Re: [Flightgear-devel] Compasses, magnetic variation, and stuff

2013-03-13 Thread Alasdair Campbell
On 13/03/13 15:37, Curtis Olson wrote: On Wed, Mar 13, 2013 at 10:20 AM, Torsten Dreyer > wrote: > Yes, it's very interesting. My chart for Ireland specifically warns > about the large variation (+5W) which I'm sure catches people out. And > that's before

Re: [Flightgear-devel] Compasses, magnetic variation, and stuff

2013-03-13 Thread Curtis Olson
On Wed, Mar 13, 2013 at 10:20 AM, Torsten Dreyer wrote: > > > Yes, it's very interesting. My chart for Ireland specifically warns > > about the large variation (+5W) which I'm sure catches people out. And > > that's before you have to add variation due to the airframe ! > > which is call deviati

Re: [Flightgear-devel] Compasses, magnetic variation, and stuff

2013-03-13 Thread Torsten Dreyer
> Yes, it's very interesting. My chart for Ireland specifically warns > about the large variation (+5W) which I'm sure catches people out. And > that's before you have to add variation due to the airframe ! which is call deviation ;-) Torsten ---

Re: [Flightgear-devel] Compasses, magnetic variation, and stuff

2013-03-12 Thread Alasdair Campbell
On 12/03/13 18:48, James Turner wrote: On 12 Mar 2013, at 17:55, Stuart Buchanan > wrote: Now the comments at the beginning of coremag.cxx imply that the module originally implemented wmm2000 and was updated by Wim Van Hoydonck (wim.van.hoydo...@gmail.com

Re: [Flightgear-devel] Compasses, magnetic variation, and stuff

2013-03-12 Thread Stuart Buchanan
On 12 Mar 2013, at 20:18, Alasdair Campbell wrote: > Thank you Stuart & James for your responses, > Stuart, I was not so much interested in what is painted on the ground, but > what is indicated on the slaved > gyro. Your comments have made me reconsider my maths. > > apt.dat shows a true headin

Re: [Flightgear-devel] Compasses, magnetic variation, and stuff

2013-03-12 Thread Alasdair Campbell
On 12/03/13 18:48, James Turner wrote: On 12 Mar 2013, at 17:55, Stuart Buchanan > wrote: Now the comments at the beginning of coremag.cxx imply that the module originally implemented wmm2000 and was updated by Wim Van Hoydonck (wim.van.hoydo...@gmail.com

Re: [Flightgear-devel] Compasses, magnetic variation, and stuff

2013-03-12 Thread James Turner
On 12 Mar 2013, at 17:55, Stuart Buchanan wrote: >> Now the comments at the beginning of coremag.cxx imply that the module >> originally implemented >> wmm2000 and was updated by Wim Van Hoydonck >> (wim.van.hoydo...@gmail.com) to wmm2005. >> The current version is now wmm2010, and I wonder if s

Re: [Flightgear-devel] Compasses, magnetic variation, and stuff

2013-03-12 Thread Stuart Buchanan
On Tue, Mar 12, 2013 at 5:47 PM, Alasdair Campbell wrote: > Now the comments at the beginning of coremag.cxx imply that the module > originally implemented > wmm2000 and was updated by Wim Van Hoydonck > (wim.van.hoydo...@gmail.com) to wmm2005. > The current version is now wmm2010, and I wonder if

[Flightgear-devel] Compasses, magnetic variation, and stuff

2013-03-12 Thread Alasdair Campbell
A couple of evenings ago, while playing around with the SenecaII at my home airport (EGPF), I noticed a small, but annoying discrepancy between the magnetic compass and the runway heading. Having had a look at how the slaved directional gyro in the Seneca works, it dawned on me that I had no id