Even in 1800, it was understood—by at least one person, a certain George Cayley—that two forces, weight and drag, were antagonistic to flight and that there must be two corresponding forces to overcome them. Today, we speak of thrust, drag, lift and weight, but—with the sole exception of weight—these forces did not then have agreed-upon names. By the time of the Wright brothers, what we know now as “drag” was being called “drift,” a term of such obvious ambiguity that the Wrights themselves dumped it in favor of drag.
Words have many facets. They possess both meanings—often more than one—and connotations, and they often suggest more or less than what they strictly mean. Those connotations can affect the way we think about flight.
The word “lift,” for instance, implies a…
