Firsty, thanks so much Claw and co for the amazing info. Does the incorrect drag for hollow parts apply to user made fairings and service bays as well? I'm using service bays for science equipment and batteries, but I'm not sure if its even needed, or just adds weight. In sandbox mode one can just add whatever advanced parts, but I'm in lower level career mode for my first game, and I've had quite some trouble getting long range planes to be viable for surveys/science. This really helpful thread describes drag as of Oct 2013 (not sure what version) saying that fairings don't help, but that's the old aero model. If they still calculate drag incorrectly, or as if opened, is there any reason currently to use these parts (eg. thermal protection for re-entry), or does adding them simply add weight?