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Kane Dead Reckoning Computer

By Murray Bourne, 16 Sep 2006

I came across an interesting series of articles recently titled "Manual Calculation - Using a Slide Rule" (link no longer available).

The author, Mark CC says...

I know a lot of people think that the idea of learning to use something like a slide rule is insane in an age of computers and calculators, and that this is a silly thing to post about.

My strong view is that a lot of adolescent mathematics students really struggle because (to use simplistic Piagetian notions) they are still at the concrete operations level and they have not fully progressed to the formal operations stage necessary for abstract thought.

So any kind of device or approach that helps to make mathematics more concrete and visual should be applauded - or at least tried out.

The Kane Dead Reckoning Computer

The discussion on slide rules reminded me of my private pilot days. I was required to buy the (unfortunately named) Kane Dead Reckoning Computer. This was a very clever device that helped in the calculation of:

  1. Time, ground/air speed and distance problems
  2. Fuel consumption
  3. Altimeter and airspeed corrections (for atmospheric pressure and temperature variations)
  4. Airspeed corrections
  5. Density altitude
  6. Drift correction (if you find yourself off course)
  7. Conversions (the flying world uses a confusing plethora of units - nautical miles, knots, km, U.S gallons, Imperial gallons, litres, feet, pounds, kg)
  8. Wind and plane velocity vector problems (hence the name "dead reckoning")

Images courtesy of Greg's Slide Rules.

The circular sliderule face of the Kane computer:
Dead reckoning 1

Detail showing how to do a time/distance/speed calculation:
Dead reckoning 2

The reverse side of the computer showing the windspeed/true direction linear slide. You would put a dot (using pencil) on the translucent circular dial indicating the wind speed and direction, then slide the large metal plate to find your true direction. This plate could be reversed for larger speeds.
Dead reckoning 4

Footnote: I was given an electronic flying calculator which I always carried as a spare - but it was never as easy to use as the Kane computer. This was because the Kane is a visual instrument - the electronic one was nowhere near as intuitive. And besides, with the Kane computer there was no need to worry about the battery dying!

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