The AFResearchLab video AFRL Tech Museum Series: Propeller Development begins with the narrator standing in front of four propellers in a sequence transitioning from wood to metal, and what stands out to me at least is a very unusually-shaped two-blade propeller whose blades are extremely wide and thick near the base and taper to a point like a short, squat twisted candle flame.
There is a sign next to it that says something like (just guessing):
Olmstead High Efficiency Propeller
This unusual propeller was designed in 1918 by Olmstead Laboratories and tested at McCormick Field...
I assume that the designer is probably Aeronautical Engineer Charles M. Olmsted (1881-1948).
Here are several other photos of similar propellers:
Question: It's certainly beautiful to look at, but what aircraft was the Olmstead High Efficiency Propeller for? When and how was it used?
The "Olmstead High Efficiency Propeller" is the widest one, 2nd from the right: