mesh collider problems

[Deltafee]

when I try to add a mesh collider for my cockpit,  when I try make it complex I don't see the green outline. If I try to load the part it simply falls downward through kerbin. 

[JPLRepo]

It's because of the shape I think.
You might have to break it up and make simple copies of the whole mesh in parts.
Or just use primitives in Unity.

[SpannerMonkey(smce)]

10 hours ago, JPLRepo said:

It's because of the shape I think.
You might have to break it up and make simple copies of the whole mesh in parts.
Or just use primitives in Unity.

What he said and i reckon you could likely do it in 3 -4 colliders,  the rear part from minimum to maximum diameter, the fwd section but not the bulge for the canopy or nose, then the canopy and finally the nose, thats the only way i can see that you get a collider that represents the shape. 

The only way to get concave colliders is to contruct the concave area from smaller convex colliders , such as in the image where the canopy meets the fuselage, there. that joint is concave, the arrangement of colliders i suggested would still allow that to be a feature of the model  rather than lost if you apply 1 large collider for the whole frontal area

Check the extreme bottom of the image posted , unity tells you why it is broken, in this case it's because your collider would exceed 255 triangles, which is the maximum for any one collider, you can have as many colliders less than 255 triangles as you want  though, so this in itself is not a real limitation 

However it does pay when making a model to remember that you will need colliders and those colliders will only cover the high points and inverted features cause issues with attached parts hovering over the surface rather than looking attached