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Pierre, is that ignoring the fact that the diameter of the earth will be reduced
as we move from the equator to the poles. so that "degrees east" and "miles
east" will not have the same value as latitude changes?

Is that "good enough" for DR, or is there a formula that would also compensate
(for both lat/lon) as latitude changed?

----- Original Message -----
From: "Pierre Boucher" 
To: 
Sent: Saturday, June 24, 2006 10:47 AM
Subject: Re: I knew where we were, but where are we now?


> 40 deg 07 min N -> 40.12 (rounded)
> 44 deg 37 min W -> 44.62 (rounded) not needed
> Course 090 -> Course N 90 E
> distance traveled 56.88 Nm
>
> To find DLat (difference of latitude in minutes of latitude)
> distance traveled x cos(course) = Dlat
> 56.88 x cos 90 = 0
>
> To find DLo (difference of longitude in minutes of longitude)
> distance travel / cos(mid latitude)
> 56.88 / cos 40.12 = 74.4 = 1 deg 14.4 min (Eastward)
>
> New DR?
> New latitude
> 40 deg 07 min N + 0 = 40 deg 07 min N
> New longitude
> 44 deg 37 min W - 1 deg 14.4 min = 43 deg 22.6 min W
>
> Pierre Boucher
>
> Guy Schwartz a ?crit :
> > This has probably been discussed here before, but hopefully someone will
help me out. I'm trying to find the formula for caculating your DR after
traveling from a know position.
> > For instance:
> > Last Fix
> > 40 deg 07 min N
> > 44 deg 37 min W
> > Course 090
> > distance traveled 56.88 Nm
> > New DR?
> > It would be a big help to me if someone that knows the formula could
incorparate the above example so I could follow along.
> > Thank you,
> > Guy
>
>
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>

   

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