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Why did the Galactic Empire choose the concept of "tanks on legs" over the older concept of tanks with caterpillar treads? Why did the AT-TE, AT-ST, AT-RT and famous AT-AT have to be deseigned as "tanks on legs"? What practical military purpose do "walkers" really serve?

I'd rather a AT-TE looked like this:
Tank

Than this:


And the famous AT-AT look like this:


Than this:



(By the the way AT-TE looks the most pragmatic out of the Republic/Imperial walkers; it has reasonable ergonomcs because it's built low on the ground and has a very low profile in comparison to the AT-AT).

...Are the pictures REALLY necessary?

Well out of universe it was just to make Imperial vehicles look different to modern day armour. It would br pretty boring sci fi if the main land battles were identical to stock WW2 footage.

In universe however using legs does increase mobility, the all terrain part of the name, meaning mainly that vehicles can cross tank pits, casms and other obstacles by stepping over them rather than needing bridge alying equipment or sappers to clear the way.
Also by elevating the main body and weaons it massively increases targeting range which would otherwise be blocked by the horizon.

It could also render mines less effective aslong as the feet are sufficiently well armoured, the crew compartment being safely out of the blast area.

tanks tanks lol

Just say it's for psychological effect and walk away. The AT-AT doesn't make much sense as a combat vehicle anyway.

However, seeing a herd of them pop up on the horizon would make most people shit a brick and give up.

In addition to the aforementioned psychological aspect and Darth Tanner's own comments, a walker can go places a tank can't - in Vision of the Future Pellaeon navigates an AT-AT (simulated) through a dense forest - granted he has to blast his way through, but as one of his companions in the simulation notes, AT-AT's aren't built for stealth anyways.

Also, see Endor - the nimbler AT-STs were moving at will through the canopy, where tracked or wheeled vehicles might have some difficulty maneuvering.

In swampland, terrain that could bog down a tracked vehicle could (providing it wasn't too deep) simply be slogged through by a walker as could shallow lakes, coastal waters, etc.

For rocky terrain that tracked vehicles can't traverse there are MT-ATs and in the Second Clone War volume, homing spider droids mount a beachhead assault by scaling a cliff.

Spanky The Dolphin wrote:tanks tanks lol

Have you not a HAB bone in your body?

Probably to scare the shit out of people. Tanks comming at you is probably rather scary, but seeing massive towering walkers/Titans/Mechs casually stomping over your mates is likely to break you.

Its power projection, like the Executor, totally unnessicary but damn effective at giving the illusion of invinciblity.

VF5SS wrote:

Spanky The Dolphin wrote:tanks tanks lol

Have you not a HAB bone in your body?

Well I certainly don't have a HAB boner...

The Empire had wheeled, tracked, and repulsorlift vehicles in addition to walkers.

Walkers, as stated, are better at tackling difficult terrain than wheeled or tracked vehicles, and are unaffected by theater shields and repulsorlift jammers.

The AT-AT's height is, more than likely, to give it a longer line of site for use of its heavy cannons, since it seems to serve as an artillery platform in addition to a troop transport.

There's really just one Imperial vehicle that I really wish had tracks or repulsor lifts: the SPHA units.



These are some SPHA-Ts. Wouldn't they look so much better if they had some giant tracks instead of a dozen small skinny legs?

It's much easier to walk over angry and uneven terrain than it is to ride a bike over it.

That's true, but it's much easier to ride a hypothetical low-slung wide-base treaded bike over angry and uneven terrain than it is to walk over it on stilts.

These are some SPHA-Ts. Wouldn't they look so much better if they had some giant tracks

I have to admit I hate the walker approach to the clone war army era vehicles, having a larger number of small legs completely removes the point of having walker vehicles in my opinion. Not only are they too close to the ground to improve their weapon range but also they probably can’t get that much speed out of such a small stride.

Howedar wrote:That's true, but it's much easier to ride a hypothetical low-slung wide-base treaded bike over angry and uneven terrain than it is to walk over it on stilts.

Technically untrue depending on the terrain. There is terrain you simply CANNOT traverse on a tracked bike that you CAN on stilts. In theory.
Mind you why anybody would BOTHER with the stilts when it's so much more easy to go AROUND that terrain or go right OVER it if need be of course anyone's guess. No repulsorlifts does NOT equal no air traffic.

Given the approximately 90ft (26m) length of an AT-AT, it could just step over some narrow rivers and similar obstacles, not needing bridges, unlike terrestrial vehicles.

I don't know if this would apply at all to the GFFA, but terrestrial tracked vehicles like MBTs are terribly maintenance-intensive with imperfect reliability; tracks can need replacement about every 1000km. Any large group of modern MBTs can decrease significantly from its original operational number after every few hundred kilometers traveled in battle. The Empire might prefer a lot more reliability if their armor is to be capable of traveling over a large area of a planet. Maybe legs don't wear out as fast as tracks?

Besides, not every armored vehicle has to be designed primarily for a low-profile or for concealment. Given their size, AT-ATs would be quite visible regardless.

There is not anything wrong with having some large vehicles, particularly not when a common assumption about cost being approximately directly proportional to mass may be incorrect. Even a terrestrial M1A2 tank costs as much as the raw materials cost of literally thousands of tons of some types of steel. Armored vehicle cost might be determined more by the per-vehicle expense of equipment like electronics than by mass in itself.

For the Empire, a large vehicle like the AT-AT might not be nearly as expensive as would be expected by the average person on earth today. People often imagine very large vehicles being inferior while implicitly assuming the opponent could field a vastly greater number of small vehicles against them, i.e. a hundred X-mass small vehicles for every 100X-mass large vehicle. Yet a large vehicle might not cost as many orders of magnitude more than a small vehicle as its mass difference, either in capital or in the crew needed to operate it. For example, the crew cockpit for an AT-AT might not cost too much more than the crew cockpit expense if the Empire had made a much smaller tracked vehicle instead.

Once a vehicle is really large, stealth or concealment is seldom an option anyway, so a higher profile from having legs instead of tracks becomes not necessarily much of a disadvantage.

Ideally AT-ATs wouldn't be toppled over as easily as happened in TESB (shorter legs better?), but otherwise their high profile makes some sense in an universe where direct-fire weapons dominate almost totally over indirect-fire weapons. Their high profile maximizes effective weapons range.

Sikon wrote:I don't know if this would apply at all to the GFFA, but terrestrial tracked vehicles like MBTs are terribly maintenance-intensive with imperfect reliability; tracks can need replacement about every 1000km. Any large group of modern MBTs can decrease significantly from its original operational number after every few hundred kilometers traveled in battle. The Empire might prefer a lot more reliability if their armor is to be capable of traveling over a large area of a planet. Maybe legs don't wear out as fast as tracks?

Legs are necessarily a very high-impact mechanical system. Given similar materials, they will not be as durable as wheels or treads.

Walkers are awesome and scary. Seriously. I know there have been excuses made about being better-able to avoid mines and maintain traction while firing high recoil weapons and blah blah, but it's not cost-effective if that's their only reason. The Empire builds walkers because they can. They build walkers because their robotics and associated engineering technology is so advanced they can make an unpractical weapon system totally feasible.

Howedar wrote:

Sikon wrote:I don't know if this would apply at all to the GFFA, but terrestrial tracked vehicles like MBTs are terribly maintenance-intensive with imperfect reliability; tracks can need replacement about every 1000km. Any large group of modern MBTs can decrease significantly from its original operational number after every few hundred kilometers traveled in battle. The Empire might prefer a lot more reliability if their armor is to be capable of traveling over a large area of a planet. Maybe legs don't wear out as fast as tracks?

Legs are necessarily a very high-impact mechanical system. Given similar materials, they will not be as durable as wheels or treads.

A source for my statement that modern-day tracks wear out around every 1000 km is here. I am fairly sure that a legged vehicle could be built with modern-day materials while having its legs last a lot more than 1000 km before needing replacement. The upper part of the leg would not experience much friction or erosion, outside of low-friction bearings. Do proper engineering with a good safety factor considering the alloy's strength after fatigue from the number of loading cycles involved (or the endurance limit for a type of steel), and legs lasting for tens of thousands of kilometers shouldn't be too difficult.

Such seems plausible. When a person walks, the soles of their shoes erode leading to eventual shoe replacement (though much less often than every 1000km on average), but their actual leg is better off.

Tracks must be relatively thin since they cover much greater area. They also must be flexible (ruling out many materials), roll over a greater area of ground, and probably get worn down by the edges of rocks more often.

Of course, wheels made of modern-day materials can last for much more than 1000km, but wheels can't go over as many types of terrain, with wheeled vehicles sometimes getting stuck.

As I implied, I don't know if the same situation still applies with the materials science of the GFFA, but it seems possible. For example, perhaps their strongest materials are neither flexible nor cheap enough to be suitable for tracks, so perhaps legs still last longer than tracks.

I really don't want this to devolve into "I'm an engineer and you're not". To prevent such a situation, please address the points that I raise. I'm not talking about the wear of the ground-contact surfaces. I'm talking about the severe mechanical stresses integral to a structure that is heavily vibratory by design. Legs by their nature must pound into the ground quickly and for long durations, thus withstanding many load-unload cycles (leading to metal fatigue) from the weight of the vehicle, compounded by high acceleration of legs that must be heavy themselves.

This poses a not inconsiderable design problem. Consider the internal combustion engine in your car. Consider how much design and manufacture goes into the connecting rods (connecting the pistons to the crankshaft). Now scale them up by three or four orders of magnitude, and take away the guidance of the cylinder walls. For good measure, add another joint or two in the middle, with at least one of them two-degree-of-freedom. Finally, lest we forget, have people shoot at them.

That's what a walker entails.

It's a foregone conclusion that AT-AT legs hit the ground hard because of the powerful audible groundshocks produced with each footfall. Having said that, it would probably be possible to design a shock-absorber system into the legs which greatly decreases the mechanical stresses, and the cross-sectional load-bearing area for legs can be made fairly generous if you don't mind wasting huge amounts of power.

Howedar wrote:I really don't want this to devolve into "I'm an engineer and you're not". To prevent such a situation, please address the points that I raise. I'm not talking about the wear of the ground-contact surfaces. I'm talking about the severe mechanical stresses integral to a structure that is heavily vibratory by design. Legs by their nature must pound into the ground quickly and for long durations, thus withstanding many load-unload cycles (leading to metal fatigue) from the weight of the vehicle, compounded by high acceleration of legs that must be heavy themselves.

This poses a not inconsiderable design problem. Consider the internal combustion engine in your car. Consider how much design and manufacture goes into the connecting rods (connecting the pistons to the crankshaft). Now scale them up by three or four orders of magnitude, and take away the guidance of the cylinder walls. For good measure, add another joint or two in the middle, with at least one of them two-degree-of-freedom. Finally, lest we forget, have people shoot at them.

That's what a walker entails.

A tank track of today lasting for typically 1000km between replacements is only equivalent to merely 30 hours of actual operation at about 30km speed, or a different figure at a different speed. Even for your car engine analogy, car engines can run for tens of thousands of hours or more, literally 1000+ times as long.

As Darth Wong implied, shock-absorbers spreading out the mechanical impulse over more than a momentary period of time could moderate the peak acceleration and stresses. Thickly padded feet could help too, although the AT-AT doesn't seem to use such.

Imagine oneself walking. The peak stress on the bones of one's legs doesn't have to be extreme. Admittedly, an AT-AT is certainly much bigger than a person, with a greater ratio of volume and weight to leg dimensions. However, AT-AT legs are still less than 20 meters long. For a reasonable weight, the legs can avoid buckling and experience much less than the working stress of even current metals. You mentioned metal fatigue, but that can be estimated for the number of loading cycles involved. For example, steel can have an endurance limit, a fatigue limit, and it can be fine well below that limit for almost any number of loading cycles. The structural situation is no worse than designing an airplane wing. Actually, airplane wings today are made from aluminum alloys without an endurance limit and have to be designed with a lesser safety factor due to weight constraints.

In the end, there seems no more reason to conclude legs built with modern-day materials would have to fail within 1000km than to incorrectly conclude they would have to fail within 1km. Given that today's tank tracks do tend to need replacement about every 1000km, apparently making suitable tracks last long is hard.

You are aware that WRT the drive mechanism the track isn't the knee joint, ankle or anything, it's the Valendamned sneaker you're wearing, yes?

If the future can build practical walkers, then the future can build more durable tracks.

Except they didn't build them in the future, or did you forget, "A long, long time ago..."