Date: Tue, 29 Feb 2000 23:56:35 -0800
Reply-To: Greg <yeff@EARTHLINK.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Greg <yeff@EARTHLINK.NET>
Subject: Re: Precision Navigation compass
Thanks for all the info,
I Take it I should Set it to True North.
Enjoy,
Greg
86 Westy
----- Original Message -----
From: John Rodgers <inua@HIWAAY.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Tuesday, February 29, 2000 8:36 PM
Subject: Re: Precision Navigation compass
> Aeronautical maps are oriented to True North, with degrees of Magnetic
Variation
> printed on the chart as either easterly or westerly.. This allows the
navigator
> to make compass/navigation corrections. Alabama is pretty close to the
"Zero"
> or"0" degrees magnetic variation line, whereas Alaska ----if memory
serves.. is
> something on the order of 15 degrees west.
>
> Pilots navigate by flying a course related to true notrh, and a compass
heading
> which is adjusted for magnetic variation in the earth and magnetic
deviation
> (compass displacement due to ferrous metals and induced electrical fields
with
> in the airplane.).
>
> If a pilot flies a true course and a true heading of 360 degrees, with a
15
> degree westerly variation and a 5 degree easterly deviation , he must
first turn
> his airplane so the compass reads 15 degrees west of true north or 345
degrees,
> then add back 5 degrees of easterly deviation, at which time his compass
heading
> will read 350 degrees. That will keep him on a true course of 360 degrees.
Now
> if you want to add in the angular vector of the wind......and the airspeed
of
> the airplane and the calculated ground speed of the
airplane..........!!!!!!
> Well that's another story.
>
> I think most other navigational maps are oriented to true north as well.
If I
> recall correctly the true north pole points at the North Star. I can't
remember
> if the earths axis is around True north or around the magnetic North. I do
> remember they are not in the same place. As a matter of fact the magnetic
pole
> moves a bit each year tracing the perimeter of a circle at the top of the
world.
>
> John Rodgers
> "88GL Driver
>
> Greg wrote:
>
> > Do you Know if maps use magnetic North or true North?
> >
> > ----- Original Message -----
> > From: Mark McCulley <transporter99@HOTMAIL.COM>
> > To: <vanagon@GERRY.VANAGON.COM>
> > Sent: Tuesday, February 29, 2000 1:39 PM
> > Subject: Re: Precision Navigation compass
> >
> > > Not sure exactly what you mean by "adjust compass deviation". You
first
> > > calibrate the compass by putting it in CAL mode and driving in two
> > complete
> > > circles. You can then set the declination according to your location
and
> > > display true north (as opposed to magnetic north). I don't know any
> > accuracy
> > > specs but I'm sure this instrument works better than your typical auto
> > > compass. The compass can detect when it's off (because of an adjacent
> > metal
> > > semi, bridge superstructure, etc.) and displays the word "Distortion".
The
> > > display shows degrees as well as direction (N, ENE, NE, etc.). The
> > altimeter
> > > shows only elevation, not barometric pressure. For accuracy you must
> > > calibrate it at a known elevation (like all altimeters except GPS).
> > >
> > > MM
> > >
> > >
> > > >From: David Beierl <dbeierl@IBM.NET>
> > > >Looks pretty cool -- how do you adjust the compass deviation and how
> > close
> > > >can you get it (to my mind, +/- 15 degrees is not too bad for an
> > automotive
> > > >compass, but +/- 5 would be really nice)? How sensitive is the
> > > >altimeter? How do you set it? Will it show barometric pressure as
well?
> > > >
> > > >david
> > > >David Beierl - Providence, RI
> > > > http://pws.prserv.net/synergy/Vanagon/
> > > >'84 Westy "Dutiful Passage"
> > > >'85 GL "Poor Relation"
> > >
> > > ______________________________________________________
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> > >
>
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