Definitely impressive as a proof of concept. A lot of the other problems can be solved with iteration. There are some IP67-rated drone motors meant to both fly and run underwater (available from Westmag for example).

There might be less that can be done about the underwater drag, but if it doesn't need to go long distances underwater that's not as much of a problem. For the RF signal, it can either run autonomously underwater, or use a fibre-optic umbilical, or even convert from an umbilical to wireless when it takes to the air.

If this what can be done with off the shelf parts and 3D printing, imagine what DARPA and the like have been doing for the past 20 years.

Makes the UFO/UAP stories about "it transitioned from the water to the air and back to the water!!" seem way more plausible.

> I'm almost surprised this doesn't already exist after looking at it.

What's the use case? We have very good dedicated aerial drones and very good dedicated submarine drones. If something is technically possible but no one makes it usually it means it's not that interesting

I feel like I've seen some of these before without the variable pitch part

ex. https://www.youtube.com/watch?v=jlMDabBfJp0

that is the thing here. While the project is cool, the drone's underwater drag is very high, while typical such drone of that size is foldable, and thus one can fold it (even if a bit, Star Wars X-wing style) to decrease drag and use say only one or two motors with much greater efficiency as result. Though high speed drone like this https://www.youtube.com/watch?v=7PTsHDFMams may be ok without collapsing.

in some sense it isn't nightnmare, it is already a reality, just non-uniformly distributed. Sounds like you just haven't watched hours of footage from Ukraine. The drones there - in the 10-30km zone from the frontline - are onmnipresent like birds, just the birds of the killing-humans-on-sight kind (and with IR cameras it is 24x7, at night it is even more effective as you don't see it coming, only hear a slight buzz of the props, while the drone sees a warm human even better at night, like a kind of a flying rattlesnake :).

Unprepared NK soldiers in Ukraine facing drones first time https://youtu.be/9BQKfSHqRDk?t=117