Contra-Rotating Propellers

[Zipper730]

I'm curious when NACA started working with contra-rotating propellers?

 

[wuzak]

Curious why you didn't trying search NACA records.

I got a result in less than 2 minutes!

 

[swampyankee]

No later than 1938. See https://ntrs.nasa.gov/search.jsp?R=...=20&Ntt=contra|rotation%20coaxial%20propeller and https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930081502.pdf

 

[Zipper730]

No later than 1938.

November, 1938 the report reads.

There was no research before that evidently.