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Strange effect with Datum position.

I have my airplane that has the wheels on surface correctly in the sim, and if I open weight debug windows in aircraft editor I can see all coloured boxes in correct position, engine, fuel tanks, load stations, are ok but the two green boxes about datum and CG are a little bit upper instead aligned with the prop nose as vertical position ( lateral and longitudinal position are ok with real data ) than If I try to lower the position of Datum ad CG than save and resync , my plane float 20/30 cm over the surface. So I go in Blender and lower my plane and export and my plane has again the wheels on surface but If I open again the weight debug window I will find the two green boxes again upper instead aligned with the prop nose.

Why ? I'm going crazy...
the airplane fly very well but I don't know if could be a problem have the two green boxes not aligned in vertical position with the prop nose , and why happen.

thanks to someone could help me or explain .
As explained previously, it is recommended to have in your 3d software, your airplane centered at the origin and not with "wheels on ground" at the origin, the way virtually all other 3d software programs do it.


This is not your fault, nor can we blame Asobo, for that we must look to Mr BGL, Bruce Artwick. If you look back to the earliest days of airplane creation in the simulator, we can see the aircraft centered. Here's a picture of a FS2004 model in FSDS.

Hi RK,
I tryed to follow your instructions. So I have moved my plane in blender as showed. In the sim I have adjusted the position of datum and cg and the green boxes are in right position.
BUT, as you can see my airplane float over the Surface.
So what I have to do? adjust the position of wheels contact points to put down the aircraft ?


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Yes, once your center is set, you can adjust contact points to meet the ground.
there is something strange again.. I have changed the contact point and when I load the aircraft on the scenery, it has the wheels on the ground, see my picture ( n.1 ) . so seem all ok. but before , when you have the "ready to fly " button and you see a preview ( picture n.2 ) , you see my aircraft float.. only in preview this strange behaviour . Is there any reason ?


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I think it means you need to change your center even further. I know it's tricky, but I haven't experimented around enough yet to be sure.