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PostPosted: Wed Nov 14, 2012 3:52 pm 
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Anyone have details on the ballast vents on an Ohio class? I haven't located any pictures of the underside, would at least like to see what they look like before I start mine.

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PostPosted: Fri Nov 16, 2012 2:45 am 
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Jeffcsr wrote:
Anyone have details on the ballast vents on an Ohio class? I haven't located any pictures of the underside, would at least like to see what they look like before I start mine.


Modern US Navy Submarines, by Robert and Robin Genat, Published by MBI Publishing company, ISBN 0-7603-0276-6

Page 42 has an excellent view of my old boat USS Alaska, SSBN-732, in drydock at the Trident Delta pier at former Sub Base Bangor (now Joint Base Kitsap). Page 43 has a good close up of the vents themselves, and between the two pages you can work out their placement on the hull fairly well. I have personally walked under her hull while in drydock, and the pic really does them justice...Basically just sewer grate-style gridded squares on the bottom of the hull.

Other trivia;
- None of the original batch C-4 Trident Ohio-class boats homeported out of Bangor had the DSRV markings on the hull.
- The USS Alabama SSBN-731 is the only boat to have the retractable cleats on the deck not painted white..On her they are red.
- No Ohio class has hull numbers painted on, they are magnetic and placed on the sail only when in port to prevent positive identification when at sea.

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PostPosted: Fri Nov 16, 2012 10:32 pm 
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Broken propeller on my Dragon kit... This sucks, now I need to get a replacement prop but what options would an Ohio class have?

Top Secret Blade design? They are always covered up so my main question would be did the Ohio's propeller ever undergo evolution or have they used the same design prop from 1st to last boat?

Would a prop jet have ever been considered on an Ohio class?

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PostPosted: Fri Nov 16, 2012 11:18 pm 
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Jeffcsr wrote:
Broken propeller on my Dragon kit... This sucks, now I need to get a replacement prop but what options would an Ohio class have?

Top Secret Blade design? They are always covered up so my main question would be did the Ohio's propeller ever undergo evolution or have they used the same design prop from 1st to last boat?

Would a prop jet have ever been considered on an Ohio class?


They were covered from us seeing them, even as crew members. All I know is it is a 7 bladed design, most likely scimitar shaped. I have both the Dragon 1/350th Ohio and Los Angeles class kits, and the LA class screw is considerably larger, with more pointed tips. As for prop jets, unlikely. The Ohio class is made for stealth, not speed. We spent most of our time slowly moving around in an assigned box in the middle of the ocean, going "4 knots to nowhere" as we called it. Actual submerged top speed is still classified I believe, but I can tell you it isn't impressive. Movies like Crimson Tide took a few liberties with exaggerating how much the Ohio boats roll about at high speed. Even at flank in a hard turn they're stable. The hard part is getting that giant blunt nose to stay within 10 degrees of assigned heading and within +/- 10 feet of assigned depth, especially at flank speed, and when at periscope depth keeping the suction effect of that giant flat missile deck from pulling you to the surface and causing you to broach, even when barely moving.

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PostPosted: Sat Nov 17, 2012 12:56 pm 
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Back in 2007, an aerial photo of an SSBN (SSBN 731) propeller ended up all over the internet, courtesy of Microsoft Virtual Earth. The propeller should have been covered in drydock, as mentioned by rx79gez8gundam above (interesting forum name, BTW. Any relation to Mr. Mxyzptlk of Superman comics?). Anyhow, it is not a real closeup, but you can get some idea at this link:
http://lewis.armscontrolwonk.com/archive/1626/secret-screws
You can rotate the view and look at it from different angles here: http://www.bing.com/maps/default.aspx?v=2&cp=ryqjnb4s57d5&style=o&lvl=2&tilt=-90&dir=0&alt=-1000&scene=10352732&encType=1

In the open literature many years ago (Norman Friedman "US Submarines since 1945: An Illustrated Design History") there was a discussion about "blade rate", which was discovered in the early 1960's and is the interaction of the (then fan shaped) propeller blades with the wake coming off the rudders and stern planes. This leads to a low frequency sound that carries for considerable distances in the deep sound channel. Blade skew reduces blade rate by having the blades enter & exit the disturbed wake in a more gradual fashion. Ths Smithsonian had an exhibit on Cold War Submarines which actually featured the first generation J propeller, fitted to the Skipjack, Permit, Sturgeon & first generation SSBNs. Soviet submarines did not have the skewed back propellers through much of the Cold War, allowing SOSUS and sensitive passive arrays to detect and track them from some distance.

If you scroll down on one of Don Murphy's Casimir Pulaski SSBN web pages: http://www.usscasimirpulaski.com/part2refit.htm, you can see the Pulaski with a J prop in drydock.

Later propeller designs (Ohio SSBN & LA SSNs) had improvements, including but not limited to the shapes, and those are still kept pretty closely held, except for slipups such as the above. Of course, the Seawolf & Virginia class SSNs now have pump jets, which is another whole topic, and the details of those designs are very closely held.


Attachments:
File comment: J Type propeller
J type screw.jpg
J type screw.jpg [ 90.8 KiB | Viewed 4529 times ]

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Last edited by Tom Dougherty on Sat Nov 17, 2012 3:02 pm, edited 2 times in total.
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PostPosted: Sat Nov 17, 2012 1:52 pm 
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Don Grasmick wrote:
I knew Tracy would have the definative word on this.... Would one be able to really see these "wider deck" changes of a couple feet in 1/700 scale?

Oh, yes. The shape of the back deck is different. You will be able to see in any scale. Take a look.
Attachment:
SSGNdeckFlo.jpg
SSGNdeckFlo.jpg [ 126.38 KiB | Viewed 4525 times ]

The direct link for a waaaaaaaay bigger version is below:
http://www.navsource.org/archives/08/0872842.jpg

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PostPosted: Sun Nov 18, 2012 1:55 pm 
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In the open literature many years ago (Norman Friedman "US Submarines since 1945: An Illustrated Design History") there was a discussion about "blade rate", which was discovered in the early 1960's and is the interaction of the (then fan shaped) propeller blades with the wake coming off the rudders and stern planes. This leads to a low frequency sound that carries for considerable distances in the deep sound channel. Blade skew reduces blade rate by having the blades enter & exit the disturbed wake in a more gradual fashion. Ths Smithsonian had an exhibit on Cold War Submarines which actually featured the first generation J propeller, fitted to the Skipjack, Permit, Sturgeon & first generation SSBNs. Soviet submarines did not have the skewed back propellers through much of the Cold War, allowing SOSUS and sensitive passive arrays to detect and track them from some distance.


That is correct and in fact the very basic number of blades is a result of that. They opt for an odd amount of blades so that only one blade at the time enters just behind the upper or lower rudder and not two blades. By further skewing the blades, there is only a single blade which gradually enters that area. So there would always be 5 or 7 blade props with only few exceptions. 1 exception is the Kilo class, which has a 6-blade prop. That is feasable since it doesn't have an upper rudder and therefore just a single blade will come there. The later Kilo version does have a 7-blade since a higher amount of blades also lower the pressure and diameter (and hence cavitation) on each blade.

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PostPosted: Tue Nov 27, 2012 12:48 pm 
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So im having a little trouble finding anything comparing the BWN Ohio and the Dragon Ohio. Anyone know which one is better?


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PostPosted: Tue Nov 27, 2012 12:57 pm 
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krgf15 wrote:
So im having a little trouble finding anything comparing the BWN Ohio and the Dragon Ohio. Anyone know which one is better?

I don't have any experience with the BWN Ohio, but I have built the Dragon one before, and it is a good, very detailed kit. I will build another, and I will use its parts to depict the current interpretation of the future Ohio replacement.

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PostPosted: Wed Dec 05, 2012 11:20 am 
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Well, I got the Cyber Hobby (Dragon) Maryland in the mail, and im wondering what all the vertical panel lines are supposed to be? Other than than that and where the leading edge of the turtleback will have to be filled, it looks really good.


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PostPosted: Wed Dec 05, 2012 11:59 am 
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Well, I got the Cyber Hobby (Dragon) Maryland in the mail, and im wondering what all the vertical panel lines are supposed to be?


They are a "legacy" of the original DML model, when some master maker thought panel lines should be on submarines. Possibly he worked on airplanes models in the past?? They're not present of course. The only legitimate panel lines are on the sail and a few on the upper deck that access line lockers, etc.

When hull sections are joined at EB (possibly what the panel lines are supposed to represent) the sections are welded together. This is a several days long process, as the weld has to be built up into the full thickness of the hull section, and welding HY-80 must be done with care and technical skill to reduce hydrogen embrittlement. Multiple X-rays are taken as the layers of weld are built up to insure there are no voids. Finally, the weld beads are ground down to a tolerance of 1/16th of an inch to the rest of the hull, to insure a smooth, hydrodynamic hull. In other words, you would have to be very close and look very carefully to see the joins of the weld sections when everything is complete.

Here's a very good photo of USS Rhode Island (SSBN 730) on the Land Level Facility at EB and because the light is right, you can see the weld beads if you look at the high resolution version:
http://navsource.org/archives/08/726/0872913.jpg

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https://www.usni.org/press/books/project-azorian


Last edited by Tom Dougherty on Wed Dec 05, 2012 2:01 pm, edited 2 times in total.

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PostPosted: Wed Dec 05, 2012 12:21 pm 
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Awesome, thank you again sir!!


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PostPosted: Tue Dec 18, 2012 2:09 pm 
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I threw the kit together so I can look at it lol. I will go back later and fill and sand it and repaint it. It seems alright, but I still want to find the BWN/Yankee modelworks kit and see what they look like together.


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PostPosted: Fri Jan 25, 2013 4:04 am 
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Does anyone know what the Ohio replacement SSBN will be fitted with?

I remember reading somewhere here about speculation about the new SSBN(X), but I am not finding it. I read here that it's believed that the sub will have sail mounted diving planes. Can anyone expound upon this?

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PostPosted: Fri Jan 25, 2013 12:29 pm 
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These 12 SSBN(X)submarines will feature 16 missile tubes rather than the 24 on the Ohio class.

Essential features are summarized here: http://news.usni.org/news-analysis/news/ohio-class-replacement-details

A few recent articles on the SSBN(X):
A good summary paper: http://www.fas.org/sgp/crs/weapons/R41129.pdf
Another article: http://www.usni.org/magazines/proceedings/2012-06/incredible-shrinking-ssbnx
It will have an electric drive propulsion system: http://www.wired.com/dangerroom/2013/01/secret-sub-design/
Contract awarded for design to EB: http://s181686668.onlinehome.us/phpBB3/viewtopic.php?f=27&t=11314
More discussion: http://defense.aol.com/2012/10/18/navy-fears-pentagon-neglects-new-missile-sub-ssbn-x-must-survi/

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PostPosted: Fri Jan 25, 2013 7:23 pm 
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I am aware of he popular reporting on the subject, but I was reading a congressional report that was describing the new design. We know that fairwater planes are diving planes on the sail and bow planes are diving planes on the bow. While the congressional report reported fairwater planes, it later defined fairwater planes as diving planes mounted on the bow.

http://www.fas.org/sgp/crs/weapons/R41129.pdf

So, this presented quite the contradiction. These reports are typically what other articles source. So, if the term fairwater plane had been misused in this report, perhaps the entire perception of fairwater planes actually being used could be wrong.

However, I have already answered my question. The report was citing an article written by the Ohio replacement program manager. It seems that the report misinterpreted the term fairwater planes and assumed that they would be on the bow. However, the author of the report is very, very well versed in naval systems, so it makes me wonder if the diving planes really will be bow or sail mounted.

So, here are two questions to you guys: Is there a chance that the term "fairwater planes" could simply be referring to the diving planes mounted forward most on the ship?

I am aware that diving planes generate some noise, and when that noise is very close to the bow sonar, it would degrade the sonar's effectiveness. It is my understanding that bow mounted planes also give the ship greater maneuverability. Our best SSNs have bow mounted diving planes, and their whole mission is to hunt, and that requires the sonars to operate at their best. The superior deign certainly seems to be bow mounted planes. Why would the Navy want to revert to sail mounted planes when you get so much more capability with bow mounted planes?

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PostPosted: Sat Jan 26, 2013 5:36 pm 
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It is my understanding that bow mounted planes also give the ship greater maneuverability. Our best SSNs have bow mounted diving planes, and their whole mission is to hunt, and that requires the sonars to operate at their best. The superior deign certainly seems to be bow mounted planes. Why would the Navy want to revert to sail mounted planes when you get so much more capability with bow mounted planes?


OK, several misconceptions here. First, you are correct, the term "fairwater planes" refers to planes mounted on the sail. In the case of the SSNs, the planes were moved from the sail to the bow position in the so-called 688I class, the third iteration of the Los Angeles class design. The motivation was to restore the capability to operate under ice. The sail on the 688 was too short to rotate the planes to a full vertical position (as on the 637 Sturgeon class) for ice breaking. The move back to the bow position allowed the planes to retract fully (into the forward ballast tank) for under ice surfacing. The bow planes are two parts, an "all moving outboard surface" mounted on a small, inboard, non-movable "stub" . The bow planes forward can be smaller than sail planes, as they are further from the ship's CG, and you get more control from a smaller surface. in a simple sense, forward (or sail) planes control the sub's depth, the stern planes control attitude in the water.

Fairwater planes were employed to move the rotating mechanism farther from the bow sonar sphere. A downside to this is the planes are closer to the surface when at periscope depth, and wave action can make it a bit more difficult to maintain depth. The newer sonar installations on the Virginia class boats have advanced signal processing and wrap around bow transducers, so it is easier to use advanced techniques to filter out bow plane activation noise (and other self noise), as well as flow noise due to the planes. It appears (for now) from the literature that the fairwater planes will be retained in the advanced SSBN (X) design.

There is really no great advantage to one plane installation over another in terms of submarine maneuverability. You don't get "more capability" with bow planes in any meaningful sense. Important submarine capabilities for SSNs are silence at tactical speeds, sonar detection range, ability to rapidly "solve" the shooting solution at long range, and quietly launching torpedoes. Modern torpedoes pay out a long (20 mile) "wire" and the shooting solution is constantly updated from the shooting submarine's passive sonar suite and computers. At current firing ranges, it can be tens of minutes between shooting and the torpedo reaching the target. Once close, the torpedo goes active with its own sonar. Newer submarines such as the Seawolf and Virginia classes have Wide Angle Arrays along the length of the hull, which use the baseline of the hull to triangulate targets.

One idea that seems to have gone by the wayside was to adapt the Virginia design for the SSBN(X). This may have been the source of confusion on use of bow planes, as on the Virginia class. Retaining the Virginia SSN design would have necessitated in abandoning the Trident D-5 for a new, smaller missile, as the Virginia hull diameter would not accommodate the missile. The SSBN(X) will retain the Ohio diameter and the Trident D-5 (with its long range and MIRV capabilities).

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"Project Azorian: The CIA and the Raising of the K-129" Book
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PostPosted: Sat Jan 26, 2013 6:25 pm 
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Fantastic, Tom. Thank you for the clarification!

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PostPosted: Sun Jan 27, 2013 12:35 pm 
Interesting. The Ohio replacement carries fewer missiles but it is a bigger submarine. Why? Is the electric drive a lot bigger?


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PostPosted: Sun Jan 27, 2013 3:59 pm 
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Interesting. The Ohio replacement carries fewer missiles but it is a bigger submarine. Why? Is the electric drive a lot bigger?


No, the electric drive will be an AC motor that is encapsulated and installed in the aft ballast tank area, so it won't even be in the engineering spaces. This saves the problem of having shaft seals in the engineering spaces, as in current submarines. These seals are rather ingenuous & complicated devices that allow the turning prop shaft to pass from the steam turbine & thrust block in the "people tank" out to the propeller without allowing the ocean in (even at considerable depths & sea pressure). Using AC motors will make for a compact installation that can fit in the aft ballast tank area (mud tank). Previous attempts at turboelectric drive (USS Tullibee and USS Glenard Lipscomb) used DC motors, which tend not to scale well in size when greater SHP is needed (i.e., they get big fast!). In the SSBN(X), the reactor will generate steam to turn upgraded turbogenerators which will act as the electrical source for the encapsulated AC drive. Current subs use steam turbines to turn the propeller shaft and also turbogenerators for ship's service electrical loads. The deletion of the steam turbines and drive train machinery (with step down gearing) eliminates a major source of radiated noise. More on electric drives: http://www.navy.mil/navydata/cno/n87/usw/issue_9/power_system.html

I am not sure why the size is not decreased; it may be due to improved crew habitability (particularly now that women can serve) or other equipment that require the space. I note the hull diameter is increasing 1 foot to 43 feet over the Ohio class's 42 ft. Also, the difference between 16 and 24 tubes is only 4 missile tubes (X2 rows) in length. The missile tubes are stacked pretty close together and are roughly 8 feet in diameter (the D-5 is 82 inches), so the savings in compartment length would probably be only 40-45 feet or so in hull length. The SSBN(X) displacement will be similar to an Ohio class SSBN.

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https://www.amazon.com/Azorian-Raising-K-129-Michael-White/dp/B008QTU7QY
"Project Azorian: The CIA and the Raising of the K-129" Book
https://www.usni.org/press/books/project-azorian


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