Interflug GmbH (Interflug Gesellschaft für internationalen Flugverkehr m.b.H.) was the national airline of the German Democratic Republic from 1963 to 1990. It operated scheduled and chartered flights to European and intercontinental destinations out of its hub at Berlin Schonefeld Airport, focussing on Comecon countries. Following the German reunification, the company was liquidated.
Source: Wikipedia

Design #4

Design #4

Design #6

Design #6; 3 variations