I've been reading a few things on other sources about superfluids and what kind of propulsion would work in them. Supposedly a propeller won't work in a superfluid, but I'm having a hard time understanding why.
As the propeller spins, it pushes against the fluid which should have an equal and opposite affect on the propeller, no? Is it that there is also fluid on the other side pushing the propeller in the other direction?
If so, this can only work when the speed of sound in the superfluid is >> than the speed of rotation of the propeller, right? If I somehow had a propeller that could spin an appreciable fraction of the speed of sound, would it be able to cause cavitation in the fluid and actually accelerate forward?
And why is a propeller, which can be seen as being a truncated corkscrew with less than a full rotation, unable to work in a superfluid, but a corkscrew with several rotations can work in a superfluid?
Edit: I seem to have mis-read about the corkscrew. http://echochamber.me/viewtopic.php?t=64408