Black, Archibald (American Society of Mechanical Engineers)
naca-tm-176
December 1922
The author discusses cost of operating commercial airplanes and endeavors to clear up prevalent misunderstandings. Curves of operating cost for varying duration, speed, reserve horsepower, etc. are developed.
An Adobe Acrobat (PDF) file of the entire report:
http://naca.central.cranfield.ac.uk/reports/1922/naca-tm-176.pdf