Armored Trooper VOTOMS Discussion

[Connor MacLeod]

Ok. I think I get it. But I'm not judging the whole series as stupid just because it has something in it I find idiotic. The breaking point really comes when the events are totally out of whack with the demonstrated capabilities in the setting. If I take trench warfare from 40K as an example, it's not the fact that trench warfare happens that grates me, it's they do it totally wrong for the demonstrated capabilities they possess. It causes SoD to buckle and break when you basically have to assume people are not idiots and what they are doing makes sense to them. From analysis point of view, I think this is one of those where you have to agree on what counts and what doesn't.

I can understand that, but when it comes to 'breaking' SoD it can vary by person or case I think. Take the Vraks stuff (trench warfare) in 40K. I knew it was probably pretty stupid, but I didn't realize HOW stupid until the actual criticims (EG Sea Skimmer) pointed out some stuff. That was my ignorance. It was silly, but it didn't really bug me because its something you can expect from the way the Imperium is set up: from the politics and bureacuracy (within the military AND civilian arms) as well as the lack of standardization in doctrine or logistics.

Finding an explanation doesn't change that its stupid from a military/practicality standpoint, of course, but it is also 'sensible' from an in-universe setting given what we know. Which when I think about it, is also a good example of how 'makes sense' can sometimes differ.

And in the context of robots, I can accept that people find them stupid (everyone is entitled to their opinion and expressing it) and I can accept that it makes less sense than a specialized design (because of compromises, increased flexibility, various reasons.) but as I said I do not equate 'I find stupid' as 'inherently stupid.' And whilst some may not cross that line (or intend to) in my experience it happens all too often. On SB for example you find tons of people who accept stuff like that as gospel without thinking why (eg 'space fighters are unrealistic therefore bad'.)

Yes this is problematic. I do think, like I said above, you have to start with the assumption that people are not idiots and they are acting in a way that makes sense to them. What is or isn't logical is pretty hard to define, but if you really can't agree on some basic things, then the discussion is pretty much over.

Stupidity does not neccesarily bug me as an explanation, but like 'inconsistency' or 'outlier' I dislike using it unless I am really forced to, because it means introducing doubt into the evidence itself. At some point, throwing shit out means you start doubting it more than trusting it. In my mind, 'stupidity' is not to be used simply because *I* find something stupid - I can find something stupid out of universe, without affecting things in-universe - but on the other hand it isn't easy to put yourself into an 'in universe' mindset to try and explain it.

I think alot of the 'big numbers' thrown around for Star Wars fit here. Whether its huge firepower, or huge population/military sizes (eg billions/mililons of ISDs based on Death Star), the capacity to make it doesn't mean it HAS to exist, although I used to think so (and I know many who have believed so.) It used to be thought that anything LESS than that (EG the 25,000 ISDs) was 'stupid' because it was minimlaist, but now I'm not so sure. IRL, militaries build according to need (either actually need or think they need.) not simply because they are capable of doing so, so why should Star Wars, except to satisfy some sort of fanboy or vs debate urge?

I've even taken it further in regards to Star Wars: If we take the absurd industrial and firepower figures as being plausible (and I do) then the 'logical' way of waging war in star wars (automated doom armies slinging around FTL delivered huge yields) would probably be utterly brief and apocalyptic to society. Given that, it makes a certain kind of sense to optimize for 'less effiicient' warfare - hence you get humans piloting fighters, starships, clones facing off against droids, giant walkers, etc. Its not like Star Wars is somehow the 'war-torn' shithole the 40K galaxy is, after all.

Indeed, you can even justify 'low yields' based on that too (again simply HAVING the yields does not mean they USE them, but people often assume that if they exist they MUST be used, becuase thats how they envision things making sense.)

Yes I agree. SoD is tricky as it is highly variable from person to person but you can't really analyze fiction without it.

Indeed. We've seen this sort of variation in the definition of 'hard' sci fi especially - for some it means 'anything permitted by scienec' whilst others is more strict - only what we are likely to make (which means stuff like fusion power may be 'fantasy'.) And this creates problems if people try applying radically different methods/approaches (Even within SoD).

Yea. I think this one of those no one is 100% right kind of questions. I think you need to view things in the larger scale and at the same time break them into smaller pieces to get a good view of both. If applying RL science helps, that's all fine and good but at the same time you should just accept that some things cannot be reconciled.

Pretty much its all a juggling act of one sort or another. This is why I've generally found that the LESS absolutely I adhere to things, the better I can react to and adjust to those sorts of changes. It never really worked when I tried to decide 40K was like Star Wars (well ICS star wars) and treat it as such, for example.

Yes, that is true. I do think the best way to do it is to apply science as needed to see if you can get anything useful out of it but while doing it you should remember that just because you can do math, the result you're getting might not mesh at all with the setting you're trying to analyze. Because we know what happens when an analysis becomes a quest for MOAR MEGATONNES!! Same applies to applying RL knowledge to a great degree. Real life intrudes into fiction because we happen to live in it and by default that affects how we view and experience fiction. Just how much is the big question.

-Gunhead

Indeed. I've run across plenty who think that simply becaues they can do calcs that means the calc is itself correct - totally ignoring that knowledge (or ignorance) fo the topic, the available information (or lack thereof), and assumptions can all affect the reliability of calcs.

Perversely I find the same applies equally whether its arguing FOR or against big yields. Basically people become fixated on one way or another as being 'the truth' and they totally ignore the fact that its not the specific yields that are the problem, but the manner in which they are applied. Context is more important in this than some abstract paradigm.

[Sea Skimmer]

Only if you are talking about vectoring and accelerating. Which maneuvering thrusters are obviously NOT designed to do. They are made to rotate a craft around its axis, which is just as important; real telescopes and other spacecraft with sensors are a good demonstration of this use. Being able to do this quickly in a shootout means being able to identify targets faster, bring weapons to bear faster (especially fixed emplacements), and point your best defenses and armor in the most effective direction. You don't necessarily want to build every ship like a dreadnought, despite what some people might believe.

Nothing about rolling requires thrusters on large moving arms, they'd be completely pointless. All you need is one fixed thruster per side with two exhaust ports, one up, one down, and a valve to switch between them. This is of course, effectively how real telescopes and spacecraft and the X-15 actually accomplish such tasks. As an alternative option you could have one port that vectors in each postion. You could also have twin main engines on the rear side by side, and just use 3D thrust vectoring on those for roll as well. Talking only in terms of roll reduces, rather then improves the case for limbs. Also roll rates are still dependent on mass, which means excess mass like giant feet you sure aren't using in space, are once more an active hindrance to performance. Indeed moving the limbs around would make a roll control system far more complex and difficult to control.

[Ford Prefect]

Also roll rates are still dependent on mass, which means excess mass like giant feet you sure aren't using in space, are once more an active hindrance to performance.

Have you ever heard of this thing called the Third Law of Motion? In a microgravity environment, moving your arms will result in the rest of your body having to move in order to conserve angular momentum. The Gundam franchise has a system, AMBAC, which leverages Newton's Third Law to provide stability and minor course correction without expending reaction mass. Working in tandem with their verniers it improves overall performance.

[Zinegata]

I'm pretty sure Gundam's AMBAC system would not work in real life, which is why it's one of the series' invented premises alongside Minovsky physics.

Flailing your arms around in space will not cause you to roll, because you don't actually have air to push against your arm movements.

[Ford Prefect]

Flailing your arms around in space will not cause you to roll, because you don't actually have air to push against your arm movements.

That's ... not important. The principle is wholly based on the Third Law, and would actually be harder in an atmosphere due to air resistance. While obviously the technology is fictional, the principle upon which it is based is real.

[Zinegata]

I don't think you completely understand how the Third Law actually works.

If you flail your arms around the only "action-reaction" happens within your body (the muscles). And because these action-reactions exert the same amount of force, you actually go nowhere - they cancel each other out.

In order to get meaningful motion relative to the environment, you need to actually "push" against something (e.g. air in the atmosphere) or actively expel something out of the spacecraft (e.g. via a thruster). This is why Skimmer pointed out that you're better off with just thrusters without the added mass of moving arms - the thrusters themselves are the ONLY thing that actually gets you rolling, and the extra arms just make you more massive and requiring more energy / propellant to get you moving.

[Ford Prefect]

That's not at all how Newtonian mechanics, the human body , or a low friction microgravity environment works.

The actual description of how AMBAC accurately recounts what the effects of inertia will be on a person's angular momentum when they're in space, right down to the rotation stopping once the movement of the limb also stops. Like there's no two ways about it: if you move a limb, the inertia of that moving limb will cause your body to rotate in order to conserve angular momentum. It doesn't matter that your muscles are acting against each other, because your limb will still have inertia. Of course, you're limited to orienting yourself around your centre of mass, but as a system which stabilises and assists rotation that doesn't really matter.

[Zinegata]

If you're just aiming to roll around your center of mass (without moving relative to the environment) and absolutely don't want to use a thruster (which is more convenient in most cases) then you'd do it more efficiently with a fly wheel, which is what actual satellites and spacecraft use now:

http://en.wikipedia.org/wiki/Momentum_wheel

Giant arms don't actually work very well for this purpose; mostly because they add mass which just makes it more difficult to get the damn thing moving in the first place.

[Ford Prefect]

Actual satellites never have to invade O'Neill cylinders.

[Sea Skimmer]

Ah so they use the same system for roll control that also physically aims a recoil producing autocannon weapon that happens to be offset to one side on top of it all. That sounds like a fantastically reasonable approach to take.

[Ford Prefect]

Yeah I bet the system designed to make use of the inertia of moving limbs doesn't account for the inertia of moving limbs

Seriously, this shouldn't be like squeezing blood from a stone: it is a system that leverages something that would actually work in real life. Would it be the most optimum solution in the real world? No. Does that matter? Also no.

[Zinegata]

Yeah I bet the system designed to make use of the inertia of moving limbs doesn't account for the inertia of moving limbs

Seriously, this shouldn't be like squeezing blood from a stone: it is a system that leverages something that would actually work in real life. Would it be the most optimum solution in the real world? No. Does that matter? Also no.

The thing is, using limbs instead of flywheels is squeezing blood from a stone. It can work IRL but it will be very, very inefficient. And IRL humanoid machine would actually work better by having internal flywheels to have it pivot and move more quickly than relying on the arms.

This is IRL talk though. If you want to come up with something similar to AMBAC magic then at least you tried to keep some science in the explanation.

[Terralthra]

Yeah I bet the system designed to make use of the inertia of moving limbs doesn't account for the inertia of moving limbs

Seriously, this shouldn't be like squeezing blood from a stone: it is a system that leverages something that would actually work in real life. Would it be the most optimum solution in the real world? No. Does that matter? Also no.

The thing is, using limbs instead of flywheels is squeezing blood from a stone. It can work IRL but it will be very, very inefficient. And IRL humanoid machine would actually work better by having internal flywheels to have it pivot and move more quickly than relying on the arms.

This is IRL talk though. If you want to come up with something similar to AMBAC magic then at least you tried to keep some science in the explanation.

Evidence that AMBAC doesn't include six flywheels? I mean, why wouldn't it?

[Zinegata]

Yeah I bet the system designed to make use of the inertia of moving limbs doesn't account for the inertia of moving limbs

Seriously, this shouldn't be like squeezing blood from a stone: it is a system that leverages something that would actually work in real life. Would it be the most optimum solution in the real world? No. Does that matter? Also no.

The thing is, using limbs instead of flywheels is squeezing blood from a stone. It can work IRL but it will be very, very inefficient. And IRL humanoid machine would actually work better by having internal flywheels to have it pivot and move more quickly than relying on the arms.

This is IRL talk though. If you want to come up with something similar to AMBAC magic then at least you tried to keep some science in the explanation.

Evidence that AMBAC doesn't include six flywheels? I mean, why wouldn't it?

I haven't seen any description of AMBAC that says it uses flywheels - it only refers to the "humanoid shape" of the machine as being the essential component for movement; the rough explanation being "Astronauts can do it, so a humanoid-shaped machine can do it too!".

That said you have a point - a more plausible AMBAC system could combine flywheels and limbs. In this setup though it would still be the flywheels doing much of the work.

[Terralthra]

Which element of the setup would be doing the work would depend largely on what movement is required. One advantage of the limb system, if you have the computing cycles to do it in an efficient manner, is that limb movement can both move the mobile suit around the center of mass *and* move the center of mass within (or even outside) the overall mobile suit. Flywheels can not. Also, as I was pointing out, to rotate within all 3 dimensions would take 3 pairs of counter-rotating flywheels, and they'd have to compose a significant portion of the mobile suit's mass.

Like most engineering, it's a trade-off. If you have to have the humanoid shape, then there's only so much mass you can devote to six flywheels in the torso before you make the mobile suit too top-heavy to walk around easily. If you lighten them too much, you can't get much torque out of them, since they have to have a significant moment of inertia relative to the mass of the suit to work properly (or be rotating very fast, and if they're rotating fast, the angular momentum will keep you from rotating much other than by tapping the flywheels).

[Ford Prefect]

It can work IRL but it will be very, very inefficient.

Prove the degree of inefficiency you're claiming.

One advantage of the limb system, if you have the computing cycles to do it in an efficient manner, is that limb movement can both move the mobile suit around the center of mass *and* move the center of mass within (or even outside) the overall mobile suit.

AMBAC is described as being able to do this as well, actually. I didn't mention it earlier because it was hard enough to get them to believe that inertia is real thing but you know :v

[Terralthra]

I should think that limb movement can move the center of mass should be obvious from the fact that runners pump their arms. And observing any of the many videos on youtube of astronauts in free-fall in LEO will demonstrate the effect on a smaller scale. Those arguing against the obvious effects of inertia are physics idiots, and can be safely ignored.

The clueful are arguing that reaction wheels would be more efficient than AMBAC. To which I reply that a) AMBAC could easily include sets of reaction wheels, b) the system of reaction wheels necessary to move a 20 ton machine involve trade-offs that could outweigh greater efficiency and most importantly c) mobile suits exist in a 'verse in which humanoid tanks are better than tank-shaped tanks, so clearly the efficiency of various combat and mechanical systems are different than the existing present-day models. It's on us, the purported analysts of this 'verse, to determine why and how, not keep shouting about how terrible the systems they use are.

[Zinegata]

Prove the degree of inefficiency you're claiming.

Ah, yes. So rather than simply concede that flywheels are more efficient IRL (hence them being actually used) you try to turn the argument upside down; forgetting that your only counter-argument to this real-world fact is "But we don't have space battles yet and we could end up having giant robots proving to be ultra-maneuverable thanks to AMBAC magic!".

Yet even your theoretical secenario was addressed when Skimmer pointed out that having your limbs for roll control is a fantastically stupid idea when it's also your weapon (and recoil-bearing) portion of the vehicle.

But nah, sure, let's all pretend Ford Prefect isn't just avoiding defeat here.

=====

I should think that limb movement can move the center of mass should be obvious from the fact that runners pump their arms. And observing any of the many videos on youtube of astronauts in free-fall in LEO will demonstrate the effect on a smaller scale. Those arguing against the obvious effects of inertia are physics idiots, and can be safely ignored.

Nobody's denying that limb movement can move the center of mass; the question is whether it's practical for 50+ ton machines without flywheels. Which is highly relevant given that AMBAC was cooked up for a science-fiction show, wherein their basis was the movement of a 150 pound astronaut.

Ignoring the massive difference in mass and scale is about the same level as the Trekkie deniers who claim that it's easy to build a much more massive object like the Death Star. Moving the limb alone (depending on the weight of the limb and your power source) could cost you more energy than just using a flywheel.

The clueful are arguing that reaction wheels would be more efficient than AMBAC. To which I reply that a) AMBAC could easily include sets of reaction wheels, b) the system of reaction wheels necessary to move a 20 ton machine involve trade-offs that could outweigh greater efficiency and most importantly

"Could", but never actually stated as such. Like I said though, it would make sense if it did.

c) mobile suits exist in a 'verse in which humanoid tanks are better than tank-shaped tanks, so clearly the efficiency of various combat and mechanical systems are different than the existing present-day models. It's on us, the purported analysts of this 'verse, to determine why and how, not keep shouting about how terrible the systems they use are.

I actually said it's fine for a sci-fi show explanation because you tried to keep some science in it.

My objection is whether or not the thing will actually work IRL; and I think I made it pretty clear I'm talking not from a verse analysis but from an IRL perspective.

If your intent is just to get me to say it's actually an okay explanation for a sci-fi show, you're wasting your time because I do in fact like the AMBAC explanation. I'm just being pendantic and pointing out its RL impracticality

I will note though that Mobile Suits work in the Gundamverse because there are also other justifications for why MS are more effective - such as limiting most combat down to visual range due to Minovsky physics (which is also fantasy, but at least they tried to create a mostly consistent system to justify it).

[Terralthra]

I should think that limb movement can move the center of mass should be obvious from the fact that runners pump their arms. And observing any of the many videos on youtube of astronauts in free-fall in LEO will demonstrate the effect on a smaller scale. Those arguing against the obvious effects of inertia are physics idiots, and can be safely ignored.

Nobody's denying that limb movement can move the center of mass; the question is whether it's practical for 50+ ton machines without flywheels. Which is highly relevant given that AMBAC was cooked up for a science-fiction show, wherein their basis was the movement of a 150 pound astronaut.

Ignoring the massive difference in mass and scale is about the same level as the Trekkie deniers who claim that it's easy to build a much more massive object like the Death Star. Moving the limb alone (depending on the weight of the limb and your power source) could cost you more energy than just using a flywheel.

That's...impossible, by definition. Angular momentum is angular momentum. Torque is torque. r * m1v1 = r * m1v1, no matter how you're getting it, and costs the same amount of energy.

The clueful are arguing that reaction wheels would be more efficient than AMBAC. To which I reply that a) AMBAC could easily include sets of reaction wheels, b) the system of reaction wheels necessary to move a 20 ton machine involve trade-offs that could outweigh greater efficiency and most importantly

"Could", but never actually stated as such. Like I said though, it would make sense if it did.

It *might* make sense. You're skipping steps.

c) mobile suits exist in a 'verse in which humanoid tanks are better than tank-shaped tanks, so clearly the efficiency of various combat and mechanical systems are different than the existing present-day models. It's on us, the purported analysts of this 'verse, to determine why and how, not keep shouting about how terrible the systems they use are.

I actually said it's fine for a sci-fi show explanation because you tried to keep some science in it.

My objection is whether or not the thing will actually work IRL; and I think I made it pretty clear I'm talking not from a verse analysis but from an IRL perspective.

If your intent is just to get me to say it's actually an okay explanation for a sci-fi show, you're wasting your time because I do in fact like the AMBAC explanation. I'm just being pendantic and pointing out its RL impracticality

I will note though that Mobile Suits work in the Gundamverse because there are also other justifications for why MS are more effective - such as limiting most combat down to visual range due to Minovsky physics (which is also fantasy, but at least they tried to create a mostly consistent system to justify it).

Yes, I'm aware of Minovsky physics and the attempts to justify the humanoid tank concept in science. What I'm saying is - if your 'verse's physics justify a humanoid mobile suit, then one must make the decisions about what an efficient rotation system through angular momentum manipulation looks like based on "the system will be in a humanoid mobile suit." You can't say "why include arms that move to change your moment of inertia, when you could just have flywheels," because you already have arms and legs. They aren't up for debate, they're part of the system.

Your choices aren't "limbs which we can move around to change moment of inertia and angular momentum" OR "flywheels to change angular momentum."

They're "limbs which we can move around to change moment of inertia and angular momentum," OR "limbs we can move around to change moment of inertia and angular momentum AND also flywheels to change angular momentum." The trade-off is not between "efficiency of limbs vs. efficiency of flywheels", it's "does the efficiency of flywheels justify including them when we can already (somewhat less efficiently, possibly) move our limbs around to change angular momentum, at the cost of a significant increase in mass and even more significant moment of inertia?"

The answer to that is much more complex than you are giving it thought.

[Ford Prefect]

Ah, yes. So rather than simply concede that flywheels are more efficient IRL (hence them being actually used) you try to turn the argument upside down; forgetting that your only counter-argument to this real-world fact is "But we don't have space battles yet and we could end up having giant robots proving to be ultra-maneuverable thanks to AMBAC magic!".

Yet even your theoretical secenario was addressed when Skimmer pointed out that having your limbs for roll control is a fantastically stupid idea when it's also your weapon (and recoil-bearing) portion of the vehicle.

But nah, sure, let's all pretend Ford Prefect isn't just avoiding defeat here.

I didn't say anything like that. You said that it would be 'very, very inefficient'. I've asked you to prove it. If you're so absolutely certain, it should be trivial for you to provide evidence in support of your claim. It isn't unreasonable for me to ask, given your earlier demonstrated misunderstanding of Newtonian motion.

[Cykeisme]

All this got me thinking, or rather realizing, that I can't intuitively wrap my head around how angular momentum would work with limbs.

Here's a question phrased in the form of a thought experiment:
- I'm floating in free-fall in a vacuum, and I wrap my arms counter-clockwise around my body.
By that, I mean my right arm is now placed across my chest, such that my right hand touches my left shoulder. Meanwhile my left arm is behind my back, so that my left hand touches my right shoulder.*

- Now, as quickly as I can, I swing my arms clockwise around my body. Essentially the end position is mirrored: now my right arm is behind my back, with my right hand touching my left shoulder. My left arm is across my chest, with my left hand touching my right shoulder.

It's pretty clear that while I do this quick motion, my torso will rotate to the left (counter-clockwise).
But when my hands reach their end-position and stop, will I continue to keep rotating counter-clockwise?

My thought is "no", because when my hands stop in the end position, they will also stop my rotation. Thus, throughout the motion, my torso will turn about 90 degrees to the left, and stop there.
Is this correct?

* - Please let me know if my description of the arm positions are terrible and unclear, such that I can clarify it so that those with a better understanding can provide an accurate answer.

[Ford Prefect]

You will only rotate so long as you're moving your arms. It sounds totally weird, but it's got nothing on this scholarly article Connor linked me which explained that you can actually swim in space and move as a result.

[Cykeisme]

You will only rotate so long as you're moving your arms.

Whew, ok, so intuition (without proper understanding of the physics) led me to the correct prediction, which is a relief.

It sounds totally weird, but it's got nothing on this scholarly article Connor linked me which explained that you can actually swim in space and move as a result.

:O
How does that work? Where does your forward momentum come from? If you started stationary for the frame of reference (zero momentum) at the start, but you're moving forward at the end.. shouldn't you need to expel something in the opposite direction (ignoring the potential for toilet humour here), such that the sum of the momentum of the expelled crap plus you still adds up to zero?

[Ford Prefect]

:O
How does that work? Where does your forward momentum come from? If you started stationary for the frame of reference (zero momentum) at the start, but you're moving forward at the end.. shouldn't you need to expel something in the opposite direction (ignoring the potential for toilet humour here), such that the sum of the momentum of the expelled crap plus you still adds up to zero?

Apparently it's something to do with the curvature of spacetime in orbit. Honestly it's pretty much entirely unintuitive to me but it's real. Here's an article about it and the MIT paper itself.