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geardrops
04-07-2009, 01:39 AM
So apparently I'm going to try my hand at writing scifi. In space. With mechs. I really like mechs.

Thing is, being who I am, I like to be as scientifically accurate, as far as I can be, while still being true to what my imagination wants. And being what I'm not (mechanically inclined), I need help on this one.

Has anybody ever looked into this? What sort of books should I read? Websites?

I'm not looking to pick up the equivalent of a 4-year degree in mechanical engineering (if I was, I probably would have done this in college instead of computer engineering). But I don't know anything about, like... materials... and... weights... and launching things into space outside of the rudimentary facts... fuels... ... yeah. The problem I'm having is I'm so uneducated in mechanics I don't even know where to start.

I did a brief Googling to get me on the way, but I can't tell what's fact and what's fake. And, you know, the internet's not a great place for trufax :)

Thanks in advance :D

Dommo
04-07-2009, 03:32 AM
I've got a 4 year degree in Mech Eng, with a specialization in vehicle systems.

Not to be the bearer of bad news, but any mech that's big, is honestly not practical. However something smaller that's more "man sized" in the form of a robotic exoskeleton or something would be very realistic, and in fact the earliest prototypes of the future battle armor being developed right now for the US military.

The primary problem with any mech, is that the weight just gets to be retarded, and it'd impossible to armor the thing. Look at what's required to make an abrams tank as tough as it is, the armor is like 6 inches thick in places. Now imagine a 30+ foot tall mech. The surface area that would need protecting is several orders of magnitude greater, and the other big problem is that the height of the mech would make it extremely vulnerable.

I'd suggest looking up things like the "Sarcos XOS" exoskeleton, or perhaps "the BLEEX" which are both currently being designed as power armor for the US military.

benbradley
04-07-2009, 06:58 AM
As a member of the club (http://botlanta.org/), I like to keep up with robotics. I looked up "mech" as I'm not familiar with the term, but it seems to be used more as an SF term than something useful for finding the current state of the art:
http://en.wikipedia.org/wiki/Mecha
I think robots-related keywords give better results. There are things like these exoskeletons:
http://www.youtube.com/watch?v=VSP46lWvxJ4
The Sarcos that Dommo mentioned:
http://www.youtube.com/watch?v=NdTS5oD_L08
Here's a "real" "Mech" but it's slow and clunky, and I keep expecting it to fall over - and it's a long ways down for the pilot! Apparently it was someone's "garage" project:
http://www.youtube.com/watch?v=oVwbUljGs3g
Here are two videos of Big Dog, it's autonomous(!) but it can carry substantial weight and I can easily imagine a larger piloted version:
http://www.youtube.com/watch?v=cHJJQ0zNNOM
http://www.youtube.com/watch?v=uZj9qKXetwg
Here are two piloted walkers:
http://gadgets.boingboing.net/2008/06/11/giant-spider-robot-i.html

Pthom
04-08-2009, 02:29 AM
Human-piloted walkers: bipedal, exo-skeleton, not necessarily armored (or weaponized), are potentially useful in environments otherwise hostile to humans, ie: high gravity, caustic atmospheres, heavy yet delicate tasks, etc.

As war machines, I think they're rather silly, since, as has been pointed out, making them durable enough to withstand attack makes them so cumbersome as to make a tank more agile.

geardrops
04-08-2009, 02:47 AM
Hm. Looks like my feet are being firmly planted in 'fiction' for this one. Oh well! :)

Thanks for the responses :) I'll be reading up on these smaller machines you guys mentioned (thanks for the ocean of links, benbradley, and thanks to Pthom for stuff to look up -- and thanks to Dommo for crushing my drea-- er, grounding me in reality ;) ). See what I can take from the real science to at least give my larger fictionalized machines a somewhat realistic feeling. Or maybe just scrap the whole thing, remains to be seen.

Dommo
04-08-2009, 07:23 AM
Dempsey a "mech" might still be possible to construct, it's just that there wouldn't be much of a reason to build one, and it most certainly wouldn't be a very good combat vehicle(although it's possible it might be useful for getting around in certain types of terrain).

A human sized exoskeleton, once the power issues are figured out, WILL be the shit. Think about it. With the extra armor that an exoskeleton would provide, it would automatically make the AK-47 useless against US forces. Short of a .50 cal round, you aren't going to for sure kill the wearer. The big selling point though is the fact that 3rd world insurgencies, would have no practical answer to a weapon like an exoskeleton. It's impossible for a man to carry .50 cal machine gun around, where as an exoskeleton could. So in effect only crew served weapons would be useful against an exoskeleton equipped army, so the soft squishy grunts would be helpless since most of the advantages of infantry(mobility, ability to use terrain) would still carry over to an exoskeleton equipped trooper.

lpetrich
04-08-2009, 10:55 AM
One can rather approximately calculate how much energy one needs to make it move, as I will demonstrate.

Jump height

I recall once seeing an illustration of a kangaroo rat and a horse jumping upward by about 1 m -- the rat jumped several times its size, while the horse jumped about half of its height.

This similarity in absolute height has an interesting origin. Gravitational potential energy

V = m*g*h

where m = mass, g = acceleration of gravity, h = height. A little algebra reveals

h = (1/g)*(V/m)

If rat and horse muscles have the same densities of available energy, as is plausible, then one expects them to jump the same height in absolute numbers. Which is what one finds.

Walk speed and energy consumption

One can estimate this by treating legs as pendulums. Oscillation time

t = sqrt(l/g)

where l is the leg length. For a swing angle of a radians, the walk speed will be around a*sqrt(l*g). The energy interchanged between kinetic and potential is about a^2*m*g*l, and the energy consumption rate per unit body mass is around a*g^(3/2)*l^(1/2) or g*v.

So being big won't necessarily mean that one can walk very fast.

Mechanical stresses

Force = m*g

Pressure = force/area = m*g/A = density*g*h

where h is the height. So a big mech will have to be physically strong.

Powering the mech?

Wikipedia has a nice article on energy density (http://en.wikipedia.org/wiki/Energy_density), listing available energy densities for a variety of energy-releasing reactions.

It's hard to compete with combustible fuels without using nuclear reactions, so would a big mech be powered by a diesel engine?

And as to nuclear reactions, it would have to be a GIANT mech to include a reactor with its radiation shielding.

Lhun
04-08-2009, 10:39 PM
The real killer for the mech is that the humanoid frame just sucks. There's not much point in building a walker that size. If you have the technology to build a mech that works, you have the technology to build something better. Which will not look humanoid.
Powerarmor is a very sound principle and it's shape is given because it will be about the size of the human using it. Maybe 4 meters in total at most.
Other than that, on the ground use wheels. Or tracks, or possibly something with multiple legs (think spider) which still should use wheels on the ends of the legs whenever possible.
If you build something flying build a plane or helicoptre. Or if you have really more power than you know how to use, build a vector-thrust tank.
The humanoid shape is plain bad, it easily tips over, is highly visible, has a large hit area, and by the way, would sink knee deep even into concrete because of the small area of the feet and the huge weight. (going by those 10+ meter high battletech mechs)

Pthom
04-09-2009, 01:05 AM
I guess I missed, in the original post, that the query was about warfare systems or anything military. Is why my comments are about non-military applications, for which I can envision several good reasons for building bi-pedal mechanical assist machinery.

Lhun
04-09-2009, 01:36 PM
I guess I missed, in the original post, that the query was about warfare systems or anything military. Is why my comments are about non-military applications, for which I can envision several good reasons for building bi-pedal mechanical assist machinery.I don't think your example are only useful civil applications. The things you mentioned would essentially mean powered armor, or power-assist exoskeletons, which would be generally human-sized and are the pretty much only sensible size for bipedal design. If you want to stick a human inside and keep it small, humanoid shape is the only way to go.

AceTachyon
07-31-2009, 10:17 PM
Stumbled on this post. Excellent material, folks. I will need to look up all the goodies, esp. the military exo-suit stuff.

I've got an SF military WIP that features humanoid mechs of the powered exoskeleton type that Dommo mentions. I've got the "suit" at about 4.5 meters tall armed with 20mm cannons.

Still working out suit details but the info here should help.

Biggest research bit is figuring out how they are deployed: as infantry, tank, or attack helicopter.

Thanks again for the links above.

BigWords
08-02-2009, 07:32 PM
I really don't care one way or another if building a Mech is impossible, 'cause I want one of these suckers (http://fc07.deviantart.com/fs12/i/2006/270/c/2/Mecha_bastards_by_machine56.jpg).

Dommo
08-02-2009, 10:23 PM
A 4.5m mech is still too large. For it to be of real combat value you'd want it to be no larger than a person. Think of the armor that the Master Chief wears in Halo. That's about the upper limit, maybe a little bigger for something that's more logistics focused(think man sized forklift, aka powerloader). The strength of an exoskeleton is that it makes a human sized target require anti-vehicle weaponry to take down. Anything bigger than a person, with the type of armoring limitations that would hit a power armor as it increased in size(basically the surface area would make the damn thing impossible to armor adequately, and would make it FAAR to heavy), would make them dead meat to tanks, aircraft, and other vehicles.

The advantage in combat of a functional power armor, is that it negates the primary weapons that insurgents/3rd world armies have access to(heck even typical modern infantry). With the prototype Sarcos suit, assuming it's militarized and it's capabilities are a little better, it would be almost impossible to take down with conventional small arms(e.g. assault rifles). Basically to drop one of the exoskeletons, you'd need like a .50 caliber weapons system, and that's simply not man portable. You can't arm an insurgency with .50 caliber weapons(and no a desert eagle pistol does not a Ma Deuce make), and RPG's can't be fired from inside of buildings (the backblast would kill the guy shooting them, to use an RPG you need to be outside or maybe a very large room) and aren't accurate enough to hit man sized targets easily.

This means that the AK-47 which is the predominant equalizer at close ranges(it's almost as good as an M-16, and with decent training can be VERY effective), is no longer that useful. The reason this is important is because for 50 years the AK has been the great balancer of armies. It was cheap, effective, and just about as good as the best rifles in modern armies. With the exoskeleton, all of the sudden insurgencies need to have some major budgets to acquire the weapon systems to try to combat exoskeletons, and short of being mechanized, it's impossible to really transport those systems. This means that for the first time insurgent infantry can't fight toe to toe with our infantry, because the weapons available to them can't do the job easily.

Basically it comes down to this.

Infantry Pros

Extremely mobile(tactically, not strategically), cheap, logistically easy to support(only need some food and water), fantastic situational awareness, versatile(can perform many tasks, from combat to building bridges), can take advantage of terrain the best out of all types of units(can go places other things simply CANNOT go), available in extremely large numbers.

Infantry Cons

Easy to kill(needs to be said), not mobile strategically(in other words they can't move a 100 miles per day), firepower limited to what they can carry easily.

Exoskeleton Pros

Potentially more strategically mobile than infantry(the armor is self supporting so the soldiers won't tire so assuming they've got adequate fuel, they can travel longer distances on foot), bigger guns(could possibly wield small vehicle weapons or crew weapons like .50 caliber machine guns, .30 caliber machine guns, or grenade launchers. However anything bigger would require a "real vehicle"), harder to kill(wearing a 150 lbs or ceramic armor and kevlar means it'll take some elephant guns to drop these guys), can go nearly everywhere infantry can(almost the same size), situational awareness almost as good as infantry(hard to see what's going on outside of a tank when the hatches are shut), psychologically intimidating(seeing an exoskeleton tear doors from hinges would scare the bejeezus out of an insurgent), potentially very useful logistically(carrying artillery shells, unloading trucks, etc.), possibly very accurate targeting/enhanced capabilities(computer assisted weapon control systems combined with a hydraulically damped body means = accurate shooting).

Exoskeleton Cons

More of a logistical burden than infantry, have some problems associated with vehicles(fuel, parts, maintenance, etc.), strategically harder to transport(in other words, a soldier who normally weighs 220 lbs fully loaded with gear, now weighs like 500-600 lbs), expensive(I estimate it'd probably cost 500k-1 million to outfit a soldier with some battle armor like this), smaller numbers(for the reasons of cost. I could see perhaps 1 guy in a platoon being equipped like this, and perhaps having specialized heavy assault squads of exoskeletons used for specific purposes).

Exoskeletons wouldn't replace infantry by any means, but in certain roles they'd be dominant(especially urban assault). In jungles, swamps, and aquatic environments though infantry would still be predominate(the weight of the exoskeleton would bog down in those places). However exoskeletons would be just as vulnerable to vehicles heavy weapons as infantry, so in open terrain I'd rather be in a tank or a Bradley, and they'd cost almost as much. So in the end it's sort of a trade off since exoskeletons are a kind of trade off between vehicles and infantry.

Shoeless
08-02-2009, 10:42 PM
This is an amazing post that I totally appreciate.

Simultaneously, it's also one of the most depressing I've ever seen because I want my Mobile Suit Gundam, dammit. Giant robots hitting each other with beam sabers and particle beam weapons is just COOL.

Dommo
08-02-2009, 10:56 PM
But so is the idea of a 500 lbs of exoskeleton and soldier, wielding .50 caliber machine guns, or using their superior strength(the sarcos suit can multiply the strength of a person by up to like 8 or 9 times) to literally tear people apart(a good way to think of it, is to look at how strong a grizzly bear is, and that's about how strong an exoskeleton kitted soldier would be). We've all seen how powerful a bear is, and if you give that ability to a man, then you've got some woop ass in can.

I can just imagine guys customizing their armor(since it'd probably be similar to a tank crew customizing their vehicle), or possibly naming their armor. The relationship between a soldier and his vehicle would be far more personal(since the armor would likely be maintained by the same guy who wears it in the field), so it would change the dynamics of things a lot. It wouldn't surprise me to see individual armor units eventually having a bit of a "uniqueness" to them since they'd all be sort of tailored to the particular guy who wears it(although undoubtedly they'd still be able to be worn by someone else with some adjustments). I could easily imagine exoskeleton based units (like I said, something like a squad of exoskeletons tasked for specific missions) having unique names, themes, and eventually lore.

efkelley
08-03-2009, 01:21 AM
This is an amazing post that I totally appreciate.

Simultaneously, it's also one of the most depressing I've ever seen because I want my Mobile Suit Gundam, dammit. Giant robots hitting each other with beam sabers and particle beam weapons is just COOL.

Well, this thread is primarily about building armored walkers using modern and near-future construction and materials. Who knows what sort of things they'll come up with in the next hundred years?

Still, the biggest argument against Robots Of Unusual Size is that we have no need of them, and short of the impending Godzilla/Mothra Smackdown of 2022, we just don't have any reason to build one.

redpbass
08-03-2009, 07:13 PM
No one mentioned it, but in the mid 90s there was a show on USA network called Exosquad, which featured smaller robot suits that were more worn than driven. It has a cult following, so you could find some interesting info on the internet.

The robot suits were called E-Frames (http://en.wikipedia.org/wiki/E-frame), and there were different types for all sorts of uses.

While I really like Gundam, I have to say that this show was much more realistic as far as size goes.

Richard White
08-03-2009, 07:54 PM
If you're going to discuss anime-ish mechs, personally, I was always a fan of the Cyclones from Genesis Climber Mosapedia (or the third season of Robotech if you're more familiar with that) or the Motoslave from Bubblegum Crisis.

Nothing like cruising at about 80mph on your cycle and then having it convert into a robot around you. ;)

However on a more realistic side, the power armor from Bubblegum Crisis seemed like a great system. Custom fitted to the individual, Heads-up displays, computer linked, arm mounted weaponry, increased strength and speed, all very reasonable and much easier to design than a 10m tall Rifleman or Warhammer. (OK, my inner geek is showing.)

Nivarion
08-03-2009, 09:51 PM
While were talking about exoskeleton armor.

Trojan Armor. (http://www.youtube.com/watch?v=N2aGMavQGks)

Isn't powered, and has stopped most everything that its inventor has thrown at it. Only cost him $2000 us to make it. took him some time cause he is alone but still pretty cool.

anyway, he is going to blow himself up with an IDE sometime soon. wondering how that's going to turn out.

Shoeless
08-03-2009, 09:52 PM
If you're going to discuss anime-ish mechs, personally, I was always a fan of the Cyclones from Genesis Climber Mosapedia (or the third season of Robotech if you're more familiar with that) or the Motoslave from Bubblegum Crisis.

Nothing like cruising at about 80mph on your cycle and then having it convert into a robot around you.

However on a more realistic side, the power armor from Bubblegum Crisis seemed like a great system. Custom fitted to the individual, Heads-up displays, computer linked, arm mounted weaponry, increased strength and speed, all very reasonable and much easier to design than a 10m tall Rifleman or Warhammer. (OK, my inner geek is showing.)

Your inner geek showed as soon as you made the distinction between Genesis Climber Mospeada and Robotech Season 3.

Although it does raise the interesting question of what kind of serious application a "standard issue" anime-ish mech would have. In the Metal Gear Solid videogame series, they got around it by basically explaining that the eponymous Metal Gear was in fact a walking, bipedal nuclear delivery system that was designed to negotiate just about any terrain and fire a warhead via a rail gun system so that the nuke couldn't be tracked by conventional means. I dunno how solidly Hideo Kojima's reasoning holds up under the harsh light of reality, but it was an interesting premise.

That and his giant robot roared like a T-Rex, so that's some Instant Geek Win right there.

geardrops
08-03-2009, 10:35 PM
Oh man, this thread got resurrected with yet more things to look up.

I love this place.

Shoeless
08-03-2009, 10:39 PM
Oh man, this thread got resurrected with yet more things to look up.

I love this place.

The giant robot cannot be killed, only temporarily disabled.

Dommo
08-03-2009, 10:44 PM
Of course with anime machines, the speed of them is proportionate to how big they are, and of course, the bad guys have some serious storm trooper syndrome, and the protaganists ship is made from a bullshittium alloy that is impervious in all ways. ;P


http://tvtropes.org/pmwiki/pub/images/bear_cavalry.jpg


This is what you get when you've got a modern effective power armor.

Shoeless
08-03-2009, 10:49 PM
the protaganists ship is made from a bullshittium alloy that is impervious in all ways. ;P

I beg to differ. At least in original U.C. Gundam series, the ships are made from NearTotalCollapseButNeverAbsoluteDestructionForSak eOfDramaonium.

Lhun
08-04-2009, 02:33 AM
A 4.5m mech is still too large. For it to be of real combat value you'd want it to be no larger than a person. Think of the armor that the Master Chief wears in Halo. That's about the upper limit, maybe a little bigger for something that's more logistics focused(think man sized forklift, aka powerloader).Well, that depends a lot on how small you make the energy storage, engine, and weapons. You'll have the vehicle humanoid shaped up to a size were it's big enough to put the human into a kind of cockpit.

The strength of an exoskeleton is that it makes a human sized target require anti-vehicle weaponry to take down.Nah, that much armor, even on a human sized exoskeleton is far too heavy and impractical. You'll at most armor it against normal rifle rounds.
And a .50cal gun is still humanly portable. Iirc a south african company even makes them in semi-auto for self defence against large animals. Not to mention all manner of easily usable explosive devices.
The real advantage of powered armor lies more in the kind of weapon they allow a single human to carry. A heavy machine gun is not easily used by infantry.

Basically to drop one of the exoskeletons, you'd need like a .50 caliber weapons system, and that's simply not man portable. You can't arm an insurgency with .50 caliber weaponsThey are. Look up elephant guns. And with some munition designed for the purpose, you don't need to put up with that much recoil either.

This means that the AK-47 which is the predominant equalizer at close ranges(it's almost as good as an M-16, and with decent training can be VERY effective), is no longer that useful.Yes, that's right, the question is how long it'd take people to rearm.

With the exoskeleton, all of the sudden insurgencies need to have some major budgets to acquire the weapon systems to try to combat exoskeletons, and short of being mechanized, it's impossible to really transport those systems.Nah. There are plenty of ways to make infantry-usable weapons that can pierce armor of that level, they're just not being made right now because there is no need for them.
Invulnerability by technological superiority is the wet dream of invasion planners and weapons developers alike, but it's never that easy. If you don't have an advantage of a few centuries, human creativity will usually bridge that gap.

This means that for the first time insurgent infantry can't fight toe to toe with our infantry, because the weapons available to them can't do the job easily.They can't fight toe to toe anyway, but they're not trying to now either. But ESP mines will still cut through that armor like it was hot butter, standard mines work very will with a large magnetometer instead of a pressure switch, cheap shotguns have a large enough caliber to allow hesh munitions, and sniper will have to use large caliber rifles with APFDS rounds.
None of those methods are as easy and cheap as an AK47, but powered armor is more expensive than a ballistic vest too.

Lhun
08-04-2009, 02:35 AM
While were talking about exoskeleton armor.

Trojan Armor. (http://www.youtube.com/watch?v=N2aGMavQGks)

Isn't powered, and has stopped most everything that its inventor has thrown at it. Only cost him $2000 us to make it. took him some time cause he is alone but still pretty cool.

anyway, he is going to blow himself up with an IDE sometime soon. wondering how that's going to turn out.If he's testing it against a real ESP mine, it's going to go badly. Those things are basically the same as the warheads of armor piercing missiles. And i'd like to see how that thing holds up against normal large caliber bullets too. The video didn't really show anything.

AceTachyon
08-04-2009, 05:29 AM
A 4.5m mech is still too large. For it to be of real combat value you'd want it to be no larger than a person. Think of the armor that the Master Chief wears in Halo. That's about the upper limit, maybe a little bigger for something that's more logistics focused(think man sized forklift, aka powerloader).

Well, that depends a lot on how small you make the energy storage, engine, and weapons. You'll have the vehicle humanoid shaped up to a size were it's big enough to put the human into a kind of cockpit.

My vision was for a combat version of the Aliens powerloader, something like the Guges from Masamune Shirow's Appleseed. The pilot/operator sits inside the "suit" with legs coming down into the upper leg, and the rest of him/her encased in the suit's torso. Operation would be with joysticks and finger waldoes.

Or better yet, much like the Gears in the RPG Heavy Gear.

redpbass
08-04-2009, 05:39 AM
My vision was for a combat version of the Aliens powerloader, something like the Guges from Masamune Shirow's Appleseed. The pilot/operator sits inside the "suit" with legs coming down into the upper leg, and the rest of him/her encased in the suit's torso. Operation would be with joysticks and finger waldoes.



Exosquad, I'm telling ya. Sure, it's a cartoon, but it fits that standard perfectly :p

Dommo
08-05-2009, 09:14 AM
http://www.news.com.au/travel/story/0,28318,25880890-5014090,00.html

This is interesting. If it can be set up to detach, and use a common fuel supply with a typical exoskeleton, you'd have some pretty amazing capabilities. Think light attack helicopter combined with house raiding mini-tank. Could be pretty cool.

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