On Sat, 19 Jul 2003 16:17:00 -0400 "Norman Vine" <[EMAIL PROTECTED]> wrote:
> Richard A Downing writes: "Norman Vine" <[EMAIL PROTECTED]> wrote: > !!!! WARNING !!!!! > FGFS is *NOT* a navigation tool and *NOT* to be used as such > > However > > >>> from math import pi > >>> SG_RAD_TO_NM = 3437.7467707849392526 > >>> rads = (51.146661 - 51.146667) * pi / 180 > >>> SG_NM_TO_METER = 1852.0000 > >>> rads * SG_RAD_TO_NM * SG_NM_TO_METER > -0.66671999989580399 > > or about 2 feet ! > > Close enough :-) > > Note the FlightGear Earth model makes some assumptions that may > not always yield this good of a result. The assumptions and what kind > of > systematic errors they produce should be obvious to those that read > the code and > understand basic geodetics however IMHO the current > system is *more* then 'good enough' for a simulator as the above > demonstrates. > > Cheers > > Norman > Norman, First, I don't fly real aeroplanes any more - I'm too old and poor. So there is no need to worry that I might try and navigate my Concorde using FlightGear! However, you are missing my point. I want to find out how FlightGear's airport and navaid data is derived from DAFIF, which I assume is derived, for the UK, from the UK AIP. I agree the difference is slight, but I am interested in the algorithm. OK, I'll delve into the code, since no one wants to point me in the right direction. I'm just not content with the UK scenery or airport modelling in FlightGear at present. The minimalist FG documentation on this needs a lot of work - if I can find out the facts I might just write it up. What I would dearly like to do is to write a graphical program to import the default.apt.gz etc, draw the airport, and graphically edit it, including drawing in the missing taxiways, stands and aprons. Position of navaids (with models), building models and the tower (for tower view) would also be useful. And before I'm pointed at FGSD, I've looked - but with almost no documentation it is not usable. Thanks, Richard. _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
