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    Re: Borrowed Bygrave
    From: Brian Walton
    Date: 2021 Jun 17, 20:07 -0700

    It is not necessary to spend money to produce a replica Bygrave type cylindrical slide rule. All parts and equipment are in your house.

    Using a standard 75cl wine bottle, find kitchen containers which are of a similar size. I used a Pringles tube, and a Saxa salt tube. The outer cursor came from a clear lemonade bottle. With his permission, I copied and used Gary LaPook's graph, published here. Only scissors and spray on photo glue, plus some scotch tape were needed.

    After practice at home, I elected to add the operating procedure on a sheet attached by elastic bands. The clear outer tube enabled me to add extra info such as MOB and refraction corrections, visible through the clear plastic. Operation, when you get the hang of it, is like marching; left right, left right, left right.  The initial input for the 2nd and 3rd movements are the answers of the preceding movement. I wrote each answer directly on the sheet on the Bygrave.

    The Bygrave works. A marine sextant works. A clock works. An open biplane works. When you combine all of those, using the equipment flying a biplane solo several times, you will quickly discover 2 elephants in the living room.

    The materials I used are deliberately fairly soft. You will inevitably knock switches, obscure instruments, and maybe drop the Bygrave on the floor amongst the rudder, stick and brake cables. 

    I reported all this on Navlist about 10 years ago.

    Brian Walton


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