NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Another rhumb line puzzle
From: Peter Hakel
Date: 2011 Jun 5, 12:16 -0700
From: Herbert Prinz <666@poorherbert.org>
To: NavList@fer3.com
Sent: Sun, June 5, 2011 12:34:14 AM
Subject: [NavList] Another rhumb line puzzle
I want to fly from New York, 40°38′23″N 73°46′44″W to Vienna. 48°06’39” N, 16°34’15” E. My autopilot is linked to a magnetic compass. Immediately after takeoff, I want to set the autopilot to the appropriate magnetic course and then not touch it again until I arrive. What is that course? (There be no wind through the entire flight.)
Herbert Prinz
40 38 23N 73 46 44W 48 06 39N 16 34 15E
From: Peter Hakel
Date: 2011 Jun 5, 12:16 -0700
I get a magnetic course almost exactly due east.
Extrapolating the data at:
http://gsc.nrcan.gc.ca/geomag/nmp/northpole_e.php
I get:
Lat: 84.8 N
Lon: 119.7 W
as the coordinates of the north magnetic pole in 2011.
Great-circle distances from the magnetic pole to:
NY: 2751.7 nm => magnetic latitude = 44.138 N
VIE: 2745.3 nm => magnetic latitude = 44.245 N (almost the same as NY's)
Initial great-circle courses from the magnetic pole to:
NY: 130.572
VIE: 40.110 ( ~ northeast… :-) )
diff = 90.462 = change in magnetic longitude from NY to VIE
I attach the calculation for the rhumb-line course from NY to VIE using these magnetic coordinates on input, resulting in:
(magnetic) rhumb-line course = 89.9
which is consistent with VIE's magnetic latitude being just a little higher than NY's.
Peter Hakel
Extrapolating the data at:
http://gsc.nrcan.gc.ca/geomag/nmp/northpole_e.php
I get:
Lat: 84.8 N
Lon: 119.7 W
as the coordinates of the north magnetic pole in 2011.
Great-circle distances from the magnetic pole to:
NY: 2751.7 nm => magnetic latitude = 44.138 N
VIE: 2745.3 nm => magnetic latitude = 44.245 N (almost the same as NY's)
Initial great-circle courses from the magnetic pole to:
NY: 130.572
VIE: 40.110 ( ~ northeast… :-) )
diff = 90.462 = change in magnetic longitude from NY to VIE
I attach the calculation for the rhumb-line course from NY to VIE using these magnetic coordinates on input, resulting in:
(magnetic) rhumb-line course = 89.9
which is consistent with VIE's magnetic latitude being just a little higher than NY's.
Peter Hakel
From: Herbert Prinz <666@poorherbert.org>
To: NavList@fer3.com
Sent: Sun, June 5, 2011 12:34:14 AM
Subject: [NavList] Another rhumb line puzzle
I want to fly from New York, 40°38′23″N 73°46′44″W to Vienna. 48°06’39” N, 16°34’15” E. My autopilot is linked to a magnetic compass. Immediately after takeoff, I want to set the autopilot to the appropriate magnetic course and then not touch it again until I arrive. What is that course? (There be no wind through the entire flight.)
Herbert Prinz
40 38 23N 73 46 44W 48 06 39N 16 34 15E
File:
