believe is when she got SHT, sonar and fire control upgrades, etc. With those upgrades we could do all and more than 688s, except go as fast.
For the most part we were too busy keeping her (Aspro) in a state of readiness to really delve into when which equipment got put on. Tunny was in MUCH better shape, even for being just a few years younger . . .


Just to clarify, you only saw this screw on those two boats (Aspro and Tunny)?


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PostPosted: Thu Aug 05, 2021 11:40 am 
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Woodstock74 wrote:

Just to clarify, you only saw this screw on those two boats (Aspro and Tunny)?


That is correct good sir.

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USS Tunny (SSN-682)
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