The Ship Model Forum

The closest image so far to an uncovered Ohio screw. While the blades are "socked", the screw boss is clear:

https://www.dvidshub.net/image/8566240/cno-visits-submarine-group-10-kings-bay-ga

This additional array complements the existing line array which is not visible on the exterior of the hull. It is located in the lower portion of the forward ballast tanks.

Well that's interesting...

https://www.thedrive.com/the-war-zone/41452/bulges-on-ballistic-missile-submarine-uss-tennessee-after-refit-point-to-new-flank-sonar-array?fbclid=IwAR0pc3yqUGsd6VMx1hTzcnGTLVG2WPBA8oFIKR-2grg5bX8TD6XkjbQmEME

If you want to incorporate some pitch into your propellers, you can use the following formulae:

p = 2?R*tan(?)

? = arctan[p/(2?R)]

where p is the pitch, R is the radial coordinate (0 at the axis of the propeller, and equal to the radius of the propeller at the tips of the blades), and ? is the pitch angle (?=0 is perpendicular to the axis of the propeller, ?=90 is parallel to the axis of the propeller).

Unless you have a good pitch curve (that plots p as a function of R), I would assume that the pitch is constant. Real propellers are typically "relieved" at the tips (the pitch is decreased) to reduce cavitation, but I doubt you'd be able to notice in 1/350 scale. If you don't have any data at all on pitch, I would start by assuming that ?=45 at the hub and calculate the pitch from there.

Also, most modern skewed propellers have a rake of around 5 degrees or so. The older skewed propellers on the Permit, Sturgeon, and 41 For Freedom SSBNs appear to have much less rake.

[quote="Woodstock74"]I'm offering my Ohio screws for sale on eBay:

https://www.ebay.com/itm/1-350-Ohio-class-submarine-SSBN-SSGN-2-x-propeller-screw-set/264794282229?hash=item3da6f818f5:g:80AAAOSwjzdeTYI8

If they show up sold, I will relist them. Or feel free to contact me directly.[/quote]
Hi Woodstock,

Your screw look nice, and it is certainly much better than the kit screw. However, it seems to lack the blade twist. And I find it awfully expensive! wish you lot of sales of course. :thumbs_up_1:

A cheaper alternative (with blade twist) is still this prop: [url]https://www.navalmodels.com/product/propeller-ohio-class/[/url]

So at least there is a choice now! :big_grin:

I'm offering my Ohio screws for sale on eBay:

https://www.ebay.com/sch/mulsannemike/m.html?_nkw=&_armrs=1&_ipg=&_from=

If they show up sold, I will relist them. Or feel free to contact me directly.

Thank you Jacob. This is a big help.

[quote="Kenny Loup"]Hello. I am getting ready to start Dragon's USS Ohio kit. I will be building it as the Louisiana. Part of the build will be to fill in the panel lines. My question is, has the USN done away with the red antifouling on the hull? I have Squadron's Ohio class book and plan on using any photos from the USN site I can fine as reference.[/quote]

Here's a photo of the Louisiana in drydock, but I'm not sure of the date.

[url]https://thechive.files.wordpress.com/2014/02/uss-louisiana-ssbn-743-920-9.jpg?quality=85&strip=info&w=919[/url]

There are two current schemes:

Black above, red below

Maryland
[url]http://i.imgur.com/5Tf2fM5.jpg[/url]

Rhode Island
[url]http://i.imgur.com/6YEUV9U.jpg[/url]

All black

Pennsylvania
[url]http://i.imgur.com/l7KvIYv.jpg[/url]

Henry M. Jackson
[url]http://i.imgur.com/Kjpyqo1.jpg[/url]

I'm guessing that Atlantic Boats (drydocked at Newport News) have red antifouling while the Pacific boats (drydocked at Bremerton) are all black. I remember hearing that during the Cold War, boats overhauled at Mare Island would be painted all-black because of a California regulation on toxic paints. Could be apocryphal and I don't know if that would apply to Washington.

Jacob

Hello. I am getting ready to start Dragon's USS Ohio kit. I will be building it as the Louisiana. Part of the build will be to fill in the panel lines. My question is, has the USN done away with the red antifouling on the hull? I have Squadron's Ohio class book and plan on using any photos from the USN site I can fine as reference.

thanks ! will directly write at his personal adress, because I already searched at naval models and also written to them for now.

[quote]hello ! do you still produce those propellers ? I need a Ohio class one.[/quote]

Hi mister You :big_grin:

The props are still available from Naval Models, however their website is not up-to-date: they're working on it, I know.

You better send an email to the shop manager Michiel Woort, info@navalmodels.com or his private email, wijkergouw104@gmail.com. Give him my regards, I'm sure he has all the sub props in stock!

Mr. Maarten

[quote="Maarten Sch�nfeld"][attachment=1]SSBN -SSN screws.jpg[/attachment]
Hi guys,

as it seems no-one is making a good 1:350 prop for the Los Angeles and Ohio classes I took the initiative: these resin props are based on the publicly available info on the internet. Diameter for the 688 screw (prop) is 15 ft, for the Ohio SSBN is 22.5 ft. The shafts are kept separate as you see, and can easily be inserted. The ring around the props are there to help in the casting and can easily be removed, but if someone wants a ringed 688i screw the ring might be reduced in width by filing and sanding.

I'm also making an earlier seven bladed variant with less skewback, which was used on every boat from the Skipjack and George Washington classes onwards, I think even on early 688 boats. I might even do a five petal-bladed version for the early Skipjack and George Washington, although these were never used operationally.

The screws are available from Naval Models in the Netherlands http://www.navalmodels.com, or send an email to info@navalmodels.com.
[attachment=0]2015-03-24 12.10.43a.jpg[/attachment]
Cheers![/quote]


hello ! do you still produce those propellers ? I need a Ohio class one.

can you give me the direct link to this item ? I cannot find it on your proposed website.

THX !!

Gents,

Does anyone know if Hobby Boss or anyone else for that matter is doing a new tooled kit of an Ohio class SSBN in 1/350 scale in the future? I'd love to see one done, as I am not a fan of the DML version.

TIA

Brad

[attachment=1]SSBN -SSN screws.jpg[/attachment]
Hi guys,

as it seems no-one is making a good 1:350 prop for the Los Angeles and Ohio classes I took the initiative: these resin props are based on the publicly available info on the internet. Diameter for the 688 screw (prop) is 15 ft, for the Ohio SSBN is 22.5 ft. The shafts are kept separate as you see, and can easily be inserted. The ring around the props are there to help in the casting and can easily be removed, but if someone wants a ringed 688i screw the ring might be reduced in width by filing and sanding.

I'm also making an earlier seven bladed variant with less skewback, which was used on every boat from the Skipjack and George Washington classes onwards, I think even on early 688 boats. I might even do a five petal-bladed version for the early Skipjack and George Washington, although these were never used operationally.

The screws are available from Naval Models in the Netherlands http://www.navalmodels.com, or send an email to info@navalmodels.com.
[attachment=0]2015-03-24 12.10.43a.jpg[/attachment]
Cheers!

Large slow revolution speed propellor to avoid cavitation would make sense. Multiple thin blades with large curvature to breakup noise from the propellor cutting through hull flow as well.

Bill

[quote]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 [/quote]
Hi guys,

I picked up this thread from the previous page, I did some measuring and calculations based on the satellite image. I come to the conclusion that the prop (screw) on the Ohio class is 22.5 feet in diameter, and this is a very likely value as it is exactly 1.5 times that of most SSN subs of the era, which seem to be 15 ft in diameter.

This dismisses the DML/Dragon/Italeri/Testors prop as way too small, probably based on a semi-official drawing I also found on the web, showing exactly the queer prop that can be found in the kit. Also the shape of the blades is hopeless, see this peek view on the tips of a real Trident SSBN prop:
[attachment=0]georgia_drydock_full.jpg[/attachment]
I'm currently working with the firm Raboesch in NL whether they can make a credible brass example in 1:350 scale (19.6mm diameter), as they already have done it in larger RC scales. They are quite interested in my idea, let's see what comes out!

So, what do people have on the SSBN(X)? I have found some stuff about both versions: the original 20 tube version and the later 16 missile version. The original looks like it is supposed to have bow planes and side, chin, and heavy bow sonar installation, and the reduced version has bow planes and only a bow sonar. There are particular descriptions that reflect the original versions, like the Virginias, had how planes vs fairwater planes on the sail.

Here are some conceptual drawings:
[img]http://eurasian-defence.ru/sites/default/files/ssbnx.jpg[/img]



http://eurasian-defence.ru/sites/default/files/ssbnx.jpg


Here is what the compromise may look like:
[img]http://topwar.ru/uploads/posts/2012-09/1347347369_OHIO_Replacement.jpg[/img]

Anyone have any ideas how a model of this could be accomplished?

[quote]Interesting. The Ohio replacement carries fewer missiles but it is a bigger submarine. Why? Is the electric drive a lot bigger?[/quote]

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 [i]Tullibee[/i] and USS [i]Glenard Lipscomb[/i]) 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: [url]http://www.navy.mil/navydata/cno/n87/usw/issue_9/power_system.html[/url]

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.

Interesting. The Ohio replacement carries fewer missiles but it is a bigger submarine. Why? Is the electric drive a lot bigger?

Fantastic, Tom. Thank you for the clarification!