Destiny Unchain Online ~Kyuuketsu-ki Shoujo to natte, Yagate『Aka no Maou』to Yobareru You ni Narimashita~ - Vol. 7 Ch. 56 - Core Exposure

[Miserys_End]

The one who made Lycoris think Crim was a scumbag. Pretty sure this will be discovered after the fight. But for now, one more attacker is more important than, "who is she?"

She is not an attacker, least as far as I can tell. She seems more like a shit stirring paparazzi. Was pointed out that thing they are holding is a camera.

 

[Miserys_End]

Sniping fiber ropes (think Old West movies) is possible but impractical and difficult. But this isn't fiber cordage. This would be braided steel cable with a safety factor of 5:1, and a diameter of about 26mm (see Assumption 3, later on). Assuming perfect shots and perfect clean-through holes, it's going to take multiple hits, likely 3-4+ at the same spot to weaken it enough that it finally snaps.

A closer look at the setup reveals a crane equipped with a multi-stranded steel cable (designed to be redundant), connected not to a simple shackle, but a claw hook, which then suspends four smaller-but-still beefy multi-strand wire ropes. And that entire setup is duplicated six times. Gut feeling says it's possible, but not practical.

Engineering time! Time for the SWAG*!
*Scientific Wild Ass Guess.

Assumption 0: The Desert Merrow's systems would not stop bullets fired at the cranes or rigging. (If it blocked shots, then sniping the cranes just can't be done.)
Assumption 1: Lycoris will make any shot she takes, and nervousness won't apply. Given she shoots electrical cabling one-handed from about 50m away back in Chapter 44, and her other exploits since, this is reasonable. (I have put bullets from a revolver into roughly the same size of group at 50m...but only from a benchrest setup. Not standing, and not one-handed.)
Assumption 2: Since the system is automated, it would need an automatic or mechanical latching system to release the crane rigging once the arms are replaced (or else the Merrow would be stuck in the cranes).
Assumption 3: Given the size of the arms and comparing real-world setups, we'll assume each sling and crane is setup for 10 metric tons (tonnes), and DUO accurately models physical materials; i.e. non-creatures are handled via physics simulation instead of hp.
Assumption 4: Lycoris's sniper rifle has power roughly akin to a 7.62x51 NATO round.
View attachment 2720
Figure 1: Something like this. It can automatically release the hook once pressure is off the load (in this case, once the arms are attached and no longer being held up by the crane).

Option 1: Shooting the main body of the mechanism would be the largest target, but that's a hardened steel box. The weak points would be the battery core or the motor shaft, but disabling either one would just lock down the hook, since IRL equipment like this is "fail safe", i.e. when it fails, it does so to a "safe" position (hanging onto the load instead of dropping it unexpectedly). Shooting the case itself would warp the metal, likely also locking it in place.

Option 2: Shooting the sling hook at the bottom. Since this is usually a forged steel part, it would be the mechanically weakest for a bullet impact. On a 10 tonne hook, the narrowest part of the load-bearing arc of the hook (i.e. a bit smaller than "F" on the diagram) would be about 42 mm. Shooting above "J" on the narrow side would not cause the load to drop; shooting above "J" on the thick side would just be additional metal for a bullet to go through.
Forged low-carbon/ordinary alloy steels such as those used in hooks at tough, but not hard (Brinell of about 200 for grade 100 alloy steel such as commonly used in crane hooks); they will smush and deform instead of shattering or breaking when under too much mechanical stress. Cast steels are hard but brittle; they resist changing shape at all until they shatter. Armor plate is a special sauce of medium-hard (sometimes with layers) that will resist both deformation/penetration and shattering. The catch here is that military testing is done against military-grade armor, not load-bearing alloy steel.

[Cue three-hour rabbit hole looking at WWI-era ballistic formulas and installing DOSBox to get an ancient QBasic program to run.]

So it turns out that the math...is squishy. Literally, because metal has to move out of the way of a bullet. There's a formula, but it's basically an estimate and requires comparing to a known result. While WWII US Navy armor steel was comparable in hardness to our hook and the stats of our steel are known...the closest reference result I could find for that material is a 75mm shell...which ends up with clearly-wrong estimates when scaled down to something the size of a human-sized rifle.

But...a crazy person on Youtube did shoot a 7.62 NATO rifle at carbon steel plate (grade 50) and got .457 inches using a sniper rifle-length gun barrel. That's 11.6mm in normal units, but in the wrong type of steel. Thankfully, if all else is held constant, penetration against steel of different hardness varies linearly with the hardness (per an article in the Defence Technology scientific journal, Volume 12, Issue 2). I'm more comfortable scaling this up or down since it's already in rifle-scale, and not starting at tank/naval cannon scale. The paper goes to use calculus so that velocity, hardness, and angle can all vary at once, but that's overkill. Basic rise/run algebra slopes time.

Penetration depth(mm) = -.116 * Brinnell hardness + y
In our YouTuber experiment: 11.6mm = -.116 * Brinnell 135 + y. Solve for y, and that gets us an intercept of +27.3.
Plug in our beefier crane hook and (-.116*200)+27.3 equals...4.1mm.
Lycoris's bullet will scoop out a finger-sized divot, but she'd need 10 or 11 shots to the exact same place to break through the hook...on a single crane.

Option 3: Shoot out the master link, that thing at the top of the hook assembly that connects to the main cable coming down from the crane hoist itself. It's a single loop, but as a critical component, such master links are made to a higher degree of safety and usually a higher hardness of steel to prevent catastrophic failure.
A bit of searching gives that a 11 tonne master link will have a material diameter of about 25mm, and a hardness value of 32-35 HRC...Rockwell system hardness. Since a softer metal would be easier to shoot through, let's give Lycoris the softer option...32 converts to a whopping 302 on the Brinell system. Plug that in to our existing formula:
(-.116*302)+27.3=-7.7?
Our formula breaks. Above Brinell hardness 230, a standard FMJ bullet isn't appreciably plow through steel with the rest of our setup.

Option 4:
Okay, but what about armor-piercing sniper rifle rounds?
...actual tests of people shooting armor-piercing military rounds at softer steels is hard to come by. We do have some stated stats and can solve for the Y-intercept on our linear hardness equation:
"The M993 7.62mm AP Round is capable of penetrating a 7mm thick high hardness armor plate[...]". "The surface hardness of this material is a minimum of 477."
7.7=(-.166*477)+Y, and Y is 86.9
Against our harder crane master link, that tungsten inner slug has 36.8mm of penetration; against the softer sling hook it has 53.7mm.
In theory, a dead-on shot would go straight through either, but a non-deforming penetrator like a tungsten rod is much much more sensitive to angle and shot placement than a jacketed-lead bullet. I don't have the references needed to quantify how bounce-happy the armor-piercing core might be.
Lycoris mentions, however, that she can't use any of the "power shot" skills.

TL;DR/Summary: Against the wire cable, it would take multiple rifle shots to disable a crane. Against the hook or master links holding up the sling assembly, it would take an impractical amount of "same hole" shots to break either; armor-piercing rounds (if separate from the game skills Lycoris lacks) might work but would be subject to angling.

P.S.: Also, there's six crane assemblies, and they're all moving.

Matt from Demolition Ranch has shot heavy elevator cable with a verity of 50cal rounds to little effect. Also while I've seen the Banana boy around, if you wana see real big bore rifles check out Kentucky Ballistics or the above mentioned Demo Ranch. TAOFLEDERMAUS is another good one, but it's mostly about custom shotgun rounds.

 

[Trostishere]

Swimsuit

 

[Daviot]

the wetsuit sleeves aren't detached, that part of the sleeve is semi-transparent

Legitimately even weirder.
P.S. Where is that image from, the raws? I didn't find it when rereading the chapters.

 

[Daviot]

Matt from Demolition Ranch has shot heavy elevator cable with a verity of 50cal rounds to little effect. Also while I've seen the Banana boy around, if you wana see real big bore rifles check out Kentucky Ballistics or the above mentioned Demo Ranch. TAOFLEDERMAUS is another good one, but it's mostly about custom shotgun rounds.

Indeed. I'm familiar with both. I mostly handwaved braided cable because it's impossible to simulate by hand, precisely because it's not homogeneous. A projectile impacting it isn't going to deliver all of its energy to one spot, and angle is going to do all sorts of wacky things. You might be able to do Finite Element Analysis given a beefy professional computer program, but most of those don't do ballistic impacts.

Ironically, one of the best methods to cut through heavy steel cable (and hardened steel for that matter) is water jets...like the 'Merrow's that was disabled a few chapters ago by Crim and Lyco.

Edit: Went back and watched the Demo Ranch video in question; only a handful of cable threads were able to hold the entire elevator cable at full load. The weakest elevator cables have a safety factor of 6:1 or 7:1, so a crane sling with 5:1 would be slightly more prone to failure, but not by much.

 

[Daviot]

I appreciate that you clearly put in a lot of work in your answer
however my thoughts behind asking the initial question were simply: did the fictional devs put this option into the fictional game that prides itself over freedom of action? and the mc being the usual manga mc and being the best at what they do, why did they not think of this?
so yeah I was asking this question from a storytelling perspective and not so much from a physics perspective.

Going back and rereading the arc, there was already a discussion on this as the bros were worried about going out of bounds, and Crim responded that the game "simulates reality" enough for both the boss and the impromptu party to go outside the traditional pathing limits of MMO's. Said Crim line is what inspired me to work up my looong answer, because I assumed narrative limits wouldn't be the limiting issue.

And honestly, VRMMO/neutral interfaces aside, the fact that DUO allows non-programmer-thought-of solutions and procedurally generated quests that make narrative sense is why the manga as a whole is science fiction. It would be near-impossible with today's approach to programming, but if it worked, something like DUO would legitimately be revolutionary instead of just an incremental improvement.

But yes, if this arc was a D&D/Pathfinder/whatever-tabletop-RPG game I was running, and a player asked if they could shoot the cables (despite no specific rules in place), from a storytelling perspective I'd say it'd be difficult but that the players could definitely try.

 

[DepartmentOfTransportation]

Legitimately even weirder.
P.S. Where is that image from, the raws? I didn't find it when rereading the chapters.

yes, it's from

Spoiler: meta spoilers

chapter 57

 

[Al_Azif]

Its already a pretty hard boss that you can only damage at certain points, and its also able to regen? You'd think it will move to a another phase but this one just resets the fight.

 

[1234muse]

Thats the most pointlessly erotic full body swimsuit ive ever seen
Why does it still show armpits
Im gonna lose it

That’s it- the armpits are one of the hotter parts of the body, and one of the biggest areas of heat loss afaik(and one of the places you can get a “proper” core temperature reading) so leaving it uncovered with a wetsuit makes no sense

 

[Kampfarsch]

And the colored patch on the crotch isn't panties; it's reinforcement.

Duh but the color choice makes the intention clear

 

[GalaxionZero]

My favorite cheese strat?
When I was a kid I realised not long after I started playing Strongholds Crusader that horse archers are broken, and cheesing them is easy since ranged attacks don't home towards your moving archers, so if you just keep them moving every enemy volley you just don't get hit at all.

 

[Drumboo]

This arc blows, I miss the main cast and old pacing. The party dynamics and such is what made this enjoyable, but now we've just got this boss fight that's lasted like 1/6 of the total series so far.

 

[x3xdd]

crim is so cute :3 thanks for the chapter!!!

 

[TensaiKuro]

Thats the most pointlessly erotic full body swimsuit ive ever seen
Why does it still show armpits
Im gonna lose it

Chill bro, is just a drawing, you don't need to make her use a hijab, and it's not showing the armpits, it's just a two-tone wetsuit and the part around the armpits is white or another color that create a similar illusion in a colorless manga.
It's similar to this one, but with another color palette:

 

[snake1433]

14 chapters and 5 months we still on this arc. Check chapter 42 I think little someone called the camera girl.

 

[Kampfarsch]

Chill bro, is just a drawing, you don't need to make her use a hijab, and it's not showing the armpits, it's just a two-tone wetsuit and the part around the armpits is white or another color that create a similar illusion in a colorless manga.
It's similar to this one, but with another color palette:

Applying to realism when the artist obviously made a deliberate choice is absolutely silly

 

[AncientWatcher]

One cheese strategy that I have occasionally abused is hammering a boss when they glitch and get stuck in something, or use a method of attack they cannot retaliate against.

 

[Grikath]

Its already a pretty hard boss that you can only damage at certain points, and its also able to regen? You'd think it will move to a another phase but this one just resets the fight.

DPS-test raid/stage boss.

Just as annoying as they are common.

 

[Hotaru09]

The artist's bombarding us with god-tier art every page

 

[Dreadkiwi]

This is seriously the coolest boss fight I've seen in any game or work of fiction.

Giant anti-gravity cyborg mermaid in a massive sci-fi hydro facility buried under a desert.