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Pilot watch slide rules
From: Paul Hirose
Date: 2019 Dec 30, 13:03 -0800
From: Paul Hirose
Date: 2019 Dec 30, 13:03 -0800
What a busy watch face: https://www.stauer.com/item/co-pilot-mens-watch-35771/35771 If that's the "Co-Pilot's Watch," one can only wonder what the pilot's watch looks like. I think the slide rule would initially disorient me, as the outer (distance) scale moves and the time scale is fixed. An E-6B is the opposite. But I could get used to it, though driving a car while wearing my strongest reading glasses and fiddling with the watch is out of the question. One customer review says, "I had asked customer service how the Tachymeter function worked (the outer movable bezel and adjacent rings), as there are no instructions for that. I have since researched this and have provided them with a document I drafted that outlines how to do time, distance and rate of speed calculations with the watch." However, I don't see a tachymeter on the watch. There is one on the "Flyboy" watch. https://www.stauer.com/item/stauer-flyboy-blue-watch-35777/35777 Of that watch, someone says, "Which brings us to the rotating slide rule bezel. This is where some improvement is needed. It is a true, bi-directional rotating slide-rule bezel, but some of the numbers are a little out of place, causing some calculations to be a little inaccurate. Treat any calculation results with this slide rule as VERY approximate. Plus, the hash marks around the bezel are too close together and too similar in size to be useful." That sounds like something I would write. One of my favorite slide rule complaints is that the graduations are hard to read without making a mistake (as on the Pickett N4). In that respect the Co-Pilot watch looks much better. I have long thought the usual tachymeter format was far from optimum, since the numbers just clockwise from 12 o'clock are absurdly high for any practical use. But the Wikipedia article explains a method for extending the range downward: https://en.wikipedia.org/wiki/Tachymeter_(watch) Unfortunately, I find it incomprehensible. It seems to be one of those "explanations" which make sense if you already have a clue, which I clearly don't. For instance, you time a mile at 65 seconds, so at the end of the mile the second hand is stopped at the 5 second mark. Speed is about 55 mph, but I don't see how to read that from the tachymeter. Of course you could make the calculation with the circular slide rule. Rotate the outer scale to set 1 mile opposite 65 seconds on the inner scale. Now all possible combinations of miles and seconds — for that speed — are opposite each other. To get miles per hour, observe 55.5 miles opposite 3600 seconds. (Flight computers of the E-6B type have special marks at 60 and 3600 on the time scale to help the user's eye.) The outermost scale on the bezel is graduated in degrees, but the watch description says nothing about a compass function. Even more mysterious are two scales on this "Explorer" watch, one graduated up to 15 and the other to 165 — ? https://www.stauer.com/item/stauer-explorer-ii-watch-stauer-knife-torch-set---plus---joseph-abboud-passcase-wallet-28960/28960