Hi, I’m currently testing some SimConnect functionality in my app. Now, I encountered a bit of a trial - I don’t see any indication of Touchdown VSpeed in the documentation. How to get it? For now, I use 6Hz queries, which check if SimOnGround status has changed, and when we touched ground, the current VSpeed is saved. But I think that solution has some flaws, because (in my opinion) VSpeed in that query can occassionaly be a value, that it was not Touchdown VSpeed.
I use the SimOnGround flag with 1 second interval. I haven’t found a better solution than that.
For now, I use SimOnGround too, but with 6Hz querying - just as I mentioned before. It’s faster than 1 second, but still, probably flawed…
I’ll recommend the way I read and calculate the touchdown Vspeed.
The 6Hz polling is fine.
You already read the VS, and it’s x02C8 - the singed offset as 256 x meters/second - so for the appropriate feet/minute the conversion goes like 603.28084/256.
Now, at the same time we can also read x030C - it works the same way as x02C8 (so it’s the vertical speed), however it is not updated while there’s the SImOnGround flag set (that is x0366).
Works very precisely in MSFS, and I rely on that with every FSTD/instructor station I design.
You should probably have said that this is using FSUIPC7. while the OP is using SimConnect directly. From the offset status documentation for 0x030C:
Vertical speed, copy of offset 02C8 whilst airborne, not updated whilst the “on ground” flag (0366) is set. Can be used to check hardness of touchdown (but watch out for bounces which may change this).
But you are correct in the way that FSUIPC determines this ‘touchdown vspeed’.
John
If the 6 Hz interval is an issue here: you can also query simulation variables “per simulated frame”. And you can also register your request such that you only get informed whenever the value actually changes.
See the SimConnect API documentation about RequestDataOnSimObject for details, specifically about the parameters:
- Period (-> SIMCONNECT_PERIOD_SIM_FRAME)
- Flags (-> SIMCONNECT_DATA_REQUEST_FLAG_CHANGED)