Need manuals/schematic for Sperry K4 gunsight for lower turret ball gunner in B17

Discussion in 'Schematics' started by Bill Akins, Jul 8, 2006.

  1. Bill Akins

    Bill Akins New Member

    Jul 8, 2006
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    I have a lower ball turret automatic computing gunsight from a B17
    bomber in very good condition. I acquired it from a cousin of mine.
    The plate on the gunsight reads..."Automatic computing sight for
    turret (lower ball) type K4 Sperry gyroscope company Inc."

    I removed the bulb cover and bulb from the back of the sight and shone
    a flashlight into the opening. I was able to see the sight reticle
    reflected onto the reflector glass and able to spread the reticle
    lines by turning the "target dimension feet" knob. Probably the first
    time anyone has looked at the reticle shone onto the reflective glass
    in this sight since WW2.

    The gunsight is very well sealed with all wire route openings capped
    with yellowed plastic caps. So no debri, bugs, etc have entered the
    gunsight. She is sealed as good as the day she was first sealed and
    put into storage. I did a bit of research yesterday
    online to try and find out more about this sight. What I need is any info
    there might be on this gunsight.

    I need an operators manual as well as a technical repair manual as well as a
    wiring schematic on this Sperry K4 lower ball turret gunsight. So far I have been unable to locate
    these WW2 manuals/schematics online or otherwise. To get the sight
    operational I must find and acquire these.

    I have been able to find out that the belly turret gunner used a left
    foot pedal which he depressed and then released, to bracket in his
    reticle the wingspan of an attacking fighter. Then he adjusted the
    "target dimension feet" knob to bracket the wingspan as well. There is
    also a mostly covered knob labled "range 100yds" and this knob has a
    small opening in its cover and I don't seem to be able to turn it.
    Not sure exactly how that knob figures in yet either, but I think it
    might be a knob that you unscrew the cover and set for different
    ranges, then screw the cover back on. Need a manual! Mine is the type
    K4 which was only used on B17's and B24 bomber belly turrets. The K3
    is an identical sight but was used on the top turrets. Mine is the
    same gunsight just turned upside down from the K3 and the printed
    lettering on the knobs and switch instructions is also upside down
    from the K3 top turret gunsight. Again, any Sperry K4 gunsight info on
    technical and operation manuals and a wiring schematic would be
    greatly appreciated.
    Send any info you have to me at [email protected]

    Here some text and websites with photos regarding the Sperry K3 and K4
    bomber self computing gunsights.
    At this website you can see my K4 gunsight hanging upside down in the
    pic of the belly turret's interior
    Sperry Ball Turret

    At this next website someone gives a very good description of how the
    gunsight operated. ball turret ops

    AT this next website you may enjoy reading about and seeing pics and
    drawings of several different types of gun turrets, but for my Sperry
    K4 belly gunner sight specifically, scroll down until you see the
    drawing of the ball turret and gunner facing you with the caption
    above the drawing reading..."The Briggs-Sperry Model A2 ball turret.
    This drawing shows the ammunition storage system, suspension ring and
    gunner's field of view." Then read the text below that drawing until
    you see... "The Sperry K4 sight was then checked..." and that is
    talking about my gunsight. Here's the link.
    Axis History Forum :: View topic - US Aircraft Gun Turrets in RAF Service

    This next website has quite a bit of info on the Sperry turrets and
    gunsights. It also lists a location for some turret manuals and
    reprints of manuals that cost inordinate amounts. Thus far this is the
    ONLY place I have found mention of manuals, but these are for the
    Sperry turrets themselves and are NOT the manuals and schematics for
    the Sperry K4 gunsights, so I don't need turret manuals. I need
    manuals/schematics for the K4 gunsight itself, not the rotating
    turret. Here's the link.
    B-17 top turret project

    This last link is from our own site here and is about B29 gunsights and info, but it did
    include this below text about the Sperry K4 gunsights used on the B17
    and B24..."Incidentally there were computing sight in turrets going
    into WWII. The B-17 and B-24 has computing sights in their upper and
    ball turrets. The K-3 sight was used in the upper turret of the B-17
    and the K-4 was used in the lower ball turret. These sights were
    similar in their computations or range and deflection but they didn't
    take temperature and acceleration into account. These sights didn't
    use selsyns for position nor did they need to calculate parallax as
    they were mounted inside the turret in front of the gunner. He would
    manually input wingspan and range information and the sight would
    adjust the gun sight. The gunner would keep the sight on the target
    and adjust the range, typically with a range foot pedal. The sight was
    connected with flexible shafts to the azimuth and elevation gear boxes
    to receive position information. They even came out with compensating
    sights for the single waste guns in the B-17, B-24 and the B-25. These
    sights were also connected to the gun mount with flexible shafts to
    give them azimuth and elevation inputs."
    Here's the link to that above text ......

    I gave you a lot to read and if you read it all I hope you come away
    with a new appreciation of WW2 bomber turrets and their gunsights.

    Please help me find the operational, maintainance and repair
    manuals, and wiring schematic for my Sperry K4 belly turret gunsight
    so I can get it operational for future generations to enjoy.

    Thanks for taking time to read all this, I know it was a lot.

    Bill Akins
    Member of the board of directors of the Florida Aviation Historical Society.
    F.A.H.S. Website... FAHS_Website : Florida Aviation Historical Society

    Director of the Sunken Warbird Recovery Team.
    W.R.T. website... The_Warbird_Recovery_Team : The Warbird Recovery Team
  2. bogdan

    bogdan New Member

    Sep 11, 2006
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    Hi Bill, Try giving Greg Rainone aka Pike Bishop <[email protected]> an email. He makes and sells copies of manuals on ebay and I've bought a couple from him. He's had a couple dealing with the Sperry sight previously although none right now. He might make some fresh for you. On ebay he goes by


    his info is

    Greg Rainone
    P.O.Box 189Arlington, TX 76004
    United States(817)461-4867

    Bill Bogdan
  3. Micdrow

    Micdrow “Archive”
    Staff Member Moderator

    Aug 21, 2006
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    Hi, Bill

    The best place that I know is to contact the EAA's (Experimental Aircraft Association) Museum. They own and operatate the B-17G Aluminum Cloud that they put on tour every year. Actually in the museum they have a complete B-17 manual that you can look at or is it a B-24. Any way Im pretty sure that the library there would be able to help you or be able to point you in the right way. Below is the link to the library.

    EAA's Boeing Aeronautical Library

    Hope that helps.

  4. Buster_Dee

    Buster_Dee New Member

    Nov 30, 2006
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    Bill, I'm doing research on the ball as well, for a 3D modelling project. You have better links than I have, but I did want to comment on the range dial. In photos I've seen, there is a cable between the range pedal and sight (of course for the reticule). I think the cable also causes the range x 100yds dial to show the numerical value of your foot position. I would think it's position doesn't make it a primary means of sighting, but it probably provides "confirmation" of the range you estimated when closing the sight ring to the wingspan. Maybe it helped a gunner "train" his foot or possibly allow him to "catalogue" a pattern of fighter attack.

    By the way, you cleared up a lot of things for me (e.g., I thought pictures were showing 100 yards on the dial cap, but now I know).
  5. Buster_Dee

    Buster_Dee New Member

    Nov 30, 2006
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    By the way Bill, does your sight have the backup sight mounted behind the optical sight? If it does, I was wondering if it could be rotated out of the way when not in use.
  6. Bill Akins

    Bill Akins New Member

    Jul 8, 2006
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    Thanks to all for the helpful info.

    Yes Buster_Dee, my sight does have the backup sight and it does rotate out of the way.

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