For the original context, here's Lewis Galantiere's full translation of the first two paragraphs of the third chapter (The Tool) of Wind, Sand and Stars:
And now, having spoken of the men born of the pilot's craft, I shall
say something about the tool with which they work-the air-plane. Have
you looked at a modern airplane? Have you followed from year to year
the evolution of its lines? Have you ever thought, not only about the
airplane but about whatever man builds, that all of man's industrial
efforts, all his computations and calculations, all the nights spent
over working draughts and blueprints, invariably culminate in the
production of a thing whose sole and guiding principle is the ultimate
principle of simplicity?
It is as if there were a natural law which ordained that to achieve
this end, to refine the curve of a piece of furniture, or a ship's
keel, or the fuselage of an airplane, until gradually it partakes of
the elementary purity of the curve of 'a human breast or shoulder,
there must be the experimentation of several generations of craftsmen.
In anything at all, perfection is finally attained not when there is
no longer anything to add, but when there is no longer anything to
take away, when a body has been stripped down to its nakedness.
It's notably longer than the wikiquote version, and closer to the French meaning.
Dredging Google Books, the earliest I can find is in 1940's The poetry of flight: an anthology, by Selden Rodman, as part of a longer section of text, presumably all by De Saint-Exupéry.
In anything at all, perfection is finally attained not when there is
no longer anything to add, but when there is no longer anything to
take away, when a body has been stripped down to its nakedness. It
results from this that perfection ...
And the same in Air University quarterly review.
This shorter section is quoted by a number of books, such as in 1949's Treasury of the Christian faith: an encyclopedic handbook of the range and witness of Christianity:
"In anything at all, perfection is finally attained not when there is
no longer anything to add, but when there is no longer anything to
take away."
And a longer quote in 1950's Michigan alumnus quarterly review: Volume 58
Sand and Stars: "If anything at all, perfection is finally attained
not when there is no longer anything to add, but when there is no
longer anything to take away, when a body has been stripped down to
its nakedness. ...
The "If anything at all" is dropped in 1950's Philanthropy in America:
Saint Exupéry wrote of airplanes, "perfection is finally attained not
when there is no longer anything to add, but when there is no longer
anything to take away."(1)
And also dropped in 1953's Metal treatment and drop forging: Volume 20. And again, later books either have "In anything at all", or "If anything at all", or drop it.
For the later quote, the only reference I could find is in The new hacker's dictionary By Eric S. Raymond from 1996:
The French aviator, adventure and author Antoine de Saint-Exupéry,
probably best known for his classic children's book The Little
Prince, was also an aircraft designer. He gave us perhaps the best
definition of engineering elegance when he said "A designer knows he
has achieved perfection not when there is nothing left to add, but
when there is nothing left to take away."
