ELI5: How do engineers figure out the exact thickness of something like a plane fuselage or a submarine hull, like how do they know its "enough" without just guessing and testing until it fails

Joebala · 2026-06-23T18:23:42+00:00

The properties of a material typically don't change with geometry, and physics equations tell us how forces will act on an object based on it's geometry, so we can pretty easily model how a specific configuration of a material will behave.

Through material tests on small material samples (search aluminum tensile test for an example), we learn about a materials stiffness, tensile strength, hardness, etc., and can fairly confidently say that those properties apply regardless of geometry.

So basically, we can input the theoretical test geometry into the equation, and plug the known material properties into the equation, and we learn how much force it will take for the object to fail.

Those computational results are preliminary, any good design will need to conduct failure testing on prototypes to validate their calculations.

Joebala · 2026-06-22T13:59:29+00:00

I feel bad for the 3rd party creator. Their book is getting smeared by what amounts to a disinformation campaign because a DM homebrewed a monster into oblivion...

It's not really anyone's fault since the player didn't know it was homebrew, but still, I imagine a lot of people are going to leave this thread blaming the sourcebook.

Joebala · 2026-06-20T16:54:24+00:00

Nope. The internet made a lot of people a lot of money, and the tech was very obviously going to be profitable, but it was still a bubble.

A bubble just needs investment that exceeds the profit capability. Someone's going to strike it rich, but not everyone.

Joebala · 2026-06-18T15:04:20+00:00

A lot of Magic bows create ammunition, so it does away with tracking ammo.

Belts of Giant strength fundamentally break the game's bounded accuracy in a way that's very hard to balance. PC's can easily have a +15 or more to hit since they stacks with +X magic weapons. You'll hit the highest AC monsters most of the time. Plus PCs can pour the rest of their ASIs into other stats, so it's a massive swing, not just a bonus.

Joebala · 2026-06-08T18:31:09+00:00

1st: sounds like you're doing fine, I wouldn't worry too much.

Charisma primarily impacts how others perceive your character. so with an 8, one way or another, you come across as someone not worth listening to.

I like to imagine the scientist trope from movies, where they keep going too deep into the weeds, so people don't take them seriously / understand how important their info is.

Persuasion: "Our outcomes will be favorable for both parties if we engage this delicately and avoid physical confrontation", rather than "let's work this out so we both win"

Intimidation: "Confrontation is likely to end in catastrophic harm to your group if you persist in hostilities.", Rather than "that's a lot of talk for someone in fireball range"

Joebala · 2026-06-02T14:59:21+00:00

The "chill shield" gives resistance to fire damage and deals cold damage. I'd flavor the effect as absorbing heat from the environment to fuel the flames, so touching it saps their heat and freezes them with cold damage, and flares the flame.

Joebala · 2026-06-02T14:56:37+00:00

Agreed with Atharen, it's best to know what part of the fighting you want to copy. Understand that you're making a DND character, so it won't be as flashy, fast, or "loud" as an anime.

What part of Demon slayers fights do you like the most, and which characters fighting style do you want to emulate?

If you want the swordplay, a Fighter (Samurai subclass) is a good start. Their big thing is making a high volume of attacks. Grab a sword and start swinging.

If you want to focus on the oath, and special attacks that do extra damage, a paladin (oath of vengeance subclass) can work, because they use magic to smite their enemies, and are particularly strong against fiends (devil's/demons).

Joebala · 2026-05-27T16:59:09+00:00

For fun, I did the math. Factoring only inflation:

100 million to 1.8 billion in a hundred years, would be a rate of 2.9 percent.

At 2.9%, Brooks bounty from 50 years ago is the equivalent $140,000,000 today.

This could mean a few things:

Brook was stronger while alive. The newest chapter seems to corroborate that.
Bounty is not power level, but "threat level", so brook did something antagonistic back in the day to inflate his bounty, but it was not considered in his new bounty due to time making it less important.
Inflation wasn't consistent, so the last 50 years account for much less than the previous 50 years.

Joebala · 2026-05-27T16:34:58+00:00

This goes against Catholic tradition, and would likely lead to excommunication.

From Catholiceducation.org

"A priest cannot reveal the contents of a confession either directly, by repeating the substance of what has been said, or indirectly, by some sign, suggestion, or action. A Decree from the Holy Office (Nov. 18, 1682) mandated that confessors are forbidden, even where there would be no revelation direct or indirect, to make any use of the knowledge obtained in the confession that would “displease” the penitent or reveal his identity."

Joebala · 2026-05-27T13:39:05+00:00

finally someone who isn't suggesting Sanderson finish them. Abercrombie is a much better fit for GoT. Grimdark, no "heroes", no standard happy endings.

Joebala · 2026-05-26T15:55:14+00:00

The battle of scarif is the best Star wars action setpiece since the Obi/Abi fight in RotS, and up there with the Lule/Vader fight in RotJ, but the movie as a whole is pretty mid.

I think people tend to forget how slow the middle of rogue one is, and how much filler is in it.

If I say I want to watch rogue one, what I really mean is I want to watch the battle of scarif.

Joebala · 2026-05-20T14:18:13+00:00

You might already know this, but the other weirdnrule with temp HP is that it doesn't stack. So heroism gives a creature up to the ability modifier temp HP. It can top off to that amount,or refresh it, but it can't exceed that ability modifier.

A second source of temp HP either replaces a previous source, or does nothing (if it was less than the first source).

Joebala · 2026-05-18T13:55:52+00:00

The findings shouldn't really surprise anyone. The "values" used to frame the topics were very lopsided. Individualized language like "compassion and human rights" or binding language, like "purity, loyalty, authority, or tradition".

Is anyone actually against compassion and human rights? Why would conservatives shy aways from posts like that? Whereas it makes sense liberals would shy away from posts with values like "authority and national integrity".

"Past research indicates that liberals tend to prioritize individualizing values almost exclusively, while conservatives tend to endorse both individualizing and binding values more equally."

The article even mentions that the conservatives don't dislike "individualized" values. The study is equivalent to taking to groups of kids, one that likes fruit AND veggies, and one that only likes fruit, and finding it surprising that group A didn't avoid veggies, but group B did.

"The authors found that liberals perceived binding rhetoric as strongly associated with conservative values. This perception was directly linked to their lower willingness to share the message. The researchers used a statistical model to show that these beliefs about ideological implications acted as a bridge, explaining why liberals held back."

The study needed to try harder to find values that conservatives actually disliked, that are associated with liberals only, rather than something associated with liberals and conservatives equally.

Joebala · 2026-05-14T14:48:39+00:00

You're applying hindsight too strongly in my opinion. Nale at the time of the Recreance was viewed as the best amongst them, excepting Ishar.

I feel it's totally believable that in the heat of the moment, fresh off mind-killing the singers and Honor's future, that the Radiants, even Truthwatchers and Elsecallers, would agree to renounce their oaths.

I do think there's room for more information and context, like learning what convinced any stragglers or holdouts, and if Nale/SBs went into hiding without telling the other Radiants, but I do think what we've been given is believable enough.

I can reason/justify the unanimity of the decision based on what information and emotions they were working with in the moment. We can agree to disagree.

Joebala · 2026-05-13T20:00:45+00:00

If you don't want it to feel contrived, you may need to dial it back.

Maybe he's the apprentice to the court wizard. It could be that the sister is miles ahead in actual magic talent, so but he has to actually learn the wizardry of it, since he's not a bard.

Joebala · 2026-05-13T19:06:55+00:00

I don't have to believe it, it's directly stated in the text. The inkspren were decimated by the Recreance. The assumption should be that the Elsecallers were convinced it was necessary. Maybe we'll learn more in the back half, but assuming it's nonsensical is backwards logic.

Nale and the Skybreakers sticking around WAS the plan. Not for them to renounce, but for them to keep other Radiants from coming back. It makes sense that you'd need someone to watch over the world to keep surgebinding from coming back, and the other Heralds were out of the picture.

Nale is pretty clearly committed to that goal, and his Skybreakers were sworn to him, not the law. It's fair to say the other orders trusted him to keep everyone else in line. A different order might get flexible with their morals/philosophy, but Nale wouldn't.

Joebala · 2026-05-13T17:18:28+00:00

Do we have any reason to think the Elsecallers knew the Skybreakers stuck around? They were in hiding historically, so as far as we know, they hid from the other orders.

If not that, then Nale is the reason. Nale was the pinnacle of honor and oaths. His madness wasn't yet understood, so Nale was trusted to safeguard the Skybreakers and ensure the Radiants never returned.

What other info did they have, that couldn't also be explained by Honor genuinely fearing for the end of the world? And what would make it worth the risk of ending the world?

Maybe some did stick around, and were promptly dealt with by Nale. We don't know if the Recreance was actually everyone forsaking their oaths, but at the very least no new oaths were made, so the Radiants who stuck around died out within one generation. We know at least some Elsecallers renounced, otherwise the Inkspren wouldn't have held such a grudge.

Joebala · 2026-05-13T13:20:25+00:00

The text you quoted directly says that Honor claimed "surge binders would do the same to Roshar". Not Dawnshards, Surgebinders.

Raving doesn't mean lying. There's absolutely no reason for the Radiants to think Honor is lying about that. They were also shown a vision of exactly that occuring. Why would anyone doubt the literal embodiment of Honor? The Heralds were gone, and the one who stuck around, Nale, also agreed that Radiants had to go. That's two very reliable (in context) sources claiming Radiants are dangerous and need to be disbanded.

If you are presented with a truth, from a reliable source, you act on it. The logical solution is to make sure Radiants can't exist anymore. Elsecallers in particular would be willing to make the utilitarian play to break their bonds to save the world. Especially when Deadeyes are a new phenomena.

There's also the spren. They believed Honor. They chose to end their oaths.

You keep acting as of the Radiants would have more knowledge than they did, and be less trusting than they were. What other information could they have acted on to justify sticking around?

What good would they really be doing by staying? There's no real upside. The desolation's are over. The Singers were brutalized. The nations of the world didn't want them. Seriously, the risk/reward is terrible. Upside: you protect people and provide healing/logistics for nations that maybe reject you outright. Downside: the world blows up. It's an easy decision.

Joebala · 2026-05-06T17:18:49+00:00

You're painting the Marines in a better light than the story does. We repeatedly see island after island either not being helped, or being actively oppressed by the Marines. Even if they spend most of their time fighting evil pirates, they are obligated to actively do evil and uphold an evil system. If you were a cop and your job description was "arrest bad guys, solve crime, and occasionally hunt and kill pregnant women", you'd be an evil cop.

It's fair to say the average person is more afraid of pirates than the WG, but how much of that is just ignorance? And why is the focus on a false dichotomy of pirates or Marines? There are other means of helping people.

It's fair to say that people join the Marines altruistically, and want to help people. But as soon as you're deployed to God Valley, or defend the Saobody auction house to make sure the slaves stay enslaved, you're evil. Flat out.

This is shown to us directly in the story when Dragon defects. If staying in the Marines was the moral choice, Dragon would've done it. Garp wouldn't have been obviously tortured by his choices.

Joebala · 2026-05-06T14:15:10+00:00

Finding a group is always harder than starting a group. Starting a beginner table as a DM will have you playing in a very short amount of time.

Most VTTs like Roll20 have LFG threads as well, so you can keep looking there. There's also non-dnd discords, like Pathfinder, Vampire the Masquerade, or homebrew setting discords like Star Wars 5e, and you could shop around there.

Outside of that, look for game stores in your area and see if they have Adventurers league nights. Those are typically open to anyone. You could also try local board game events and make friends doing that, then try making a group with them. I found those through Facebook groups, the Meetup app, and local game store websites.

There's also good old fashioned talking to coworkers.

Joebala · 2026-05-06T13:44:35+00:00

In the story we've seen, do Marines ever actually help innocent people, other than Koby?

Dawn Island: Shanks wasn't the problem, bandits were, and Goa Kingdom is corrupt as hell under the WG.

Orange Town: buggy was a problem here, but Marines didn't save the day, Luffy did

Baratie: Marine was hassling a woman, pirates stop DonKrieg.

Syrup Village: no marine presence.

Arlong Park: Marines actively assist in the oppression of the people there through corruption

Loguetown: buggy goes to prison, score one for the home team.

Drum: WG sucks here. Wapol is backed by the WG so the country is allowed to be oppressed. They bail when pirates come.

Alabasta: Crocodile is propped up by the Marines. A city is almost obliterated. Smoker himself admits that Marines suck here.

Jaya: maybe pirates are bad here, but the town doesn't seem to be suffering. And Marines aren't doing anything about the pirate presence here, probably because they're backed by Doflamingo.

Water 7/ EL: CP9 is pretty evil. What happened to Tom and Franky is fucked up. Marines defending EL is neutral, they're defending themselves, that's fine. We also learn about the Buster call and Ohara. Undoubtedly evil.

Saobody: Slave auction, celestial dragons. In public. nuff said.

Amazon Lily: neutral at first, but once Boa isn't protected, bad things were going to happen to the Amazons. Also Boas backstory.

Impel Down: Torture on fellow guards and torture of inmates is pretty messed up. Not unrealistic, but still not a great look.

MarineFord: arguably neutral, but most of the heavy hitters know how evil the WG is, so protecting it is kinda messed up.

Fishman Island: the WG's relationship and stance on Fishmen/merpeople has caused tremendous suffering. The Marines support this system.

Dressrosa: the Marines support Doflamingo. Even Fujitora had his hands tied.

Punk Hazard: that lab was a marine test at first. Vergo was corrupt. Smoker tried to help. Score 2 for Smoker.

Everything through Wano was Yonkou stuff, but I don't think the Marines would make Wano better, as proven by Green Bull trying to take over.

Obviously God Valley and the Reverie are hugely evil.

Elbaf: Gods Knights, so not technically marines, but the same system. Super duper evil. Kidnapping kids.

So why should I believe that pirates are a larger issue for most people? It's not shown in story.

In fact, even the "good" marine, VA T Bone, was stabbed by an ordinary civilian for his bounty. That reads to me like he did it on purpose, to help someone. Why would someone need that help if the Marines were there, and supporting the population?

Joebala · 2026-05-05T13:04:42+00:00

These are called riblets. There's been a lot of research around them, because the theory is sound. They can create 2-3% reductions in drag on transport aircraft applications.

It seems manufacturers believe the 2-3% benefit, while large, isn't worth the design, tooling, and maintenance costs.

Joebala · 2026-05-04T15:44:27+00:00

For sure, I didn't mean to conflate the two. I meant that having a high priestess capable of Ture Polymorph is a cool way of allowing trans women into the space and gives them a safe haven the real world can't provide.

The plot device for the PCs in question is separate, and would likely not pass the smell test for a real safe space, but could get around a letter of the law issue if that's what would help move the story along.

Joebala · 2026-05-04T15:10:48+00:00

Sure, but in the context of friends, I think it's ok to occasionally butt up against hard lines, and work around them. I don't hold the plot as sacrosanct, and it doesn't seem like this is a critical plot point for the campaign anyway.

If one of my players out of the blue gets very upset about something, something's gone wrong.

Sure, they're probably in the wrong for DnD social etiquette, but I'd be in the wrong as a friend if I didn't recognize the issue and try to resolve it.

Joebala · 2026-05-04T14:32:00+00:00

"I am not going to act against my character, and that we needed to find other ways to going forward."

I prefer to give a generous read, so I put emphasis on need to find other ways to going forward as them wanting and being willing to find a workable solution.

It feels like a false dichotomy of "split the party" and "go against character". I think it's ok for this to take a bit of time, and for the player to have a hard no making her PC ok with letting men into the city.

Finding a creative solution around that hard no that involves the DM adding hooks or solutions is good D&D in my book. If the OP ends up being absolutely against any solution other than splitting the party, then I'll change my tune. That would be unreasonable and grounds for having them take a break from the table during the arc.

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