James Turner writes: > As a result of playing with with routes / flight plans, one thing I > forsee in the future is driving navigation instruments from a non-radio > source (i.e something like the NAV / GPS toggle which I'm led to believe > is common in many GA craft with a GPS fitted). > > Now, the problem is that such systems (as far as I can tell) expect to > drive a CDI bar on the HSI based on distance (in nm) off course. So, I > have two problems: > > - we don't have an HSI. I'm pretty sure I could knock something up, but > perhaps someone with some actual artistic talent ought to have a go.
Also try --aircraft=c172-ifr > Bonus points if it supports multiple sources (eg VOR + ADF or 2 > VORs), I believe our current HSI supports one VOR + ADF. > or an integrated glide slope display. Yes, it has an integrated glide slope. I don't know if we model any specific real life HSI or if we just have something that is generically representative. > Mechanical or digital, either is fine with me. Well ultimately this is software so it's all "digital" but I think we are trying to make it appear as if it's a mechanical HSI. :-) > As I said, I don't think there's any special problem building such a > thing with the current layers model in the panel (except that the > HSI gauge will be more complex than usual), I just don't have much > experience doing such a thing. You are in luck. :-) > - I'm not clear how to generate (in radiostack.cxx) the course > deviation in nm based on the VOR signal. How is this done in real > life (google didn't turn up any useful docs)? I can imagine a way > to calculate the distance off course *if* the VOR has DME > co-located, since you use the heading deviation (which is what the > current code deals with, and the current gauges display), and then > do some trig to find the distance deviation. But this doesn't seem > 'right', unless HSIs are a lot more complex than I thought (and they > used to be mechanical, I'm pretty sure) Someone correct me if I'm wrong, but my understanding is that the needle deflection is relative to how many degrees you are off course. Let's say for instance that the needle deflects 1 tick for every degree you are off course. So, if you have the 45 degree radial tuned in, but you actually need to fly a heading of 42 degrees to get to the VOR station, the needle will be 3 ticks to the left of center. Similar behavior for the glide slope needle. Thus as you get closer to a station (or closer to the threshold on an ILS approach) the needles get increasingly sensitive. Regards, Curt. -- Curtis Olson IVLab / HumanFIRST Program FlightGear Project Twin Cities [EMAIL PROTECTED] [EMAIL PROTECTED] Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
