What is the fine-grained topic of the following text: On the other side of the Iron Curtain, by the mid-1970s, there were three airplanes that could consistently deliver: the then-still-Douglas DC-10-30 (1972, 10,600km range), the Lockheed L-1011 (1972, 7850km), and the Boeing 747 (1970, 8550km). Only return the topic.
Long-range airplanes from the mid-1970s.