Programming Question Need to rotate an airport to correct runway directions

[jambooger]

I have finally adjusted my White Sands.cfg and Earth.cfg files so that Auto FCS works with White Sands. My problem is that the runway is Rwy 05, but I had to land the shuttle in a 60 degree direction so that it will land centerline. I know how to reposition the base by longitude and latitude but is there a way to rotate the base so I can have the runways aligned in the correct direction?

 

[jinglesassy]

Um why don't you just rotate the runway?

 

[Hielor]

I suspect it has something to do with [ame="http://en.wikipedia.org/wiki/Magnetic_declination"]Magnetic declination - Wikipedia, the free encyclopedia[/ame]. Orbiter shows headings based off true north, while runways are numbered off magnetic north (I think that Orbiter might actually get runway numbers wrong in things like the ILS display when the variation is large enough, but I haven't checked). For example, IRL, you should have a heading of 335 when you're pointed straight down runway 33 at KSC. In Orbiter, it shows your heading as 330. This is correct, since the variation at KSC is ~5 degrees W -- the true heading of the runway is 330, while the magnetic heading is 335.

White Sands has a variation of ~11 degrees, which fully accounts for the discrepancy you're seeing. I imagine the correct magnetic heading is around 049 (which would mean that "Runway 05" is the right name), while the correct true heading is around 060.

If the lat/long of both ends of your runway are correct, then your runway is in the correct orientation.

 

[Wishbone]

A question: does anybody need declination displayed in an MFD? Am asking since I already have IGRF 2010 programmed in Precession MFD.

 

[jambooger]

Well my issue is, at the real White Sands that particular runway is 5/23. The way I have it in Orbiter, Auto FCS shows runways 6/24. It works perfectly but I was trying to make it realistic. I can change the runway settings in the White Sands .cfg so that Auto FCS shows 5/23 but then the Shuttle doesnt land on the runway.

 

[fort]

I remember an old topic about autofcs on the M6 forum where Mike Norman, the author, was talking about its module in consideration of that question of true or magnetic north.

But: if one turn the monitor of some degrees...does that could resolve the problem ?

 

[Hielor]

Well my issue is, at the real White Sands that particular runway is 5/23. The way I have it in Orbiter, Auto FCS shows runways 6/24. It works perfectly but I was trying to make it realistic. I can change the runway settings in the White Sands .cfg so that Auto FCS shows 5/23 but then the Shuttle doesnt land on the runway.

Then I suspect that autofcs is deciding what it wants to name the runway based on true north, not magnetic north. Considering that Orbiter names it off of true north, the autofcs author may have done this to match built-in readouts.

If you rotate the runway so it shows 5/23, then it will actually be in the wrong place.

Personally, I'd prefer realism of the location of the runway over realism of what Orbiter calls it...

 

[jambooger]

One thing I might need to add. My White Sands is Hi Res. Im not sure what addon Ive installed contained it. It does really look nice.

 

[fort]

"...The "problem" with runway numbering isn't really an AFCS problem, though I can address it. AFCS gets runway information from the configuration files, involving reading coordinates from the runway description. If the coordinate system is True North based, AFCS will glean a True Heading from the information. The actual runway name isn't based on True Heading at all, but Magnetic Heading. The difference is Magnetic Variation, literally the deflection of a compass needle from True North at a specific location. MagVar at Cape Canaveral is only about 3 degrees, so the difference is barely noticeable. At Edwards, however, it's about 14 degrees. The actual True Heading of Runway 04 is 058 degrees (magnetic heading is 044 degrees). My solution to this will be to include a line for MagVar in the base config file, so Runway 04 gets labelled as Runway 04 instead of runway 06. Note that some config files handle this differently. I've noticed at least one Edwards config file where the true heading of runway 04 was 040, as it was "built" that way..."

Mike

mikey451 Posted: lundi 7 août 2006 about v2.0 and 2.1 and for the case for Edward's runways.

 

[Wishbone]

Added declination and inclination to the current development version of Precession MFD. Will be available as the present workload tide subsides.