Anatomy of a Mecha (more Full Metal Panic related discussion

This was copy pasted from MS Word, so apologies for formatting issues. I think I fixed a lot of them, but there are still some present.

This thread is kind of a spin off of the ‘Anatomy of a Helicopter’ thread that focused on the helicopters used in the anime Full Metal Panic, particularly the MH-67 Pave Mare that was used to transport Arm Slaves. This thread itself however focuses on the Arm Slaves themselves. I kind of feel like I should be focusing on the actual storyline of my fanfic, but Arm Slaves are a pretty prominent part of FMP, and as a FMP fanfic writer I find having a solid grasp on them is a bit of a confidence issue.

This thread is intended to discuss some issues with Arm Slaves, but the first post contains a lot of
info on various aspects of Arm Slaves that I’ve gathered from different sources. I figured it would be useful for other participants in the discussion to have that info. So basically, the first post is a mix of
facts, issues, and speculation, all sort of bundled together. I hope you’ll forgive the crazy length...


A Brief History of the Armored Mobile Master-Slave System.

I’m still unclear as to where the Wikipedia article on Full Metal Panic’s Arm Slaves got its information, however it doesn’t seem like something someone just wrote at random, so what I have here is kind of going to be based on it.

The origins of the Arm Slave in the FMP universe date back to the early 1980s and an attempt to build an exoskeleton type suit of powered armour called the XM3. This was not particularly successful, but led to the development of the XM4. The XM4 eschewed the exoskeleton layout in
favour of a much larger mecha with a cockpit that used a Master-Slave control system to mimic the movement of its pilot. This layout allowed the use of an internal combustion engine as a powerplant, improving endurance. The XM4 was of somewhat marginal usefulness, but was effective enough to see production as the M4 and ensure further development of the Arm Slave as a weapons system.

Second Generation Arm Slaves like the M6 Bushnell and RK-92 ‘Savage’ represent an incremental but important leap in Arm Slave evolution. Like first generation Arm Slaves, they use a combustion engine and hydraulics, with artificial muscles only for precise movements. However they are quicker,
more powerful, and have more advanced electronics then first generation Arm Slaves. They are also more modular for easier maintenance. Second Generation Arm Slaves are the most widely used Arm Slaves in the Full Metal Panic universe and have essentially made first generation models obsolete. There’s some question as to who developed the first Second Gen AS, some fans theorise the RK-89 Shamrock was first and that the M6 Bushnell was developed after the Americans saw how effective second gen ASes were in Afghanistan. However, some material indicates that the M6 was a prominent weapon in the Gulf War and that the AS-ensured Soviet victory in Afghanistan occurred during a second Soviet invasion of the country sometime later. Personally, in spite of this, I don’t find it that hard to believe that Soviet Arm Slaves like the RK-92 were heavily influenced by Mountain warfare, while perhaps Western AS designs had somewhat different influences.

Third Generation Arm Slaves like Mithril’s M9 Gernsback use an all electric drive system consisting of a Palladium Reactor and artificial muscles without the second gen AS’ hydraulics. They are much lighter and much more agile then second gen Arm Slaves in addition to being far quieter (the gas turbines used in second gen Arm Slaves are very noisy at full power).

Compared to real world weapons system, the development of the Arm Slave has been greatly condensed (XM3 to M4 supposedly took about three years). This is even noted in the FMP novels themselves. Those of you who have a decent knowledge of FMP shouldn’t have too much trouble figuring out why that is though.

Aspects and Issues of Arm Slaves

Size

Two of the most prominent AS designs in Full Metal Panic are the second gen RK-92 Savage and third gen M9 Gernsback. The RK-92 is about 8.1 meters in height and weights about 12.5 tons. The M9 is about 8.5 meters in height, but weights only 9.5 tons. The Mistral II, a western second gen AS, is apparently more like 14 tons, and it wouldn’t surprise me if the M6 Bushnell was of similar size. I strongly suspect these are the weights of the AS itself, as I see it the weaponry those things carry could easily add a ton or more. In the case of the second gen Arm Slaves, fuel could also add some weight.

Mobility

The third gen M9 has a top speed of 280km/h per hour and a 45 meters jump height, apparently.
Mobility of a Second Gen AS is much more limited at 130km/h and 20 meters jump height. Again, these are what’s listed, not necessarily how the thing are portrayed in series. Actually, the M9 seems a bit ludicrously fast.

Vetronics

The AS equivalent of Avionics on an aircraft. Arm Slaves are equipped with advanced sensors, including IIRC radar on at least some models. A millimetre wave radar like that used on the Apache Longbow helicopter seems like it could be useful to an AS to me, particularly a third gen model that has a high jump height. Also, ECS is used on Arm Slaves in addition to aircraft. Supposedly newer ECS systems can do stealth across the visual spectrum, while older ECS is limited to radar. Also, the M9 apparently cannot operate its ECS (at least not in visual mode) at the same time as conducting
combat manoeuvres due to power draw.

Additionally, Mao’s M9 is noted as being a command unit specialised for Electronic warfare, IIRC. It seems to have some special capabilities in the jamming department.

Protection

According to one source, the M9 can withstand RPGs, shaped charges, and calibres up to 20mm. In the novels, Arm Slaves also seem to at times survive hits from the cannons of other Arm Slaves. Personally, in my own writing, anything like that would have to be a glancing hit. Arm Slaves are simply too light for their size to pack protection against large autocannons. As far as actual composition of the armour goes, I kind of assume something comparable to real life LIBA (Light Improved Ballistic Armour). LIBA is essentially ceramic pellets suspended in an ‘elastomeric matrix’ and is usually put over a base material such as metal. It can be repaired fairly easily in field, and can withstand multiple hits in close proximity better than ordinary ceramic plates. In the guise of
vehicular armour, it can stop multiple 14.5mm hits in close proximity to each other. I figure I can stretch that to massed 14.5mm and sporadic 20mm hits in my writing. Not sure if LIBA handles HEAT rounds so well though, even in the form of lightweight RPGs.

Armament

Assault Rifles

Gigantic assault rifles (actually autocannons) seem to be the main armament for Arm Slaves in FMP.
The main issue I encounter with these things is that they’re shown with reasonably sized magazines and sustained rapid fire capabilities, despite being of fairly large calibres (such as 37 and 40mm).
Some types of ammunition, like the 40mm round used by Bofors AA guns are extremely heavy and would be difficult to make a high capacity magazine for because of the bulk.

I figure the best way to deal with this issue is to tweak thing a little. I figure the Western 30x173mm cartridge (used by the Bushmaster III autocannon and the A-10s gun) and its nearest Eastern Bloc equivalent the 30x165mm are reasonably sized enough to allow for a large capacity with reasonable magazine height if the magazine is a quad stack design. The 30x173mm round in real life has a necked up 40mm ‘supershot’ round based on it. This round is much more compact then the 40mm Bofors round and can theoretically be fired through a 30mm Bushmaster autocannon with minimal modification. So I figure second gen AS armament could have used 30mm rounds, then upgraded to 37 and 40mm cartridges based on combat experience. Of course, this doesn’t solve the issue of the
massive weight of 40mm rounds, I wouldn’t be surprised if some types of 40mm supershot didn’t weigh in at over a kilo a round, especially if the case material was steel rather than aluminum (A-10 ammo uses an aluminum case, but not all 30x173mm ammo does). Then again, perhaps that could be part of the justification for the existence of the new Oerlikon GEC-B 40mm rifles used by Mithril that have caseless ammo, although then again I doubt it would save more than a few hundred pounds (on a class of vehicles that already weight over 20,000 pounds). I wonder if the GEC-B could be justified on ammo cost (doesn’t need a metal cartridge) and lower risk of jamming...

Another issue would probably be ammo type, there might be cause for carrying different magazines with different types of ammo for different targets, given the difference between say a sabot round and a HE round. High Explosive Duel Purpose seems like it could be a good compromise, but if Arm Slaves already have armour that can take shaped charges then HEDP might not have enough diameter to ensure penetration of AS armour.

Sniper Cannons

In the FMP novels, the sniper cannon used by the M9 is a 76mm. There are indications it’s supposed to use the 76mm cartridges developed for naval guns. Again, ammo size is an issue, particularly cartridge length. Using Cased Telescoping Ammo would help reduce that length, though the cartridge would be fairly wide. I seem to remember a 75mm autocannon using CTA ammo was developed but didn’t see service in the past, and could defeat a T-72 tank with three shots (I think it was referred to as ARES). Something along those lines doesn’t strike me as a bad idea for the FMP AS sniper cannons. Also, due to the need for a long barrel, a bullpup layout seems advisable. Lastly, I figure to justify its existence the thing should be able to do more than snipe other Arm Slaves I figure with HEAT rounds and rounds with programmable priming, a 75mm ought to be able to make quick work of helicopters, infantry, and bunkers, which would give it wide utility as a long range direct fire weapon. Also, 75mm is big enough to do multiple projectiles in one cartridge… if the thing was a smoothbore for use with sabots and heat rounds, then it could probably use a canister round for close range defence.

Shot Cannons

This one has really bugged me to be honest. It’s the series’ lead’s favoured AS weapon, but 57mm? It’s kind of small to do multiple projectiles, but big enough to have sustained rapid fire issues in
comparison to the already quite powerful 40mm guns. So what advantages is it in CQB really? I suppose a short barrelled weapon based on the above suggested 75mm CTA round might work, it would allow for multiple projectiles, as well as heat rounds and such for bunker busting. Recoil could be pretty heavy firing such a round in a light weapon, but from what I understand shorter barrelled weapons can actually have lighter recoil then longer barrelled ones.

Sidearms

Crop up a few times in the novels, but don’t make much sense to me. Shorten an autocannon, you lower the velocity of the projectiles. Probably just going to pretend these didn’t exist.

Throwing Weapons

Another category that kind of bugs me. Canonically AS’ have weapons called Anti-Tank Daggers, there’s also something referred to as a ‘HEAT Hammer’ which can be used by the RK-92. These are essentially melee/throwing weapons with a HEAT warhead. There are also grenades that Arm Slaves can use. The idea of an AS lobbing grenades doesn’t bug me so much, they’re a simple way to give it a capability comparable to artillery but with a lower acoustic signature. The anti tank daggers and such on the other hand… well, what’s the point? Can you imagine the difficulty with precise throws? Wouldn’t an anti-tank missile be simpler? About the only advantage I can think of is the lack of a rocket’s firing signature to give the target warning.

Underbarrel Grenade Launchers

Seen in the anime used against Arm Slaves. Doesn’t seem like such a hot idea for direct use to me, though you might be able to justify it as a weapon for indirect fire support. For that sort of application, a low velocity round that stacked in the barrel (kind of a giant version of the 40mm Metal Storm grenade launchers) might have merit. Could potentially do some rather large heat rounds for bunker-busting this way, and those could have secondary use against enemy armour close up. Also, being large bore, a shot cannon type weapon could use this kind of approach although it probably wouldn’t work so well with the multiple projectiles approach due to low velocity (and thus low kinetic energy for the projectiles).

Monomollecular Cutters

These are cutting weapons for melee use, and vary in size. They’re used in melee combat. Personally, I can see them making some sense as tools, but it seems a bit odd to me that they’re used so extensively for melee work. You’d think if they were used for that it would be more of an act of desperation thing.

Missile Weapons

We’ve seen AS’ use basically giant versions of rocket launchers. Again, this class kind of bugs me. There may be some really huge targets like buildings or bunkers that might warrant such a rocket, but for general anti tank use, these weapons are overkill. M9s have hardpoints on the upper torso just in from the shoulders of the arms… seems to me you could attach a couple armoured box launchers for Hellfire missiles there. You wouldn’t be able to carry them when using the emergency deployment boosters of course, but for other deployments…

Anyone got any thoughts so far?

BTW, don’t any of you dare compare me to Shinji Kazuma.

Piero wrote:Anyone got any thoughts so far?

oh, a few. In all cases, though, please correct me if I'm wrong. This is all pretty much conjecture based on very limited information.

Piero wrote:Mobility
The third gen M9 has a top speed of 280km/h per hour and a 45 meters jump height, apparently.
Mobility of a Second Gen AS is much more limited at 130km/h and 20 meters jump height. Again, these are what’s listed, not necessarily how the thing are portrayed in series. Actually, the M9 seems a bit ludicrously fast.

...a little math will tell us how close the ASes are to scale human performance.
in terms of running speed:
-assuming a 10 second 100m dash time to make it simple: 10m/s=36km/h
-assuming a human height of 2m and a mech height of 8m to make it simple... in terms of height (not mass or even volume), a mech= a 4x scale human. thus: 36km/h * 4 = 144km/h, or roughly half the top speed of an M9 (also, a little over the top speed of an M6. I'd say second-gen ASes are pretty much 'athletic human' performers here, whereas third-gens definitely classify as 'superhuman').

for jumping, I'll assume a 2.5m jump height for a human being's peak output.
-assuming a 2m height again, the human peak jump height is 125% their body height. (2.5/2)
-an M9's peak jump height is 530-ish% their body height(45/8.5)
-an M6, assuming an 8m height, would have a peak jump of 250% their body height (20/8)

So, run speed seems plausible(ish) to me, whereas jump height... can you say battletech jump-jets? I mean seriously, the leg strength (not to mention material strength of the ground) required to achieve that sort of height for a 9-14 tonne mech with no external propulsion is nothing short of ludicrous.

Oversized firearms in general

I'm not so sure there would be as many problems as you suggest. Given the size of the weaponry/magazines, the simple designs we're all familiar with for firearms are automatically out the window. The material strength required to feed a 30/40/57/76mm shell into an explosive blowback-cycled weapon with a simple spring mag strikes me as rather ludicrous.
That being said, we have plenty of essentially linkless chain fed designs which would scale well for a meter-long, perhaps half-meter wide magazine. Here's an example of the basic design concept I'm talking about.
I realize the mags I'm talking about are pretty oversized if you're just scaling up infantry weapons... but from what I've seen of the series, arm slave weaponry has nothing like the slender profile of modern assault rifles. They seem designed more along the lines of light machine guns, to me (from the brief glimpses I can remember from the anime. Admittedly I've been having trouble finding the sort of documentation I can always find for Star Wars tech). Basically, imagine making a weapon with the functionality of a Steyr AUG, but make it the size of a M249/FN Minimi. Now scale it up for an 8(ish)-meter tall mech.
Once you start thinking of the myriad design possibilities available for a weapon that size, reliably loading an (for a generic, oversized example) 80x300mm round into a semiautomatic breech is practically a non-issue.

Shot Cannons

I've always thought of this term as a misnomer. The way Sousuke employs the weapon in the anime, it never seems like a scattergun... more along the lines of a large caliber, semi-automatic carbine. I've always thought of the 57mm as kind of the 7.62NATO of the AS world, whereas 76mm strikes me as the .50BMG equivalent.

Piero wrote:Monomollecular Cutters
These are cutting weapons for melee use, and vary in size. They’re used in melee combat. Personally, I can see them making some sense as tools, but it seems a bit odd to me that they’re used so extensively for melee work. You’d think if they were used for that it would be more of an act of desperation thing.

One parallel I can draw here is the stereotypical attitude portrayed for infantrymen. They're always the psycho with the big knife, more than willing to throw down a firearm in favor of the visceral feel of killing with sharpened steel when the situation allows for it. Gauron definitely fits that mold, and Sousuke is continually put in situations where he needs to use the things out of desperation.
Also, since the action we tend to see ASes used for tends to be essentially Spec Ops work, being extensively trained in the use of backup/improvised weaponry is pretty much par for the course... hence, propensity to want to use such weaponry is par for the course... as impractical as it usually is.

Piero wrote:Missile Weapons
We’ve seen AS’ use basically giant versions of rocket launchers. Again, this class kind of bugs me. There may be some really huge targets like buildings or bunkers that might warrant such a rocket, but for general anti tank use, these weapons are overkill. M9s have hardpoints on the upper torso just in from the shoulders of the arms… seems to me you could attach a couple armoured box launchers for Hellfire missiles there. You wouldn’t be able to carry them when using the emergency deployment boosters of course, but for other deployments…

the only thing that comes to mind is people drawing parallels with Battletech, Gundam, or any other mecha-combat franchise and crying about lack of originality. Basically, FMP took the scaled-up infantryman concept a little too far, while damn near every other series took the "all non human-shaped giant-mecha weapons are now obsolete" concept way too far.

The M9’s joints are supposedly based on those of grasshoppers and cats in spite of the rather humanoid appearance. Not sure about the M6. I do have to admit I sometime wonder about the durability issue, a landing from that kind of height is going to transmit a lot of force into the frame, though supposedly Arm Slaves have a measure of shock absorption. Actually I sometimes wonder if the M9 should realistically take some cues from experiments with vehicles using high strength plastic as armour, as it might withstand the wear and tear of repeated impacts a bit better (and plastic can be used as a base material for the above mentioned armour with the bonded ceramic pellets). Though I think the M9 is canonically supposed to have a fair bit of titanium in its construction.

As for the issue of ground strength… yeah. I imagine a lot of surfaces wouldn’t be strong enough to allow for that sort of jumping… (actually, as I see it ground pressure is one of the major issues regarding Arm Slaves in general).

Now with regards to the autocannons, that’s a quite useful observation. I guess I’d kind of assumed a mag spring because the magazines externally resemble infantry rifle magazines so much. I have to admit however, that I don’t understand much about how linkless feed systems work. A mag with a spring pushes rounds in, while a
linked feed system pulls them, but how does a linkless feed system work?

While we’re on the subject of linkless feed systems, I’d gotten the impression they might be a good option for the feed systems for the pair of head mounted .50 machine guns on the M9. Possibly duel feed, so as to allow for the use of more than one type of ammunition.

As far as the ‘Boxer’ shot cannon goes, you’re right, it does seem to just be a harder hitting cannon more so then a scattergun. It still seems strange to me though,
considering that the 40mm should already be powerful enough to make short work off the armour of other Arm Slaves, especially at the up close and personal
ranges the Boxer seems to be geared towards. (I should note, while the Boxer in the anime uses a pump action, the one in the novels seems to be capable of automatic fire.)

Missiles wise, I suspect this is one of those cases where I may just simply ignore an unrealistic element from canon without directly contradicting it (like I plan to do with the sidearms issue). There’s nothing saying the M9 couldn’t mount a set of armoured box launchers on its back or upper shoulders, after all. Melee weapons, on the other hand, are another matter, as they figure fairly prominently in the series, and as such should probably show up.

BTW, I don’t know if you know the answer to this, but are a HEAT round and a shaped charge the same thing? (Or perhaps more correctly, is a HEAT round a form of shaped charge?) I’d considered the possibility of the AS 40mm guns using an HEDP round similar to the one used by the Apache’s chaingun but much heavier (it would seem a 40mm Supershot (the necked out 30x179mm derivative) can fire a HE shell heavier than two entire 30x113mm cartridges). However, it seems penetration for HEAT rounds is heavily linked to diameter, which would mean the 40mm round wouldn’t necessarily be able to penetrate much more then the 30mm round. And of course, there’s the fact that most RPGs are of much larger calibre then 40mm… if an AS can survive hits from those, it seems logical that the 30 and 40mm rounds could have issues penetrating, at least if they worked on the same principals.

Not that that would make an HEDP round useless, there’s plenty of things it would probably be good for, it’s just a more specialised AP round might be needed for anti AS work.

Edit: forgot I was going to include a couple images to show the magazines used by the autocannons. Personally, I think this is probably a place where tweaking is in order, as I seriously doubt magazines that thing could hold very many rounds, though I'm not sure going for too much thickness is a good idea either. Also, I notice that in both these shots the M9s autocannons are ejecting casings, even thought text materials say that the GEC-B rifle used by Mithril's M9s uses caseless ammo.

Oversized weapons for giant robots are just so ridiculously awesome. They're like tank-caliber cannons that fire full auto. Can you imagine the amount of damage something like that could do to an IRL armored column? Man.

I'm gonna have to see about getting a pic of my Armored Core 3 mech in here.

LoC978 wrote:Basically, FMP took the scaled-up infantryman concept a little too far, while damn near every other series took the "all non human-shaped giant-mecha weapons are now obsolete" concept way too far.

Yes, yes, a thousand times yes. Don't get me wrong, I absolutely love FMP, and I really do love giant robots. To this day I still want my variable fighter! The honest truth though is that if I ever stop to think about something like this, it usually ends badly....

I mean there are a thousand ways for me to tear apart the combat, and tactics of the FMP universe. Is the human form really the optimal fighting machine? Why bother with hands? Why not just have hard mounts? That reduces the cost, weight, and complexity. The cost means you can buy more. the weight you can turn into speed, armor, or ammo. While the reduced complexity means more reliable, and easily maintained gear. The weapons would probably be more stable to boot. Why do all the weapons have magazines? Do you ever see an armored slave carry extra mags, like ever? Even if they did why not just the internal mag of the weapon that much larger? For that matter, why are all the weapons basically infantry weapons? Serious there is so much wasted space, or ergonomic features you just don't need. Why have an under-slung grenade launcher, and not an under-slung missile launcher? Why two legs? Four would offer a more stable weapons platform, and probably improve speed over mountainous terrain. Why is the cockpit always in the middle?

There are two sources that I really respect in terms of how they look at the universe of gaint robots. First would be Chrome hounds. Why? The game variety in design of the mech's. The game had a lego like feel to it, and people did some really smart things with the construction. Very rarely did these machines look remotely human. The second would be Patlabor. Gaint robots in that show struggled doing relatively basic things sometimes. A feature you almost never see elsewhere. That, and in the second movie a whole squad of giant robots get owned by a couple of troops, and a single tank. Totally support that!

Now that I've got that out of my system lets talk about how to patch some of these whole, and pretend it's an entirely self consistent universe. First of all 280 kph seems crazy when you consider that 100-110 kph armor is considered stupid fast? Warfare in the FMP universe is definitely more advanced. Still it's definitely something I'm weary of. Also the explanation that the joints are based off grasshoppers smells really fishy. A grasshoper scaled up to a humans size would collapse under it's own weight. The physics is radically different between the small, and big.

As for armor that's tricky. Nine tons is really just a stupid small number for what we see the M9 do. At the same time materials like carbon nanotubes could make it a possibility. Slashdot had something about a company that had produced a paper thin sheet of carbon nanotubes that could stop various pistol, and rifle calibers. That's crazy, and exactly what the M9 would need. So with nano-material backing it up, it may just be possible.

When it comes to the weapons I mostly agree with LoC about the armaments. I too always assumed the shot cannon was firing slugs. The only thing that really bugs me is that they seem too large. While simultaneous having so few bells and whistles. I mean why don't the weapons have their own sensor systems so you can 'blind' fire with perfect accuracy. That, and why does the weapon have a barrel shroud if it's going to be held by a metal hand? It certainly shouldn't be an issue of heat.

As for throw weapons, precision doesn't seem like much of an issue to me. The computer that's helping you walk will handle the complexity of the throw. Yes it would make far more sense to use a missile in my opinion, at least most of the time. With a grenade you could do some interesting things like bounce it off a wall/building. That, and it since it's little more then a warhead it so produce a big bang on the cheap. The HEAT hammer does sound just plain wonky. HEAT rounds use a shape charge to turn metal, usually copper I think, in the warhead into a molten jet of armor penetrating death. Which means directionality is crucial. Tossing that seems like the worst possible way of ensuring that direction. I don't know much about HEDP rounds, just what's on Wikipedia. Most main battle tanks have guns that are, what about 100 mm, or more? I don't think a 40mm HEAT, or HEDP round would do much good against heavy armor. Then again it's more about would it do more good then a regular 40mm round. HEDP rounds sound better all around though.

Missile weapons seem stupidly under used in my opinion. Fire, and forget homing weapons that can knock out a target in one hit. Yet I don't ever recall seeing one used, let along working. Yeah...

I do have to disagree about the whole knife thing. LoC makes a good reason why you see it so much. At the same time when was the last time you saw two tanks ram each other? It just seems absurd. It's not like you can use it for a stealth kill. One AS destroying another it's not going to be something you can hide. AS battles seem like they aught to involve large ranges, making it difficult to close. It's pretty integral to the universe, and Lamba drive fights though. So what ever just roll with it, just don't think to hard about it.

Oh, FMP certainly doesn't have hardcore realism. Arm Slaves are supposed to be rough and urban terrain weapons, but seriously, real life light tracked vehicles can do pretty well for themselves in rough terrain (especially some of those ones which are split in two sections and articulated). The thing is though, the series still has a 'more realistic then usual' approach to mecha as part of its shtick. And I guess I'm the type of person who can accept a degree of unrealism in a series like that, but gets boethered by it if it goes too far. Hence I'm trying to use these threads to sort out a few issues and strike a balance. I don't want to contradict canon too hard, but I also want to deal with some of these issues.

As a note, according to FMP canon, Arm Slaves are good rough terrain weapons but aren't so great for open terrain warfare. There was a sequence in Approaching Nick of Time where the De Danaan's forces rescue the remnants of a another Mithril force from attack in a Desert environment, and they got a lot of pressure put on them by conventional tanks because said tanks were so heavily armed and armoured. Actually, I personally found that a bit iffy myself, as MBT guns have a kind of low rate of fire for targetting something as crazy agile as a M9. Against something like that maybe a tank chassis equipped with a large calibre autocannon of it's own would do better. But it still goes to show that the author considered the AS as a platform that had both strengths and weaknesses and wasn't the ideal weapon for all environments.

Also, that sequence has Mao's M9 using 'javelin high speed missiles' though the illustration used (FMP, being a light novel series, has the ocassional illustration) pictured a M9 using a bazooka type weapon kind of like those see being used by some of the M9s in the later parts of the first season). Actually, I get the impression both the M9s bazooka-ish weapons and the RK-92's RPG-ish weapons may be supposed to be missiles of some sort rather then simple rockets. Mithril also equipped some of their older M6s with surface to air missiles during the defence of Merida Island in Continuing On My Own (actually, I think some of the M6s may have used anti-tank missiles as well in that novel). So there are missile weapons, used by Arm Slaves, it's more the form I have an issue with. As noted earlier, if anti tank missiles come up in my fanfic I'm liable to just have the Arm Slaves mounting armoured box launchers on hardpoints. After all, there's nothing in canon saying those sorts of launch system don't exist...

Armour wise, I've been kind of reluctant with regards to carbon nanotubes, as that opens the whole can of worms of 'okay, so what if someone decided to build a much heavier tracked vehicle with them?' (Though I guess cost could stand in the way of using the stuff in large quantities.) It might work for the M9 though if it was one of the first platforms to use it. The M6 however probably shouldn't, because if the well established AS designs use it then one needs to consider 'okay, does this mean the design of tracked vehicles in this universe is way different too? The bonded ceramic stuff I talked about earlier might not actually be quite good enough, but it's certainly pretty strong for it's weight and it's actually used as add on armour for some real life vehicles, so I figured it might make a decent choice if one is willing to stretch things a little. Oh yeah, and it can be repaired relatively easily in the field (a big difference between it and other types of ceramic based armour). Another possibility is giving the M9 the bonded ceramic stuff for much of it's construction with the newer carbon nanotubes used for some components.

Weight wise, yeah, Arm Slaves are pretty light for their protection level, but I also figure they're already at the point where they should be having ground pressure issues and heli-borne transport issues, so it's a bit of a catch-22. Damned if you go one way, damned if you go the other.

As far as the other armament issues, you're quite right regarding the grenade throwing, at least with regards to certain types of targets, and I honestly think that's one of the more practical thrown weapons for Arm Slaves (at least as long as they're not being treated as an anti-Arm Slave weapon like some of them have been). I also think the HEAT Hammers are wonky, and they're another of those thing I'm liable to just ignore. The throwing knife like anti-tank daggers are a bit of another matter though. They're HEAT weapons as well, but they feature prominently in the novels, and the monomollecular cutters feature prominently in both the novels and the anime. So as mentioned previously, they're likely to stay.

Lastly, on the issue of autocannon rounds... my understanding is basically that the Apache's chaingun used shaped charge ammunition fitted with elements that make it more effective against soft targets, hence High Explosive Dual Purpose. HEAT rounds, to my understanding, are just giant large shaped charges. Now, if the penetration of a HEAT round is heavily affected by diameter (as I understand it, the jet narrows as it goes along, hence the wider it is to start the deeper it can penetrate) then the same should apply to shaped charges in autocannons, assuming I'm correct in thinking they work the same way. And since the M9's autocannon is a 40mm, well... it seems that if an RPG has issues with AS armour, a 40mm HEDP round should have issues as well based on the small diameter.

The alternative to shaped charges is of course kinetic energy rounds. M9 armour has been described as being able to take hits from calibres up to 20mm, and if that's the best it can do, 40mm sabots should cut through that armour like butter. But then, I was kind of under the impression that the Apache's 30mm HEDP rounds were fairly potent, possibly even more so then 20mm kinetic energy rounds (though that might be a tad range dependent). So maybe really I should just go with the idea that Arm Slaves are fairly vulnerable to shoulder launched rockets (though possibly with the caveat that it needs to be well enough placed to damage something critical -hit an arm and you might damage the thing rather then destroy it).

The big advantage of HEDP, btw, is that it's multirole and its effectiveness isn't affected as much by velocity drop offs over range as a kinetic energy round. Also, I'm not really trying to make the 40mm capable of penetrating heavy armour like that of the front of a tank, but I figure it at least needs to be adequate against light armoured vehicles and other Arm Slaves, even if it has to switch to KE rounds to do it.

Oh, and on the spare mags issue -no, we don't really see Arm Slaves carrying spare mags in series. Some of the concept art for the show has them with spare mags and other equipment attached to their external hardpoints though. Call it a case of the animators being lazy when they actually had to draw the stuff for the series itself.

upon reading all that, the only issue I could come up with an answer for (in my current state) was that of human-shaped mecha.

the issue is that the pilot is human, and the controls function by reading body movements, rather than being a joystick/buttons/pedals/steering wheel. when you try to adapt human movement to a quadrupedal/tracked/multiarmed form... you're pretty much gonna fail.

Piero wrote:Oh, FMP certainly doesn't have hardcore realism.

I know which is why I don't analyze it at any real depth. You know there is a page on TV Tropes that feels relevant. FMP is like a 3 on that scale. Kind of realistic, but not terrible. This is an anime in which there is a machine that manifests thought into energy, and matter in seeming complete disregard of all know physical laws. Sure you could push the series towards the harder end of the spectrum. If nothing else there is no reason not to smooth out the internal inconsistencies. Honestly my opinion is don't let it become work. The moment that happens what's the point? Suspension of disbelief is a wonderful thing, and people come to a FMP fanfic without one are in the wrong place.

I never read the books, and don't intend to. Just not interested. Armor Slaves do make sense in say mountainous terrain. Yeah tracked vehicles do pretty well. An AS would be able to scale a vertical cliff though. War machines with legs make sense, but they wont replace things like tanks. In the anime it seemed like just the sheer numbers of conventional forces in the pacific squadron story arc was the issue. In the desert battle you mentioned there are a few things to think about. First the tanks have weapons that are two, or three times the diameter of the armor slaves. At range the tanks have a stupid big advantage. The tanks can still destroy an M9 in one hit while the M9's rounds are literally falling out of the sky. Second the tanks probably have way better armor. Finally the M9 is only so mobile. Jumps leave them completely ballistic, and thus predictable. That, and inertia is a bitch when your cruising along at 280 kph. Combine all that with concentrated fire, the tanks should win. Nothing iffy about it.

Any I never saw anything in the anime that suggested the rockets we saw there where guided. Considering how ineffective they where I would be surprised if they where guided. Very surprised.

That was a good catch with the armor, and unintended consequences. Really maybe we should just gloss over the weight as much as possible. What say you?

I wont lie. When you started talking about the rounds my eyes just sort of glazed over. Your thinking to hard in my opinion about what kind of ammo their using. That said I will try to reach your level of caring, but I'm out of my depth anyway. First off I think your wrong about what HEAT rounds are. The way it's described yes shape charges are important, but their explosive component don't do the damage. The jet of liquid metal the shape charge produces does the damage. Which is amazing against armor, and not much else. Basic HEDP rounds are HEAT rounds that also produce some shrapnel. While the more advanced HEDP rounds have sophisticated fuses that can tell the if what they've struck is hard, or soft. The fuse then detonates the warhead to either produce more shrapnel, or that armor destroying jet of liquid metal. At least that's how I understood it. I think that's as much as I can be compelled to care about what kind of ammunition my giant robots are rolling around with.

LoC978 wrote:(in my current state)

This is one reason I like LoC so much. Right now I'm knocking back a screw driver.

Anyway as for the point he raised. Why not just have two operators, a pilot, and a gunner? I hardly think that the user interface being to difficult is going to stop someone. No the reason they don't exist is they just don't, and I'm okay with that. So long as I don't stop to think about it.

*shrug*
if you're hell-bent on losing your mobility and thus the advantages of having 8 meter tall infantry rather than vehicles...

Not that multiple-pilot mechs in other-than-human form are a bad idea... they're actually an awesome idea for utilizing en masse and striking an enemy from an unexpected direction due to enhanced terrain traversing capabilities... but when you lose the natural movement your pilots have in their human form, the mech becomes only slightly more maneuverable than a tracked vehicle, and without the flat-out speed of said tracked vehicle. Its main features at that point are the abilities to 1. right itself when it falls over and 2. climb stuff.
Once you take away natural freedom of movement from a soldier, a silent approach becomes impossible, as does a swift, nimble escape.
Basically, they lose their application (as it's handled in FMP canon) as Spec Ops.

I have to admit, if I was doing truly 'realistic' mecha, I'd got more for the powered armour approach. As in exoskeleton type powered armour, not the giant things FMP has. Much as I like FMP's Arm Slaves, I look at the was the controls and stuff are set up and think they ought to be clumsy as hell compared to a human.

As for the novels, I hope you didn't feel I was deriding your knowledge or anything. It's just that I've read a number of them myself and figured I'd interject with relevant examples where appropriate.

And yeah, I probably am going a bit too far... but my mind has a tendency to fret over things like this for some reason. And I also to some degree actually like discussing things in depth at times, which doesn't help matters. (Though even I find my own tendency to overthink things a hindrance at times.)

I suppose as far as ammo goes it's sort of the issue of whether it's realistic to try to simplify things to have Arm Slaves primarily use one type of ammo (HEDP) or whether I've got to have them swap ammo types for different targets (KE for arm slaves, other rounds for targetting buildings and infantry, etc.). But perhaps I am overthinking things, and should just go with the 40mm HEDP rounds. Even if it's a bit unrealistic for an AS to be particularly vulnerable to them if it can sruvive a hit from a RPG...

I am still wondering if anyone could explain how a linkless feed system works to me though. It would be nice to have an approximate idea of the capacity and size of the magazines used by AS autocannons (size would affect where they'd be carried on the mech). It's kind of nice to have a rough idea at what point a character should be trying to do a reload, even if you aren't keeping an exact tally of the number of rounds fired.

Another bit of AS related discussion is trying to develop a distinct fighting style for a character in the fanfic I'm writing, but I don't think it's a good idea to try to hash that out before I get some of the storyline and characterisation details a little more solidly grounded (there they're, but not necessarily set in stone yet).

here's the original patent:

http://www.freepatentsonline.com/3747469.pdf

...it's considerably simpler than designs that are actually in use (and would sometimes fail to feed rounds... usually not to the point of jamming, just dry-firing), but that 'belt of round clips' shown in detail on page three is pretty much the basis of modern feed systems (they just make the belt cycle through the entire mag). Loading 'em requires special equipment... but then, what step in the maintenance and usage of such large-scale weaponry doesn't?

as for ammo types versus target types... I'd guess they just use HEAT for everything. A hole through a soft target and burning dirt behind it is a preferable outcome to a mere scorch mark on an armored target. You can't always have optimum equipment in every situation, so it's best to plan for the worst.

That's simpler then the ones in actual use?

Well, anyhow, I'm having a little difficulty understanding it, but I understood enough to be able to come up with a design concept of sorts. I'm guessing the AS mags will use an external power source to run the conveyer belts, but I'm thinking the weapon they're being used to feed can probably provide that. Now as for design, I'm thinking of actually using two seperate conveyer belts that are sort of synchronised to be out of sync. The cartridges start on the outside of the magazine, move downward, make a 180 degree turn at the bottom of the magazine, and the the two feeds (being as I said synchronised to be out of sync) meet up in the centre to form a double column feed going up. You might need a fake cartridge or something attached to one of the belts to help give the last round a final push or something, I'm having a bit of trouble figuring out how that last bit woud work.

Assuming the use of a round like the 40mm Supershot/Super 40 (something like 39mm diameter, 290mm overall length -note that's overall length, not casing length), then the end result of such a system would be a one hundred round magazine with a height of about a meter, a length of about 12 inches, and a width of about ten inches. Some of those figures are probably a little low, especially the width one, where I assumed the width added by the conveyor systems would only be equivalent to two extra columns of cartridges. But I think it works well as a rough idea of the magazines dimensions, don't you think?

Loading would simply be a matter of hooking the magazine up to something that could run the conveyor belts in reverse as cartridges were dropped in.

Now does all that make sense, or am I screwing up somewhere? I am far from being mechanically inclined.

Ammo wise, I was thinking possibly an HEDP round, it it had enough armour penetration, could be used for general applications against both hard and soft targets. The problem was just that if AS armour can take shaped charge rounds from RPGs, it should logically be able to take shaped charge rounds from a 40mm cannon, since the 40mm rounds have a smaller diameter (of course, there is the issue of how advanced the warheads in question are, but as I understand it, generally with shaped charges larger diameter translates to greater penetration, and the RPG round would be significantly bigger). Hence, if that was the case, it would probably be advisable for Arm Slaves to carry kinetic energy rounds for use against other Arm Slaves while using the explosive stuff on soft targets. I suppose straight HEAT rounds in 40mm might have greater penetration then multi-purpose HEDP rounds, but they're both still dependent on a shaped charge for penetration, so I wonder if using straight HEAT would really solve the problem.

Sorry, I'm probably repeating myself a bit on the ammunition thing, but I wasnted to make things clear.

The graphics actually make it pretty straight forward. A pressure bar pushes the rounds in the columns towards the loading gears. The loading gears in turn put rounds on the conveyor belt. I have a question or two about the loading gears, but not enough to try to read the damn thing. I am curious why you want to have two magazines? Also I'm a little unsure about the round traveling down, and then up. Are you trying to shrink the distance between the two rounds being feed by the different magazines? Or is it an attempt to increase ammo capacity by having the conveyor belt be full?

As for the matter of of dimensions. First I would simplify things by rotating the rounds 90 degrees between the mag, and the chamber. That would bring it more in line with the dimensions we see in the anime. Your smallest dimension should only be about 2 inches longer then the actual round itself. I figure that aught to be enough to accommodate the drive system. Which using your numbers that works out to about 14 inches. I would call that dimension width.

The next dimension is going to correlate to the number of rounds you up in the columns. I would put the conveyor belt at about three rounds. The pressure bar assembly looks like at least another two. All the mechanical drawings in the patent are split across this dimension. Which is meant to imply that it columns can contain a ton of rounds. Lets go with eight rounds per column for now. So that works out to about 13 times the caliber of the round, or about 20 inches. I would call that dimension length.

Finally the last dimension is based off the number of columns you have. The patent shows 16. Assume the drive system for the pressure bar takes the equivalent of 4 columns. Then the conveyor belt looks like it goes on about 2 more columns out beyond that. So that works out to roughly 34 inches. I would call that dimension height.

So a 34 by 20 by 14 magazine would give you a definite 128, plus say another ~16 on belt. Obviously all these numbers are adjustable if you change the number of rounds per column, or number of columns. Why you, or I, should care about those kind of details is an entirely different story.

Loading aught to just be basically a matter of running this in reverse. I think your going to have to play a bit with the loading gears to stop it from jamming. Nothing worth fretting about though.

As for the ammo. I don't think that a HEDP round is any less effective against armor then a HEAT round. RPG-7 heat warhead is about 85mm. So a 40mm HEAT, or HEDP round is pretty much worthless against around that can handle that. So against heavily armored targets like other AS, or tank you would have to use a Kinetic Penetrator. However explosives are still great for light targets. So I imagine that pilots often have a mix of the two in their mags. That, or mags of each. For the explosive rounds I would use HEDP rounds, because they are better against armor then regular fragmentation rounds. However they are more expensive, but that hardly seems like a concern for Mithril.

Unfortunately, I'm still having trouble figuring out how that magazine works.

As far as the one I proposed however... you know those Beta-C dual drum mags? I'm thinking something sort of along those lines, but by using a pair of conveyor belts, you get a much flatter shape more akin to a conventional magazine. I'm having trouble figuring out how to work a few details, but that's sort of the general concept (although I'm not sure I had the Beta-C in mind at the time). And it has the belts assisting the ammunition along pretty much the whole time.

Depending on the width of the conveyor belt system though, it might end up being super wide, which would make the magazines quite bulky. I was sort of hoping not to make them too bulky, the mags in series aren't (although then again, those mags arguably have realism issues). And I might have to alter my ideas on stowage if they were.

And yeah, I probably shouldn't care that much, but I can't really help it. My mind just dwells on stuff like where these mags are stowed on the chassis. And size could affect that.

hmmm... I see I've confused you guys a little...

that patent was an extremely early design. The pressure bar fed columns have pretty much been replaced by a full chain system run by one or two gears that hook up to whatever weapon they're installed in... usually with an electric motor and a simple sensor that detects when a round is chambered.
So you'd still have columns of rounds, but they would all be on the same chain inside the mag. Wil's estimated dimensions seem to have a slightly high number of rounds to 'em at first glance, but without actually drawing up some blueprints, I can't say for certain. Rest assured that a 34"x20"x14" mag would hold more 40mm rounds than a modern contemporary assault rifle holds 5.56mm rounds, though (well over 50).

As for armor piercing... I guess I have to correct myself. Anything that can stand up easily to an 85mm HEAT round from one of those RPGs would probably have nothing to fear from a similarly built 40mm autocannon (unless every round was built with a penetrator and an impact fuse). So yeah, a separate mag full of AP rounds would probably be in order.

So my idea of two U shaped feeds (each with it's own conveyer belt) merging into a double column feed isn't so viable then?

What about doing a single conveyor belt in the middle of the mag then, with the cartridges just running around the edges of the magazine? Seems to me you could make a fairly tall, narrow mag that way, and with a height of about a meter, probably do about fifty cartridges (as noted above, the Super 40 round necked out from the 30x173mm has an overall cartridge diameter that is pretty much the same as it's calibre). Best of all it would be very simple mechanically.

Now the feed system for the head mounted .50s... that I don't want to try to think about too much. (Then again, maybe the .50s are best just using linked feed... I'm trying to think how a conveyor belt could possibly run from the torso up into the head when the head happens to need some measure of movement. Though then again, loading linked ammo into a system like that would probably be a huge pain...)

As for ammo types... I did a bit more research on the armour I was basing the AS armour off of, and it sounds like it may be able to protect against at least some models of RPG (there is a huge difference between the capabilities of different RPG warheads, development on those things has not been static). Perhaps that shouldn't be surprising, considering it's composition. So yeah... probably best to go with KE for targetting Arm Slaves. I'm not sure the idea of a multirole combat mix is so hot, as getting even a reasonable ballistic match between the KE and HE/HEDP rounds would require full calibre AP rounds, and the most effective AP rounds are sub calibre sabots. But really... with an interchangeable mag system an AS could switch ammo types fairly easily. Sabots for Arm Slaves, HEDP for use against fortifications, HE rounds with programmable priming for infantry and aircraft...

Yeah, it's probaby best to just treat the AS rifles as being weapons which can swap roles based on the ammunition being used.