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Aerospace Identify this aerospace astronomical navigational device?

  1. Mar 25, 2014 #1
    Just got this at an auction and I'd like to know what it is. it's very heavy, and geared to heck and back. nine inches tall. seems serious enough to guide something big. it is machined and engineered beautifully, and everything is still working. clearly high-grade, possibly government contract.

    Surely analog, probably pre-1970. start spinning a gear and almost everything else starts turning rods and gears. what doesn't turn, it turns out, starts turning when you start spinning some other part of it. It is PRECISE, whatever the heck it is. it is not damaged. it's got a (partial, some of it is missing) black metal cover with two high-grade plastic view holes in it that more or less match up with some readable gauges on the device.

    one wheel says 100 MILS Azimuth; another says ELEV 100 MILS. it could be some sort of guidance device...ordnance? nuke? seriously, this is something special. feel free to pass it on to anyone who might be able to help ID it. I feel it is analog; pretty sure it was designed before computer aided design (meaning, it might have taken months, if not years, in engineering time, then many, many hours of assembly). it's got a hand-etched serial number, in four places that I can see: 8572 (stamped in one place, etched in others).

    it weighs about 11 pounds. I think there is little or no steel on it--cast aluminum frame/housing, nickel gears, maybe some titanium. at any rate, reaching out to those who know more so that I can eventually know more. thank you!

    Attached Files:

  2. jcsd
  3. Mar 27, 2014 #2


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    The use of “MILS” identifies it as military, angular measurement. A MIL here is some particular approximation to a milliradian, (1 yard offset at 1000 yards). The elevation dial maximum is exactly 1600 MILS for 90°, that makes 6400 in 360° which identifies it as NATO equipment.

    It is certainly not a navigational device, it lacks the accuracy needed.
    It is not a bomb sight from an aircraft, which would have employed declination, not elevation.

    It was most probably used for ground based gun laying or radar controlled anti-aircraft fire.
  4. Mar 28, 2014 #3
    I'm guessing it's part of a gun turret.
  5. Mar 29, 2014 #4


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    Am speculating, but might have been a part of a mobile air defense turret.
    The NATO ADATS system springs to mind, Swiss designed, used to launch short range anti aircraft missiles from a turreted tracked vehicle. Martin Marietta built a bunch of them in the 1970s, but they were taken out of service very quickly. Before that, in the 1950s\, the Army used the Skysweeper, twin radar directed 40mm cannon on a tracked chassis.
    Looks like a wonderful piece of quality engineering and manufacturing. A manufacturers label would help pin it down.
  6. Mar 31, 2014 #5


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    It is a mechanical analogue “Ballistic Computer”, the computational part of a fire control system.
    It integrated the visual sights or radar with the ammunition characteristics and gun aim.

    The colourful anodised aluminium gears suggest circa 1960.
    If it was from a tank the outer case would probably have been painted white.
    As I wrote earlier, the 6400 MILS on the dials identify it as NATO equipment.

    The large diameter drums sandwiched between gears, are I believe spur gear differentials.
    There are two long cylinders with spiral tracks. One is certainly elevation correction of trajectory.
    The other is well hidden deep on a central shaft, I believe that one is for fuse time setting.
    The time fuse setting suggests it is from a radar directed anti-aircraft gun, rather than a tank.

    The 246 R.P.M. specification suggests a timing function such as used in a predictor or fuse setting.

    Consider the US Army, models M10 – M16 era.

    Does it have “glow in the dark” dial drums marked with radium? It may be classed as hazardous waste.
  7. Mar 31, 2014 #6
    Sir (if that's not presumptuous), I applaud you for your thoroughness and doggedness, surely. I started out knowing that it was a marvelous instrument that I could not bear watching being sold as junk, and now I'm 90 percent of the way to knowing just what it is I rescued, thanks to you. It is quite something to handle and work, I assure you. Not sure yet what I will ultimately do with it--will probably end up selling it somehow to some appreciative buyer--but knowing that it's something that represents hundreds if not thousands of engineering hours, and probably hundreds of assembly hours (and no doubt tens of thousands of government dollars!), I am pleased to have had a hand in keeping it from being scrapped, which is where it was headed. Again, thank you thank you. John
  8. Jun 22, 2014 #7
    Why don't you sketch the parts on the paper as it is and then start working the design backwards to understand its function. That means to reverse engineering. Then u can sell it to the right customer.
  9. Sep 5, 2014 #8
    Out of curiosity, how much did you pay for it? It looks to be quite a nifty piece of machinery.
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