This whole "battlemechs would sink into the ground" thing is a myth, isn't it? Or at least, if they're used on solid, dry ground then they won't sink. Even on a soil on a grassy field I think they'd probably be OK.

I think it really depends on the ability of the surface to support the weight and on its deformation properties (At worst a solid surface would just crack, but one would expect that a surface made of particulates like sand or mud (especially with liquid between them) would really deform a lot more which may lead to some extent of sinking.

On a really muddy field or a swamp then sure, they're probably going to sink to an extent but I guess that depends on how deep one has to go to get to a dryer subsurface level at which point they wouldn't sink further.

A sand surface might be interesting (especially wet sand, like on a beach) - walking up a dry uncompacted sand dune may be a problem but walking on a flat dry sand surface should be OK?

It's fairly easy to calculate ground pressure given the area of the feet but the challenge is in figuring out how far a mech would sink in each surface type. I'm just not sure how one can figure that out (maybe it even needs really complex finite-element modelling?). #science #battletech #robots

@evildrganymede There's probably a page with the forumula on it if you poke around on Atomic Rockets. 😂 @nyrath

@FredKiesche @nyrath I was literally just looking there, surprisingly I couldn't find an indepth analysis of ground pressure for large mecha , probably because the conclusion was that they can't walk without biological level flexibility (and there was a lot about how "giant robots are stupid" :) ).

@evildrganymede @FredKiesche

That's one of the technical areas I shy away from. Analysis appears to be non trivial, and it is a hot button issue for fans. If I could find a more comprehensive analysis, then maybe

@nyrath @evildrganymede @FredKiesche I wonder if mechs might actually work better in soft forest environments from an infrastructure PoV – I could see the feet destroying pavement, bridges, underground plumbing, etc.

Anyho Wikipedia has a little neat example section:
https://en.wikipedia.org/wiki/Ground_pressure

So, doubling a human 3x:
1.75m*(2*2*2)=14m flesh/Harryhausen golem.
8psi*(4*4*4)=512psi??? (am I wrong here?)
That'd be more than a stiletto heel (or horse hoof strike) just standing neutrally on both feet.

@androidarts @nyrath @evildrganymede do mechs have stiletto heels or is it dispersed like the way tank treads disperse?

@FredKiesche @androidarts @nyrath they're somewhat dispersed at least. Some mechs have claw like feet, some have long flat pads, some have round pads.

If a mech had human-proportioned feet (length about 15% of their total height, width about 6% of their height), then a 10m tall mech would have 1.5m long feet that were 0.6m wide, which is 0.9 m² area. If it weighed 20t (20,000 kg) then its ground pressure if all its mass was on one foot would be 22,222 N/m². which is only 22.2 kPa. (so if standing on both feet, that would be halved). That isn't much at all on that scale. Even if the 10m tall weighed 100t the pressure would be 111 kPa, which isn't anywhere near a stilleto heel (and heavier mechs have larger feet too so that would be even less).