Please note that in aerodynamics, “lift” is any aerodynamic force that acts perpendicular to the relative wind on an object, so it’s lift whether it pushes a plane up, down, left, right, or pushes a sailing boat across the wind.
Also the keel of the boat that keeps it sailing in a straight line is technically providing lift in the water, although that “lift” is sideways. Also it isn’t aerodynamic lift, but hydrodynamic. The general field is called fluid dynamics, which covers both gasses and liquids.
You’ve got some good answers, but the problem with the air bouncing idea is that it ignores the air on top of the wing, or to the leeward side of the sail. The sail is pushed on by the windward air, and pulled on by the leeward air. (Edit: technically not pulled on, but you can model it that way if you take atmospheric pressure as 0 and anything lower than that as negative; it will give you correct results)
A better way to think about it is flow turning - as the wind moves past the sail, its flow is turned and the momentum change causes an equal and opposite change in momentum of the boat: www.grc.nasa.gov/www/k-12/…/right2.html
So ideally the leading edge of the sail should be parallel to the oncoming wind, and the trailing edge will be by definition parallel to the outgoing wind. The difference in velocity between these two winds multiplied by the mass of air passing over them over time will give you the force acting on the sail.
If the leading edge isn’t parallel, the air’s transition from free flow into contact with the sail will not be smooth, and will cause losses that reduce the efficiency of the sail.
In practice, the way to achieve this parallel flow is to let out the sail until you see “luffing”, which is just the leading edge flapping a bit in the wind. Then you tighten it until the luffing disappears, at which point the sail should be correctly trimmed. As you carry on you can occasionally repeat this process to check that you’ve still got the right angle, as minor shifts in wind or boat direction can change the ideal angle of attack.
This is also called “setting” the sail. So when a ship “sets sail” it’s referring to the fact a skipper would order the crew to “set sails”, which would start them moving. Now the term also means to commence a voyage.
In some bigger boats you have strings called “telltales” on the surface of the sail. If you see them flapping you know the air flow is turbulent, and you can trim the sail until the telltales on both sides of the sail are blown into a smooth line along the sail. If you tighten the sail too much, the leeward telltales will flap. If you let it out it too much, the windward telltales will flap.
A flat surface is much less efficient as it will cause a lot more turbulence on the leeward side. A lot of work has been done to make sails form the most efficient shape, and they are always deliberately curved. The shape will change depending on the tightness of the sheet (the rope that sets the sail) and on its manufacture, but ultimately your sail shape was basically set when it was made. Different sail shapes will be optimised for different types of tack and different tasks, but I don’t know enough about that to explain more. Mainly I know that spinnakers are made for running downwind and the other sails usually have to make do for the rest of the situations, but this article tells you a lot more: en.m.wikipedia.org/wiki/Sail_components
I only just found that article, so if it disagrees with anything I’ve said here I’d defer to it.
Very high performance sails and setups can do some cool things, like racing catamarans with their very sleek hulls and optimised sails allow you to sail in a close haul within 30-something degrees of the wind, whereas most normal sailboats can’t get much closer than 45 degrees.
Edit: This seems like a decent resource for first time sailors, and gives some more in depth explanation of how to set your sails correctly: www.cruisingworld.com/learn-to-sail-101/
This is also where I learned what telltales are called. I’ve never sailed bigger boats much tbh.
Okay, I think that’s most of what I can info-dump on the basis of your question. You landed on an intersection of two of my special interests lol :)
This is one answer to the fermi paradox that makes no sense to me. If we did live in a dark forest universe where everyone was hiding from some oppressive existential threat, how would any of the civilisations learn about it?
They would need to be in contact with one another to discover that other civilisations were being wiped out, but for that to happen, the wiping out civilisation would have to be able to find them as well. If they destroyed civ A, they’d definitely be able to find references to civ B in their ruins, somewhere. I see no mechanism by which a civilisation could observe this enemy in action without being detected.
Unless someone has come up with an answer to this issue, in which case I’d like to see it.
Also, if you can detect them, just telling them that you’ve detected them should change their strategy, because if a basic civilsation like ours can do it then they’re not actually that safe by hiding. The dark forest seems like a really fragile arrangement.
Right but then that relies on not existing in a dark forest. That is, you can detect signs of alien life, but then those signs tell you horrible things.
The situation we have is that we see nothing.
I guess the answer is that some civilisations reach a point where they broadcast themselves and get destroyed, whilst other civilisations reach a point where they receive those broadcasts and don’t reply before hearing the other civilisation get destroyed. So somehow they were listening at the exact right moment to discover that others are getting killed without responding, and that happened enough times that there is a whole universe full of quiet civilisations.
I still don’t see the A to B. I cannot imagine any species curious enough to detect alien life and insular enough to not respond. If we got those signs we would reply immediately, almost definitely.
Right but that’s fragile. All it takes is one group to break the ice and suddenly they’re all talking.
Also, is the theory that we could live in a dark forest because every single species is insular enough to be afraid of such a threat? That means they all have to believe in the threat and yet also no species is aggressive enough to become the threat. But none of them thinks, “Wait, either we’re alone or everyone is hiding. If everyone is hiding, then the threat can’t exist, so we may as well say something.”
Again, it’s fragile. I find it completely unconvincing.
The Prime Directive concept is way more believable to me, as is the idea that life is just sparse.
I remember a writing prompt that talked about how we’re broadcasting all our TV and radio for years then we get a reply that says, “Be quiet, they will hear you.”
Oh okay, so this insular civ broke radio silence to transmit something that will definitely be a big deal and recorded in our news and science papers in extreme detail, and they’re not worried that when the threat arrives they will trace that signal back to them?
I’ve never heard a good explanation for how the dark forest develops and stays stable for any length of time.
As I said elsewhere: that’s no longer a dark forest. The moment one civilisation speaks up, they all know they’re not alone. Then they’re in a different universe, one where there’s no longer a paradox because they’ve found each other.
Idk who downvoted you, I guess people who think the problem with Musk is that he’s cringy or like a cartoon supervillain. No, all billionaires are evil. If you think Gates is a good guy that’s because you don’t understand what it takes to be a billionaire, what he does with his “charity”, or the history of how he’s run his business or destroyed antitrust purely because he was embarrassed at how bad he looked under cross examination. He has the charity specifically to launder his image, and as a result he’s found ways to be evil using it as cover that he wouldn’t have found back in his embrace, extend and extinguish days.
EDIT: Also behind the bastards did episodes on both these absolute jackoffs:
Im curious as I usually use the site very occasionally to get certain electronic parts or order from PCBway like I just picked up some cheap but infinitely better than stock gps antennas for my LoRa T beams and im about to get a set of also still cheap but much better than stock 915mhz antennas but i kinda wanna throw some other...
Oh dang, that’ll save me a bit of time stripping that stuff out. It’s amazing how easy it is once you have just a little bit of understanding of how URLs work. My most common URL hack is getting youtube shorts to play with full controls. You just replace /shorts/[videoID] with watch?v=[videoID]
I used it today to go through this video frame by frame to discover that she in fact didn’t hit her face:
You ever see a dog that’s got its leash tangled the long way round a table leg, and it just cannot grasp what the problem is or how to fix it? It can see all the components laid out in front of it, but it’s never going to make the connection....
If you go through his old videos you’ll see him doing exactly that. There’s a non-zero chance your computer’s guts are in there in excruciating detail.
Unfortunately alt-right crypto weirdos have coopted the term “decentralised”, and so it is with this site. It’s a crypto-based… video… hosting… platform? I cannot for the life of me figure out how it works other than that it mines crypto in the background while you have the site open and if you have an account, you get a cut of the crypto you mined.
I have tried looking into it, but they don’t explain anywhere in their promo materials, it’s literally just “earn while you watch!”, which… yeah no thanks. I’ve been on the internet and paying attention for more than 5 minutes, I know that grift when I see it.
“Decentralised” isn’t enough, you need a way to ban people that is also decentralised, and that’s where federation comes in.
I don’t know if they’re eventually going to coopt “federation”. I wonder if that’s the ultimate test of a social technology - if it can be coopted by reactionaries. The less able they are to do so, the better it is.
I think I just realised that the term “conservative” is just a lie. Just like “pro-life” or whatever other BS they come up with, it’s just a smokescreen to cover their real agenda, which is to dominate others.
That really doesn’t explain how it works. So… the host mines crypto as well as sending you videos? What is the economy supposed to work like? What does the blockchain actually achieve here? Why do people host in that case? Where do they explain this?
Anyway, I’m still not interested in crypto anything. The moment I saw it was blockchain based I noped out pretty fast. I’m guessing a lot of people do and that’s part of why it’s such a reactionary cesspit.
Like we don’t need blockchain for this; regular federation already works.
Peertube is also p2p, so the videos can be hosted apart from the host instance, and there’s nothing stopping peertube instances from maintaining a distributed ledger of references to videos without the blockchain.
Everything you say blockchain does can be achieved via distributed plaintext ledgers. It is solving a problem that doesn’t exist.
As for the earning money part, eventually you do have to connect your personal details in order to transfer crypto to a usable currency, so that problem isn’t really solved either.
Immutability is irrelevant if the point is to maintain a record of posts to prevent censorship. The only thing that matters is that some instances keep the record. Bad actors could try to lie about the posts, but that doesn’t delete the ledger from other instances.
And no, no single instance is responsible, that’s what it means to have a distributed ledger. Distributed ledgers are already a proven technology that is extremely robust against censorship. You may have heard of them, they’re called bittorrents.
In fact, federation is also a kind of distributed ledger since once content federates a record is kept by any instance it is distributed to. It’s a solved problem and not even that hard. Synchronisation consists of, “here’s my latest posts, keep a record of them please”. This is such a basic concept and I don’t know why you called it a “single point of failure”. It is exactly the opposite of a single point of failure.
Privacy is not guaranteed even with Monero, and you’re still getting paid in crypto which is inherently unstable because the only thing it is worth is what you can sell it for, so it goes through boom-bust cycles constantly, and the immutability - when forks aren’t happening - only serves to enable scams. To defeat that crypto people have created banks, defeating the point of a zero-trust system.
There’s no public trust in it and it takes enormous carbon footprints to run, so it’s unsustainable on so many levels. I don’t want to support crypto on any level on principle, so no, I don’t want LBRY tokens. A lot of people feel the same way, and looking at the population of Odysee, a large number of the people who are on board are a bunch of right wing assholes.
I was trying to give pointers to people in comments but it seems whenever I wrote uBlock Origin, “u B lock”, SponsorBlock or “S p onSor Block” (without quotes) the comment would vanish within first minute....
I’ve had the word aliexpress get me a warning for “spam & scams”, and another very short comment got me a temporary ban. I have no idea why, maybe because it looked like fake engagement? I mentioned the phrase “youtube channel”. So strange.
I feel like I shouldn’t keep putting my energy onto that platform and am looking for a good peertube instance to start uploading to.
Windows as a software package would have never been affordable to individuals or local-level orgs in countries like India and Bangladesh (especially in the 2000’s) that are now powerhouses of IT. Same for many SE Asian, Eastern European, African and LatinoAmerican countries as well....
When I was working IT in a place that produced transcripts - so we had loads of typists all using Windows and MS Word loaded down with a thousand macros - the IT department made all of the servers linux based, and all our production was stored on samba shares. The only reason they hadn’t transitioned the entire workforce to linux was resistance from management.
I imagine there would’ve been resistance from users too, but all of the inertia was due to familiarity and had absolutely nothing to do with technical barriers. The entire IT team was frothing at the mouth to be free of Microsoft’s arbitrary BS. Windows caused us no end of headaches.
In fact, because every typist needed a browser open at all times to research legal terms and other details, I had a number of people complain their computer was running slowly. For every one of them, I installed firefox and made it the default browser and told them they’d need to login to all of their online accounts again. Every single one told me I’d “fixed the computer” and it “works so much better now”.
I really like the idea of an activitypub platform tailored towards writing, fanfic or otherwise. You wouldn’t need to specify because the various styles would probably gravitate to different instances.
I’m sure someone will pick it up eventually, because it just makes sense. I actually do have programming skills but no time to devote to something like this. I have no idea how much work it would involve but the general rule I have for things like this is “more than I expected”.
Would a perfectly flat, tight sail on a boat be more efficient than a sail like we all know?
Okay hear me out and this may sound like the ramblings of a lune but i just thought the following....
If many extraterrestrial civilizations were nearby but trying to keep quiet, how would you suggest drawing them out?
What do you think would finally be their, “Enough, we gotta say something!” situation?...
Microchips (i.postimg.cc)
I had to try it to believe it (startrek.website)
What inconsequential or surprisingly good thing can I get from Aliexpress?
Im curious as I usually use the site very occasionally to get certain electronic parts or order from PCBway like I just picked up some cheap but infinitely better than stock gps antennas for my LoRa T beams and im about to get a set of also still cheap but much better than stock 915mhz antennas but i kinda wanna throw some other...
What's the simplest thing humans are too dumb to grasp?
You ever see a dog that’s got its leash tangled the long way round a table leg, and it just cannot grasp what the problem is or how to fix it? It can see all the components laid out in front of it, but it’s never going to make the connection....
[Louis Rossmann] Piracy is COMPLETELY justified: Louis tries NetFlix and remembers why (odysee.com)
Does YouTube block mentions of uBlock Origin or Sponsorblock in comments?
I was trying to give pointers to people in comments but it seems whenever I wrote uBlock Origin, “u B lock”, SponsorBlock or “S p onSor Block” (without quotes) the comment would vanish within first minute....
List of experts advising the EU in support of CSAM legislation has been published (digitalcourage.social)
Random thought: Windows is largely successful because of Piracy
Windows as a software package would have never been affordable to individuals or local-level orgs in countries like India and Bangladesh (especially in the 2000’s) that are now powerhouses of IT. Same for many SE Asian, Eastern European, African and LatinoAmerican countries as well....
What do you think about the idea of creating a fan fiction network based on ActivityPub?
This thought arose when I tried to go to a site with fan fiction, but it was blocked....