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SSBN Design Differences - Distinguishing Characteristics

Place for general submarine conversation

Postby Jim Kerswell » Fri Mar 28, 2003 5:59 pm

It is well known that the fairwater design of the Gato/Balao submarines evolved significantly during WWII. Articles in the SCR have even sought to define sail height differences among the Permit-class boats. I would now like to throw out for discussion distinguishing design features between the Lafayette and Benjamin Franklin classes of SSBN.
If one were to refer to the text and drawings in sources such as Friedman's U.S. Submarines Since 1945 or Christley's United States Naval Submarine Force Information Book, you would think that, externally, the boats of these two classes were identical, differing only in some internal mechanical systems. However, in researching the photographs available on several Internet websites prior to starting a modeling project, it became apparent that there is a quite distinguishing difference: The sail-mounted dive planes on the later Benjamin Franklin class are about four feet lower than those on the Lafayette class. Less obvious is the addition of small vertical surfaces inboard of the tips on the fixed portion of the aft dive planes on the Franklin-class boats.
Now the questions: What was the reason for this change in sail dive plane location and was this change so important that earlier boats were modified? The second question arises from a series of photographs of the USS Stonewall Jackson appearing at the authoritative website The launching photos are clearly of the Jackson. But a photo, that Navource obtained from the FAS website shows an unmarked boat with a Ben Franklin-configuration sail and dive planes. Similarly, the only photo Navsource provides for the USS U.S. Grant, a Lafayette-class boat, comes from the same FAS source and shows a boat with low-mounted sail dive planes. Either, these boats were modified during overhauls, or the identifications of the photographs are incorrect.
Any comments from the experts and/or former SSBN crewmembers?
Jim Kerswell
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Postby Dolphin » Sat Mar 29, 2003 2:07 am


Edited By Dolphin on 1049258473

Postby Dolphin » Sat Mar 29, 2003 2:37 am

Hello Jim,

I wrote that Permit article mentioning the different sail heights for the Thresher/Permit class.

The 41 Polaris/Poseidon system SSBN's saw improvements and refinements in the design all along their rapid development & construction. These vital ships in the nation's defense were developed so rapidly and so well, from so many varied sciences, rivaling the American program to put men on the moon from that same era. It was a bold & new advancement and it had to work perfectly from an operational view point from the very get go. It also had to afford within the program (now from then refered to as a 'system') design room for future technologies that likely had not been developed to a mature level fully yet. A remarkable national technological achievement.

You mentioned astutely the Benjamin Franklin (SSBN 640) differences externally. The small thin fixed stabilizer fins on the horizontal stern planes AND the lower sail plane position changed on the Benjamin Franklin (SSBN 640) through to final boat Will Rogers SSBN 659) onward.

The reason for the change to the lower sail plane position was for slightly better depth control handling effectiveness while maintaining periscope depth. The broad flat turtle back missile deck area at moderate speeds could create lift, the sail planes sometimes trimmed down slightly to compensate. The Permit class attack boats with their short sails had to operate at slightly shallower periscope depths. Periscope depth is determined by the overall length of the periscope masts. The taller the sail, the longer the periscopes, the deeper the periscope depth. In rough seas, a few feet deeper afforded some more measure of control. Notice the large very versatile Sturgeon (SSN-637) class with their taller sails in relation to the previous Permit (SSN-594) design?

In the SSBN's, the big major difference operationally between the Lafayette and the Benjamin
Franklin's was not so much in external appearance but was in internal sound quieting.

So why does the image of the Ulysses S. Grant (SSBN 631) in the NavSource web site show lower position sail planes? Because it is mis-captioned! The image shown is actually of the USS Will Rogers (SSBN-659) from a photo taken by Adm. Yogi Kaufman USN (ret.). See his book 'Silent Chase', pp. 105.

Disregard the above simular message reply, I pasted in the wrong message the first time......sorry!

Steve Reichmuth

Postby Dolphin » Sat Mar 29, 2003 2:50 am


Edited By Dolphin on 1049258534

Postby wlambing » Sat Mar 29, 2003 6:54 am

USS Ulysses S. Grant (SSBN 631) and USS Stonewall Jackson (SSBN 634) were both 627 (James Madison) class ships. These are the first group of "re-engineered" 616's. The esteemed Mr. Christley and I served on both of these ships, at different times. At present, I work at EB doing technical support work for the Moored Training Ships, Ex-USS Daniel Webster (626) and ex-Sam Rayburn. Besides subtle differences between classes, these ships were built by different yards, 626 at EB and 635 at Newport-News. N-N was allowed to do some strange things when you compare "design" against "as-built". Don't forget overhauls and ShipAlts accomplished over their service lives.
Pick your ship, pick the era, get the pictures, and be happy that you'll be CLOSE. Best we can do, now that they're gone.
Take care,
"If you ignore the problem long enough, it will go away. Even flooding stops eventually!"
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Postby Dolphin » Sat Mar 29, 2003 3:07 pm


Edited By Dolphin on 1049258601

Postby Jim Kerswell » Mon Mar 31, 2003 4:22 pm

Steve and Bill,

Thank you both for taking the time to reply to my query. If I may summarize, I would say that there is no unambiguous evidence that earlier SSBN's were modified to the Benjamin Franklin-class sail configuration. I am intending to model the USS Von Steuben, SSBN 632, which falls in sequence between the two boats I mentioned. The model is the re-released kit from Revell of Germany, probably from the old Renwal molds. This kit has serious planform errors in the depiction of the sail dive planes and the upper rudder. These, along with other problems, were mentioned in a Ken Hart article in an early SCR.

In a larger context, though, the problem of loss or non-existence of design documentation remains. In the field of aircraft history there are now dozens of books giving walkaround photographic closeups and "detail and scale" of numerous aircraft. Submairne modelers can't seem to get official and accurate drawings of the exteriors of boats which have long since past into history. It is like having no accurate drawings of the F-4 Phantom or of the F-105. I tried to get drawings of the Lafayette and Permit from Taubman's service and received a note saying they were "no longer available"! No longer available? Can't another copy be made?

Over the weekend I too noticed that Kaufman's photos of the Will Rodgers in both the Silent Chase and Sharks of Steel seemed to be identical to the purported Grant photo in Navsource. This is a copyrighted photo. It bothers me that this important source of naval photographs would not check out a source before using it.

Jim Kerswell
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Postby Dolphin » Tue Apr 01, 2003 12:30 am

Hello Jim,

Design documentation? Email me.


Postby Britt Boyette » Tue Apr 01, 2003 10:47 am

Hi Steve,
To get rid of the extra replies, just hit the edit button.

Edited By Britt Boyette on 1049208472
Britt Boyette

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