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The same reason that rays and skates have wings, they're useful in any fluid medium, even when they aren't generating lift.
by EA-3167 3y ago
The same reason that rays and skates have wings, they're useful in any fluid medium, even when they aren't generating lift.
- krisoft 3y ago> even when they aren't generating lift. Yes. But these do generate lift. This is basically an underwater glider[1]. It can change it's buoyancy which would make it sink/raise straight down/up. It uses then its wings to turn this vertical speed into horizontal propulsion. It basically flies underwater in a sawtooth pattern (when seen in a side view). This is a very energy efficient way to go the distance. These machines can loiter for months on a single charge typically. They only need to spend energy on the top and bottom points of their vertical swoops to change their buoyancy. 1: https://en.wikipedia.org/wiki/Underwater_glider https://en.wikipedia.org/wiki/Underwater_glider