On 01/03/2009 06:58 AM, James Turner wrote: > - everyone seems agreed that the GS is a 1.4 degree volume, so 0.7 > degrees above and below the GS line.
I concur. > And the '0.35' degrees per dot > comes up, which basically implies 2 dots from the center line to the > 0.7 degree limit. Sorry, no. Here's a counterexample: http://www.aircraftspruce.com/catalog/graphics/11-05106.gif > Referring back to the ICAO docs that John Denker > posted, and the Mk-VIII manual, which says 0.0875 DDM per dot on the > GS, and the ICAO docs say the GS 'sector' is 0.175, and the half- > sector is 0.0875. Please let's not confuse ICAO (which is quite general) with Mk-VIII (which is just one instrument). > I.e two 'dots' would be the very edge of the sector (0.175 DDM). This > is important because the 'soft' alert limit is defined as 1.3 dots, > and the hard limit is 2 dots. Which again makes sense, and brings us > back to the fact that most high-end GS indicators (Primus, Honeywell/ > Boeing) use two dots either side for the indicator. Please let's write code that works for all instruments, not "most" instruments or "most high-end" instruments. > Sooooo .... my inclination is to add the degrees deviation properties > as discussed, and to avoid 'dots' in the navradio code, Yes, dots are to be avoided. Anything involving dots is just begging to be misunderstood. While we're on the subject: It is good practice to spell out what is meant by "full scale". It could be either center-to-side or side-to-side. (I've made this mistake myself :-) Talking about 1.4 degrees "full sector" (peg to peg) seems reasonably convenient and unambiguous. Also talking about an interval in the form [0 ± 0.7] is unambiguous. > but to add - > ddm properties. DDM? I can't imagine why anyone would want to mess with that level of detail. Deflection as a fraction of full sector is all any Sim World instrument designer needs. Maybe once in ten years somebody should check that the full-sector width is what we think it is, but that's been done now. > Obviously I won't touch the existing 'deflection' > properties, but I hope over time they'll rot. I think they're just fine. I don't see any need for additional complexity. If it ain't broke, don't fix it. > For the Mk-VIII, I'll > convert to 'dots' using the terms defined in the INSTALL manual, which > of course match the ICAO 'half-sector' values exactly. Since the deflection values are exact, why not use them? > I'm not sure where all of this leaves Syd, or other panel designers. > Working in DDM seems a little awkward, Agreed, awkward and unnecessary. ------------------------------------------------------------------------------ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
