Anyone ever hear of Battletech?

[Sillychris]

Instead of comparing mechs to tanks overall, why not consider their individual advantages?

A tank is generally superior, I think. faster, tougher, simpler, etc.

What a mech has going for it is the same thing infantry have going for them: Legs. A mech can step up or over thing that a tank can't cross. A mech could cross steep loose terrain, walk through a deep river, walk on ****ty terrain that would clog treads etc.

Head to head I think a tank will flatten a mech everytime. What mechs will end up being is specialized niche vehicles that are used for their ultimate all terrain capabilities.

Want to walk a tank on top of a mountain? No problem!

Mechs will also be useful for baddassery propaganda purposes. Don't underestimate the power of national pride.

Of course, if we ever figure out some sort of anti-gravity hover drive mechs will completely lose their one tactical advantage.

[Red Iron Crown]

I just looked up the Abrams, and you will not guess how high and wide it is.

2.44 meters high, 3.66 meters wide, and 7.93 meters long.

My mech will have a maximum height of 3 to 5 meters. A maximum width of about 2 to 2.5 meters. And a maximum length of about 1 to 1.5 meters.

Those are simply because it will be modular, and will have multiple configurations.

Minimum for mech: 6 m^3

Maximum for mech: 18.75 m^3

Abrams: 70.818072 m^3

So, for the same armor, my mech would have MORE protection, as it actually takes up less space than 6 m^3 because that is the surrounding box.

http://en.wikipedia.org/wiki/M1_Abrams

You're comparing vehicles of grossly different masses, not a valid comparison. And the shape of the mech has far more surface area than a similarly dimensioned boxy tank.

[KASASpace]

1. It will be slower than the equivalent tank, so easier to hit and more vulnerable.

2. So we're back to armored legs and the mech having less armor to protect its vitals, and the heavier armored legs are harder to move so the mech is even slower. OK.

3. I'm open to what you think a better comparison would be, especially as you feel my comparison of biologically powered legs to biologically powered wheels is somehow not analagous to mechanically powered legs and wheels.

4. I don't think the cheetah can do 40kph offroad, and an equivalent, unarmored wheeled vehicle like an ATV will be significantly faster over all but the most difficult terrain. Bipedal motion is just inefficient, there's no way to handwave that away.

5. You didn't answer the one question I asked you.

1.) I already posted that the Abrams takes up more space. Please pay attention from now on, Mr. Crown.......

2.) The legs are armored, but there is nothing else in the legs except a limited skeleton, so it is still light compared to the tank treads having to support a whopping 60+ tons! (Abrams)

3.) Bicycles are biologically AND mechanically powered. Bad comparison, because a gear and chain system increased speed.

4.) Perhaps, but it is getting closer and closer....

5.) Repeat the question then.

Follow that example further:

1. The hits in the "empty" space are analogous to hits to the limbs of the mech, which even if mostly empty will suffer damage to the structure (monocoques like you describe rely on the skin continuity for strength) as well as the control mechanisms for those limbs. This will seriously impede the mechs ability to continue battle.

2. Hits to the non-critical areas of the mech are complete misses against the tank, which can only be an advantage for the tank.

3. I could fold my paper over itself to a greater thickness since I'm covering less area, so the paper has a better chance of stopping any hit to the critical area.

4. Even if 3 above wasn't true, the critical areas of both objects is equal, but the mech has all that other area where, deny it as you might, hits will affect it. Thus the mech is more vulnerable.

5. Your example doesn't take into account that the critical area on the tank is low to the ground and more easily hidden behind cover (cover that protects a mech's legs leaving its torso exposed will protect the everything but the turret of a tank, with no compromise to the tanks ability to maneuver as needed.

1.) No, they aren't as these representations are only representing the main bodies of the respective vehicles, counting legs in the mech.

2.) Yes, but the tank will eventually get hit, and it is more likely to be critical to the tank.

3.) Yes, but it is mesh and can barely move compared to my flex armor, which moves to help even more accommodate the blast.

4.) Actually, hits won't affect it, as all there is leading from the primary torso (75% of it's volume is the engine, the rest for the autocannon) a small limb that is flexible mounted on a type of shoulder which itself mounts a Javelin launcher

5.) It doesn't take cover into account at all for both vehicles. However the tank is wider and longer, so if the tank is caught behind, say a 2 story building longwise it is almost certainly doomed, or width-wise even, as it would need more turning time, whereas the mech can turn it's legs easily in place.

[KASASpace]

You're comparing vehicles of grossly different masses, not a valid comparison. And the shape of the mech has far more surface area than a similarly dimensioned boxy tank.

Yes, but it takes up less space in the box, thus needing less armor because it actually isn't as likely to get hit, as only one axis is a problem for the mech, whereas the tank has two axes where it's dimensions would be problematic.

[Red Iron Crown]

Please pay attention from now on, Mr. Crown.......

And with that, I bid you farewell.

[KASASpace]

Hmm, tanks have only really one thing going for them, low to the ground, whereas the mech has the opposite.

Otherwise they are fairly equal, and if put into combat they would work together to build on each other's weaknesses and use each other's advantages.

Tank:

1.) firepower

2.) Low to the ground

Mech:

1.) enough firepower to take out light to medium armored vehicles

2.) can allow for greater infantry mobility, picking them up and putting them on the second floor of buildings, or safely evacuating a team on the top of a small building

in truth, they would be a quite advantageous combination.

[KASASpace]

And with that, I bid you farewell.

Hey, you DIDN'T pay attention.

[Camacha]

Have you guys looked around the internet yet? There are some interesting articles out there

4. I don't think the cheetah can do 40kph offroad, and an equivalent, unarmored wheeled vehicle like an ATV will be significantly faster over all but the most difficult terrain. Bipedal motion is just inefficient, there's no way to handwave that away.

I can not let you get away with that one Bipedal motion is more efficient than wheeled propulsion, the latter just uses a lot more power to overcome that. Walking costs barely more energy than merely standing as it is basically a pendulum motion that uses its own energy to move forward. In short, you just control falling forward. Driving, on the other hand, means continuous friction between the wheel and the surface, friction within the wheel (deformation) and loss of energy due to the suspension. You also tend to touch the ground with more wheels at the same time, increasing the cost.

The cost of legged motion is of course complexity, but that is mostly from a (crude) technology point of view. Fossil fuels and the abundance of energy they pertain mean that we do not really care about efficiency as much as biology does, but that might change in the near future. There are good reasons animals use legs.

[Sillychris]

I don't think that legged motion is more efficient than wheeled motion, and I don't think that's why it was chosen by evolution over wheels. I think evolution favored legs because they are actually plausible with biological methods.

That being said, I often ask biologists how we could perhaps engineer an organism with wheels instead of feet. What do you guys think?

Also, I think we are overlooking that the mechs of the future would probably have wheels on their feet. Maybe a wheel tripod or something like that that can be locked for walking purposes and can be driven for high speed driving purposes. Let's inject THAT idea into the discussion!

[Sillychris]

Look at the scorpion tank from Halo: Not a bad idea. Variable geometry treads for improved terrain abilities. Let's make the treads more variable and more variable until they function as legs as well as treads! Maybe in the future the distinction between tanks and mechs will get somewhat fuzzy?

[KASASpace]

Have you guys looked around the internet yet? There are some interesting articles out there

I can not let you get away with that one Bipedal motion is more efficient than wheeled propulsion, the latter just uses a lot more power to overcome that. Walking costs barely more energy than merely standing as it is basically a pendulum motion that uses its own energy to move forward. In short, you just control falling forward. Driving, on the other hand, means continuous friction between the wheel and the surface, friction within the wheel (deformation) and loss of energy due to the suspension. You also tend to touch the ground with more wheels at the same time, increasing the cost.

The cost of legged motion is of course complexity, but that is mostly from a (crude) technology point of view. Fossil fuels and the abundance of energy they pertain mean that we do not really care about efficiency as much as biology does, but that might change in the near future. There are good reasons animals use legs.

You sir, are very knowledgeable.

Of course if you try and chicken walk, that's a completely different story.

[KASASpace]

I don't think that legged motion is more efficient than wheeled motion, and I don't think that's why it was chosen by evolution over wheels. I think evolution favored legs because they are actually plausible with biological methods.

That being said, I often ask biologists how we could perhaps engineer an organism with wheels instead of feet. What do you guys think?

Also, I think we are overlooking that the mechs of the future would probably have wheels on their feet. Maybe a wheel tripod or something like that that can be locked for walking purposes and can be driven for high speed driving purposes. Let's inject THAT idea into the discussion!

How many joules to move ~ 113 kilograms?

How many joules to rotate ~ 25 kilograms?

How many for ~10 kilograms?

Answer these, and you will discover a great revelation.

[KASASpace]

Look at the scorpion tank from Halo: Not a bad idea. Variable geometry treads for improved terrain abilities. Let's make the treads more variable and more variable until they function as legs as well as treads! Maybe in the future the distinction between tanks and mechs will get somewhat fuzzy?

That would be worse, as it would be over 6 meters, in fact the Scorpion is bad period, the main gun reaches over cover, which basically just obliterates the ONE good advantage of tanks over mechs.

[KASASpace]

Actually, yeah, come to think of it, walking is more efficient, maybe more so, than wheels. You see, wheels DO need to constantly act on the ground against friction, whereas a leg merely has to swing it across a distance and place the foot down a multitude of times. It requires less energy to move the leg hinges a little bit than to constantly rotate the heavy wheel.

So, hey, it won't get speed, but that's not as important, because if you can outmaneuver tanks (like rotating the legs in place after hiding behind a building and almost instantly coming back out, surprising the tank and firing, say, a Javelin), go over rubble, and carry heavy loads, then you are all set.

Plus, a tank's speed doesn't really matter, as it can only go as fast as the slowest in the convoy, which is usually how they go about things.

[Camacha]

I don't think that legged motion is more efficient than wheeled motion, and I don't think that's why it was chosen by evolution over wheels. I think evolution favored legs because they are actually plausible with biological methods.

Circular type motion is actually possible, but only found in the smallest of creatures (in the form of a bacterial tail, for instance). You can be pretty sure there are good reasons for that. Wheels are simply not useful when scaling them up to bigger creatures. Of course, there are some organisms that simply rotate their whole structure (think tumbleweed), but they typically do not expend energy to get anywhere.

When it comes to efficiency, the story is a little more complex. When you do the calculations for a bicycle (one of the most efficient types of transport around) versus walking, the bicycle takes the lead in efficiency. What we should not forget, however, it that this is only true on good, flat roads, with a light and properly setup bike and at a low speed. Any variation in the terrain or any of the other factors and bicycle efficiency starts to plummet, up to the point where you are simply not capable of getting around anymore. Compare that to feet and you see why the latter are a winner.

Bacterial 'axle':

Edited March 22, 2014 by Camacha

[Stargate525]

I was under the impression that wheels on a macro scale never evolved because the wheel and the load are by necessity two things. If it were a biological thing, it would have to be shedded or somehow detached in order to rotate. And, if you need a new one, you're completely immobile until the new one grows.

[Mecha Pants]

If a mech only needed to input energy to flex the joints in its legs to move, then yes it might be more efficient than wheeled movement. This isn't the case. With every step it needs to lift the mass of one leg while at the same time stiffening the joints in the other to keep it from collapsing under the mass of the body. Additionally, at the end of every step the legs lose energy to the impact of the foot against the ground.

In modern robotics, wheels considered the most efficient mode of movement over flat ground because they actually need very little energy to gain and maintain velocity.

I also feel the need to point out that even today, The 120mm cannon in the Abrams tank using its standard kinetic penetrator cannot defeat the front or side armor of an Abrams tank even at absurdly close ranges. Also, it carries countermeasures against ATGMs in the form of the AN/VLQ-6 Missile Countermeasure Device which uses a massive directed infrared signal to disrupt the guidance systems of incoming missiles.

Hell, the Russian Arena Active Protection System can automatically detect and actively destroy any incoming projectile moving between 70 and 700m/s, with a 0.05s reaction speed. Germany has an active defense system that responds in microseconds. Both protect against guided and unguided projectiles, making RPGs ineffective.

What I guess I'm trying to say, is that killing tanks with missiles is going to be even harder in the age of mechs than you might expect, as they are going to advance just as fast technologically. If your mech is a one-man unit because of the advanced neurohelmet tech, who's to say that the tank it faces isn't as well?

[KASASpace]

If a mech only needed to input energy to flex the joints in its legs to move, then yes it might be more efficient than wheeled movement. This isn't the case. With every step it needs to lift the mass of one leg while at the same time stiffening the joints in the other to keep it from collapsing under the mass of the body. Additionally, at the end of every step the legs lose energy to the impact of the foot against the ground.

In modern robotics, wheels considered the most efficient mode of movement over flat ground because they actually need very little energy to gain and maintain velocity.

I also feel the need to point out that even today, The 120mm cannon in the Abrams tank using its standard kinetic penetrator cannot defeat the front or side armor of an Abrams tank even at absurdly close ranges. Also, it carries countermeasures against ATGMs in the form of the AN/VLQ-6 Missile Countermeasure Device which uses a massive directed infrared signal to disrupt the guidance systems of incoming missiles.

Hell, the Russian Arena Active Protection System can automatically detect and actively destroy any incoming projectile moving between 70 and 700m/s, with a 0.05s reaction speed. Germany has an active defense system that responds in microseconds. Both protect against guided and unguided projectiles, making RPGs ineffective.

What I guess I'm trying to say, is that killing tanks with missiles is going to be even harder in the age of mechs than you might expect, as they are going to advance just as fast technologically. If your mech is a one-man unit because of the advanced neurohelmet tech, who's to say that the tank it faces isn't as well?

You have to stiffen the leg, yes, but that is much less energy reducing then you might think. A simple hydraulic locking mechanism.

Now, the missiles might just be moving faster than 700m/s, and might just be unguided.

Plus there is ECM for ECM, you know that right?

[Mecha Pants]

Now, the missiles might just be moving faster than 700m/s, and might just be unguided.

Plus there is ECM for ECM, you know that right?

I do, but what I'm getting at is that there seems to be a trend of assuming that mechs will drop unannounced and unexpected into modern combat scenarios, instead of dropping into a world where tanks and other conventional systems have had the same amount of additional development time to grow and adapt to whatever threat mechs might produce. I'm only saying it won't be as simple as "mech encounters tank, is better by default, and thus wins"

[Camacha]

I was under the impression that wheels on a macro scale never evolved because the wheel and the load are by necessity two things. If it were a biological thing, it would have to be shedded or somehow detached in order to rotate. And, if you need a new one, you're completely immobile until the new one grows.

There are many ways of solving detachement. Some type of fluid might be used as a bearing and also as a interface. Of course, animal wheels could also simply be inert structures like nails, horns or hair.

The immobility thing is easily solved by using multiple wheels. Beyond three or four any extra wheel will add redundancy, maybe even less.

[Camacha]

If a mech only needed to input energy to flex the joints in its legs to move, then yes it might be more efficient than wheeled movement. This isn't the case. With every step it needs to lift the mass of one leg while at the same time stiffening the joints in the other to keep it from collapsing under the mass of the body. Additionally, at the end of every step the legs lose energy to the impact of the foot against the ground.

I think you are discribing quite accurately why it is so hard to replicate bipedal motion in robots. Yet, when done succesfully, the controlled fall that is a dynamic gait will actually be quite efficient.

Finally, it is dangerous to compare wheels on flat terrain to legs on different types of terrain. It is exactly when things become a bit rougher that wheels lose their edge quickly, and legs become more and more useful. It is quite a challenge to absorb all the shocks (which means losing energy) while still staying in contact with the ground for efficient traction and preventing wheelspin.

[Sillychris]

Circular type motion is actually possible, but only found in the smallest of creatures (in the form of a bacterial tail, for instance). You can be pretty sure there are good reasons for that. Wheels are simply not useful when scaling them up to bigger creatures. Of course, there are some organisms that simply rotate their whole structure (think tumbleweed), but they typically do not expend energy to get anywhere.

When it comes to efficiency, the story is a little more complex. When you do the calculations for a bicycle (on of the most efficient types of transport around) versus walking, the bicycle takes the lead in efficiency. What we should not forget, however, it that this is only true on good, flat roads, with a light and properly setup bike and at a low speed. Any variation in the terrain or any of the other factors and bicycle efficiency starts to plummet, up to the point where you are simply not capable of getting around anymore. Compare that to feet and you see why the latter are a winner.

Bacterial 'axle':

http://upload.wikimedia.org/wikipedia/commons/thumb/3/3c/Physical_model_of_a_bacterial_flagellum.jpg/450px-Physical_model_of_a_bacterial_flagellum.jpg

How long do you think until somebody breeds or engineers a tiny toy car shaped cellÉ

[Camacha]

How long do you think until somebody breeds or engineers a tiny toy car shaped cellÉ

Possibly about as long as it takes to get fed up by the atom sized ones

Article.

[Seret]

Why do you guys so desperately want to compare tanks to possible mechs? I think a lot more obvious and natural role is that of heavy infantry.

Definitely. If an exoskeleton could be developed that had resistance to small arms, reasonable agility and long enough endurance then it could be useful. Conceivably walking robots on the scale of Boston Dynamics Big Dog could also be useful carrying a weapon that is normally crew served, for recce, or for IEDD/EOD. I'm not convinced the load carrying role the designers have in mind is going to find much support in military circles except for very niche use cases.

[sgt_flyer]

Well, bipedal / quadrupedal robots will become really useful the day they will be able to run efficiently on various terrains

One key feature needed for that is the work done by our tendons. tendons (in addition to keeping things attached together) send back informations to the brain, regarding how much force is exerted on them.)

Of all tendons, there is one which is key in allowing us to run : the Achilles tendon.

It's this one which allows energy efficient running, because it stores the energy generated by the feet impact, and gives it back when you want to 'push' on this feet to continue the running motion (achille tendon is basically the nature's equivalent to the KERS)

So basically, for a good bipedal / quadrupedal running robot / mech, we would need to 'sense' the ground with the robot's feets and process all theses informations fast enough to allow running, and use a way to recuperate the kinetic energy of the feets impacts for an efficient system.