VS on Landing.

[ricardoherrera]

Hi.

I’m trying to determine the Vertical Speed of the aircraft when it first touches the runway so I can determine how hard the landing was.

I can read the VS of the aircraft and also determine if it’s on the air or on the ground, so what I’m doing now is waiting for the ground flag to turn true to read the vertical speed, but I always get lower values that I’m supposed to.

If anybody has a better clue of doing this I will really appreciate a comment.

(P.S. I’m working with C#)

Regards.

[ddawson]

You probably need to keep track of the previous value you read. A sudden change from one update to the next will be your indication that the aircraft has hit the ground - even if the aircraft has bounced back up into the air before the Sim On Ground variable has become True.

Doug

[Pete Dowson]

I’m trying to determine the Vertical Speed of the aircraft when it first touches the runway so I can determine how hard the landing was.

I can read the VS of the aircraft and also determine if it’s on the air or on the ground, so what I’m doing now is waiting for the ground flag to turn true to read the vertical speed, but I always get lower values that I’m supposed to.

I think it will be extremely difficiult to get an accurate figure, as the vertical speed will be changing a lot faster than you can reas it. The best you could hope to do from an external program is to match or better the FS frame rate in you read loops -- e.g. for 20 fps, read every 50 mSecs. However, of course, doing this you risk slowing down FS and thereby effectively altering what you are trying to read.

However, assuming that you wouldn't expect the touch-down V/S to be substantially different to the V/S a fraction of a second beforehand (based on the pilot's inability to affect it very quickly), I would imagine that you'd get close to the value you want by reading it at, say 250 mSec intervals, and taking the one BEFORE the ground flag gets set, or even the one BEFORE that (or averge the two?). I suspect this is what Flight Keeper does, as if anything it seems to reckon you hit a bit harder that the pilot things.

The only other solution would be for me to try to do it for you, inside FSUIPC, and provide a "touch-down" V/S by getting the last V/S I saw before the "on-ground" flag is seen. It still wouldn't be precise, but at least FSUIPC can guarantee to read it on every frame.

Regards

Pete

[Pete Dowson]

The only other solution would be for me to try to do it for you, inside FSUIPC, and provide a "touch-down" V/S by getting the last V/S I saw before the "on-ground" flag is seen. It still wouldn't be precise, but at least FSUIPC can guarantee to read it on every frame.

I've done this now, in 3.522. Please check the Interim Versions announcement at the top of this Forum.

Regards,

Pete