Men did not make the earth. ... It is the value of the improvements only, and not the earth itself, that is individual property. ... Every proprietor owes to the community a ground rent for the land which he holds.
Economics is not simply a topic on which to express opinions or vent emotions. It is a systematic study of what happens when you do specific things in specific ways. In economic analysis, the methods used by a Marxist economist like Oskar Lange did not differ in any fundamental way from the methods used by a conservative economist like Milton Friedman.
Thomas Sowell, Ch. 1 What is Economics? in Basic Economics
Enhancing the efficiency of propulsion can reduce fuel consumption and emissions in the air transport sector. Novel concepts such as multiple distributed propulsion systems and integration of propulsion into the airframe could help achieve goals.