We started in the railgun post, but this is probably substantial and common enough for its own thread.

quote: Original post by Dauntless Kangaroo-style? Like hopping motions? Or more like AT-ST style backwards-knee motion? For hopping motions, I''d imagine the stress on the joints would be even greater due to the jumping movements.

I intended hopping motion, yes, with backwards knee to boot. For a large kangaroo, which might weigh in excess of 200 pounds, the mechanics are very easy. Even the delicate "ankle" joint (really the equivalent of our base toe joint) doesn''t fail, which leads me to believe it''s not a hard thing to design for. Two other basic points I have to make at this juncture: 1) I wouldn''t consider mechanical failure a major problem - in the case of this type of technology, you''re talking about materials that will be far stronger, with tensile strength of "ligaments" on the order of buckytube weaves (~30x tensile strength of steel) and compressive strength of the "bones" on the order of diamond (~100x compressive strength of steel). So the body is lighter, and the joints are far stronger, than might otherwise be true. 2) Assuming that you DO consider mechanical failure, you''re landing with two feet, so your stress load per joint is lower, and if you design your hopping motion correctly, it is amortized over a much greater distance, so the net effect is much lower than you might think. Stability is much greater and stress much lower when standing than in the normal situation, since you have basically a tripod in standing position, although blowing off the tail makes things a lot worse for the pilot, of course. But then, blowing off a leg makes things bad in any case. the secret is to avoid that possibility by making dodging easy, ergo high-speed hopping.

quote: So as for four legged designs, I''ve given this some thought too. Four legged designs would be even better at crossing rough terrain, and could move laterally as well making it harder to track like you said. Plus, in a spider like form, you can make the main chassis hug the ground much more closely. Again, with my designs, they are only about 10-12'' off the ground, though since they are a little longer are more massive than the ExoShells.

I like fast four-leggers like cheetahs, less flexible in pure directional terms but far easier to design for speed and lethality.

quote: Just on a side note...in my game universe, pilots have to interface with the machine through bio-feedback mechanisms. This requires them to be put in a VERY strange and unusual cockpit. The cockpit is actually a sensory deprivation chamber that is flooded with a gel. A side benefit is that the gel bath acts as a concussion dampener, so that fairly extreme drops, jumps and kinetic weapon damage don''t stun the pilot inside. It is also very effective if flame weapons are used so that the pilot doesn''t get cooked inside (and the oxygen gets recycled in an internal compartment if the temp goes to high).

This is an interesting concept, and one I''ve toyed with as well. When we used to play Rifts PnP I came up with a scheme wherein the pilot is, as you say, immersed in a gel (mine is oxygenated, much like the one from The Abyss), and a nanotech ''tap'' splices into his spine just below the brainstem, so for the duration of play, the pilot IS effectively the machine. Since in Rifts the player is augmented a great deal when piloting a mecha (and in a number of other situations), I also tried to come up with a scheme (for a Rifts MMOG) where the player would gradually ramp up in reactive speed as their level increased. It seems, however, that the only way to do it well is to give the computer some autonomous control in those situations, so that it can do some "dodging". I didn''t think this would work, but I understand it may have been used in Heavy Gear to good effect, so what do I know?

quote: The disadvantage and side-effect to this control scheme is that the pilot can develop psychological problems after long exposure...typically resulting in megalomania (he starts thinking he''s as powerful as the machine) or in agoraphobia (he becomes afraid when he leaves the protection of the machine).

I imagine this takes quite a game design to support, however. Have you mapped it back to the player? I''m fascinated with the thought of how this would affect things in game terms. thanks, ld

I''ll start off here on a slight tangent by considering who pilots the mechs...

In my game world, there are several variants of "augmented" humans. I was greatly inspired by Frank Herbert''s Dune world, and the concepts behind the Bene Gesserit and the Mentats were very interesting to me.

In my game, there are genegineered humans that have been custom-made to have various physical, mental and psychological enhancements. There''s also the HPE subjects (Human Potential Experiment) which are regular humans which have undergone intensive training since childbirth to maximize human capabilties. Imagine growing up in ancient Sparta where all you did was train to fight...it''s on a scale like that, but not just for physical prowess, but also mental ones (like the Mentats in the Dune universe). And a very select few genegineered humans underwent the HPE program. Like in Rifts, there''s also chemically augmented humans, but like Rifts, the disadvantages often balance out the advantages, and they are used very sparingly.

But in my game, the augmented humans are more than just suprahuman, they belong to a subculture within themselves that sets them apart. Just like a monastic or military orders (indeed, I have mendicant orders as well as martial houses), they grew up with different rules, social lives and customs.

As for mecha, they are just another asset on the battlefield. The augmented humans are too rare to be used as typical frontline combat troops, however, they do exist in specialized commando units, as well as in special fighting organizations (imagine a modern day concept of the Sohei monks, Templars, Teutonic Knights or Hospitallers, with a spiritual bent rather than an overtly religious one). Since mecha are really extensions of the human mind, they have become favored vehicles by the more martial art oriented combat troops.

In my own game, conventional tanks are still the most common main ground battle force. Mecha are used in rough terrain areas, especially woods and urban areas. The most important thing to understand though is that mecha are not the be-all end-all of my game, and that I do not focus the game on them. In fact, you have to understand all the technological pieces and how they fit together.

For example, in my game background, the war is partially a civil war, as well as a conventional war. Because of the threat of orbital bombardment and aerospace power, land engagements must be absolutely as quick as possible to capture important targets. Loitering on the battlefield out in the open is only a viable option if you have space superiority. Therefore land engagements take blitzkrieging to the nth degree. Everything in my game world is centered around the mobility of your troops...speed is your best friend (well, actually warships are your best friend...speed is your best defense). Mecha fit in this role by being good units to use in rough terrain, where conventional vehicles may falter and get bogged down.

As for the actual construction of mecha, I envisioned a very human like physiology for the mechs. They are composed of "bones" made of a material that is "yielding" (much like our bones) to absorb high stress impacts without deforming over time and with a "metal memory" so that it "remembers" its original shape. It is anchored by joints tethered by "ligaments" and "tendons". I envisioned a "myomer" substance which is an artificial muscle to power the mech. Several gyroscopes in several positions allow for precise feedbacks to the pilot (along with a helping neural net AI built into the vehicle). Armor is composed of composites of ceramics along with some kind of high carbide based metal to maximize temperature resistance and make the armor very tough, but not too brittle. Btw, I posit that computers in my timeframe are now quantum based computers based on optical and biomolecular structures.

In my game, the big guns are still reserved for tanks, and they will be the primary force used in most engagements. Infantry are still very important however, as they are excellent for defensive positions of rough terrain, and their knack for ambushing. Power armor exists, though expense makes it a not too common battlefield commodity. One thing to note here is that infantry possess weapons that can take out tanks. When you give infantry that kind of power, it makes even infantry a force to be feared. Everything in my game has its strengths and weaknesses, and there''s no rocks/papers/scissors style balancing in that say....VTOl beats Tanks beats mecha beats infantry etc etc. Each unit type has variable strengths and weaknesses depending on many factors. It''s up to the player to maximize his strenghts, mitigate his weaknesses and try to expose his enemies weaknesses while reducing his strengths.

Don''t forget the effects of scale on such designs. An ant the size of an elephant would collapse under its own weight, and all the larget exoskeleton-bearing creatures are marine, so that bouancy will help them avoid this fate. Gigantic slender mecha that are so popular in anime would be nearly impossible to implement in the real world without limiting them to outer space. Even then, limbs would snap off like twigs with any serious impact.

The solution to this is of course magical metals that cannot break. If you''re shooting for physically possible things, though, any big mecha that walk the Earth would have to be very stout indeed.

Just a few little thoughts. Nothing that a little sci-fi can''t avoid.

limited antigravity coupled with partial neutralisation of inertia should do nicely... provided you can work around the side effects like the large increase in speed of light, reduction in the planck length, etc (at least that''s the sort of thing I''m guessing would happen... depends on just how interwoven these fundamental things are)