Vertical Speed & Vertical Speed at Touchdown

[Mikock]

Hi!

I have some problems with two values of the vertical speed.

I read out to values:

Vertical Speed: 02C8 ( Output = VS * 60 * 3.28084 / 256 )

Vertical Speed at Touchdown: 030C ( Output = VS at TD * 60 * 3.28084 / 256 )

When I am airborn both values show me the vertical speed.

But they have a significant difference.

If the VSI is round 1 - 400 ft/min, the difference will be round about 50-100ft/min and if the VSI increase, the difference will also increase.

When I am flying Cessna to compare the values with my VSI indicator, only the value of "Vertical Speed at Touchdown" (030C) seems to be correct!

What is the difference between these two values?

Thanks for your help!

Michael

[Pete Dowson]

When I am airborn both values show me the vertical speed.

But they have a significant difference.

If the VSI is round 1 - 400 ft/min, the difference will be round about 50-100ft/min and if the VSI increase, the difference will also increase.

When I am flying Cessna to compare the values with my VSI indicator, only the value of "Vertical Speed at Touchdown" (030C) seems to be correct!

What is the difference between these two values?

None. The touchdown value is continuously copied from the current actual value, until the "on ground" flag is seen. That's all it is for, to record the last value before touching down.

Not sure why you think it is a problem. You should only be reading it after landing. What's the point otherwise. Why a "problem"?

As to why they may be different, maybe you are reading them at different times? You've not bothered to tell me which Flight simulator you are using, as that could make a difference too. I haven't looked at the code, but on FSX and ESP the V/S is supplied to FSUIPC by SimConnect when it changes, and FSUIPC will populate both offsets at the same time. Since SimConnect is asynchronous this may be slightly behind the true current value. On other versions of FS the V/S offset might be mapped directly into a "live" FS value, in SIM1.DLL, whilst the touchdown copy can only be copied every frame or so, and so remain slightly behind as in FSX/ESP.

Regards

Pete