I sent the link to my partner, who designs propellers (Michigan BS in aero/Stanford MS in aero) for a lot of what we do:
"I’m pretty close to calling BS on the toroidal propeller. I can see where they get the noise reduction, but there is no way it is as efficient. I believe the noise data, but the scale they are working and how they are doing the measurements makes me very suspect."
Much more but I didn't understand it...he'll get into the weeds faster than a Ferrari with bald tires.
Quick Sea Story:
In the 80's DESRON 32 was the surface group that chased Russian subs in the Bering Sea...I did one detachment for a month and we had a lot of contact time of their Yankee-Class submarine with the SH-60B helicopter.
The amount of data that is known based on the noise ant submarine puts in the water is incredible. We knew their side numbers
