Hardy: Rising elevation after repositioning?

[Will]

Hi Hardy,

I don't know if you are following this thread, but maybe you could take a look at this post:

https://aerowinx.com/board/index.php/topic,7196.msg79473.html#msg79473

When I reposition to RCMP Rwy 20 (takeoff position), the Alt on the Instructor Page rises in a span of about 20 seconds from 392 to 400.

The approach plate for the ILS to Rwy 20 shows the runway elevation as 392', and the elevation given in PSX on Instructor > Analysis > Airport for Rwy 20 is 392.

So why is my aircraft rising to 400?

The answer to this may help solve a different problem, namely that the 400' gets sent to MSFS, and MSFS shows my aircraft hovering over the runway. I tried different combinations of weather settings (including Internet off and on), and the altitude on the instructor page stays at 400. Anything else I can try?

[Jeroen Hoppenbrouwers]

Does changing the subscale a few HPa make the aircraft going up and down? That at least points at a certain data feed.

[B747-400]

I did some test that morning. Below are the exact steps and findings:

- MSFS and PSX running, psx.net router/client NOT startet yet!!

- PSX acft move to RPLC RWY 20 TO position
  initially ALT 392 was set, rising slowly to 399

- now, psx.net router/client were startet, MSFS & PSX successfully connected
  ALT started changing back to 389

- PSX acft move to RWY 20 TO again
  ALT value startet at 392 jumps to 399 and finally jumps back to 389

- psx.net router/client shutdown
  ALT remains at 389

- PSX acft move to RPLC RWY 20 TO
  ALT starts at 392, after 20 sec it changes to 391

All steps above could be repeated as often as desired, with exactly same results.

So, we have three different behaviours: before, while and after psx.net connects both simulators. As I don't know what the progs are doing internally, I am excited to hear the comments of Hardy and Gary!

BR
Hans

[Hardy Heinlin]

Hi Will,

I see a difference of 8 feet at the takeoff position some seconds after the Instructor's repositioning action. The initial elevation command at the new aircraft position is 392 which is derived from the runway database. Then there is an intentional 3 second delay for stabilization. After that a smooth interpolation algorithm starts which interpolates the current elevation according to the elevations of the nearest runway light dots in the PSX scenery. This RPLC runway has a great slope. In PSX a slope is always a straight line from end to end as the database contains just these two elevation points. So in real life a runway profile may look like a roller coaster, but PSX will make that a straight line. Now if you place the aircraft some feet away from the runway end, the aircraft altitude may change by a few feet accordingly, depending on the slope angle. As the PSX scenery is very simplified this slight deviation is actually invisible. In real life with sloped runways the altitude will vary along the profile as well. So, a little variation should be exprected anyway.

I don't know why this 8 feet difference causes a 20 feet difference in your MS scenery. Shouldn't the MS scenery elevation override the PSX elevation anyway? When an add-on injects an elevation data stream into PSX, PSX will use that data instead of its internal data.


|-|ardy

[Will]

Hardy, that's very helpful.

Hans, thanks as well-—that's helpful too.

Putting this together, it seems my PSX behavior is correct, and what's missing in my case (but working in your case, Bode) is that MSFS isn't getting its altitude data into PSX for some reason. It's probably a switch or setting that I misconfigured.