Contra-Rotating Propellers - an analysis

[Basil]

There is an excellent analysis about the history and (dis)advantages of this always interesting propulsion configuration by Antonio Filippone:

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/45DA106778D5FF8F7FDD3EB09ACC3479/S0001924022000926a.pdf/historical_development_of_the_coaxial_contrarotating_propeller.pdf

(There are apparently a few editing errors related to the description of pusher / tractor configurations of propellers in connection with the illustrations.)