When i planes in gmax and export them to mdl and try to see them in fs2k2 they are really huge. Why?I design them in the actual sizes!

A possibility: you're building to English units and your gmax setup is in metric?

I have tried making a box i both 1x1x1 metres and 3x3x3 FeetIn both cases when i try to open them i fs2k2 they are very big.

You probably need to change your scale. Check out the setup portion on this web page.http://www.oregon-coast.net/FS2002/scaling/setup.htmAlso check which version of makemdl.exe you are using, the one that came with FS2002pro or the one from the SDK. It does make a difference.