Here in Germanyicon, it is definitely verboten to apply any symbol designating National Socialism on anything that is on public display. So therefore, a vintage aircraft that is privately owned could display the Iron Cross, but not a swastika on the tail. The only exception is for items displayed in a museum depicting their historical relevance. Germans generally might find the US practise of openly displaying Nazi symbols amusing, but slightly naive. And definitely not to be tolerated locally. Personally, I´m not complaining ...