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    Re: Cel Nav and missile submarines
    From: Gary LaPook
    Date: 2012 Apr 11, 02:48 -0700
    "Close only counts in horseshoes, howitzers and hand grenades."
    For nukes accuracy is extremely important because the yield needed to produce a certain overpressure varies with the cube of the distance. For example, it takes 500 psi overpressure to take out a hardened missile silo. If you need a 95% assurance of destruction and the CEP of your nuke is .5 miles then you will need an 18 megaton device. If you can improve the CEP to .25 miles than you only need 2 MT and if you can improve the accuracy to 1/8th mile you only need 500 kt, 1/2 MT. Nukes cost by the pound, for the device itself and for the delivery system so it is a wise investment to spend money to improve the accuracy of the delivery system instead of making bigger nukes. See attached.

    gl

    --- On Tue, 4/10/12, Lu Abel <luabel@ymail.com> wrote:

    From: Lu Abel <luabel@ymail.com>
    Subject: [NavList] Re: Cel Nav and missile submarines
    To: "NavList@fer3.com" <NavList@fer3.com>
    Date: Tuesday, April 10, 2012, 6:08 PM

    Just a couple of quick points:

    It is my understanding that the periscope on many WW II subs had a "sextant" mode where a navigator could shoot sites while submerged.   Pretty useful for getting daytime (moon, sun) shots.   I had a friend who was a real nut about US subs in WW II (they mostly operated in the Pacific since Japan depended on ships to supply all of its conquered Pacific islands).   In the autobiography of one of the most famous (and, unfortunately, I forget whom -- it was years ago) he described getting a junior officer to take very high-angle sun sights (like 88 or 89 degrees and then draw a circular LOP on their chart by simply plotting the GP of the sun at the moment the shot was taken.

    As to 0.1' accuracy -- with nuclear weapons, as with hand-grenades, "close" is usually effective.   In fact, the problem with much of the cold war may have been accurately knowing the lat/long of the target rather than of the missile launch site!


    From: Alexandre E Eremenko <eremenko@math.purdue.edu>
    To: NavList@fer3.com
    Sent: Tuesday, April 10, 2012 5:14 PM
    Subject: [NavList] Cel Nav and missile submarines


    Thanks to Fred and Gary
    who helped to clarify the picture.
    And I apologise again for the message which begins with
    "Fred,..." while this was really an answer to Gary:-)

    Here is a short chronology.
    The first submarine ballistic missle was Zemlia R-11FM (SS-1 Scud A).
    It had an inertial guiding system.
    It was launched from the submarine Zulu B-67, some say in 1956,
    and even give exact date: September 16,
    others say in 1955, and became operational by 1959.
    It had a nuclear warhead, and was liquid-propelled.
    There was only one missile on the sub, it was launched from surface
    position, and had to be put vertically before the launch.

    (I imagine this mess: fuleing the missile standing vertically on
    the deck, with liquid fuel. The fuel was nitric acid + liquid oxigen :-)
    I would be delighted to see this:-)

    As the very first satellite was launched only in 1957, the submarine
    clearly relied on Cel Nav. And the whole accuracy of the missle
    depended on Cel Nav. Inertial navigation for the submarine itself is a short time
    solution; inertial navigation cannot give your position for long time
    without checking it with some other means.

    Further development on the Soviet side were
    R-13, R-21 (1962) and R-27 (1967) missiles,
    (SS-N-4, SS-N-5, SS-N-6), all with inertial navigation,
    and Yankee class submarines. They already had missiles permanently
    in vertical position but the missiles were still liquid fuel propelled.

    Now, in the 50-s (don't know exactly when) Soviet dip meter spreads,
    and on the US side, Shufeldt makes his research in 1958-61.
    Which was first classified, but then quickly unclassified,
    and the satellite system Transit 1 comes in use in 1964,
    and is made open to everyone in 1967.

    This system does not measure any angles (as I wrongly assumed in the beginning) but uses the Doppler effect created by the motion of the
    satellites. Few satellites do
    not cover all Earth surface.
    The accuracy 0'1-0'2 is better than Cel Nav.
    Only by 1980-s the Soviets apparently developed their own satellite
    system.

    Concerning other non-Cel nav systems. Inertial system for submarines
    is probably insdispensible when the submarine sails under ice
    (or under a helicopter which tries to find it).
    When it is near the water surface, a sextant can be used through the
    periscope, and I read somewhere about such sextants.
    The systems based on shore radio stations, like LORAN, have limited
    range.

    Now, in te case of a nuclear attack, all satellite systems might
    be switched off, and it will remain to rely on Cel Nav for missile launch from a submarine... if there still will be people who know how
    to use it:-)

    Alex.






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