Fair warning, this is a text wall that would make Trump hire me around the Mexican border.
Edit: this question is not different from the other post, but the other post does not contain an answer and does contain the many pitfalls I see in mech discussions.
Whenever people talk about Walker Mech's (WM's), there's usually two camps: The people who point out that the legs have weaknesses and wouldn't be useful, and the people who are so in love with the idea that they hope or sometimes actually think it has to be possible. But the discussion rarely ever evolves from there, it usually devolves into nothingness.
I want to have a real discussion about what role WM's could have in future combat. For this I'm assuming that future combat isn't completely dominated by drones and that AI's will communicate and dictate our lives to prevent wars in the first place. So despite technology having advanced we assume a sort of balance in warfare between cost/effectiveness as we see in today's military, which is kind of the baseline most people uses for worldbuilding anyway.
Let's try to break some stuff down. A common argument is "just shoot the legs". I think this is extremely narrow. It would be like saying "tracks are inferior to wheels because if you shoot down a single track the tank stops and 6 to 8-wheeled vehicles would be able to keep going! So what we need is a pro's and cons list similar to the pro's and con's lists we have for wheeled vs tracked vehicles, which are both in use in the militaries of today for the roles they can perform on (and off) the battlefield.
The argument "just shoot the legs" doesn't seem very good if you think about it. You are going to shoot an anti-tank weapon at legs that are way thinner than other tank targets and are constantly accelerating and decellerating during the walk, while the main chassis is moving at a constant pace. So anyone worth their salt will be shooting the hip-joints. The big Con that everyone thinks about is ofcourse the fact that if a walker falls, it's pretty much game-over for the Walker. This is true and a big problem for the walker, but in a real combat scenario any tank that gets immobilized is also basically dead, which is why immobilizing a tank is referred to as a mobility kill. In the end, shooting the legs is a similar vulnerability as shooting the tracks/wheels, but with larger consequences for successfully immobilizing the Walker.
Energy consumption. Many people argue that Walker energy consumption would be through the roof, you would have to constantly keep that Walker up in the air! So let's look at a leg-equivalent: Excavators http://footage.framepool.com/en/shot/801513429-charleroi-vehicle-industry-warehouse-excavator This footage shows inactive excavators who draw no power with their arms up in the air. During operation the arms don't require constant energy to keep up either, all you need is energy to move the arm. You can accomplish this with brake's or in this case hydraulics. For moving forwards a Walker is going to need more energy than a wheeled/tracked equivalent. The legs will be heavier than wheels/tracks and require more energy to operate. However, the human body uses 90% of the previous steps energy in the next step. Using this type of technology in a future Mech would reduce the energy cost and make Walkers viable energy wise. They would still require more energy but not as tremendously much as many people think. Again, a con for the Walkers.
Leg strength. Many people think that the legs wouldn't be able to carry a tank. I've calculated long ago that using legs build out of Excavators, which have incredible strength to withstand the maximum pressures and forces when excavating and those maximums have a safety margin build in, you could build a 120 ton tank if you used up to 8 Excavator legs that are 1/4rth the capability (and hopefully size to give the legs room) of current-day excavators. This puts WM's in-between Wheeled vehicles and Tracked vehicles in capacity, as it would be unlikely that a 120 ton Walker would be that useful. A pro over wheeled vehicles, a con vs tracked.
Speed. While having longer legs and a larger stride will make the Walker faster, I don't really see a way for the Walker to be faster than tracked or wheeled vehicles. However, I estimate that a well-designed Walker would be able to reach anywhere between 40 to 60Km/h, with 60Km/h only for lighter Walkers.
Surface area. Many people point out that a leg would immediately sag away into the terrain. But why would that be? If you design a leg with a teeny tiny surface area, ofcourse it's going to sag away! But you can shape the feet yourself, and create the surface-area you need as long as the legs are far enough away apart. This is harder with 2-legged WM's, but 4 to 8 legged WM's would be able to extend the surface area towards the middle of the tank, and even with relatively small feet the surface area would easily be better than those of wheeled tanks, giving the WM's a pro over wheeled and a con vs tracked tanks again. But there's another way to design the feet of a Walker: Use that surface area to have the feet dig into the ground. Using a large conical leg-shape you immediately increase the surface area the farther you go into the ground, and by dividing the forces both downwards and sideways you will divide the pressures put onto the ground as well. This feature as a huge advantage: Every step anchors the Walker into the ground regardless of the WM being on the move or not, giving it unparalleled traction compared to wheeled and tracked vehicles. A first full and true pro for Walkers.
Recoil. When firing a gun the vehicle is accelerated the other way. Using it's suspension the vehicle will absorb some of the recoil and transfer it into the ground. The longer the distance you can decellerate the vehicle in, the lower the peak force of the recoil is upon firing. This is a great advantage for the legs of walkers, as they will be able to collapse and absorb more recoil and extend the braking period tremendously compared to wheeled or tracked vehicles. This allows a walker of similar weight to carry a larger gun than it's wheeled or tracked counterparts, a pro for walkers. If you also add the energy effeciency system, the recoil energy that is absorbed can partially be converted into energy for walking. It's a small extra pro.
Travel through terrain. Wheeled vehicles can reach most places tracked vehicles can, tracked vehicles have that extra edge when moving through rough terrain, and WM's would have an even superior capability to cross terrain. Tracks are continuous, and every bit of terrain change is felt. Legs are carried over the terrain and placed down. Depending on the leg design (IE more than 2 legs) the Walker could also step onto things that are higher than it's hip joints. Coinciding with the much better traction this would give WM's the ability to climb slopes and go through soft terrain that a tank wouldn't dream off. There are plenty of mountain-ranges across the world where tank combat would be virtually impossible, and even air-combat would be restricted. Alps, Himelaya's, Caucasus are a few of those places and those places would be dominated by specialized troops like Alpine troops traveling over mountains and infantry traveling over tiny paths while tanks would be stopped in chokepoints and any passage would result in vehicular graveyards as artillery would have no problem taking out the tanks or even just the roads. But a well-designed Walker could follow the infantry and bring vehicular firepower into extreme terrain, giving them a leg-up (heh) in combat and allowing them to easily take out the far more restricted wheeled/tracked vehicles. It would also allow for (slow and expensive) supply lines across mountainous terrain where airlifts might be too risky because of AA (mounted on Walkers for example) or enemy interception aircraft. A big pro for Walkers.
Height and elevation. Height is both an advantage and disadvantage. Being able to spot enemies easier is a pro, but it also means everyone is more likely to shoot you. A 2-legged Mech wouldn't have the option to crouch-walk, but a 4+ legged walker would by spreading out it's legs. This would ofcourse take up a lot of space, but allow Walkers to design their height for the terrain. If a hill or building is a bit too tall to look and shoot over you can raise the chassis and peek over the feature in a perfectly tailored hull-down mode. In cases where friendly tanks are around you can position yourself behind them and shoot over them (this is extremely uncomfortable for the friendlies in the tank though, but less inconvenient than lacking the firepower to take down an enemy who might return fire). Another advantage is that the tank isn't reliant on camouflage to pull this off: The Mech can wait below the ridge until a spotter gives the signal, then pop up over the hill and open fire. An option that wheeled and tracked vehicles don't have. By manipulating the legs you can also change the elevation to look up/down slopes, and keep the turret far smaller as the gun elevation can be compensated with the legs.
Amount of legs. 2-legged Mechs are the most common across games, and they just suck. It's not a smart design, one leg off and the Walker is going to fall. The only 2-legged Walkers I could see happening would be small Mechs half the size of a car at maximum for urban combat purposes. They would be as cheap as possible and basically function as a gun carriage for some extra firepower when the streets are so filled with rubble that a tracked gun wouldn't work (and 'Murica already has .50 cal anti-tank machine guns on robotic tracks in development for infantry). 4-legged Mechs would probably be no more than the size of a Humvee. Designed to travel through extreme terrain for supply runs or to carry anti-tank missiles and function as small gun-emplacements. 6 tp 8 legged Mechs is where I think it's at. With proper design, these tanks could have 2 to 4 legs shot away and still keep walking, although heavily hampered. The weight capacity and the best ability to climb up slopes make them formidable, and the weapons they could mount would be rivalling that of their tracked counterparts.
Pro's and con's list: Con's - Legs are more vulnerable when taken out - Legs cost more energy - Legs will have slower speeds than wheeled or tracked vehicles. - Legs will be far harder to repair when damage is done compared to wheeled/tracked vehicles.
- The legs could carry loads larger than wheeled vehicles but smaller than tracked
- Legs can have better traction than any other tank, and can anchor with each step
- legs can withstand greater recoil forces, allowing for a bigger gun without ripping the turret off.
- Walkers can cross terrain wheeled and tracked vehicles can't.
- Height can be altered to suit the need for a hull-down using terrain features.
So what function could WM's have? Considering the few pro's and con's listed I would expect these Walkers to fulfill two functions: Mobile artillery and extreme terrain warfare. As Mobile Artillery they can mount guns far larger than those on a wheeled/tracked vehicle of equal weight, and every time all legs are on the ground they can fire and be on the move the moment the recoil has dissipated. On relatively flat terrain any Mech would be extremely vulnerable and lose to tracked and wheeled vehicles, but the moment you enter hilly and mountainous terrain the WM's will start to become more and more effective, up to the point where tracked and wheeled vehicles aren't even an option anymore while walker vehicles would still be able to keep up with infantry.
What do you think? Am I off? Would Walker Mechs have a better function than mountain-warfare? Would they still suck balls?