7 replies to this topic

[Myrakridia]

I'll start with this; I'm very new to the Battletech Lore and fiction, but I have played almost all of the games that have been released to date and understand enough about the game mechanics to make this observation.

One consistently inexplicable concept is the Mech's weight classes. Eg. A Medium chassis weighing 55 tons, despite being much larger in every dimension and more complex than a modern Tank. It made my brain numb trying to work out why.

There is a few explanations on the forums already as to how the weight works, but never has anyone explained why a mech, when totally stripped of all equipment and modules, weighs nothing.
How is it that a 15m tall, bipedal tank, weighs nothing when its Engine, AC20, ammo, SRM racks and Medium lasers are on the ground next to it? That just makes the kind of sense that doesn't.

This is my uneducated conclusion.

Perhaps mech's do weigh a lot. A tremendous amount, even when totally stripped of all its equipment, but given the nature of these futuristic, bipedal tanks, they are limited by what it can carry.

I'd imagine that a mech', with its extremely complex myomer muscles, gyro's and armour plating would have a really hard time compensating for additional weight being put around its centre of mass.
It would be a delicate balance, and the upper limits of that acceptable balance of additional weight it what I have rationalised as what we call 'tonnage'.

This, (at least to me) is the only logical conclusion that explains that ambiguous mess that is a 'mech's' weight'.

tl;dr. Tonnage = Mech's carrying capacity, not overall weight.

Let me know your thoughts.

[SilentScreamer]

Myrakridia, on 29 June 2016 - 07:03 AM, said:

There is a few explanations on the forums already as to how the weight works, but never has anyone explained why a mech, when totally stripped of all equipment and modules, weighs nothing.

How is it that a 15m tall, bipedal tank, weighs nothing when its Engine, AC20, ammo, SRM racks and Medium lasers are on the ground next to it? That just makes the kind of sense that doesn't.

Where ever you came to this conculsion you are incorrect. If you used the MWO mechlab and strip a mech you would know that the mass does not go to zero.

All mechs have mass/weight associated with structure/frame.
- Structure is 1/10th of a mech's mass. Ex: 50 ton mech has structure that takes up 5 tons.
- If you go with Endo Steel the mass required drops to half that, in this case 2.5 tons.

From frame, you then put in an Engine, Armor, Weapons, Ammo and Special Equipment like heat sinks. In Battletech (table top) there is also a Gyro (variable weight) and Cockpit (3 tons, includes pilot, sensor and life support). I believe PGI has simply added Gyro and Cockpit values to Engine weight to simply their mechlab but they do take up 5 of the 6 crit slots for the mech's Head in the mechlab.

If you want to learn more two great resources are:
http://www.sarna.net
http://bg.battletech...the-board-game/

Edited by SilentScreamer, 29 June 2016 - 09:13 AM.

[Myrakridia]

Thank you for that.

Even at 1/10th, Mech's' still seem insanely light for their size, and the weight is still a mess.
An AC-10 weighs more than Atlas, or 6 unfitted Locust's.

After having a read on Sarna.net, I see MWO does a great job of convoluting the topic further, as the scale of so many mechs are off. The tallest ones are only 30 feet tall in the fluff and a Black Knight stands over the top stories of many buildings in the Frozen city.

I see the most common explanation for the discrepancies in size/weight is simply, "Its science fiction, the metal is super duper light and super duper tough."

[Karl Streiger]

Myrakridia, on 29 June 2016 - 11:26 AM, said:

I see the most common explanation for the discrepancies in size/weight is simply, "Its science fiction, the metal is super duper light and super duper tough."

FTFY

anyhow GURPS TL10 CN9-A Centurion

TL10 CN9-A Centurion

Crew: 3 total. 1 crew station covering vehicle maneuvering system, 2 sensors. 2 weapon loaders.

Subassemblies: Vehicle +6, Leg +4, Body +5, Left [Body] +3, Right [Body] +3, Head [Body] +3, Left Arm [Body] +3, Right Arm [Body] +3, Center [Body] +4. 

P&P: 4.000-kW fusion reactor (200 year duration; short term access) [Center], 20 rechargeable E Laser 90 Shots - rec[YP] [Center], 2.500-kW Legs (short term access) [Leg]. 

Fuel: 

Occ: cramped crew station (ejection seat, crashweb) [Head], cramped toilet [Head], 1-man total life support system [Head], 1-man NBC kit [Head], 1-man environmental control system [Head]	Cargo: 

Armor     F       RL    B     T     U
Leg       4/600   4/400 4/100 0/0   4/250
Left      4/500   0/0   4/200 4/200 4/100
Right     4/500   4/600 4/200 4/200 4/100
Head      4/300   4/150 4/150 4/100 0/0
Left Arm  4/300   0/0   4/200 4/200 4/150
Right Arm 4/300   0/0   4/200 4/200 4/150
Center    4/1.000 4/150 4/250 4/250 0/0

Weaponry                     Malf Type   Damage           SS Acc 1/2D m     Max m      RoF TL
50mm Luxor3R Launcher        -    Cr     0d               20 0   0          0          1/1 10
80mm Luxor D HAC             Ver. Cr     6dx14            30 17  2.743      8.778      5   10
80mm APEX 20 5shot magazines -    Cr     6dx14(2)         -  17  2.743      8.778      -   10
240  Luxor 3R LRMs           Crit Cr/Exp 23d(2)+8dx10[4d] -  -   0          11.000     -   10
Photech 806c Rear            Ver. Imp.   5dx10            20 18  1.700(x10) 5.200(x10) 1   10
Photech 806c Front           Ver. Imp.   5dx10            20 18  1.700(x10) 5.200(x10) 1   10

Equipment
All: sealed.  Leg: composite armor volume.  Left: -0,028-m^3 anti-blast magazine; 240 52mm 240 Luxor 3R LRMss (big APEX warhead; Skill-18 ARH); ten 50mm fast autoloader Luxor3R Launchers; full fire suppression system; composite armor volume.  Right: 0,717-m^3 anti-blast magazine; 100 rounds 80mm APEX 20 5shot magazines; full fire suppression system; composite armor volume.  Head: compact fire suppression system; digital recon camera (Infrared, Low-Light); sound system; life detection package; seismology package; chemical sensor array; advanced radiation detector; magnetometer; magnetic anomaly detector (scan 13, 2-mile range); ranging sound detector (sound level 18); composite armor volume.  Left Arm: arm motor (ST:200); laminate armor volume.  Right Arm: arm motor (ST:150, poor coordination, striker); 80mm Luxor D HAC (very long barrel; heavy auto); composite armor volume.  Center: full fire suppression system; 4.000-kJ Photech 806c Rear (B, close range; concealed); 4.000-kJ Photech 806c Front (F, close range; concealed); composite armor volume.  

Statistics
Size: [LxWxH] 2,74 m x3,35 m x9,91 m 	Payload: 4 tons	Lwt.: 49,5 tons
Volume: 89,8 m^3	Maint.: 10,4 hours (9,24 mh/day)	Price: $3.705.025 

HT: 9	HP: 900 [Leg], 1.800 [Body], 376 [Left], 450 [Right], 524 [Head], 1.200 [Left Arm], 1.200 [Right Arm], 750 [Center]. 

Not Wheeled Ground Performance: Speed Factor 8, Top Speed 64,4 kph, gAccel 25,7 kph/s, gDecel 32,2 kph/s, gMR 1,25, gSR 2, Ground Pressure 3.094 lbs./sf, Off Road Speed 32,2 kph.


Design Notes: 
TL10 robotic heavy frame standard materials [Vehicle].
U TL1 DR 250 standard composite, L TL10 DR 400 standard composite, R TL10 DR 400 standard composite, F TL10 DR 600 standard composite, B TL10 DR 100 standard composite [Leg].
T TL10 DR 200 standard composite, U TL10 DR 100 standard composite, R TL10 DR 600 standard composite, F TL10 DR 500 standard composite, B TL10 DR 200 standard composite [Left].
T TL10 DR 200 standard composite, U TL10 DR 100 standard composite, L TL10 DR 600 standard composite, F TL10 DR 500 standard composite, B TL10 DR 200 standard composite [Right].
T TL10 DR 100 standard composite, L TL10 DR 150 standard composite, R TL10 DR 150 standard composite, F TL10 DR 300 standard composite, B TL10 DR 150 standard composite [Head].
T TL10 DR 200 standard composite, U TL1 DR 150 standard composite, R TL1 DR 300 standard composite, F TL10 DR 300 standard composite, B TL10 DR 200 standard composite [Left Arm].
T TL10 DR 200 standard composite, U TL1 DR 150 standard composite, R TL1 DR 300 standard composite, F TL10 DR 300 standard composite, B TL10 DR 200 standard composite [Right Arm].
T TL10 DR 250 standard composite, L TL10 DR 150 standard composite, R TL10 DR 150 standard composite, F TL10 DR 1.000 standard composite, B TL10 DR 250 standard composite [Center].
Operating Duration:  9 M 22 S.
Payload Cost: $2.638.000
Vehicle Features: computerized controls, ruggedized, pressure proofed, no streamlining.
Head: limited rotation.
Volume: 11,8 m^3 [Leg], 38,2 m^3 [Body], 4,07 m^3 [Left], 4,08 m^3 [Right], 6,36 m^3 [Head], 7,93 m^3 [Left Arm], 7,99 m^3 [Right Arm], 9,33 m^3 [Center].
Area: 37,2 m^2 [Leg], 74,3 m^2 [Body], 16,3 m^2 [Left], 16,3 m^2 [Right], 23,2 m^2 [Head], 27,9 m^2 [Left Arm], 27,9 m^2 [Right Arm], 27,9 m^2 [Center].
Empty Space: 37,6 m^3 [Body], 2,2 m^3 [Right], 7,51 m^3 [Left Arm].
Not Wheeled Ground Performance:; 

Edited by Karl Streiger, 29 June 2016 - 11:44 PM.

[RedDragon]

Myrakridia, on 29 June 2016 - 11:26 AM, said:

Thank you for that.

Even at 1/10th, Mech's' still seem insanely light for their size, and the weight is still a mess.
An AC-10 weighs more than Atlas, or 6 unfitted Locust's.

After having a read on Sarna.net, I see MWO does a great job of convoluting the topic further, as the scale of so many mechs are off. The tallest ones are only 30 feet tall in the fluff and a Black Knight stands over the top stories of many buildings in the Frozen city.

I see the most common explanation for the discrepancies in size/weight is simply, "Its science fiction, the metal is super duper light and super duper tough."

First, don't go by MWO. "A Battletech game" in this context means that they use the same names as in Battletech, basically that's it. Especially when it comes to sizes they take very many liberties - not to mention that the actual gameplay gives no feeling of a mech's size at all.

Second: A mech's structure is a lightweight frame, that's it. There is nothing else in it, no electronics, no engine, no weapons, no armor. If you strip a modern tank down to its frame, I guess it also wouldn't weight much, although that's hard to say because tanks are not built as modular as are mechs.

[Nebfer]

A Generic battlemech roughly would have the following fixed mass ratios

Cockpit 3%
Chassis 10%
Gyro ~3% (while variable they tend to run at between 1 and 4 tons, though in theory they can be as much as 10 tons)
A 20 ton mech that was 5/8 with the engine, weapons armor and other equipment removed would have spent 30% remaining with the Gyro (1t), Cockpit (3t) and Chassis (2t).
Conversely a 100 ton mech that would be 4/6 would only have 17 tons devoted to the Chassis (10t), Gyro (4t) and Cockpit (3t). Though one could shave 8 tons off that with lighter components.

The Chassis it seems only serves as the location of the Actuators, and internal mounting framework for the various components (I.e. engine, weapons and armor). Even so various automotive elements like the Mechs Myomers and actuators have no independent weight, the only thing that gets heavier when a mech gets faster is the weight of the engine, so it would seem the engine contains the weight of the myomers and other components.

Even so it's some what well known that the weights of battlemechs are a bit lighter than what they more realistically should be, particularly when noted by the volume they would take up (they should float in water, not sink).

Tanks (both tracked and wheeled) on the other hand spend 15% of it's mass on it's chassis and controls. Though again the engine it seems to take up a fair bit of the units automotive elements. Hover Tanks and WIGEs require a minimum of 30% of it's mass in motive and lift equipment, plus the 15% on it's chassis and controls. Where as VTOLs only require an extra 10% of their mass on VTOL equipment.

For B-tech vehicles it would seem that the engine is comprised of the following elements, motor, if applicable the fuel tank (stated to be 10% of the over all mass of the engine), transmission, suspension, tracks and final drives. Though vehicle Fusion power plants do have a listed transmission weight being half again of the over all engine weight, though extra shielding is included with this mass.

Though historically speaking a Tank Generally spends about 50% of it's mass on armor (for units like MBTs, light tanks often spend less on armor) and about 30% on automotive (engine, tracks and suspension). With B-tech tanks 30% spent on motive typically gets them 3/5 or 4/6 on units above 50 tons, interestingly 3/5 is fairly close to what a modern tank would be if we use their governed off road speeds as a basis (I.e. a M1 Abrams has a Governed speed of about 25-30 mph off road or 40-48kph or ~4 B-tech hexes per turn, it's stated road speed of 42mph or 67.5kph would be a movement of 6, which works with a 3/5 vehicle with a +1 movement bonus for traveling on roads that ground vehicles get).

Oddly fighters do not have any listed mass out side of the units cockpit, so remove the weapons and equipment, armor, engine, fuel tanks and heat sinks all your left with is a cockpit (which is 3 tons, though for Conventional fighters it's 10% of the units mass). So for ASFs it's engine provides mass for it's Chassis, flight control systems & reaction control systems (strong enough that their actually VTOL capable), Conventional fighters do not have the RCS (why would they need to, they don't operate in space), though they can be given VTOL capability, as a add on.

[MW Waldorf Statler]

Problem in MWO , in the Lore all mechs smaller , a Shadowhawk only *9,6 m Height (thas the Lenght of a AbramsTank), most Mass have the multiple Weaponssystems and Engines,Gyroskop, Myromermuscels, a Awesome with 3 Small laser have not the Weight as with 3 PPCs...How many Weaponssystems have a modern Tank ?

[Nebfer]

Old MW4 Ranger, on 02 July 2016 - 12:05 AM, said:

Problem in MWO , in the Lore all mechs smaller , a Shadowhawk only *9,6 m Height (thas the Lenght of a AbramsTank), most Mass have the multiple Weaponssystems and Engines,Gyroskop, Myromermuscels, a Awesome with 3 Small laser have not the Weight as with 3 PPCs...How many Weaponssystems have a modern Tank ?

Battletech mechs are smaller than their MWO counter parts, but that dose not change the fact that even at the size they are in B-tech many mechs still have enough volume to float in water given their mass.