The helicopter has never achieved much success and, for the present purpose, it may be classed with the ornithopter as obsolete. The autogiro, therefore, is the first practical moving-wing aircraft.
Oliver Stewart
Aeolus, or, The Future of the Flying Machine, 1928. The title is explained in the first paragraph of the Introduction:
“The aeroplane is an aerial sailing-ship, its wings are the sails, its source of power the wind. It can claim to be a direct descendant of the family of sailing-ships whose father wsa Aerlus, god of the winds and the inventor of sails.”