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    Re: Celestial Simulator
    From: Paul Hirose
    Date: 2018 Apr 1, 16:22 -0700

    On 2018-03-31 20:01, Phil Sadler wrote:
    > This does look like it sits on top of the Hound Dog missile star tracker. 
    Sadly, it does not mate with the MD-1 star tracker that I do have. I found 
    the second cable that I needed as well, now I just need a power supply for 
    175 and 280 volts 400 hz to fire it up.
    That's a peculiar power requirement. Some military flightline
    maintenance equipment does run on 400 Hz because that's the aircraft
    frequency. It's convenient if test equipment can plug into the same
    power cart that runs the plane. The B-52 even has an outlet in the
    ceiling of the navigator compartment. However, aircraft voltage is the
    ordinary household value of 120 V with respect to ground, or 208 V phase
    to phase.
    My ASB-16 bombing navigational system maintenance manual from 1980 has
    an illustration of a "three-star simulator" which could be installed on
    top of the MD-1 astrotracker. The part number is 18-0001-00583. I don't
    know the manufacturer.
    It looks far simpler than the device Phil owns. The basic shape is a
    cylinder, width greater than height. Two small vertical cylinders
    project from the top. Possibly these contain the collimators that
    generate the stars. (I suspect there's a third one, not visible in the
    illustration.) Three pillars support a triangular plate above the
    simulator proper. On the plate is a telescopic sight, free to move in
    That plate was the official basis for measuring the B-52 attitude when
    leveling the vertical gyro of the ASB-16. I.e., you would install the
    three-star simulator over the glass dome of the MD-1, then put a
    precision clinometer on the plate to measure the aircraft pitch and roll
    to 1 minute. The mount of the vertical gyro was adjusted so its
    electrical outputs matched the aircraft attitude.
    Pitch and roll could also be measured at a plumb bob target in one of
    the wheel wells, but the book says the three-star simulator is the
    preferred method.
    The telescope provided a precise aircraft centerline for aligning the
    antennas of the bombing and Doppler radars. This required a target stand
    accurately positioned in front of the plane. A guy on top of the B-52
    looked through the scope and talked the stand operator into position.
    I have never seen the three-star simulator in the flesh. Most of my
    duties were in the shop, and when I did work the flightline, a job never
    came up that required the simulator. It didn't belong to the bomb-nav
    shop anyway. If needed it was borrowed from the people who maintained
    the MD-1, who I think were the instrument / autopilot shop. Not sure —
    this was 35 years ago!

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