Wow

[rcjordan]

Amazing Americas Cup vessels that are part aircraft : EngineeringPorn

https://old.reddit.com/r/EngineeringPorn/comments/10nfc0d/amazing_americas_cup_vessels_that_are_part/

[littleman]

If you showed that to me in the 1980's and told me it would be from the year 2023 I would have believed you.

[littleman]

From that same sub and sticking to a boating theme:

https://newatlas.com/aircraft/toroidal-quiet-propellers/

Toroidal propellers: a radically quieter and more efficient design that can boost fuel economy by 20% when swapped onto a marine motor

Scroll down to see quiet drone propeller prototypes.

[rcjordan]

>quiet drone propeller prototypes.

Toroidal propellers turn your drones and boats into noiseless machines
https://www.designboom.com/technology/toroidal-propellers-quiet-efficient-alternatives-aerial-marine-sectors-01-27-2023/

reminds me of...
Blue Thunder (1983) - IMDb (silent helicopter)
https://www.imdb.com/title/tt0085255/