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Starsector 0.97a is out! (02/02/24); New blog post: Simulator Enhancements (03/13/24)

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Author Topic: realism overhaul: Replacing flux system with reactor system and energy system  (Read 9368 times)

intrinsic_parity

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LMAO imagine using experience playing tank video games to make arguments about hypervelocity physics. (this was made by the aerospace engineering gang)

I clearly stated that only a small fraction of the energy would need to be converted to heat to vaporize the object and I wasn't suggesting that anything like a 100% energy conversion would actually occur.
... even if a small fraction of the total energy were converted to thermal energy, aluminum would vaporize...
If as you stated, the velocity changed from 20 km/s to 19 km/s and only 1% of the lost energy was converted into heat, aluminum would still reach 1.55 million degrees C (again using a bunch of bad assumptions, but the even if the order of magnitude is off by 2, it still proves the point). There's so much energy involved that if any noticeable amount is converted into heat, the object would vaporize.

Tank shells are fired at a small fraction of orbital velocities, and kinetic energy grows with velocity squared so the difference between a 1500 m/s armor penetrating round (https://en.wikipedia.org/wiki/Armour-piercing_fin-stabilized_discarding_sabot) and 20000 m/s is a factor of 177 (i.e. 177 times as much energy). Tank shells are designed to work at specific velocities and with the material properties associated with impacts at those velocities. Arguing those principles extend to much higher velocities is ridiculous. Any chemically reactive material would undergo reaction on impact (i.e. explosives detonate on impact), and then the result would be a bunch of plasma (explosion + impact would definitely release enough energy for that) that could be redirected with magnetic fields. Would that actually work? Who knows, but trying to use modern military tank shells as evidence for the behavior of a 20 km/s projectile is nonsense. We have very little idea how those sorts of events would actually occur, because they've never happened where we can observe them to take measurements etc. We can't do much beyond computer simulations (based on our assumptions) of that sort of velocity on earth.

For reference, here is video of an impact experiment at 2 km/s
The aluminum sphere and impact area are clearly behaving as a fluid and that's only 2 km/s, slightly faster than the high velocity armor penetrating tank shells cited (you can find that information in the youtube description)

Also here is a paper studying some hypervelocity material properties through computer simulations
https://www.researchgate.net/publication/257657164_The_12_th_Hypervelocity_Impact_Symposium_Large-scale_Molecular_Simulations_of_Hypervelocity_Impact_of_Materials
There's some discussion of ionization so magnetic field based deflection approaches seem potentially plausible.

I found some other papers but I can't share them because I only have access through my university
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Goumindong

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Kinetic impacts do indeed produce thermal impacts.  Most modern kinetic penetrator “explode” as a result of the kinetic impact. Other examples include meteor strikes. When meteors enter the atmosphere they collide with the gas and heat it up via compression. This produces what we know as reentry heat. This can heat the meteor enough to cause them to explode in the air. If it impacts the ground it will also produce heat and an explosion.

So like, you can say the math doesnt work all you want but well... it clearly does... You have probably seen it happen.

Realistically hypervelocity weapons aren’t the be all and end all of space combat nor are missiles nor do whipple shields protect from hypervelocity rounds*. Lasers can kill kinetic rounds just as well as they can anything else (you can vaporize a projectile as easily as a ship with a laser) and hypervelocity weapons are mass and energy intensive. Lasers of course have range issues but these become increasingly less relevant  the closer you get to the energy required to shoot hypervelocity weapons

*the splatter is, after all, still traveling very fast. You’re at the mercy of the same total energy equation as if it has hit the ship and the total energy equation turns your ship into a slag of molten parts regardless of wether or not you you have a kilometer of whipple shielding in front of you.

Of course none of that matters because I don’t want to play a realistic space simulator. In a realistic space war simulation either no one ever meets or everyone dies instantly. Which is boring. I want to turn the safeties off and make “dakka dakka” noises as and teleport over missiles. That is not boring.
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Mr. Nobody

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Y'all niggas need Children of a Dead Earth
Ancient meme plz no ding dong bannu
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On the left half of the Bell curve

Sutopia

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LMAO imagine using experience playing tank video games to make arguments about hypervelocity physics. (this was made by the aerospace engineering gang)

I guess I should change my previous post to TL;DRT(didn't read through)

Aerospace does NOT care about artificial projectiles encountered, at least you don't see them on public papers. Maybe they do exist in military researches.

I have no idea why you insist using aluminum, not to mention sphere is not even made to do any penetration. None of the AP shells are made of those fragile metals. Plus, the projectile is not large enough.
A typical modern APFSDS or APCR shell would be made of Tungsten carbide, which has a melting point at over 3k K and boiling point at over 6k K.

The point is, heating process does not instantly heat up entire shell and vaporize it, given the shell large enough. Only the impact area would be heated up.
For properly designed  warhead, it would be designed to deal with such impact-caused wear. For instance, additional coatings or just make it a literally kinetic "pin".

Molecular simulation is not very credible to say it would be same for macroscopic hyper-velocity impact. What I see in the report is they fire nano-particles all around, but that would be very different from the case when moles of particles - that is some kg-weight warhead - just shatter like that.


 Lasers can kill kinetic rounds just as well as they can anything else (you can vaporize a projectile as easily as a ship with a laser) and hypervelocity weapons are mass and energy intensive. Lasers of course have range issues but these become increasingly less relevant  the closer you get to the energy required to shoot hypervelocity weapons


I'm not sure about this but LASER have very narrow spectrum thus if enemy knows your operation wavelength they can apply high reflectivity coating against it. For instance, silver has 99.9% reflectivity against any visible light.
« Last Edit: December 26, 2018, 05:25:22 PM by Sutopia »
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Goumindong

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Material doesn’t matter all that much at hypervelocity speeds. Only mass. Aluminum was just convenient to get it going that fast*. If you get hit by a potted plant going 30km/s you will explode in a ball of fire. Back of the envelope it contains about 14 tonnes of TNT worth of explosive energy(1KG plant)

If you want to rule out lasers for whatever reason you can still kinetic kill hypervelocity projectiles with non-hypervelocity projectiles.

*semi-technically hypervelocity occurs when the impact velocity is higher than the speed of sound in the object. This is the point where solid materials can behave as liquid. Vaporization won’t occur until much faster speeds however we are talking dumb science fiction so we can suppose Delta V at whatever fraction of C we want!
« Last Edit: December 26, 2018, 07:12:22 PM by Goumindong »
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intrinsic_parity

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**some of this was already said by @goumindong but I typed the whole thing so I'll leave it**

The exact material doesn't matter for the point I was demonstrating, aluminum is an easy example and commonly used material in aerospace applications. Doubling the melting temperature does not matter if the energy involved is orders of magnitudes higher than the the amount required to melt either material. Tungsten carbide actually has a lower thermal capacitance than aluminum meaning it takes less energy to raise its temperature so it may perform worse in that respect.

Molecular simulations are necessary to understand hypervelocity impacts because assumptions about molecular interactions break down at such high energies. A macroscopic collision is just a bunch of molecular collisions. The point of citing the article was to point out that ionization is happening on the molecular level during a 20 km/s collision meaning it may be plausible to deflect the projectile using magnetic fields once it has gone through an initial impact causing ionization. Not to mention you could heat it will a laser to help ionize it also.

More broadly from the article, you can see that we have a poor understanding of what really happens when material collide at 20 km/s. Arguing that something would happen at 20 km/s based on happens at lower speeds is nonsense. The design principles that work at certain temperatures and velocities do not hold for all temperatures and velocities. 20 km/s is dramatically different from 1.5 km/s so ideas that work for tank shells will not necessarily work for a hypervelocity projectile. Citing tank projectiles as evidence is not valid.

Another example of high energy/velocity phenomena is reentry gas dynamics. Figuring out the aerodynamic forces and temperatures for a vehicle reentering the atmosphere at a couple km/s is totally different from figuring out the forces on an aircraft, even at supersonic speeds. This is because the assumption that the gas is in thermodynamic equilibrium no longer holds for reentering vehicles and chemical reactions begin to occur because there is so much latent energy (stuff like atmospheric O2 and N2 disassociating into O and N that have different chemical/physical properties causing new reactions like the formation of O3 ozone). These new behaviors/ interactions totally change the behavior of the system such that trying to apply equations and principles from low speed flight will result in wildly inaccurate results. Trying to apply tank shell designs that work at 1.5 km/s to a 20 km/s projectile is like trying to use commercial airplane designs for a reentry craft.

You can see what happened to aluminum on impact at only 20 km/s. Tungsten carbide (TC) is harder and stiffer than aluminum, but that just means TC deflects less when force is applied. If the forces applied are high enough, TC will also behave in the way aluminum did on impact, and 20 km/s is almost certainly fast enough to cause that. Feel free to prove me wrong on that point. The projectile will not maintain its shape so designs that depends on it maintaining its shape will not work. Coatings are just layers of particles that are also impacting at 20 km/s, they would do nothing to change the structural impact. The exact interaction (structural and thermal) would depend on what surface it is impacting which could also be made of whatever material you want in whatever geometry you want. Basically, we (all of humanity) have very little idea what will happen under such extreme conditions. That's why science fiction is fun.
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Sutopia

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Meteorite are already good enough examples. They got ionized, burned, vaporized or whatever interactions on their surfaces but some eventually managed to keep it's core intact and eventually land on earth.
I don't really care about how the frontal part of warhead is destroyed as long as the following kinetic hit or payload is delivered.
Human have yet to fire anything over kilogram scale at hypervelocity. Observing surface interaction DOES NOT justify your argument that such destruction would be apply to entire bulk GIVEN THE PROJECTILE LARGE ENOUGH.
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intrinsic_parity

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An impact is not a surface interaction... a shock wave will travel through the projectile, and if the magnitude of the shock is large enough material behind the shock will become liquidized/vaporized. The shock will lose strength as it travels into the material, but certainly it can travel through the entire object if there is enough energy. A larger projectile may require a thicker shield to see the same behavior, and there are likely some other interactions from relative hardness of the materials. As I said, I am not an expert and do not know exactly what would happen, but I have learned enough from material science and dynamics courses to know that the projectile will not be staying in anything remotely resembling its original shape during an impact at 20 km/s.


Here is some more light reading if you are interested:
https://www.rand.org/content/dam/rand/pubs/research_memoranda/2006/RM3490.pdf

This is a journal article, but unless you have access through a university, you will likely not be able to read it. You should still be able to read the abstract:
http://iopscience.iop.org/article/10.1088/1742-6596/98/4/042025
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Sutopia

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You see, the impact is bi-directional, which also applies to the object it hits. If your statement hold true, same goes for the target, so it's mission completed.
Viewing from projectile, it's rather the case when target fly at it at 20 km/s.

Material science focuses on single layer or pure materials, however, structural science is where you should be looking into where they use different materials in layers to serve different purposes.

Simply by multi-layering a shell, creating disposable impact-mitigating layers would allow the shell to dig deep enough into the hull, then it can be free to just vaporize and implode.
« Last Edit: December 28, 2018, 12:28:25 PM by Sutopia »
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intrinsic_parity

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Material science does not study only single layers of materials or pure materials. Most interesting materials being studied now are composites meaning mixes of different materials and interesting arrangements of molecules (crystal structures). The molecular structure of materials is interesting because it dictates the macroscopic properties which is why many material science studies are focused on micro-scale stuff. The goal of this however, is to determine the macro scale properties such as hardness, stiffness, thermal resistance and capacitance etc. Interesting molecular structures can cause behavior like anisotropic properties (properties that are not the same in all directions meaning a material may bend more in one orientation than in another or may be harder in one orientation etc.). Molecular interactions also dictate what happens during impacts on a thermodynamic level etc. Carbon fibre is an example of a composite with anisotropic properties. The application of material properties to larger structures is structural engineering which is also relevant certainly.

A shell with layered protection would be interesting, however, in order for the outer layers to do anything, they would have to be sufficiently far from the core and thick so that they do not crumple into the core causing their own impact at a similar velocity. If they offered very little physical resistance, they would do nothing. Also if the outer layers are absorbing a significant amount of the impact energy (and velocity) are are also attached to the core, they would be slowing the core projectile down meaning they would reduce the effectiveness of the actual projectile.

This design could result in the projectile becoming quite large/heavy meaning the strategy is more of ramming the enemy ship with an unmanned vessel than firing a projectile. You would have to do a lot simulation to figure out if that would work and also how large/massive the projectile would have to be (and how/if you could actually accelerate something that large to sufficient velocity for it to be effective without damaging it etc.). It's certainly not obvious that it would work, but also not obvious that it wouldn't. Im sure someone with more expertise could give a better estimate of what would happen than me though.

Also defenses like lasers could potentially remove outer layers if they are thin enough rendering the design ineffective. There are many considerations to be made, but certainly an interesting idea.
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Sutopia

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A shell with layered protection would be interesting, however, in order for the outer layers to do anything, they would have to be sufficiently far from the core and thick so that they do not crumple into the core causing their own impact at a similar velocity. If they offered very little physical resistance, they would do nothing. Also if the outer layers are absorbing a significant amount of the impact energy (and velocity) are are also attached to the core, they would be slowing the core projectile down meaning they would reduce the effectiveness of the actual projectile.
It does not have to be thick by any means, it just need a relatively weak connection to main bulk such that all the energy on first impact does not conduct to other parts.
An easy design would be a projectile that is consist of a chain of simple shells connected with fragile fodders. The fodders gets destroyed when frontal shell impacts the target, leaving the following shell almost intact and keep on the destruction, until the target eventually got penetrated.
An advanced design, well you have probably guessed it, a chain of bullets aimed perfectly in one line. The doom of first bullet would have nothing to do with the second. An N layered defensive bulk go doom with equivalent N count of perfectly aimed bullets.
« Last Edit: December 28, 2018, 04:08:47 PM by Sutopia »
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intrinsic_parity

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The core of the projectile will still collide with the inside of the layers around it, but if the design worked, that collision would be less damaging. If the outer layers were too thin or not spaced far enough from the core, that internal collision would not be sufficiently different from a 20 km/s collision to change the outcome.

Multiple separate projectiles hitting the exact same location would definitely be an effective method of penetration. In that sense, starsectors armor mechanic is most similar to the defenses we are discussing here. Multiple successive hits in the same location will penetrate further until ultimately reaching the hull.
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Deshara

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A shell with layered protection would be interesting

no its wouldn't lol

it would be such an intricate detail that you would never be able to interact with the mechanic in any meaningful way (size of ships * how slowly they change momentum * how small the projectiles are * how many there are * how fast they move) -- effectively meaning you've implemented the world's most complicated [10% chance to ignore the player's armor]
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intrinsic_parity

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Not actually modeling it as a game mechanic , just interesting as a concept. All of this can be thought of as some lore for the armor mechanic. Armor is a bunch of layered whipple shields, HE are special projectiles designed to penetrate etc.
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Troika

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I'll take a hard pass on this suggestion. I like the flux system the way it is.
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