As said before, apart from the "one-man-companies" most of them had a (often registered) trademark.
Here are a few of them from here and there:
It is not a surprise that many of them contained stylised wings or birds, some of them propellers. Others were mainly a typical lettering.
Interestingly the swedish Thulin company and the danish Nielsen & Winther had almost the same brand logo.
Rod, since you posted a few advertisements, this New Zealand website (
The Vintage Aviator | Constructors Of Military Aircraft) has a whole bunch of company posters as decoration of the site at left hand. You can also obtain them there, a few british ones but dominating are the colorful german posters.
Does anyone know where one can find similar advertisements of french and US companies?
Cheers
Aquilius