Compare uses of tracked vehicles and combat walkers?

[Harry Tuttle]

One bonus for walkers could be crowd control. A twenty foot tall walker would be great at suppression.

[Sandman]

Originally posted by Kuciwalker
There are many valid criticisms of walkers, but I don't believe this is one. It's not difficult to place the computer in a such a way that the drive mechanisms would be inoperable long before the computer was destroyed.

It wouldn't need to be destroyed, just 'rendered inoperable'. By mud, dust or water, maybe. Or by losing its sensory apparatus. That said, I have no idea how often other kinds of battlefield computer break down.

[LordShiva]

Originally posted by Aeson
The possibilities are endless...

Tired of fighting? Dance-off!
Troops' morale waning? Baseball!

[Q Classic]

If you actually look at it logically, yeah, there's no point.

But on the other hand, they look so damn cool!

[Elok]

Originally posted by Blake
I'll attempt to explain this further...

A track does not move relative to the ground. If you look at the motion of a tank track, you see, the track does not move. A track segment gets plopped onto the ground, it sits there, and once all the wheels of the tank has rolled over it, it's pulled back off the ground (and then travels along the top of the wheels at twice the speed of the tank, relative to the ground). The track segments do not move relative to the ground and the energy required to lift them back off the ground (the "suck") is not particularly significant.

Wheels work best on flat hard surfaces and a tracked vehicle basically carries it's own flat hard surface around with it.

I don't get it. If that were so, and the friction with the ground just a nuisance, wouldn't the tank's wheels just spin the track around and around without moving over the ground, like legs pushing on a treadmill? The part that touches the ground has to be pushing against it to make the vehicle move forward, no? So the friction is quite important.

[Dis]

I thought scientists were examining spider like robots for possible military uses. Recon being the only useful one. These would be extremely small of course.

So they were trying to figure out the dynamics of spider movement and incorporate it into a robot. This is no simple task. The japanese can barely get a 2 legged robot to walk.

In the end, they will rely on flying vehicles. But very small spider robots could be useful when stealth is needed over a loud, noisy probe plane.

[Proteus_MST]

Originally posted by Dis
I thought scientists were examining spider like robots for possible military uses. Recon being the only useful one. These would be extremely small of course.

So they were trying to figure out the dynamics of spider movement and incorporate it into a robot. This is no simple task. The japanese can barely get a 2 legged robot to walk.

In the end, they will rely on flying vehicles. But very small spider robots could be useful when stealth is needed over a loud, noisy probe plane.

I think it is easier than for a 2 legged robot.

The problem about walking is the balancing, which is very difficult if you´ve got your centre of gravity high above the ground and have to shift it for each step so that you on the one hand can make a step forward and on he óther hand balance on just one leg (as the other is above the ground while making the step).

In spiders however (whose movement is well understood) you have just 4 legs above the ground (no, not all 4 on one side, but 2 on each side ) while the spider still stands on the 4 remaining legs, making movement of an 8 legged robot much easier and more stable than that of an 2 legged robot.

[Provost Harrison]

Originally posted by Blake
Think things like spider bots able to climb over rocks and even climb up trees and stuff.

Arachnotrons

[Kuciwalker]

Originally posted by Elok


I don't get it. If that were so, and the friction with the ground just a nuisance

Nononono, it's not a nuisance, it's the opposite. The friction with the ground (called static friction, since it is the force that acts when the surfaces are locked together rather than moving relative to each other) is the force that propels the tank forward. The treads push against the ground and the ground pushes back (per Newton) against the treads, but they don't move relative to each other until the tread is lifted off the ground.

[Elok]

Yes, that's what I was saying! Well, except I didn't specify when exactly the tank begins to move. Anyway, yer preaching to the choir here.

[Serb]

Combat walkers suck completely.
The Germans abandoned the idea in 1945, iirc.

[Maniac]

This article was posted on CFC, where I posted the same question:

The question of whether mecha could ever be used in the real world as practical war machines is a widely debated topic on many mecha forums. Due to their intended purpose, mecha are usually compared to tanks (or, in the case of Gundam or Macross, fighters).

Mecha as a Replacement for Tanks

Mobility

One of the arguments in favor of the viability of anthropomorphic mecha over tanks is its use of bipedal 'legs' system for locomotion instead of a tank's 'caterpillar' track system. Mecha's proponents believe that its mobility would be superior to a tank because, using humans as the model, a mecha would be able to traverse a variety of terrain where a tracked vehicle would be rendered immobile or be forced to seek an alternative (and potentially more dangerous) route. For example, a mecha could conceivably negotiate relatively steep, hilly terrain that would cause a tracked vehicle to lose traction — of course, if the slope is sufficiently steep, even the mecha would lose traction, or worse, could fall backwards. Tank traps such as dragon's teeth, or czech hedgehogs, which are very capable of stopping the forward progress of tanks may not be an issue to a large mecha with legs that can simply walk over them.

The counter argument against this centers around balance. The biped mecha would need sophisticated stabilizing systems to maintain balance (even when not in motion); one false step could cause the mecha to topple. The likelihood of this occurring is greater if the center of gravity (CoG) is high off the ground. High CoG appears to be the case based on the way mecha are depicted in various anime, games, etc. Generally most, if not all, of the weapons are mounted on arms/hands, on the shoulders, or on the back; the propulsion systems in or around the torso/trunk; the pilot(s) in the head or trunk; and all of the associated armor. All of these elements suggest a CoG at, or above, the level of the 'abdomen'. To lower the CoG, the legs would have to be very heavy and/or the above-noted elements would have to be very light. Howevver, given the fact that the legs would have to support the entire upper portion of the mecha, they would likely contain large structural metal and/or composite strucutres that take up most of their volume, with the rest being used only for motivational systems. Note: in zero/near zero gravity conditions or on low-gravity planets/moons, the CoG would be less of an issue. But, high mass would still be an issue and would have to be addressed (see the agility discussion below).

Similarly, a biped mecha could cross relatively uneven terrain. Assuming that the mecha's legs have a range of motion and articulation similar to human legs, the legs and feet could be positioned a varying distances apart so that greater flexibility in moving is offered in contrast to tracked vehicles where the alignment, orientation, and physical separation between the left and right tracks cannot be adjusted. It could be argued, however, against mecha, and for that matter tanks, that if the terrain was extremely difficult to navigate, why not fly over it? Also, the use of legs means that all of the machine's weight is focused on two relatively small points. Considering that most mecha are depicted as very large and heavy, this could cause severe problems if the mecha were to traverse any kind of soft terrain where its feet or legs could sink into the ground, or get stuck in heavy foliage, and inhibit movement. This is in contrast to a tank's treads which allow the weight to be distributed over a larger surface area. In addition, the tank's treads emulate the method a caterpiller uses to move, which gives it excellent all terrain movement.

Not only computers, but the movement system of the legs would need heavy machinery to do the actual lifting of the legs. MechWarrior mechs overcome this obstacle by a lightweight muscle-like tissue and a fusion generator powering it, but such technology is far ahead in the future.

Agility

Another argument is superior agility. Proponents state that a biped mecha should be able to alter its course faster and more unpredictably. Assuming human-levels of leg articulation, the mecha could 'shift' horizontally (to its left or right), vertically (jump up or crouch down), diagonally, or a combination thereof. In order to accomplish this, a mecha would need to have a range of motion very similar to a human being. This range of motion precludes the battlefield use of the vast majority of mecha depictions, which tend to be limited in range of movement (like BattleTech mechs) or which have mechanical control systems that limit the range of movement by limiting the range of controls. Also, in order to be agile, the mecha would have to be of sufficiently low mass employing lightweight materials in its construction AND the weapons carried would also have to be light in mass. Otherwise, the inertia of a heavy machine will require more energy to accelerate, decellerate, and accomplish any changes in direction. Analogies can be found in observing lightweight boxers, racehorses, sprinters, or gymnasts. Mechanical analogies can be observed in motorcycles, race cars, combat aircraft, and spacecraft. In all instances, low mass allows for more efficient use of energy.

Theoretically, a mecha can move in an unpredictable manner to present a more difficult target and/or dodge incoming fire. In the context of 21st century projectile weapons, dodging such attacks would be just as absurd as any human being able to do so, unless the distances involved were large AND the target was aware of the incoming fire AND the projectile or missile was moving especially slow. Also, if the incoming fire was a sophisticated guided missile, the guidance system of the missile would be able to compensate for any motion of the target. Lastly, for many explosive weapons, it is NOT necessary to actually hit the target — explosive weapons destroy the target via concussive effects, shrapnel/flying debris, and heat. It is possible, however, for mechas to reduce their targetability through agility.

Height

Another argument, and perhaps the weakest argument, is the greater height of the mecha compared to a tank. Cited as a superior trait to tanks, the belief held is that a higher vantage point (i.e. with the appropriate sensors on the mecha's 'head') would allow more opportunities for detecting and attacking a target (because you can see it a target even if its hidden behind an object) and the ability to project firepower greater distances or more favorable angles. One of the counter-arguments is a taller mecha is in fact an easier target to detect and hit because its bulk would be much higher above the ground than that of a tank. There is, after all, a reason why soldiers, when under fire, crouch down; being taller is NOT an advantage in this case. The stance of a mecha also means that the use of armour for protection-by-deflection would not be of use, as armour plates are more likely to be perpendicular to the direction of incoming fire from the ground. The mechs would most likely have trouble having sloped armour because of their general shape, and without it would need thicker straight armour to withstand hits, dramatically increasing weight. As another example, modern day tanks are more 'low-profile' than their predecessors for this reason (compare an M1A1 Abram MBT at 2.42 meters in height or Israeli Merkava MBT at 2.66 meters in height with an M4 Sherman MBT at 2.74 meters in height, with the Sherman actually being the most lightweight of these).

Additionally, it is not unusual for a target to be 'beyond visual range' (BVR) - thus, being able to 'see' the target from a higher vantage point is moot. A modern example is one of the methods that a vehicle such as an US AH-64 Apache helicopter attacks its target. It can do so by launching a missile (such as the Hellfire) from behind a hill without the crew precisely knowing the location of the target because the target is identified and 'illuminated' using a laser operated by a soldier on the ground — the missile launched by the helicopter is guided to the target by the sensors onboard the missile that detect (and therefore, 'home-in' on) the laser energy bouncing off of the target vehicle. Another example is the BGM-109 Tomahawk cruise missile — the sea- or airborne crew that launch it never actually 'see' the target.

Also, most modern armies will not operate in isolation. Instead, there will be a network of intelligence-gathering devices, methods, and vehicles. These assets include space-borne spy satellites, aircraft, or recon soldiers that will alert ground assets such as tanks to the presence of enemy vehicles, troops, or installations. Lastly, the 'higher vantage point' argument is not applicable when addressing airborne targets — a plane flying at 500 miles per hour (such as an A-10 Thunderbolt II) at a tactical combat altitude of 1000 feet or less does not become more visible simply because you are 30 feet higher above the vantage point of a tank. Detection of the enemy may occur sooner, but the time advantage would be negligible. Similarly, the enemy most likely detected the 30-foot tall mecha just as quickly.

Method of Motion

Maximum velocity is another restriction upon mechas, as they would be limited both in how quickly their legs could cycle while running, and by the amount of stress the legs could take from impacts on the ground while doing so (to say nothing of how the ground would react). Note that in order for the legs to cycle quickly, they would have to be sufficiently low in mass (observe a sprinter whose legs are very lean). The legs would also need heavy machinery (like swing-wing aircraft are much heavier than fixed-wing). However, this has to balance against the weight of the vehicle that it supports and the problem, as mentioned previously, with maintaining a low center of gravity.

It is also pointed out that a mech's leg drive system would be far too complex and costly to be practical on the battlefield. Articulating the leg via various motors, electric circuits, etc. mean that every part of the leg must be protected with armor (with the corresponding increase in mass, increase in physical size, and loss in agility). Without sufficient armor, even modest damage would render the mecha immobile. Also, it should be noted that the more complicated a system or device, the more time and skill necessary to repair damage - in battlefield conditions, extensive 'downtime' would not be acceptable (assuming that the skilled mechanics and time were even available). Conversely, a tank's tread is relatively simple and easy to repair or replace should the need arise. Lastly, if a leg were damaged or destroyed, the mecha could topple uncontrollably leading to extensive damage to the mecha and injury or death for its pilot(s). Damage to a tank's tread merely renders it immobile.

These restriction could be mitigated by the use of an alternate mode of travel, but the frequent depiction of flying as this secondary mode would likely turn a battlefield into a trap shoot for opposing units. Also, adding the capacity to fly requires more powerful engines and fuel tanks which results in a heavier upper body. And, since the mecha would not have wings, whatever flying capacity it did have would be limited to very short movements with limited maneuverability (this itself would make the mecha an easy target because a slow-moving, lumbering airborne target would be easy to hit even with relatively unsophisticated weapons). Also this feature would beg the question that if such equipment can be mounted on a mecha, why not a tank?

Another solution would be the use of a secondary means of locomotion (in addition to walking), such as feet mounted wheels or treads, as seen in Front Mission and Ghost in the Shell: Stand Alone Complex, or the SMS, or Secondary Movement System of Heavy Gear. Utilitarians counter this by posing the question of why not revert to a tank chassis if this is how the vehicle is moving around? And wouldn't this negate all of the 'advantages' over tanks that were stated above?

Weapon Systems

The available weapons that a mecha could carry/operate are subject to debate. In stark contrast to mecha depicted in fiction where their arsenals are usually more varied and powerful than their tank counterparts, it is more likely that the weapons would be limited to lightweight missiles.

A tank, being low and having a low center of gravity, is a stable platform from which to fire weapons, especially any weapon such as a large gun that has a significant recoil. A mecha, on the other hand, would likely suffer from the recoil effects. To counter this, the mecha would need to have arms that articulate when firing a recoiling weapon to dissipate the energy; otherwise, the recoil energy would likely shift the mecha backward (literally lean backward). Another solution would be to have the weapon's longitudinal axis (the bore axis) at the same vertical height as the center of gravity. Firing the weapon would shift the entire mecha backwards. In both cases, however, the weapon would have to still be held firmly to ensure accurate aiming. Depending on how weapons on a mecha are mounted, the mech could adapt leg and body posture and body weight distribution to absorb the recoil energy progressively and dynamically (ie. laying down prone or bracing the recoil with a wide stance) - assuming that the mecha has this level of flexibility to begin with. However this solution means the mecha typically can not move while bracing for recoil, unlike a tank which can shoot and move at the same time, putting the mecha in a severe tactical disadvantage.

These problems with recoil effectively remove the possibility of mounting large caliber weapons on a mecha, resulting in the mecha being unable to 'outgun' a main battle tank. In the event that none of these solutions could be achieved, the only non-guided/non-self-propelled projectile weapons a mecha could mount are small caliber armor piercing weapons such as a 20-40mm (approx .66 caliber -1.30 inch) cannon. However, these weapons are typically reserved for light armored vehicles or troops and are ineffective against tanks or similarly heavy-armored vehicles and installations. But considering the potential size of mecha proposed by shows like Gundam, a 120mm assault rifle is plausible due to the gun being nearly the size of a tank. Considering the majority of the tank is not the gun, and the majority of an assaultrifle is taken up by mechanisms to make the weapon fully automatic, the additional room for the cannon due to the lack of a tank chassis could be used for fully automatic capability, giving a large fire power advantage over a tank. Future development of powerful lasers or electromagnetic rail guns, (if they ever become practical on the battlefield) could address some deficiency in mecha armament.

Mecha, as generally depicted, also could carry missiles. Furthermore, a missile does not generate recoil if the tail exhaust is allowed to fire outside the vehicle. The missile also need not be fired directly at its target, i.e. the missile could alter its vector once airborne. In the other hand, tanks can do the same.

Defenses

While not the most noticeable, the mech has defenses that are very beneficial, not just for the mech, but the pilot. Just as a tank's tracks provide some protection to the sides, a mech's limbs help protect its body, in ways that are better than that of other vehicles. The limbs themselves provide a physical barrier between the danger and the pilot. If a mech were to step on a land mine, the leg would take the blow, protecting the pilot. (However, the pilot could get killed if the mech were to fall.) A tank, on the other hand, could run over a land mine and take in the explosion, killing the crew.

The tank's size would also provide a problem, as the tank would take in a majority of the energy, forcing it to flip over. Even worse, a tank that has flipped over (or any other wheeled vehicle for that matter) could not get back up by itself. Mechs, with their limbs, will stand back up after falling. On the other hand, an explosion powerful enough to flip a tank over would very likely destroy the mechanisms needed to operate a mecha's legs, which, as mentioned above, are sophisticated and need to be lightweight, and therefore probably do not have much armor protection.

The secondary defenses of the limbs could reduce the need for armor on parts of the torso, saving weight for mobility. The flexibility of these limbs would also provide additional protection for the already armored parts of the body, such as the arm protecting the body to defend against RPGs, shaped charges, or KE penetrators. The arm would then continue to remain useful as a shield (or melee weapon), until it was completely destroyed. However, the penetration of modern anti-tank weapons is so great that they would most likely fully penetrate the mecha's limbs and then hit its torso armor: again, the need for lightweight limbs prevents them carrying the kind of armor main battle tanks have on their hull and turret fronts (the only sides of a modern tank likely to stop an incoming anti-tank round).

Although the mech's limbs provide plenty of protection, the main armor would not be able to do as well, because the armor itself would add additional weight on the mech, making it slower, since limbs would already weigh down the mech. Also, using the limbs as secondary protection would sacrifice the mech's offensive capabilities (but the mech could still put up a fight as long as it was able to move). Regardless of the disadvantages, the addition of limbs is clearly beneficial, in terms of the pilot's survivability.

Mecha as Aerospace Combat Vehicles

Another use for mecha, as opposed to replacing tanks would be for them to function in a similar manner to aerospace or conventional fighters, as is depicted in various Gundam shows or Macross. The notion of a "flying robot" is sometimes considered absurd, until mecha enthusiasts point out the Mecha's ability to take advantage of reactionless maneuvering accomplished through a mecha's use of its arms and legs (known as AMBAC in the Gundam UC universe). However the ability to properly debate how such a machine would function in the real world is currently impossible due to an inability to test it. Mecha enthusiasts argue that freeflying, (a derivative of parachuting) is a very similar real world application of humanoid maneuvering in mid air. Using their arms and legs, freeflyers are able to have full control over the three flying axes (roll, pitch, and yaw). While planes are able to do this, it is possible that the movable arms and legs of a mech might be able to perform the maneuvers faster. This is ideal for close ranged air combat where the positioning of forward arc of the machine could mean victory or defeat. This idea of reactionless maneuvering is also useful in space combat where there is no air for an aerodynamic plane to use flaps for maneuvering. In such an environment, changing facing is only possible through thrust vectoring or AMBAC. Despite that, some point out that even if AMBAC were to work, its concept would be better utilized in non-mecha designs.

In addition, these advantages are mostly useful at close range which is rare in modern air combat, which utilize lots of radars; while it is possible to make a fighter or mecha very fast and maneuverable, it is easier to make a missile even faster and more maneuverable. Utilitarians also argue that creating an atmospheric flying robot is impossible in the first place. Mecha would have to possess fictional technology that allows continuous lift without wings or rotors, which makes debating the points previously mentioned completely irrelevant. On the other hand, common appearance of AMBAC is in a battlefield involving heavy electronic warfare (sometimes disabling powerful generators altogether, such as N-Jammers from Gundam SEED), which jammed not only radars but all form of lower band frequency (sub-infrared), making only visual sensor usable, which encourage dogfights and swarmfiring—conditions that encourages agility. Furthermore, most of the concepts for aerospace mecha is designed for usage in space (where air resistance is non existent).

Other Proposed Uses For Mecha
Image:HunterHeavyGear.gif
A Gear from Heavy Gear is a good example of small mecha bordering on powered armor.

It is also speculated that, rather than replacing tanks, a mech could be used for urban combat scenarios in an infantry support role. Such a mecha would probably only be 5-7 meters tall and would be verging on power armor. The size of such a mecha would enable it to carry heavy weapons such as a chaingun that would otherwise be unavailable to an infantry squad, yet its legs would allow it to maneuver more freely than a tank in the close confines of an urban environment. Furthermore the presence of actuated arms would allow a mecha to deal with infantry that manage to get into direct physical contact with the mech, something that tanks are currently unable to do. In addition it would grant several enhanced prehensile attributes unavailable to vehicles and improved over infantry capabilities. The paved roads of an urban environment would also negate the problems of weight distribution. Despite this, a mecha in an urban environment faces the difficulty of maneuvering; the sheer amount of clutter that can be present in urban terrain might prove too much for a mech's gyroscopes to handle.

Another consideration for military use of mecha would be for non-combat support functions. The example in the movie Aliens is one such depiction, where the vaguely humanoid shape allows for an unmatched versatility in manual labour tasks. Under these circumstances, where development of such a mecha was undertaken for other reasons, it might be worthwhile for a military service to arm them after the fact. Indeed this is already seen in existing militaries as evidenced by the IDF Caterpillar D9. All of the above issues would be mitigated by the fact that combat would not be the mecha's primary role, but would instead be a secondary function only used when circumstances are dire. This would naturally point us towards the development of mecha for purposes other than military (heavy police action, industrial firefighting, mining, etc.). If this were to take place, no doubt some military service would apply the concept of mechas to a fighting force, were some other sector to take the cost of development upon themselves.

Considerations for the future

In order to appear on the battlefield in any role, mecha would have to fulfill the following requirements.

1. Mecha would have to be physically possible. Given ongoing developments in the field, this can be assumed to be true.

2. Mecha would have to be reliable, strong and capable of navigating rough, real-world terrain. The Finnish Forest Walking Machine has shown that a six-limbed mech is possible.

3. Mecha would have to be militarized to go into combat, presumably with armor, weapons and fire control systems, which would produce a much heavier vehicle than a "basic" civilian version that would be useful in construction, forestry or other engineering tasks.

Even if these three requirements are met, they would only produce a crude walking infantry-support platform or combat engineering vehicle, which would undoubtably be very useful in a narrow range of circumstances but which would never replace traditional fighting vehicles. In order to make a battlefield-dominating war machine, more steps must be taken.

4. Mecha would have to be grown drastically from current designs to produce something on a more "anime-esque" scale that could compete with armored fighting vehicles on their own terms. This is extremely significant - most current designs are relatively small.

5. These large fighting mecha would have to be sufficiently agile to at least equal the flat-ground mobility of conventional fighting vehicles, as well as be able to successfully exploit the advantages of their movement system in crossing otherwise-impassable terrain. Humanlike agility and speed scaled to a ten-meter mecha would be more than sufficient (in fact, such a machine could dodge current antitank cannon fire without much of a problem), but that is far easier said than done. The engineering challenges involved in making a truly agile mecha are daunting.

6. Mecha would have to be equippable with weaponry powerful enough to destroy conventional tanks, as well as carry enough armor to survive severe attacks. A large, armored mecha would be close to the mass of a main battle tank and could presumably carry and fire heavy antitank cannons on the move, as well as mounting missiles, heavy rapid-fire autocannons or grenade launchers large enough to completely destroy any armored vehicle, but again the engineering challenges are nontrivial and the case rests of a huge pile of flimsy assumptions.

7. Finally, heavy, tank-busting mecha would have to be economical, deployable, and useful in the tactical scheme of the future, not that of the present. Given the current logistical issues surrounding large AFVs, the extreme cost of many complicated weapons systems, and the haziness of the future, none of these are assured.

Assuming all seven of these are met, mecha would become as useful and omnipresent on the real battlefield as they are on imaginary ones. However, mecha require so much development from their current embryonic forms that any argument for or against their usage on the battlefield is made standing on the air of bad assumptions and can be easily challenged and "disproven".

Some summary:

1) negotiate relatively steep, hilly terrain that would cause a tracked vehicle to lose traction
in uneven terrain: human/crawler > walker > tracked

2) walk over obstacles > tracked

3) center of gravity less a problem in weightless environment

4) can't carry heavy weaponry to remain agility
ability to use heavy weapons: tracked > walker/crawler > infantry
agility: infantry > walker > tracked

5) urban combat scenarios in an infantry support role
more agility than tank, heavier weaponry than infantry
Furthermore the presence of actuated arms would allow a mecha to deal with infantry that manage to get into direct physical contact with the mech, something that tanks are currently unable to do.

6) combat only secondary function besides others: heavy police action, industrial firefighting, mining, forestry...

[7) close ranged air combat, AMBAC in a battlefield involving heavy electronic warfare and space]


Btw, I was thinking about fully self-functioning walkers/crawlers, so they could be small, not needing to carry a pilot.

[Blake]

I used to build walkers out of Lego Technic.

I did manage to build one 2-legged walker but it was one designed so that it could balance on either leg without falling over (to put it simply, the feet both overlapped the under the center of gravity and passed "over/under" each other while walking, it's not complicated actually)


It's possible to make a 4-legged walker with spindle legs, but it's very unstable, it tends to tip "diagonally".

Any walker with 6 or more legs is quite stable, although with 6 legs more weight is placed alternately on either side, creating higher stresses on the individual legs.

8 legged walkers are ideal, although they were quite difficult to build out of lego technic due to size issues.

All of these (except the biped) were "Brick with legs" designs.

I'd walk the walkers over frozen ice and stuff.

They weren't really true walkers because the feet moved in a strictly circular motion.

[Maniac]

Originally posted by Blake
It's possible to make a 4-legged walker with spindle legs, but it's very unstable, it tends to tip "diagonally".

Isn't "constantly tipping over" basically the human method of movement?

[Blake]

Not in quite the same sense .

Rigid-body 4-legged walkers are ungainly. Organic creatures use various methods to compensate for only having 4 legs, such as pivoting waists or galloping gaits, this is to prevent the "tipping diagonally" problem (when you tip diagonally, one leg is rammed into the dirt (requiring great force to lift the body back up) and the other leg can't reach the dirt (providing no traction!)).

Humans have some pretty complex compensation for the limitation of only having 2 legs, such as pivoting hips and swaying arms. This allows for an efficient gait.

Humans fall forward then catch themselves, they don't tip.