290 replies to this topic

[Dragon Lady]

Kartr, on 13 June 2012 - 03:53 PM, said:

Actually he's not right, there is no possible way for a "BattleTech Ton" to be a metric ton. If this were the case then the Atlas would be less dense than water and be unable to submerge, possibly not even go more than waist deep in the water. Its a convenient scale to design and classify 'Mechs around not an actual measure of mass or weight.

Where do you get that idea? In the Table Top game, the mighty Atlas has a total height of 13 meters (most range from 10 to 12 meters). I've always felt that an Atlas had the build of an American Football Linebacker (1.8 meters tall, 110kg mass). If you scale up that linebacker to the size of an Atlas, then he would weigh 41 tonnes.

The Atlas masses almost 2.5 times what a human being of that size. Humans are generally neutrally buoyant. Therefore, that Atlas will sink in water.

(Of course, in MWO, they've exaggerated the height all but the smallest 'Mechs. I guess to make the heavy and assault pilots feel better about themselves. )

[RedDragon]

LackofCertainty, on 18 June 2012 - 05:10 AM, said:

Ta dah. I have solved the mystery of the 100 tonne atlas and the atlas that floats like a cork in one fell swoop.

Congrats, we already did this on page 7

As to comparing a modern tank to a mech: I don't think we can draw any conclusions from this. We have absolutely no idea of the materials used to build a mech and how much "free" space a mech chassis includes. The only thing we're save to say is that a mech won't float on water

[LackofCertainty]

RedDragon, on 18 June 2012 - 05:20 AM, said:

Congrats, we already did this on page 7

As to comparing a modern tank to a mech: I don't think we can draw any conclusions from this. We have absolutely no idea of the materials used to build a mech and how much "free" space a mech chassis includes. The only thing we're save to say is that a mech won't float on water

Yeah, I got to about page 4 before I was tired of hearing people talk about fully loaded-floating atlases. Honestly, I always pictured a mech as more structured like a guy in full plate than a tank. If you send in a human (mech with no armor/gear) they'll more or less float. If you send in a human with plate armor strapped on and carrying a sword, they'll sink, and when they stumble out they'll have water pouring off them for a few minutes. (and the mechs would have a little advantage there because they wouldn't have padding to wring out. )

I only draw the relation to the tank, because it's a massive land vehicle of war, and it's a reference point that people can look at and understand. It's easier to stretch and squish a tank to the form/function of a mech than anything else nowadays, because nothing else is very similar in both role and mass.

Sure there's big considerations and still a fair bit of handwavium, but with how far tech can advance in 100 years, let alone 1000, it's easy to pass that off as, "we based this on some facts and I'm sure they'll figure out the rest by then."

[Jaguar Knight]

The 100 tons of the Atlas is not it's weight, but is the weight limit of the amount of weapons, ammo, heat sinks and armor it's endo-skeleton can carry. Therefor a 100 ton Atlas in fact could very well weigh in at 150 or more tons.

[LackofCertainty]

Jaguar Knight, on 18 June 2012 - 05:45 AM, said:

The 100 tons of the Atlas is not it's weight, but is the weight limit of the amount of weapons, ammo, heat sinks and armor it's endo-skeleton can carry. Therefor a 100 ton Atlas in fact could very well weigh in at 150 or more tons.

Nah, the 100 tons is the total mass of the atlas + all its internals, doo-dads, fiddly bits, armor, weapons, fuzzy dice, hula girls, and it even includes that bucket of chicken the pilot sneaked in.

Sure, one atlas might be 99.5 tons, and another might be 101 tons, but it's not going to vary by as much as 50% without silly repercussions

Edited by LackofCertainty, 18 June 2012 - 05:49 AM.

[Jaguar Knight]

I've been playing Mechwarrior games to know. The "weight" of a mech is not it's real weight, but it's payload carry capacity of it's chasse. A 25 ton mech carries only 25 tons equipment, a 100 ton mech can carry only 100 tons of equipmant. Equipment includes, but not limited to, it's engine, reactor, armor, weapons, ammo, heat sinks, CASE ( if it can be equiped), AMS, sensors both active and passive, ECM, ect, ect.... It's endo- skeleton, depending on wether it is standard or endo-steel, only takes up Crit spaces, not weight. Both can carry the same payload (100 tons) the defferance is that the newer endo-steel is less bulky and is able to free up the all important crit spaces...allowing one to add on that extra heat sink or Medium laser..or even a better sensor suite. Endo-steel is very import for the heavy and assault mechs then the Light mechs. Light mechs will run out of it's weight limit before running out of crit space, while heavier mechs will run out of crit space before they run out of their weight limit.

[LackofCertainty]

Jaguar Knight, on 18 June 2012 - 06:03 AM, said:

I've been playing Mechwarrior games to know. The "weight" of a mech is not it's real weight, but it's payload carry capacity of it's chasse. A 25 ton mech carries only 25 tons equipment, a 100 ton mech can carry only 100 tons of equipmant. Equipment includes, but not limited to, it's engine, reactor, armor, weapons, ammo, heat sinks, CASE ( if it can be equiped), AMS, sensors both active and passive, ECM, ect, ect.... It's endo- skeleton, depending on wether it is standard or endo-steel, only takes up Crit spaces, not weight. Both can carry the same payload (100 tons) the defferance is that the newer endo-steel is less bulky and is able to free up the all important crit spaces...allowing one to add on that extra heat sink or Medium laser..or even a better sensor suite. Endo-steel is very import for the heavy and assault mechs then the Light mechs. Light mechs will run out of it's weight limit before running out of crit space, while heavier mechs will run out of crit space before they run out of their weight limit.

A mech's internal structure (Or endo skeleton as you put it) has a defined weight. If you were building mechs otherwise, you were doing it wrong. Normal IS = 10% of a mech's total weight. I think Endo-steel drops it down to 5% and it's counter-balance is that it takes up -more- critical space, not less.

Endo-steel = Lighter and bulkier.

Edited by LackofCertainty, 18 June 2012 - 06:14 AM.

[Jaguar Knight]

Had to re-read my mech manuals and I found out where I got confused. Yes the endo-skeleton does contribute to the weight of a mech....100 ton means 100 tons. I got confused from both of the Mechcommander games' manuals as it stated that the weight limit was not the total weight of the mech, but the amount it can carry. I then re-read the manuals from MW 3 and 4. The endo-steel is lighter but bulker, I had the bulk backwards, and since it also said lighter, that means the skeleton is part of the weight system. .

[CarlBar]

All i can say is. How many times can you guys screw up.

An atlas, (and indeed most mechs), have significantly thicker arms, legs, and much deeper, (i.e. frnt to back thickness), torso's than a human that size would. Trying to scale a human upto atlas size and saying that proves the atlas is denser than water is total mathmatical nonsens. But then so is using the OP's shoebox design. Lets see if we can't do better.

Usinf MW4's atlas model, (it's easier to get specific angles than the wiki image's odd angle), it is roughly 3 times taller than it's total torso width. It's legs are slightly under half the width of the torso, and the arms are about the same size as the legs. The head proportions are about right. Thickness wise it looks to be about 0.75 times the torso width, but lets go for 0.5.

For myself these meashurment are about a quater my torso width for arms narrowing to less on the lower forearm, except at shoulders where natrually they're a tad wider, legs are a littile smaller, (maybe 0.35) at the thighs as they are quite well built, and about 2/3 that on lower leg. Hieght to torso width is 4 to one instead of 3 to one.

Obviouslly getting any kind of meaningfull figures out of this is hard, i'll try my best using 13M base height and ignoring the head.

Torso highet is about 1/3 total. That gives us 4.5 meters as the width ad height, and say 2.5M for thickness of torso. Arm's are about 2.5 M and the upper forearm is to the bottom of the torso with an equivelent length/thickness forearm. Legs are about double length of torso.

so that works out at:

Legs and arms:

2.25^2*9*4 (all four limbs), 182.25m^3

4.5*2.5*4.5 (torso), 50.625m^3

Total 232.875m^3

Density: 429.4KG's per m^3

Just under half that of water. Now square cube law being what it is and a fair bit of fudging being involved there's room for variation on that. Not to mention 50 diffrent depictions. Overal however it is going to be very hard for such a miss-proportioned mech to come relmotly close to human densities, it might be barely denser than water, but thats a push IMHO. I als don;t buy the percolation thing, the armour supposedlly incorporates a self sealing foam layer for water and space oporation. Why have that if it's not waterproof anyway.


Of course this ignores the whole reality of it. Namely a group of people with no idea of scale drew the thing up using virtually zero knowlage of any real science. It dosen't really have to be workable, just look cool .

[Zeitzef]

has anyone ever considered that the "100 ton" atlas might be just a weapons limit to avoid certain DOOOOM of it annihilating the worlds it hates sooo much?

I mean even today we have "laws" about the use of certain weapons.

Edited by Zeitzef, 18 June 2012 - 08:11 AM.

[zareth]

Y'know...when someone puts this much effort into trying to debunk a *fictional* creation, they probably should be locked up in a looney bin and have the key thrown away.

[Partybwal]

This has been a very interesting read, and all you people going on about it being fiction and to leave well alone, please just leave and let those who wish to discuss discuss without your interference. You are not contrubuting AT ALL to the discussion.

Personally, I'm having a hard time deciding. Mathematics-wise I'm on the it-will-float side, but conceptually, I think the idea of only the cockpit being sealed seems legit. Why would you want your entire mech full of sealed-in air? On the other hand, as I think has already been pointed out, newer armor materials with lower weight will naturally also have lower density, and if the mech is actually made out of materials that are less dense than water, then it will probably float, water tight or not.

I haven't read any books (yet, just started on the Dagger and Sword), nor any of the game's manuals, so I don't know anything about materials used or wether or not the 100 tons is total weight or payload. But I have a hunch that the guys who made it all up way back when meant total weight. But if we need to change it to mean something else just to avoid floating mechs, fine by me.

In any event, interesting discussion, but is it over? Does anyone have any new replies that doesn't repeat what someone else already said?

[zudukai]

//unsubscribes to this nonsense.

[Dozer]

To put 'floating' into perspective:

In physics if an object whose 'density' is greater than that of the liquid, gas or other fluid in which it is submerged will tend to sink unless another force acts upon it.

The problem is whether you define 'density' as 'weight density' or 'mass density'. In it's purest form - removing all other forces - 'density' can be considered 'mass density' as mass is the base property of the object; a numerical measure of its inertia and the fundamental measure of the amount of matter in the object, and because 'weight density' is determined by mass x the acceleration of gravity exerted upon it which, as we all know, changes throughout the universe.

Regardless, it is scientific fact that a 100 tonne Mech COULD float simply because the 'density' - be it mass or weight - of the water creates a higher upward force.

But frankly it's a game and we're probably over-thinking it.. even if we are just killing time until we get into Beta

Edited by Dozer, 25 June 2012 - 01:16 AM.

[Melcyna]

Quote

and if the mech is actually made out of materials that are less dense than water, then it will probably float, water tight or not.

technically false because that discount the equipment inside it.

unless if they too are made of some form of physics defying ultra light material that have less weight than the water volume they displace.

Let's face it...
When proper physics and maths are involved, Battletech lore is going to fall apart just like most Science fiction (especially one for games and show, which have even less concern of them than hard scifi)... trying to justify it and make it fit is like trying to explain Star Wars Jedi...

pointless, and will never work because the creators did not design them with a university physics major graduate helping him making the design make sense from science point of view.

To give another point:
Less dense material being used for mech construction makes ZERO sense overall especially for ground combat, because the basic of ground combat where armor and projectile compete against each other (the eternal race between the two where armor and projectile tries to outdo each other) basically MANDATES the use of ultra dense material to build a structure that have enough tensile strength to either resist or penetrate another materia

[Dozer]

Melcyna, on 24 June 2012 - 11:37 PM, said:

Technically false because that discount the equipment inside it.

unless if they too are made of some form of physics defying ultra light material that have less weight than the water volume they displace.

Let's face it...
When proper physics and maths are involved, Battletech lore is going to fall apart just like most Science fiction (especially one for games and show, which have even less concern of them than hard scifi)... trying to justify it and make it fit is like trying to explain Star Wars Jedi...pointless, and will never work because the creators did not design them with a university physics major graduate helping him making the design make sense from science point of view.

See my previous reply about 'density' above. It is quite conceivable an ultra-light material can sink or ultra-heavy float under the right conditions. That's proper physics The game may not describe the 'how's' and 'why's' but we can use our intellects to fill in some (not all) of the blanks don't you think?

And tbh I feel that the creators and developers of this wonderful universe had a better grip of science than you give them credit for and, as history shows us, what is science fiction today is often science fact tomorrow so I wouldn't call it pointless, rather an interesting, discussion. But hey, that's just me

Edited by Dozer, 25 June 2012 - 01:17 AM.

[Vanguard319]

kargush, on 13 June 2012 - 02:40 PM, said:

The mechs aren't solid. Lots of open space inside them.

Besides, Rule of Cool and Bellisario's Maxim.

Lt muffins, on 13 June 2012 - 02:41 PM, said:

Advances in metal working and stronger and lighter composite metals decreases the weight compared to current tanks.

It Also helps safisfy the Square/Cube law (Where if you double an object's size, you triple it's volume and mass)

[Zergling]

Mechs can weigh more than 100 tons; the recent Jihad: Final Reckoning book has rules for Mechs weighing up to 200 tons.

They are pretty inefficient, due to their internal structure weighing twice normal and can't go very fast, but they gain a huge amount of internal space for mounting bulky equipment.
Plus they can mount significantly more armor than lighter mechs... IIRC, a 200 ton mech can mount 37.5 tons of standard armor, compared to the 19.5 tons on a 100 ton mech.

And they are at least 18 meters tall; in Btech rules, they stand 3 Levels high (1 level = 6 meters), compared to 2 Levels for regular mechs.

There's only one official Super-Heavy mech design so far: the SHP-X4 Omega, a 150 ton design that moves at a meagre 2/3 speed, but has 3 Gauss rifles and 2 LB-10X AC as armament.

[Melcyna]

Dozer, on 25 June 2012 - 12:03 AM, said:

See my previous reply about 'density' above. It is quite conceivable an ultralight material can sink or ultra-heavy float under the right conditions. That's proper physics The game may not describe the 'how's' and 'why's' but we can use our intellects to fill in some (not all) of the blanks don't you think?

And tbh I feel that the creators and developers of this wonderful universe had a better grip of science than you give them credit for and, as history shows us, what is science fiction today is often science fact tomorrow so I wouldn't call it pointless, rather an interesting, discussion. But hey, that's just me

You can't argue on 'grip of science' with giant bipedal mech in the same sentence since you know... the whole bipedal giant combat machine is pure nonsensical from both physical and military stand point of view since it neither has the logical sense physically to use such form, and neither does it have any logical sense from the military utility usage.

That's fine though since we can suspend our disbelief to an extent, and as long as the game is consistent about it we can sort of pretend about it while it suits the game context.

But the moment it's dissected with REAL logic, it will break apart very quickly.

And yes 'ultralight material can sink or ultra-heavy float under the right conditions' or you know to just condense it in the direct term 'does it weigh less than the water it displace with it's volume.

Just put it in the simplest term:
does the mech weigh LESS than the volume of water it displace? yes? it floats... no? it sinks... the end.

[Bambusbar]

Thats like the odd discussion from Iron Sky, if you can shot a weapon on the moon.
I mean - yeah, SpaceNazis? Pft, not that important - but can you shot the weapon!?!