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    Re: Another artificial horizon
    From: Brad Morris
    Date: 2014 Jan 1, 23:12 -0500

    Hi Stan

    The reason I asked about the auto settling is that the coefficient of friction of the materials at the interface, combined with the down  force, 'may' overcome the last angular motion.

    I say may, because its going to be two opposing forces.  One working towards level, creating a torque at the interfaces.  The other frictional force working to resist that torque.  If the frictional force overcomes the torque, the AH will not settle in the level position. 

    Before trying the experiment again, thoroughly clean the grooves, knife edges and flats.  Leave no particulates behind! 

    Brad

    On Jan 1, 2014 8:57 PM, "Stan K" <slk1000---.com> wrote:

    Brad,

    Nothing on the instrument, and the box just says "Springfield Power Squadron", the previous owner.

    I set it rocking and watched it for a while.  The axis with the knife edges in grooves settled much more quickly that the axis with the knife edges on flat surfaces, but both axes were a bit off.  I tried adjusting it with the Allen screws.  It was getting better, but I ran out of patience after a couple of tries.  I then noticed that there was some scum on the glass, which should probably have been cleaned off before screwing with the screws.

    Stan


    -----Original Message-----
    From: Brad Morris <bradley.r.morris---.com>
    To: slk1000 <slk1000---.com>
    Sent: Wed, Jan 1, 2014 6:32 pm
    Subject: [NavList] Re: Another artificial horizon


    Hi Stan
    Any markings on the box or instrument?
    Self leveling AH.  Have you performed any experiments to determine how good it levels?  Set it rocking and wait until it stops (leveled) and then determine how level it actually is.
    Brad
    On Jan 1, 2014 6:12 PM, "Stan K" <slk1000---.com> wrote:

    I originally sent this message in November 2012, expecting it to elicit much discussion.  Instead, there was only one response, and that was four months later, so I suspect something went wrong.  Since there has been much discussion on artificial horizons recently, I thought I would try again to drum up some "business".

    Stan

    --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
    Since there has been some discussion of artificial horizons lately, I thought I would show one that someone, I don't know who, put a lot of effort into.

    The first photo shows a top view.  The outer diameter is nine inches.  The left and right pivots are knife edges resting on flat surfaces.  The top and bottom pivots are knife edges in grooves.  There is a bubble level for each axis.  The reflecting surface is black glass.

    The second photo shows a side view, where the lead weight, which has lost some of its black paint, can be seen.  It weighs more than I do.  It also shows the stand.

    The third photo shows the case.  Blocks in the lid prevent movement during transport.

    The fourth photo shows the lead weight.  It can be seen that coarse leveling was done by drilling out some of the lead.

    The fifth photo shows the stand alone.

    The sixth photo shows the device in its case.  In the lower right corner you can see an Allen wrench.  Fine leveling is done with four Allen screws around the periphery of the circles, two for each axis.  Once it is leveled there should be no reason to play with these adjustments again.

    If you start the axes rocking, they take a good ten minutes or more to settle, so the leveling works nicely if you stabilize manually, but it needs to be sheltered from the wind.

    Stan




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