Rotation Jump off Runway

[Greg Hateley]

I am getting this effect with xplane, (I think also with fsx) and is anyone else having the aircraft jump off the runway during rotation. For me, rotation is not a smooth effect, and the aircraft seems to suddenly jump upwards when airborne.
I looked at the side view and it seems that the wheels go below the runway during rotation and then they suddenly jump up as the whole aircraft get airborne.
I suspect that the lat and long boost coordinates are centered in the body of the aircraft may account for this effect, and hence the aircraft rotates around this centre coordinate.?? Is there some tweek in xplane I have missed, or some adjustment to null out this effect?
Regards
Greg

[United744]

I see this as well. It is as if the altitudes are not quite the same, so as soon as the aircraft lifts off in PSX, the FSX view jumps vertically.

[Garry Richards]

This is a consequence of PSX having sloping runways, but FSX/P3D having only level runways. To overcome it and achieve a smooth liftoff in FSX/P3D you should set the offset for the departure runway in use (reference: page 13 in the VisualPSX manual).

[United744]

you should set the offset for the departure runway in use

Still seems to do it after setting the runway. It's not always obvious when it happens.

[Garry Richards]

Could you give me an example?

Which scenery generator FSX or P3D?
Which airport?
Which runway?
If this is an addon airport, which one?