[ARDF] Have I figured out something new, or not?

[Matthew Robbins]

I wrote this a few weeks ago, then typed "ardf" in the to: block, and
my e-mail sent it to the wrong domain name. Probably a beta glitch...

I was wondering why no one responded.  I figured it was because I
broke the peg on the geek-meter with this one.

Matthew


---------- Forwarded message ----------
From: Matthew Robbins <cedarcreek at gmail.com>
Date: Sun, 26 Sep 2004 23:44:44 -0400
Subject: [ARDF] Have I figured out something new, or not?
To: ardf at gmail.com


I know I tend to be long-winded, at least when I write, but I have to
tell the long version of this story.

As many of you know, Moscow compasses have needles which are held in
place by two pins, one on the bottom, like every other compass made,
plus one on top.  The one on top's major function is to keep the
needle from bouncing when you run.

Earlier in this century, Silva invented the liquid-filled compass
capsule, which greatly steadies the needle.  Liquid-filled compasses
are essential to orienteering.  I'm sure the older readers will
remember dime-store compasses with dry capsules and infinite settle
times.  (Interestingly, the US Army is a hold-out for dry capsules in
their Lensatic Compass.  However, it is not undamped.  It uses
inductive damping to settle the disk.)

The old-style Silvas and most other inexpensive orienteering compasses
use a single pin to hold the needle.

This is the first important part:  Back when I owned only single-pin
compasses, I liked to test their damping by letting them settle, then
flipping them like this: The north side of the needle straight up and
over so the compass is upside down and the north needle is pointing
south.  I then flip it to the side so the compass is now right-side-up
and the north needle is still south.  I then watch the needle and see
how it damps out.  I like this because it's the biggest error you can
input.  The needle attains its maximum speed probably as it passes 90
degrees off, and then it damps.

It was sometime in the late 80s or early 90s when I first heard of
Moscow compasses and how much people liked them.  I didn't know
anybody with one, so I ignored it.  Sometime in the mid-90s, I decided
I was making enough money to buy a new compass (having bought all my
other compasses in college), so I bought a Silva Type 5.  This has a
double pin needle (the wide orange-and-white needle).

When I tried my double flip test, I found the needle would no longer
stay still when the compass was upside-down. You can still do the
test, you just have to immediately perform the second flip.

I've known that the needle won't stay still upside-down for at least 8 years.

Now this is the second important part:  About 2 years ago, I realized
that not only will the needle not stay still when upside-down, it
actually points to north when upside-down.  (Side note: All of my
double-pin compasses seem to be just a tiny bit sticky when
upside-down.  But it seems to be only when you're doing very small
inputs.  For ARDF-type back-and-forth motion, it seems pretty smooth.)

Bob and Dick make these reverse-rosette stickers to stick to compasses
to make them read bearing directly.  In Brno, we bought some Moscow
Compasses that came from the factory with reversed rosettes.

Now this is what I figured out tonight.  I was standing outside in the
dark, in front of my grill, cooking hamburgers.  A few hours earlier I had
run a Brown Course (1 hour 6 minutes---Dick Arnett beat me by 3
minutes---Congratulations!), and my Silva was in my pocket.  I was
thinking about mounting my new Moscow compass to my 2m yagi.  I
currently don't use a reversed rosette.  So I was thinking about what
changes I'd need to make to my workflow to use one.

When I went to college (a science, engineering, and math college), my
best friend and I had endless arguments about whether we were geeks.
It was my position that we certainly were not.  It was his position
that not only were WE geeks, but every single person that went to our
school was a geek.  (Here I'll invoke long-story-short:) He convinced
me.  So I pretty much freely admit that I'm a geek.  Not only that,
but I'm pretty much proud of the fact.

I want you to get this picture in your head.  I'm standing, in almost
complete darkness, in front of my gas grill.  My hands are over my
head, holding my Silva compass upside-down, and I'm looking up at it.
It's dark.  Did I say it was dark?  I can make out the needle, but not
the numbers.

This is how much of a geek I am: The first thing that popped into my
mind (the very first thing) as I looked up at my Silva was: The
rosette is reversed.  That is, when you hold your normal rosette
compass upside-down over your head attached to a yagi (north line of
the rosette lined up on the yagi), you can read the bearing to the T
in exactly the same way as with a reverse rosette compass held
right-side-up at waist level.

So is this widely-known, or is it something new?

{8 Oct 04 Addendum: I have yet to find a needle smooth enough to use
upside down.  I just don't trust it if it's even a little sticky.}

Matthew
AA9YH
Cincinnati, Ohio USA