What are Issues of Transforming Robots or Robots that Combine into Bigger Mechs?

[Johnny1A.2]

Originally Posted by Anthony

Actually, it's not the square-cube law -- the square-cube law is only a barrier if your artificial muscles and bones have the same performance as real muscles and bones. If your artificial materials have ten times the strength of human tissues, you can achieve ten times the size (thus, after applying the square/cube law, the 10x size version is 100x stronger because of increased cross-section, 10x stronger because stronger materials, for a total of 1,000x stronger, which makes up for being 1,000x heavier).

However, the human shape controlled by a human brain model still doesn't work, because the speeds are wrong. A human at a brisk walk takes about 0.5s per step, and each step is a bit under a yard. A 60' giant would take about 1.6s per step and each step would be ten yards. Reflexes that are suited to 0.5s steps aren't really very good for 1.6s steps.

I mentioned the speed too, though I used arm motion as an example.

But the square-cube still applies, it's a difference of degree. Yeah, stronger materials and power sources and power trains can make up for it, to a point, but the same technologies can make non-human-shaped vehicles and machines more effective too. The conceit of humanoid mecha is that you can scale up human interaction to giant machines, which doesn't generally work.

[cvannrederode]

Originally Posted by Johnny1A.2

Let's say the pilot splits up Combatra to attack the enemy from all sides. They defeat the enemy, but in the process let's say Groundrover 5 gets heavily damaged, as does Skyskater Two. Fine, now the pilot wants to put the parts back together into Combatra...but the feet and upper torso are damaged, which means the head and lower torso can't connect properly, and the feet are damaged, and the reintegrated giant mecha can't even stand up. Damage to one element of the set makes the combination impossible or useless.

Guntron

[Johnny1A.2]

There's another issue with large humanoid mecha, not so much technological as tactical.

Let's say you're striding about the battlezone in your 50 foot tall or 100 foot tall humanoid mecha. Fine. Problem is, you're now a big, visible object, and big, visible objects in a battlezone tend to draw fire. An infantry man with his shoulder-mount missile-launcher can easily see you, aim at you, and fire at you. He can do so from cover, too.

Aircraft can see you, too. You kind of stand out, in effect you're a 100 foot tall guy wandering around the battlefield. You might make a nice place to get rid of a few air-to-ground missiles...

In real life, a favorite tactic of tanks is to park themselves on an uphill slope, go up just far enough to expose the main gun, and fire it from cover. You can't readily do that, granted your mecha can squat down but you're still pretty big and need a big hiding place.

There just isn't much advantage to the giant humanoid form, but there's a lot of vulnerability and vulnerable spots like joints.

Even if you're fighting another 100-foot humanoid mecha...you probably won't get into melee too often. Just as true dogfights between fighters are the exception, not the rule, so probably would be melee combat between giant mecha. Usually, one would nail the other with a missile or a beam at distance by surprise...and if you're doing that, what not use a more practical design?

[Disliker of the mary sue]

Part of me thinks dispite all that humaoid mecha's will be a thing in the future if only as the toys of eccentric billionaires. But as you guy's pointed out, the typical humanoid mecha would basically be not very good in a war without a lot of modifications to the point it would not resemble anything close to what we think a mecha is.

[RogerBW]

Originally Posted by Disliker of the mary sue

Part of me thinks dispite all that humaoid mecha's will be a thing in the future if only as the toys of eccentric billionaires. But as you guy's pointed out, the typical humanoid mecha would basically be not very good in a war without a lot of modifications to the point it would not resemble anything close to what we think a mecha is.

It is part of my unofficial head-canon for Transhuman Space that some of the Martian Millionaires have founded the Battletech Re-Enactment Society.

[whswhs]

The other thing to be said is that humanoid mecha are okay in some forms of cinematic SF. "It looks like a human so it moves like a human" is mostly okay in a form driven by visual logic.

[The Colonel]

And I would still suggest that the transforming is an order of magnitude less practicable than a humanoid AFV...

[jeff_wilson]

A somewhat humanoid, transformable robot may be feasible and useful for some circumstances, like bomb disposal bots that can approach the IED in protected vehicle form, then unfold to do the manual work. AFVs may have one or more arms that can deploy to clear debris, open and close gates, or maintain treads.

Also some designs that already incorporate "wasted" space might be good transformer candidates, like an exoskeleton that can roll around when empty, Metroid Prime-style.

[Johnny1A.2]

Originally Posted by jeff_wilson

A somewhat humanoid, transformable robot may be feasible and useful for some circumstances, like bomb disposal bots that can approach the IED in protected vehicle form, then unfold to do the manual work. AFVs may have one or more arms that can deploy to clear debris, open and close gates, or maintain treads.

Also some designs that already incorporate "wasted" space might be good transformer candidates, like an exoskeleton that can roll around when empty, Metroid Prime-style.

It occurs to me that a 'collapsible' car, plane, boat, or whatever, could have its uses. That is, a vehicle that could be collapsed down into a much smaller volume for storage, then restored to its initial form. Difficult from an engineering POV but possibly handy for certain purposes.

[johndallman]

Originally Posted by Johnny1A.2

It occurs to me that a 'collapsible' car, plane, boat, or whatever, could have its uses. That is, a vehicle that could be collapsed down into a much smaller volume for storage, then restored to its initial form. Difficult from an engineering POV but possibly handy for certain purposes.

There are folding bicycles, of several kinds. It inevitably adds weight and cost, but the advantages are worthwhile for people who need to make part of their commute on public transport.