This is an instance in which the original patent document by which we found the classification does not display the nature of the classification. This classification may involve peculiarities of design and technical principle which are not at all exclusive to aeronautics. The classification has nevertheless entered our data via patents covering inventions which do apply to aeronautics and aviation.
This wiki has 1 patents in category "AT 21a".
Patents in category AT 21a
- Patent AT-1903-20467 (English title: Apparatus for activating a mechanism held aloft by kite or captive balloon, Inventors: Theodor Scheimpflug, Filing date: 1903-11-12)
|Enclosing categories||AT 20, Austrian patent classifications, Patent classification systems|