10 replies to this topic

[KANE06]

ive always wondered that mechs should weigh alot more than what they do, because if you think about it, a german tiger tank from world war 2 weighs in at around 65-70 tons and thats about the same weight as a thor mech. i know its a video game so it aint a big deal but perhaps all the mechs should be 5 times heavier or sumthing. and lets just say jump jets are real powerful n can lift that.

[TheOnlyNom]

The reasons are super strong and super light metal frames and armor. Trying to attach logic to BattleTech doesnt work...

[Ragenule]

The mech tonnage isn't their weight, afaik. It's the total weight of equipment they can carry.

I once heard that the Atlas is weighing in at about 600 tons fully loaded.


I'm not completely certain though, so take this with a pinch of salt.

[Razor Kotovsky]

PzKpfw VI weights 57 tons.

[Ouranos]

Materials difference and technology. Think about it, these things carry a FUSION REACTOR that weighs between 5 and 40 tons depending on type, etc. A controllable reactor using fission (modern nuke plants) is the size of an apartment building. A current tank built using their materials and tech would likely weigh less then the average CAR does these days.

[Major Bill Curtis]

Two calculations I made in a long-forgotten thread:

Quote

A 'mech, according to canon (and not numerous goofy illustrations) usually stands between 10 and 14 meters in height.

Now, let's take anthropomorphic 'mechs only (i.e. generally humanoid), and compare them to a 1.8m, 100kg human.

A 10 meter 'mech has 170 times the volume of our 1.8 meter human (10/1.8 = 5.55, then cubed =~170), so if it has the same density as our human (~1.01 g/cm3), it will also have 170 times the mass, i.e. 17 metric tonnes; ergo, a 10 meter high 20-ton 'mech is denser than a human, coming in at about 1.18g/cm3, which means that the mean density of a 'mech is about the same as epoxy resin (which includes the air spaces in it---keep in mind that every ocean-going vessel has a mean density of less than 1.0g/cm3, including this very heavy object).

Now let's look at the other end of the scale: a 14 meter tall 100-ton 'mech is about 470 times the volume of a 1.8m human (14/1.8 = 7.77, then cubed =~470); ergo, a 14 meter tall human will scale up to a weight of 47,000 kg, or 47 metric tonnes; thus a 100-ton 'mech at this height has a mean density of ~2.15g/cm3, including the air spaces, which is the density of things like Opal and Teflon.

TL;DR? 'mechs sink in water, as they have a mean density somewhere between that of epoxy resin and rocks, depending on the tonnage.

Anyone seeing any issue with this anthropomorphic calculation of volume and extrapolation of mass? (and I'm not talking about "'mechs aren't shaped like people --- plenty of them roughly are, and this is reasonable for estimating volume).
Cheers.

Quote

I intentionally kept the human weight high (100 kg) for two reasons: 1) ease of calculation (not for me but for others); 2) 'mechs do appear to be a bit bulkier than people.

If you had a truly anthropomorphic 'mech of 20 tons at 10 meters in height, based on an 80kg, 1.8m human, its mean density would be ~1.48 g/cm3; at 14 meters and 100 tons, it's a whopping ~2.67 g/cm3. In the former case, that's a mean density (including air spaces) of Calcium, in the latter, it's hovering around Aluminum or Strontium (i.e. considerably denser than aircraft).

As dense as a modern tank? No. But a 14-meter statue of an average human male (1.8m/80kg) made of solid aluminum would weigh 100 tonnes.

Only bad math will make 100 tonnes of solid aluminum float.

For those of you keeping score, aluminum is roughly 1/3 of the density of steel, so you could also make a hollow 14-meter statue of a human that weighs 100 tons out of steel. 2/3 of the volume of the statue would be air, but the other 1/3 of the volume would be solid steel. That is a lot of steel. In some places the statue would have steel over 30cm thick. Keep in mind there'd be nothing inside the statue, just air, but this is the other extreme.

Also keep in mind that density is good in armor, but it isn't everything: copper is denser than steel; silver is denser than steel; lead is denser; gold is nearly 3-times as dense; tin (yes, tin) is usually within 5% of the density of steel. No one wants tin armor.

Finally, since 'mechs use armor that works differently from most contemporary armors --- it's ablative --- it is not a stretch to imagine that 'mech weapons might penetrate the armors we're used to quite easily --- if that were the case, 19 tons of steel wouldn't be enough to protect a 100-ton 'mech. Instead, devising a highly advanced lightweight low-density alloy that fractured externally without spalling would be one solution. In that case, the armor might fracture better in certain, more complex shapes (like a 'mech), than in other, less complex shapes (like a tank). 'Mechs are more resilient than tanks (in TT) because they have more armor locations, which rationalizes this

Are there physics reasons for this? There could be, given the right materials: have a look at area rule, in aerodynamics, as a rather odd phenomenon. Why isn't your jet as sleek as you think it should be? Area Rule. Lots of apparently common-sense explanations don't work in the real world. Developing a complex-fracture ablative armor to deal with weapons that go through very heavy weights of hard and dense ceramics and metals is a reasonable rationalization of game rules.

Ceramic, by the way, is only slightly denser than aluminum.
Going Sci-Fantasy there at the end, but for us, it still makes a good game.

I await everyone ignoring these actual calculations while continuing to wonder if a 'mech is denser than their shoes, a bird, a tank, the Golden Gate Bridge, concrete, and styrofoam

Cheers,
M.B.C

Edited by Major Bill Curtis, 19 August 2012 - 11:05 AM.

[Telecleez]

basically as technology moves farther along the lighter and stronger the materials get

Edited by Telecleez, 19 August 2012 - 11:13 AM.

[Randalf Yorgen]

I forget where I read it, but it was in the old TT books I an certain, the problem with going heavier than 100T is that the ground you are standing on starts to not to be able to support your weight. Space ports and cities with FeroCrete surfaces can hold the wieght but as soon as you step out into the countryside you run the risk of sinking into the ground. Marshes, shores, deep earthen beds, shale deposits, porous rock, deserts sand, sand stone, and what ever other kind of surface you can think of would all start to give way. remember when the 100T mech is walking at 10kph there is a few seconds where most of the weight is supported by the ground that is under one 4X7 (roughly) foot. This is one of the reasons so many "old timers" have a huge problem with the Jihad and WOB's Colosus mechs.

Also to answer the question, The mech tonnage is the total of everything, Internal structure, actuators, molymar bundles, engine, gyro, weapons, ammo, heat sinks, sensors, armor, paint job (the last one is a tip to any pilots out there as the weight of the paint on the plane gets factored into aircraft weight for fuel purposes) and anything else you can think to have in the mech. So, an 100T Atlas weighs 100T with full combat load and pilot.



fixed a few of the SP errors, but not all of them

Edited by Randalf Yorgen, 19 August 2012 - 11:12 AM.

[Brenden]

If they use the Metric system for most, if not everything they have, than wouldn't these tonnes also weigh in the Metric versions of themselves? 100Ton Atlas would than, really, be 110Tonnes. Not much of a difference, but still need to factor that in.

[Major Bill Curtis]

I'll add to what I posted above: a 14-meter hollow statue of a human could be made of 18cm thick ceramic (>7 inches) forming its 19 tonnes of armor, and then filled with coarsely crushed iron ore (mean density in this case 2.15 g/cm3) or red brick, both of which have plenty of air spaces.

This statue would weigh 100 metric tonnes. It will do poorly in the field, since it is made out of ceramic, bricks, and coarsely crushed iron ore, has no weapons, sensors, or life support. Nonetheless, it will weigh 100 tonnes.

Cheers.

Brenden, on 19 August 2012 - 11:15 AM, said:

If they use the Metric system for most, if not everything they have, than wouldn't these tonnes also weigh in the Metric versions of themselves? 100Ton Atlas would than, really, be 110Tonnes. Not much of a difference, but still need to factor that in.

A 100 Ton Atlas = 100 tonnes. They use the metric system and then use standard American weights to designate it. I believe this is stated in the Tech Manual.

[Mordino]

Quote

I forget where I read it, but it was in the old TT books I an certain, the problem with going heavier than 100T is that the ground you are standing on starts to not to be able to support your weight.

I`m not really a fanboy of Battletech universe, but if I remember right, it`s all about neuro-helmet. Mechwarrior not only operates the mech, but also keeps it stable by his own brain.That is why mechs are so mobile and can get up from the ground. It`s like controlling our own body. :] 100tonnes(150 made by word of blake) is a limit for mech. Morbidly obese ppl cannot stand and walk at some point. :]] Or walk like russian drunks at monday mornings(special kind).


PS Perhaps I am wrong. It was a long time ago.

Edited by Mordino, 19 August 2012 - 11:43 AM.