On Fri, 2002-06-07 at 22:42, Curtis L. Olson wrote: > You are in luck. :-) Hmm, I'm quite worried that my brain didn't register that this instrument was an HSI (given that I've used the 310 and DC-3 quite a bit). I think maybe I've been using (virtual) digital HSIs too much, and forgot they can be that simple :-)
> 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. This makes sense, but doesn't agree with my reading of the KLN-89B manual (which is what I'm basing a lot of this off). As far as I can tell, the HSI drive (I assume it boils down to an analog signal of some kind, but I know nothing about avionics signalling) does somehow send course deviation in NM. Now, maybe it's implicit that the CDI value is converted into a heading deviation before it's transmitted out, I don't know. The other thing is, IIRC, the 'big' navigation displays in glass cockpits (which, at some level, are a glorified HSI) do use CDI in nm again. As I remember, there's some calibration that each 'pip' corresponds to 1nm, except for ILS localizers where the accuracy is increased by a factor of 4. IANAP, as always ... anyone care to confirm or deny any of this? H&H James _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
