Glide Ratio widget shows (completely) wrong values about osmand

[vshcherb]

Yes would be good. Minus 40 means that you were not descending... I have tested it during airplane flight
2023-08-13_16-38_Sun.gpx.zip

Please run this track simulation (developer settings) and check if you see something wrong with glide ratio widget. Also please make sure you've downloaded 3D maps

[ManDay]

I downloaded the Polish terrain map and ran the simulation; it looks similar to what I see in real life. The altitude decreases constantly but a GR of ca. -40 is advertised (btw: it shouldn't matter for GR whether I have 3D maps, right?):

output.mp4

A GR of ca. "+"50:1 looks approximately correct in your example, back-of-an-envelope (-18 km/h Vspeed, 870 Speed), perhaps it's just a coincidence? I can not 100% rule out that I, too, had a "+"40:1 GR and the only mistake is the sign, but I think it wasn't even ~40.

[vshcherb]

You should have 3D maps downloaded but not necessary enabled. You have only the average glide ratio but not the target. I have configured average glide ratio for 15 seconds and it displays correct positive numbers as plane is descending.

[ManDay]

Okay, the wrong values come from the fact that I had a 30 minutes GR timespan! With 15 Seconds I also get your values!

I think the algorithm for the GR calculation should be changed. Using a fixed timespan is often not helpful. I will propose a PR for that as soon as I can and I hope for your approval!

In the meantime may I suggest that the range for the duration be changed? GR for aviators is typically used to estimate the current sinking behaviour (which angle, how far will it carry) and this would typically average over something like 5 seconds to 1 minute, depending on the aircraft. For paragliding, for example, 15 seconds is already too long. I don't think a 60 minute average makes a lot of sense.

(Since it's not a bug I would think it okay if we close this issue, if you think so too)

[vshcherb]

Well we need to change min / max value and obviously default to 15 seconds at least

[yuriiurshuliak]

The bug was not reproduced. To reproduce the issue, I imported the mentioned track, loaded the 3D maps, added the Glide Ratio Widget, and set the average glide ratio to 15 seconds. Consequently, the widget displays a positive value.

OsmAnd~ 4.8.0#2422m, released: 2024-05-31

[ManDay]

Yes, there is no actual bug. It was just the setting of 30 minutes average which caused the problem.

Re "not using a fixed duration" average, retract my previous claim that I could come up with another solution. Even when I try to reasonably determine the GR by some other criteria (like speed or oscillation), it eventually all boils down to a single characteristic time, over which we pretty much have to average.

Surely though, the averaged times should be configurable to something like 1, 2, ... 60 seconds, though, as @vshcherb said.