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    Re: recommendation for slide rule ?
    From: Greg Rudzinski
    Date: 2009 May 24, 11:14 -0700

    The Pickett N3-T virtual slide rule works well. I was able to solve
    the Hc altitude formula to three digits but to get the inverse sin I
    went to Bowditch table 31 (natural trig functions). Slide rule purists
    will cringe but this is a simple practical way to overcome the 10"
    slide rules poor inverse sin scale resolution for calculated altitudes
    above 30 degrees. The WW 2 PBY Catalina navigators may have used
    similar tricks to accommodate the 10" slide rules they favored.
    
    On May 21, 4:00�pm, Paul Hirose  wrote:
    > Greg Rudzinski wrote:
    > > Gary,
    >
    > > � � �It does appear as you have illustrated that the K&E 4080 has
    > > multiple advantages over the Pickett.
    >
    > The K+E 4080 family has the disadvantage that its rear (trig) side lacks
    > a C scale. While you can easily do 2 * sin 20�, or 2 / sin 20�,
    > something like 2 * 3 or 2 / 3 requires flopping the rule to the other
    > side. Also, if you simply want to read the value of sin 20�, you must
    > first align the S and D indices.
    >
    > Like most high-end rules, the Pickett N3 you mentioned has scales C and
    > D on both sides of the rule, eliminating the above annoyances. Scale S
    > is not adjacent to D as on the 4080 family, but this is a matter of
    > taste rather than computational power.
    >
    > The Pickett N3 is one of the few rules with a double tangent scale.
    > This doesn't give the rule any greater accuracy or range, but sure makes
    > life easier when dealing with tangents and arc tangents.
    >
    > Lest anyone think I'm a Pickett shill, let me say the only slide rule
    > I've ever liked enough to buy two identical ones is the 10 inch K+E
    > 4181! It's a nice competent workhorse with everything I need but no
    > frills. The shortcomings I pointed out above are charming blemishes.
    > Part of the fun is working around them. However, if using a slide rule
    > were just a job, I'd rather have an N3.
    >
    > I believe the Pickett "Eye-Saver" yellow was just a marketing gimmick.
    > It's not any easier to read, and I find a white rule more attractive. As
    > far as I can tell, readability is a tie.
    >
    > Note the Pickett doesn't necessarily mean yellow. Their high end rules
    > were all available in white. You'll find them on eBay, but expect to pay
    > more because they're less common.
    >
    > As far as I know, Pickett trig scales were always marked in decimal degrees.
    >
    > On the following simulator you can use a (white!) Pickett N3 to work
    > Gary LaPook's sight reduction example. Just drag the slide and cursor to
    > make the settings. The only difference is that where he says to "line
    > up" the S and D scales (bring their left and right indices into
    > coincidence), you use C and D.
    >
    > http://www.antiquark.com/sliderule/sim/n3t/virtual-n3-t.html
    > (The virtual slide rule requires that Javascript be enabled. After the
    > page loads, it's self-sufficient, requiring no Internet connection.)
    >
    > Note that Gary's azimuth computation has a mistake. The message text
    > says to set the cursor to cos 14�, but the picture and the final result
    > indicate it was set at cos 20� instead.
    >
    > Hein Bodahl wrote:
    > > The Faber Castell 2/83, or even better the FB 2/83N Novo Duplex, is by
    > > some said to be the best ever made. It is a desktop model of double
    > > length. Unfortunatly that makes it sensitive to temperature changes (or
    > > so "they" say).
    >
    > The famous Novo-Duplex, the so-called "ultimate slide rule", is dear to
    > collectors. But I wonder how many of these just sit in display cases.
    > They are so collectible, I'd hesitate to put one to work at home, never
    > mind take it to sea on a small craft.
    >
    > Recently I bought a Faber-Castell 63/82, which has several of the same
    > features:http://www.sliderulemuseum.com/Faber/P030_Faber-Castell_63-82_Biplex.jpg
    >
    > It looks impressive, but in actual use the 63/82 is cluttered and
    > gimmicky. Those auxiliary hairlines are the worst part. They're hardly
    > ever useful, and all those extra lines make it hard to read the scales
    > quickly. And the slide has too much friction and stick slip. Its feel is
    > the worst of any of my plastic rules.
    >
    > To be fair, I grew up with American slide rules. Fancy features like
    > extra hairlines, Pythagoras scales, etc. have never been popular here.
    >
    > Not that we always know better. One ridiculous practice, common on
    > American rules, is to chop off all scales to exactly the same length as
    > C and D. Look at the left end of ST in that N3 simulator. Wouldn't it
    > make sense to carry the scale down to .56�? The K+E 4080 family has the
    > same problem.
    >
    > As the picture of the Faber-Castell 63/82 shows, German makers often
    > extend such scales a little to end them at a sensible graduation.
    >
    >
    >
    > ns...@hotmail.com wrote:
    > > British brand UNIQUE offered several sliderules of cheap
    > construction, but
    > > interesting scale layouts. Among them was so called "Unqiue
    > navigational". In
    > > addition to normal log scales it featured sine and tangent scales
    > located both
    > > on slide rule body AND slide. Allegedly this would make certain trig
    > > calculations easy.
    >
    > That's true. For example, to compute sin A sin B on a rule with trig
    > scales on the slide only:
    >
    > 1. Align the indices, i.e., center the slide so the C and D scales coincide.
    >
    > 2. Set hairline to A on scale S.
    >
    > 3. Pull C index under the hairline.
    >
    > 4. Set hairline to B on scale S.
    >
    > 5. Read product on D at hairline.
    >
    > But with trig scales duplicated on slide and body, step 1 is unnecessary
    > if you use the S scale on the body for step 2.
    >
    > --
    > I filter out messages with attachments or HTML.
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