So i was able to remove the striped parts with meshmixer (FlipNormals tool) then i could add my holes correctly
There are still bunch of errors even if i could remove many of them

structure.jpg

Pretty sure my slicer can deal with the errors on the body, but for the cockpit...it looses all the details

cockpit.jpg

So here is the best i could get :
https://www.dropbox.com/s/2se9hjbve0...cture.stl?dl=0