201–210 of 233 posts
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It’s hard to understand, as that’s more or less moving her so he doesn’t kill her.
Great for his fam, bad for the other 8M jews (my grandparents’ families included)
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> Rotor ships take advantage of this same effect by spinning a large vertical cylinder, typically using an electric motor, and using the resulting force for propulsion. I always thought sails were partially defined by being passive. I wonder why these aren't called "rotor fans" if they're electrically driven? Is there anywhere it's discussed when rotors are expected to outperform normal fans? They seem to be used onl…
"Fan" implies the propulsion is in response to air being forced backwards. These rotors create lift in a forwards direction from the wind blowing across them, a bit like having a fixed wing pointing up.
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I wonder how long a magnetic cleaning robot could survive on the hull of such a ship.
After manned narco subs and towed sub capsules were mitigated by new police efforts drug traffickers experimented with magnetically attached parasite containers on the side of large shipping boats. But they didn't have to move.
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You might be thinking of helium, which becomes a zero viscosity superfluid when cold enough.
Hydrogen can diffuse through certain metals and weaken them [1]. Currently, hydrogen storage is costly and tricky for a number of reasons [2]. It’s also very important to avoid leaks into enclosed areas since it’s extremely flammable. [1]: https://en.wikipedia.org/wiki/Hydrogen_embrittlement [2]: https://www.energy.gov/eere/fuelcells/hydrogen-storage-chall...
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Ignorant question: if operational costs trump all, especially fuel (Maersk says in the article 60% of operational cost) why not pure sail power? Is there some other maintenance cost or infeasability there? Or is there another hidden variable that is not satisfied?
I'm not an expert in this topic - I've just read a few books and shipping was covered in a few of my upper division classes. They are the most important factors in the context of reliably shipping goods from port to port. If there was a sail technology that allowed reliable transit, predictable speeds and times (really slow is OK, a little late is not), and didn't cause an increase in other costs (say, insurance or m…
China mines and ships bauxite from Fiji to China.
https://aluminiuminsider.com/bound-chinese-shores-fiji-ships...
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Maintenance is not repairs. The work needed to prevent repairs has to happen ever day. A crew at sea doesnt sit around waiting for an alarm. They are tending to equipment, verifying sensors ... even touching up paint is an essential daily task.
Interesting perspective. I hadn't considered that. Part of me starts to wonder now about building boats that are more resilient, but then I remember that salt water is terrible and surely by now someone would have if it were possible, since we spend so much money on humans doing that maintenance!
> has installed 100-foot-tall rotating cylinders on one of its product tankers
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Why not use electrical propulsion and charge batteries from wind and solar? At first, as a fuel saving measure in optimal conditions (rely on internal combustion engines most of the time). Seems better than pure sail power, even though that is more efficient (due to direct wind to motion conversion).
Re:solar - there was an experiment where they covered a whole tanker with solar panels. During the day, they provided 10% of power....needed to run the lights on the ship. Solar is just nowhere near good enough compared to the needs of a massive ship like this. Wind would maybe work, but then remember that a turbine would effectively slow you down as you'd be pushing against the air.
This is not nothing. It's roughly as much power as a redlined sports car engine. It might be sufficient to fight the worst ocean currents, since propulsion power scales so frighteningly faster than speed.
https://www.maritime-executive.com/editorials/the-future-ult...
It would also make sense, with larger ships, to just implement the nuclear tech we already have.
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Why not use electrical propulsion and charge batteries from wind and solar? At first, as a fuel saving measure in optimal conditions (rely on internal combustion engines most of the time). Seems better than pure sail power, even though that is more efficient (due to direct wind to motion conversion).
Re:solar - there was an experiment where they covered a whole tanker with solar panels. During the day, they provided 10% of power....needed to run the lights on the ship. Solar is just nowhere near good enough compared to the needs of a massive ship like this. Wind would maybe work, but then remember that a turbine would effectively slow you down as you'd be pushing against the air.
A big cargo ship's engine can be 25000kw. The biggest wind turbines (750') generate about 8000kw. So.. three of them? The ship would need to be 1500 feet long just to make room. But the wind isnt constant. Five turbines? Bridges might be an issue.
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"Fan" implies the propulsion is in response to air being forced backwards. These rotors create lift in a forwards direction from the wind blowing across them, a bit like having a fixed wing pointing up.
I'm really interested in how dimpling would affect the drag/lift properties of these. Years ago on /. I saw a post about how wales bumps on the leading edges of their fins/flippers were to increase/modify the eddies around their fins in such a way as to provide them more thrust (or something, it's been years since I read the article) - and I was curious what it would look like to have helicopter blades with leading e…
https://www.autoblog.com/2009/10/22/mythbusters-golf-ball-li...