A "realistic" Power Armor unit

[Eleventh Century Remnant]

Well, in theory.

Astartes aside, there is one useful and I hope never really actual use I can think of for PA, and it follows on the 'Iron Men' of OGRE; units capable of doing the infantry task, working with terrain, holding ground and using it to advantage, on a nuclear battlefield.

Of course, this assumes a limited nuclear war rather than heavy strategic warheads flying everywhere, which may or may not make sense, but using some kind of mechanised framework to haul enough armour and radiation shielding to allow men to survive and fight in the immediate proximity of a nuclear detonation seems a reasonable use for power armour.

Otherwise, you have conventional armour and artillery still- yes, tanks are good for this- but nothing to do sieze and hold. Granted, the local population may be dead too, and anything worth taking may be slightly chargrilled and glowing, but...

OGRE; a universe where the Davy Crockett was not only a feasible idea, but is issued at fireteam level.

[Zixinus]

Infrantly units equiped with heavy weapons, armoured to the teeth and augmented so much that they can wipe the ass of regular soldier with their pinky finger?

Urban warfare.

In such a situation, you get something that a tank can't do yet still have familiar capacity.

Superior to most soldiers that may occour on such a battlefield, roughly about as much firepower as a tank yet still several times more mobile and less bothered by such things as thight streets or landmines. Plus, if the power armour can operate for a long time, its users can use the enemy's equipment, thus able to technically live off the land.

If the city is important enough, you have a situation that justifies the cost and be effective.

[Crayz9000]

Infrantly units equiped with heavy weapons, armoured to the teeth and augmented so much that they can wipe the ass of regular soldier with their pinky finger?

Urban warfare.

In such a situation, you get something that a tank can't do yet still have familiar capacity.

Superior to most soldiers that may occour on such a battlefield, roughly about as much firepower as a tank yet still several times more mobile and less bothered by such things as thight streets or landmines. Plus, if the power armour can operate for a long time, its users can use the enemy's equipment, thus able to technically live off the land.

If the city is important enough, you have a situation that justifies the cost and be effective.

That only works if the power armor is light enough, which pretty much rules out tank-level weapons.

The reason: Most buildings won't be able to support a guy in powered armor who weighs even a half ton.

Basically, for urban combat, you wind up with powered armor that is maybe equivalent to a single squad in firepower. I'd say you are looking at 5-600 lbs as the upper weight limit to avoid collapsing buildings.

Here's what I'm guessing you'd already find as a loadout on an existing Marine, for urban combat. Any armed forces members can feel free to correct me.

Modular Tactical Vest: 15 lbs
MCLH Lighweight Helmet: 3 lbs
ILBE pack: holds up to 120 lbs (although for most operations, I hear generally you won't want to carry more than 40)
M4 carbine: 7 lbs with ammo

So already you're up to approximately 65 lbs over the solder's weight. Assuming your typical solder weighs 250 lbs, you're already looking at 315 lbs.

So, for urban combat, you need to find a way to make your powered armor weigh less than 300 lbs. As it stands, UC Berkeley's lightweight BLEEX exoskeleton weighs 120 lbs and can only carry 70lbs load. And that's just a pair of leg supports and a motor to drive them.

[Zixinus]

That only works if the power armor is light enough, which pretty much rules out tank-level weapons.

Maybe not tank-level excatly, but assuming you can get a armoured power armour walking, you can still carry weapons of far greater firepower then your average bloke can possibly carry (like a machine gun or the XM29, weapons that are simply too heavy for your average soldier to carry). Of course, like I said, such a power armour would fill the role of a miniature tank and not much else. The point isn't to replace regular troops but to complement them with something that's a cross between them and a tank.

[Crayz9000]

If anything, I think powered armor of the sort you're talking about is all but useless for urban combat. Urban combat, judging from past history, would be best performed by combined groups of soldiers and small robots, such as the ones from iRobot used in Iraq today.

What would be useful is better armor for soldiers as they're clearing out buildings, but it can't hinder their flexibility much -- they still need to be able to maneuver through a standard obstacle course since that's practically what you'll find in an urban war zone.

The robots, of course, would wind up doing most of the dirty work: scouting ahead, going around blind corners, basically anything that would be too high profile or risky to have a soldier do. They also have the advantage of having the same profile as, or smaller than, your typical soldier in a crawl.

But in an urban war zone, anything large, heavy or slow is death, since RPG derivatives will be literally everywhere. And if current RPGs have no problems blowing holes in current tanks, then unless the power armor is made out of unobtanium or someone figures out how to make particle shields, then the trooper inside will be turned into red paste by any RPG hit.