Why mecha?

[koz]

Simply-put, are there any genuine, non-bullshit reasons for wanting a bipedal (or, for that matter, quadrupedal) war machine (assuming it was feasible and efficient) rather than a wheeled or tracked one? I'm just trying to think of why mecha would be viable in a setting (or for that matter, something anyone would want) other than Rule of Cool or some kind of weird in-setting explanation.

[Calibron]

No idea for sure, but perhaps human like mobility would allow a pilot, probably wired into the thing while in use, to move more naturally, efficiently, and skillfully than an otherwise more practical armored vehicle. I doubt it could ever make sense as a normal weapon of war, but for less frontlines type combat, or more likely actions taken by small elite forces of mercenaries or spec-ops, they could be seen as not moronic.

Maybe making relatively small hydraulic powered hops and leaps for dodging and positioning would be more fuel or time efficient than thrusters.

[Koumei]

People are used to walking like people walk (funny, that), so if you're using a control system where it emulates your actions, it's easiest if it moves the way you normally do. It would still likely be easier just to have that be the case for torso-up, and have waist-down be "just use these pedals" with the lower half of the mech basically being a tank. Or actually being a tank, complete with cannon (located basically at crotch level) and pilot in there. That way, the person manning the "body" can focus on aiming the guns.

As for having 4 or more legs, it can give the same stability and potential low profile as treads/wheels, while still having overall less space to target. Depending on how the legs work, it can also navigate rocky terrain more easily, walk over obstacles etc.

[Chamomile]

Four-legged or, better yet, eight-legged walkers are viable tanks because they can much more easily cross a variety of terrains than treaded equivalents. There's no reason to skimp on legs, though. You want the profile to be low even when moving, and you also want it to be able to keep functioning even after losing some of those legs, so spider-tanks are the way to go for that particular role.

Actual bipedal mecha are useful basically only if your ability to make war machines vastly exceeds your ability to find pilots for them. If a mech is versatile enough to act as at least three of tank, artillery/bomber, anti-air, and air superiority, then it wins points for that versatility. Problem is, just like the Bard, there is no way that it can be as good, dollar-for-dollar, as dedicated machines made just for that role. However if you've got an excessive amount of funds and a very limited number of pilots, it's better to give those pilots a small number of extremely versatile superweapons instead of a huge pile of backup tanks and planes that do you no good until one of your pilots loses a machine and needs a replacement. As such, small movements that are inexplicably extremely well-funded can plausibly make use of some kinds of mechs, though ironically only the crazy-awesome anime ones, and not the more grounded western-style mechs, which are basically just tanks but with more joints (read: more weakspots), pointlessly overcomplicated and expensive engineering, worse agility, and a much lower top speed.

The main advantage to being bipedal is the ability to change how tall you are. A mech can hide behind a ridge, then stand up and shoot over it, whereas a tank will either be small enough to hide behind it or big enough to shoot over it, but can never go back and forth. In places where line-of-fire blocking terrain is very common and your mechs are tall enough to shoot over it, bipedal tanks can be superior to regular ones. Note that the terrain must block line-of-fire and not just line-of-sight, which means an urban environment is unlikely to qualify. It's much easier to make a tank that carries the gun and and some kind of spotter drone that can aim it at targets on the other side of soft cover than to create a mech that can do both.

[Winnah]

How big is big enough to be considered a mech? Does a bulky exoskeleton with a lot of armour count?

I know that GE did build a couple of 'mechs' in the early 60's. A mechanised pack mule and a sophstocated piece of hardware dubbed the Beetle.

[Username17]

Power Suits in the 2-4m range are extremely good at navigating cities compared to wheeled or tracked vehicles of any kind. As long as we are talking the "Power Armor" end of mechs, the human shape makes total sense.

For bigger mechs (like 6m and more), it would require war to be different from the way it has been in the past. In traditional tank battles, being taller is a disadvantage (you have a "higher silhouette" and are easier for the other tanks to hit), but if you were more concerned about other kinds of attacks, that might not be true. If the primary threats to your tanks were people running up and placing shaped charges on it or planes dropping bombs from the sky - it might be that being tall and thin and being able to kick might be very good for your tank.

-Username17

[Wesley Street]

Given that warfare has evolved from (mostly) bombing/artillery/strafing/dogfighting/trench warfare to (mostly) SWAT style urban encounters there's no genuine need for heavy armor, let alone heavy armor in a humanoid form.

Some sort of Iron Man/Bubblegum Crisis-style anti-bullet/anti-rocket getup would probably make sense for urban combat though there other ways to protect a soldier other than wrapping him in metal.

[CapnTthePirateG]

You want your enemies to use mecha so you can shoot off a leg and steal that shit. Anyone who's ever played EarthSiege 2 knows what I'm talking about.

[Pseudo Stupidity]

There are real things being developed right now that demonstrate why you might want legs on a robot instead of treads. Granted, we build them roughly human-sized because the whole point of not-wheels/treads is "This can go where people go."

Just look at Alpha Dog, it does things you can't necessarily do with treads (climb a very rocky slope, navigate high obstacles for its size, etc). If you scaled up Alpha dog to the size of a tank you've got a tank that isn't defeated by decently deep and wide ditches. It's also fucking terrifying because it is a robot dog that walks towards you with an unholy whirring sound. Hell, the thing can even pick itself up if it gets knocked over. Tanks can't right themselves (though I have no idea how somebody would tip a tank over), so I guess that's useful as well.

Two legged mechs are stupid because of balance issues (a gust of wind would be a serious problem while it moves), but four legged mechs actually make sense and provide utility that wheels and treads don't.

Legged machines are also more mine-resistant. You're less likely to trigger them, and going over one with legs means the crew will be alright unless they can't survive their mech falling over/getting a leg blown off. Sure you'd be immobile, but at least everyone wouldn't be dead.

We already have a robot that scurries under the treads of tanks to blow them up. It could be a future where "tiny things that detonate themselves under tanks" became so prominent mechs were built as a counter-measure, because a legged mech can flee more effectively and not get everyone killed if it does get hit.

Edit: We do have some pretty hilarious looking "power suits" as well, but the problem with making a power suit is that shit is super expensive and super vulnerable when strapped to a person. Why not cover it in armor and turn it into a vehicle? We already have fairly effective ballistic protection for humans.

Edit 2: I'm trying to remember the technology demonstrator, but somebody made a small quadruped robot that can climb obstacles that are almost as tall as itself. It did so hilariously and slowly, but it still did it.

[Vebyast]

Having legs is useful for a few things.

• Mobility. Something with legs can change direction in a hurry, either from stationary (start moving in any direction easily) or when moving (post off a leg, turn and keep moving, etc).
• Rough-terrain capability in compact packages. A general guess is that, with legs, you can climb walls that are as high as your waist. A minimum-size legged bot with its waist a meter off the ground is a hell of a lot smaller than a minimum-size vehicle with wheels big enough to climb a meter wall. Even better, legs can support your robot given only a few places to stand, letting you deal with things like stepping stones and shifting rubble.

Being bipedal in particular is useful for approximately three things:

• Manipulation. Being able to fall over means that, if you want to, you can fall over with a sledgehammer aimed at something to do bonus damage, or that you can fall over backward to give you the leverage you need to lift heavy things, or that you can fall over forward to offset the kinetic effects of the shell you're about to take. My lab works with balancing robots specifically because they're stronger and more stable than equivalent statically-stable platforms.
• Using things designed for humans. We've built our entire civilization assuming that the things using it have two legs and two arms; having two legs and two arms means you can do things like use cars, go up stairs, and operate control panels.
• Looking human. When you look human, people's brains suddenly expose all kinds of psychological functionality that you can hijack for your own purposes.[/li]

Frank notes that human-scale power armor is very good for cities; this is because power armor can use things designed for humans. Iron Man can go inside buildings, fit through doors, use any weapons he finds on the ground, operate levers, and so on, all because he's shaped like a human. However, if we're talking about full-size mecha, this goes out the window.

Psychology is really powerful. Spider tanks are weird and alien, but watching a giant skeleton with guns walk over a hill is fucking terrifying. Unfortunately, this is only useful if your Gundam is so stupidly OP that you can get away with trading functionality for looks.

Manipulation is a bit less important for mecha; once you get that big, you're carrying around hydraulics that would let you put your hand straight into a granite cliffside... if your hand didn't break first. At this scale, materials are the biggest limitation on your strength, not actuators. You can already break your arms in half trying to lift something too heavy, so adding more strength is useless. Being able to lean into explosions to avoid being flipped is nice, but not necessary.

Mobility is important. In addition to dodging unguided bombs and putting cover between you and incoming missiles, a really high-power mecha might be able to literally dodge bullets - a tank shell from two miles away has a one-second or two-second travel time, and a Gundam-like sense-decide-act loop could definitely get out of the way.

Rough-terrain capability is by far the biggest feature here. Legged robots can go anywhere. They can climb sheer cliffs, they can casually stroll across insane rubble fields, they can step over fallen trees and the burning wreckage of enemy tanks. A streetful of czech hedgehogs can stop a tank column cold; there is no such equivalent for stopping mecha.

[JigokuBosatsu]

Now, having operated some heavy equipment, I know that you get used to it. The pedals that operate your vehicle's scoop get to be second nature, to the point where you find yourself sitting at a table trying to lift your coffee cup to your face by moving one of your feet. So I don't think ergonomics or efficiency is an issue. However...

That facility takes time to achieve. So the fridge horror is... mecha are for untrained suicidal volunteers. All they have to do is walk and hit some buttons to kill some enemies. And if they fuck up and overheat their reactor? They still kill some enemies.

EDIT: Remember the beginning of Robotech? Picture Rick Hunter doofing around in a highly populated enemy city instead of his own.

[FatR]

Given that warfare has evolved from (mostly) bombing/artillery/strafing/dogfighting/trench warfare to (mostly) SWAT style urban encounters there's no genuine need for heavy armor, let alone heavy armor in a humanoid form.

Heavy armored vehicles are essential for the current cutting edge of urban warfare tactics.

Some sort of Iron Man/Bubblegum Crisis-style anti-bullet/anti-rocket getup would probably make sense for urban combat though there other ways to protect a soldier other than wrapping him in metal.

Yeah, if sufficiently compact and reliable power sources are developed, we'll probably see power armors in no time. Larger bipedal mechas, though... hard to imagine technology that will make them at all preferable to 4- or 8-legged walkers even if reliable mechanical legs will become a reality.

[Josh_Kablack]

Well here are a few things that exist in various stages of prototypes and sales pitches:

BigDog

Timberjack

Under Body Armor Cooling System

Now projecting into the future, I can actually see some use for legged vehicles in rough terrain -- although that may change as man-portable unmanned aerial vehicles get better (RQ-16, RQ-20), etc

However I can see a fair bit of use power-armor human/augmentation stuff not merely in urban combat but in support roles, but I also think it likely that the primary use for that stuff will be in noncombat roles in dangerous environs. Soldiers are cheap and expendable, and while materials may get cheaper it seems unlikely that dense fuel sources will. So unless the Arc Reactor leaves the realm of pure fiction. it's unlikely to be cost effective to outfit troops with Iron-Man style power armor. However, medical doctors and specialized combat engineers are NOT cheap, and their training is unlikely to get cheaper, so it may very well be worth it to encase your battlefield medics and the people supervising reconstruction in an occupied city full of insurgents in armor that protects them and extends their useful working endurance in harsh climates.

I think that restricting such things to the officer corps and overstating would be a very powerful recruiting tool for a military trying to recruit specialized skill sets.

[Wesley Street]

Given that warfare has evolved from (mostly) bombing/artillery/strafing/dogfighting/trench warfare to (mostly) SWAT style urban encounters there's no genuine need for heavy armor, let alone heavy armor in a humanoid form.

Heavy armored vehicles are essential for the current cutting edge of urban warfare tactics.

Are we talking about as a safe troop delivery method or as a way to deliver ordnance on a target? By heavy armor I was referring to your classic MBT rather than APCs. Unless you're bunker busting, which can also be accomplished through air support, tank fire support in the form of a 120mm gun can become impractical.

The Israelis have been more successful with bulldozers, APCs and with troopers breaking through walls (potential power suit use!) rather then using streets, than with the M-113.

[Avoraciopoctules]

Heavy Gear has powered armor sized mechs as the archetypical war engine. But they are mainly good for versatility. Tanks will tear them to pieces, and entrenched infantry in bunkers are very difficult for them to take out even with their dedicated antipersonnel armaments.

The depiction in HG seemed fairly reasonable to me.

[Pseudo Stupidity]

Well here are a few things that exist in various stages of prototypes and sales pitches:

BigDog

Timberjack

Under Body Armor Cooling System

Now projecting into the future, I can actually see some use for legged vehicles in rough terrain -- although that may change as man-portable unmanned aerial vehicles get better (RQ-16, RQ-20), etc

However I can see a fair bit of use power-armor human/augmentation stuff not merely in urban combat but in support roles, but I also think it likely that the primary use for that stuff will be in noncombat roles in dangerous environs. Soldiers are cheap and expendable, and while materials may get cheaper it seems unlikely that dense fuel sources will. So unless the Arc Reactor leaves the realm of pure fiction. it's unlikely to be cost effective to outfit troops with Iron-Man style power armor. However, medical doctors and specialized combat engineers are NOT cheap, and their training is unlikely to get cheaper, so it may very well be worth it to encase your battlefield medics and the people supervising reconstruction in an occupied city full of insurgents in armor that protects them and extends their useful working endurance in harsh climates.

I think that restricting such things to the officer corps and overstating would be a very powerful recruiting tool for a military trying to recruit specialized skill sets.

Big Dog is pretty old now, you want to look at Alpha Dog, which looks like Big Dog with a Hannibal mask.

The exact opposite of soldiers being cheap and expendable is true (volunteer army and we already invest a lot of money into their equipment and training), though. Raytheon made something called the Hercules specifically to help soldiers load/unload trucks without hurting themselves, and the entire point of micro-unmanned vehicles is money < soldiers.

For body armor, we already have pretty cheap materials that make people much more bullet-resistant. The problem is that it's all very heavy. Cue carbon nanotube material, which is incredibly effective against bullets (particularly when used with a vest). Densely packed (folded 100 times if I remember) CNT stops some decent caliber handguns at close range by itself and weighs fucking nothing. It's like covering yourself in a half-inch layer of bulletproof felt.

Making a suit out of metal to stop bullets is pretty impractical, especially since people come in so many different shapes and sizes. There's just no reason to have a full-body suit designed for one person.

There are totally real reasons to want a quadruped (or more, as somebody mentioned) robot, but no reason for a biped.

[Juton]

Two examples spring to mind of practical Mecha. Avoraciopoctules mentioned Heavy Gear, in that setting most Mecha are fairly small, 12-18 feet (4-6 meters) and operate in a very rocky undeveloped landscape. That landscape hinders traditional armour to an extent, although when tanks engage Mecha in Heavy Gear the tanks usually win.

The second, slightly less plausible use of Mecha is SDF Macross (first part of Robotech in the states). In this setting an alien space ship crashes on earth, Humans know the aliens are about 40 feet tall and humanoid from the wreckage. The Mecha here are intended to be able to use any alien weapon, technology, or space ship they come across.

[RadiantPhoenix]

The Mecha here are intended to be able to use any alien weapon, technology, or space ship they come across.

I'm pretty sure they also don trenchcoats and infiltrate.

[Juton]

The Mecha here are intended to be able to use any alien weapon, technology, or space ship they come across.

I'm pretty sure they also don trenchcoats and infiltrate.

He's not being sarcastic, this actually happens in an episode.

[K]

I always thought that the point of giant humanoid mecha was to shatter the will of the populace through intimidation and fear.

[Previn]

Big Dog is pretty old now, you want to look at Alpha Dog, which looks like Big Dog with a Hannibal mask.

Actually, you probably want to look at AtlasProto and/or Petman.

[Pseudo Stupidity]

Big Dog is pretty old now, you want to look at Alpha Dog, which looks like Big Dog with a Hannibal mask.

Actually, you probably want to look at AtlasProto and/or Petman.

Bipedal!? Can they get it to walk in bad conditions without falling over constantly? If they can then holy shit.

Speaking of badass robots that are still in test stages, Cheetah!

Fuck you, Usian bolt. Once that thing can run on the ground you are officially obsolete.

[kzt]

Four-legged or, better yet, eight-legged walkers are viable tanks because they can much more easily cross a variety of terrains than treaded equivalents. There's no reason to skimp on legs, though. You want the profile to be low even when moving, and you also want it to be able to keep functioning even after losing some of those legs, so spider-tanks are the way to go for that particular role.

This works fine as long as you can arrange to fight all your battles on 18" thick reinforced concrete surfaces. However, once you get off of airport runways you'll sink into the ground.

[Prak]

More legs distributes weight across a wider area, meaning that the machine is less likely to sink into the ground.

[RadiantPhoenix]

More legs distributes weight across a wider area, meaning that the machine is less likely to sink into the ground.

I am now picturing a spider-mech on snow-shoes.