July 29, 201411 yr Commercial Member Can someone tell me what this is? I have the figure of 6378137.000 metres from somewhere but everything I calculate (great circle, bearing, cross track, etc.) is slightly off. Actually, sometimes miles off. For example: KORD - 3CK should be a bearing of 308 degrees and 27nm (43km) but I'm getting 318 and 43nm (71km). Could be that my formulae are up the creek but let's start small... -Dai
July 29, 201411 yr Try using the GPS functions to calculate the distance from 0°N 0°W to 0°N 90°W and multiply by 2/pi?
July 29, 201411 yr Author Commercial Member Good thought Doug. I'll have a go at that when I get home and post my results. -Dai
July 29, 201411 yr The FSX SDK gives the two radii - the polar and equatorial. They are in Terrain and Scenery - Appendix II: The World Coordinate System Gerry Howard
July 29, 201411 yr Following up, the P3D SDK is the same as FSX and doesn't use WGS84. P3D SDK simObject API References calls GetWorldConstants() to return the polar and equatorial radii, so those values can be checked. Gerry Howard
July 29, 201411 yr Author Commercial Member The FSX SDK gives the two radii - the polar and equatorial. They are in Terrain and Scenery - Appendix II: The World Coordinate System Right in the obvious place :blush: Thanks for that. -Dai
July 29, 201411 yr Which formulae are you using for your calculations? I have found the techniques in the Aviation Formulary web site work very well for creating apps or subroutines for solving navigation problems. http://williams.best.vwh.net/ Jim BarrettLicensed Airframe & Powerplant Mechanic, Avionics, Electrical & Air Data Systems Specialist. Qualified on: Falcon 900, CRJ-200, Dornier 328-100, Hawker 850XP and 1000, Lear 35, 45, 55 and 60, Gulfstream IV and 550, Embraer 135, Beech Premiere and 400A, MD-80.
July 30, 201411 yr Dai , I'm using : Earth radius = 3440.065 nmiles 1852.0 meters = 1 nm 3440.065 x 1852.0 = 6371000.4 meters Cheers Karol PS ; from page 182 of FS9GPS MODULE an empirical xml guide v.1.1 By Bob McELRATH June 2011 Earth radius, R = 3437.74677 nautical miles R= 6378.7 kilometers R = 3963.0 statue miles
August 1, 201411 yr Author Commercial Member Which formulae are you using for your calculations? I have found the techniques in the Aviation Formulary web site work very well for creating apps or subroutines for solving navigation problems. http://williams.best.vwh.net/ Not as accurate as he could be e.g. in the example the locations for LAX and JFK are rounded to the nearest arc-minute of longitude and latitude, or 1/60th of a degree. That gives a distance of 2144 when it's actually 2151. If that's out, what else is not quite right? Dai , I'm using : Earth radius = 3440.065 nmiles 1852.0 meters = 1 nm 3440.065 x 1852.0 = 6371000.4 meters Cheers Karol Bob McElrath! I half contemplated buying that book recently but decided it was overkill. COBS... hmmm. That's what the French girl at work called me last Tuesday, then she admitted she'd only learned the word 'cantankerous' on the previous day! -Dai
August 8, 201411 yr Bob McElrath! I half contemplated buying that book recently but decided it was overkill. Sheesh Dai, it's free.
August 13, 201411 yr Author Commercial Member :blush: Eejit here was thinking of something else - of course I've already got that downloaded and safely tucked away!
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