really nice shading! since this ship is almost touching the ground and jugding from your light situation and the light source i would say that the casted shadow could be a bit darker and harder. this is no diffuse light situation where the shadows might get blurry that much. its a direct light from above so the ship must cast a harder shadow imo
but besides the shadow it looks really great! really nice shading mate this image seems to be your best one in terms of shading and realism congrats!