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The Joy of High Tech


Rodford Edmiston

Being the occasionally interesting ramblings of a major-league technophile.

Please note that while I am an engineer (BSCE) and do my research, I am not a professional in this field. Do not take anything here as gospel; check the facts I give. And if you find a mistake, please let me know about it.

Powered Armor

     Powered armor of various types is a long-time concept in science fiction, the basic idea having been around since at least the Forties. Stories featuring it are still being written and printed. This article is intended as an overview of the possible technology behind the technical feasibility of real-world man-sized suits of powered armor.

     The difference between suits of powered armor and the older, traditional (i. e. unpowered) type is that the powered suits carry their own weight, and more. They also allow the use of heavier weapons than the operator could carry without the armor. As usual, SF anticipated a real-world situation by several decades. As of a few years ago, the US Army was working on at least one such piece of equipment, the SIPE. This stands for "Soldier, Integrated Protective Ensemble." If built this will not only provide protection from small arms fire and shell fragments but also carry its own weight and all the equipment a modern foot soldier needs, such as extensive communications and sensor gear, and provide full ABC (Atomic, Biological, and Chemical) protection. Other, similar equipment is probably under development, both in the US and elsewhere. Additionally, non-augmented suits which provide protection and sensor and communications capacity are also being developed.

     The SIPE is not intended for "hand-to-hand" combat, and there is no provision for strength "amplification." It is primarily a one-person armored personnel carrier, keeping the burden of its own weight and of the equipment carried off the back and legs of the operator. The SIPE - at least in the version I have read about - is a mixture of hard and soft armor supported by an exoskeleton. Technical details are still classified, and are probably still being researched. Even this admittedly crude device would have communications and sensor gear more sophisticated than what is presented in most suits from fiction. Power would come from a small internal combustion engine in the backpack, probably a Wankel rotary. At our current level of technology this is about as good as we can do for primary power, and for the intended function of the SIPE it is quite adequate.

     That's what is available currently (at least as far as non-classified information goes). Predicting future technological developments with accuracy is difficult, but some reasonable guesses can be made. In each of the following areas I'll provide a rough outline of what is available now, with forecasts of what can be expected both near-term (say, within the next 20 years) and further along.

     Armor: There are several approaches to this. Keep in mind that we aren't building a walking tank, but something which will protect a soldier from small arms, heavy machine guns and perhaps light machine cannon. Such a piece of equipment would, indeed, be a one-person armored fighting vehicle (AFV). For further information on armor protection, see the JOHT article Material World Part 2: Gimmie Shelter.

     Soft armor - such as is used in ballistic vests - has the advantage that it is lighter for the same level of protection, in part because it yields with impact, catching the projectile like a net. However, for protection of the level and type needed for an AFV soft armors aren't really suitable. There are situations where you don't want your armor to flex. A rigid structure also better resists impacts by objects with sharp edges and points (such as shell fragments and flechettes, not to mention ice picks) and the shocks of explosions.

     Currently, the best we can do for a true "hard shell" suit of armor would be a laminate of some sort. Perhaps titanium and graphite/epoxy composites, with maybe some boron fibers included. Faceplates would also be multi-layered, with an outer surface made from something like a ceramic glass, backed by polycarbonate. Polarizing material and anti-fogging heating elements would be incorporated as additional layers. As mentioned below, the faceplate should also have some display capability built in.

     In the near future we can expect to be able to use things now known to exist but available only in laboratory quantities. This includes monocrystalline iron filaments, which have an incredibly high tensile strength (as mentioned in a previous JOHT). These could be a component in any of several different types of composites. At a rough estimate, a one centimeter thickness of such a composite would be approximately equivalent to about 4 cm of RHA (Rolled Homogenous Armor, a military standard of comparison). Since it would have a lower density than RHA, the benefit in terms of weight saved would be even greater than this 4-to-1 ratio.

     Something in the works which is better than perfect iron whiskers would be perfect diamond whiskers, embedded in an advanced epoxy bonding agent. This would produce a lightweight, inexpensive composite with strength and resilience even greater than that provided by monocrystalline iron. One centimeter of this would be approximately equal to about 10 centimeters of RHA, and with a density about one-third that of the homogenous metal armor it would be far lighter for the same protection level.

     Theoretically, making diamond whiskers should be fairly simple and easy. One suggested method is to extrude graphite fibers under conditions of heat and pressure which cause the carbon to assume the same atomic bonding that is found in diamonds. The most successful current technique is using vapor phase deposition of carbon atoms to create diamond-coated wire. (This coating isn't perfect, monocrystalline diamond, but tests have shown it to have nearly the same strength.) This process could also be used to diamond coat the outside layer of the faceplate. (Talk about scratch-resistant!)

     Another near-term material is SWNT (Single-Walled Carbon Nanotubes) made from tubes of carbon atoms ("Buckytubes"). These are nearly as strong as diamond, are less brittle, and one type conducts electricity very well, while another is the best known non-superconducting conductor of heat. They also have some other interesting properties. For instance, being hollow tubes they can have something wrapped inside them. Buckytubes are already being made in large laboratory quantities. At least one company is selling them to experimenters and the public. If the right process is found, they may be much easier (and cheaper) to produce than diamond whiskers or diamond-coated wires. Buckytube composite armor would offer a protection level per centimeter of thickness a little under that of the diamond whisker composite described above, but at about half the weight.

     Beyond even these is a theoretical material, ring carbon. This would be at least an order of magnitude stronger than perfect diamond whiskers and both more chemically stable and harder. Suit armor made from interlocking, benzene-like rings of carbon atoms would protect the wearer from anything short of a heavy anti-tank weapon, with very little weight. Even then, more danger would come from the transmitted shock of impact than from penetration. A centimeter of this would be equal to roughly 100 thousand centimeters of RHA. Assuming such an armor could be made, it would survive without a scratch impacts which would not only pulp the wearer but powder the equipment inside. It would be best used as a reinforcement for a more conventional composite armor. A few grams spread through the outer layer of the composite would greatly increase the protection of the armor (meaning the armor could be made thinner and lighter and still stronger).

     An important factor in armor effectiveness is geometry. Armor works better when it is angled, because of two factors. The first is purely geometric; a flat plate at an angle to the line of attack presents an effective thickness much greater than that of the plate itself, because the path of penetration passes diagonally through the cross-section. Secondly, the shallower the angle of impact the greater the chance that a projectile (or the fluid jet from a shaped charge) will simply bounce off. Shells designed to penetrate armor have long had a cap under the frangible ballistic nose for the purpose of "digging in" when hitting at an angle, to increase armor penetration. However, even these can bounce off a steeply angled plate.

     Armor on a tank or a battleship is angled in the vertical plane - that is, away from the horizontal - but that isn't practical for armor on a human. Instead, the angle should be in the horizontal plane, around the torso and limbs and leaving a sort of pronounced prow down the front. This does not have to be extreme to be effective. Even a relatively shallow angle provides a vast improvement over a flat plate.

     I recall seeing a film segment of an armored vest and helmet being demonstrated for the military back in the Thirties. The main piece went from the shoulders to the knees, and it and the faceplate on the helmet had a vertical fold line down the front, where the metal was angled back. The man demonstrating it - presumably the inventor - simply stood with his arms behind his back while being shot with a military bolt-action rifle. He rocked back a bit each time, but was not otherwise affected. I've never come across mention of this particular armor or anything like it actually being used in the Second World War, most likely with good reason. First, it was too heavy. Second, it appeared to offer no protection for the sides and back, arms and lower legs. Providing all-round protection could have been done with such a suit, but at a cost of even more weight.

     Historic digression. Individual armor for protection against small arms has been around since long before the invention of firearms, and armor specifically intended to resist bullets from guns since shortly after the first guns appeared. During the War Between the States it was not uncommon for officers (especially in the cavalry) to buy and wear steel vests capable of withstanding penetration by the soft, pure lead bullets used by handguns and rifles of the day. I have a book with a photo of one such vest on exhibit in a museum. The vest has several minor dents, and one large hole. The caption explains that the cavalry officer wearing it charged a cannon emplacement. The lesson here is that nothing is bulletproof, because there's always someone with a bigger bullet. During WWII, many services on all sides offered various types of armor to soldiers. This ranged from steel helmets for infantrymen to elaborate flak jackets for aircrews. They were often simply discarded as too heavy. Protection from small arms and shell fragments continued to improve, though, and by the time of Vietnam many foot soldiers routinely wore (relatively) lightweight ballistic nylon vests.

     Another tactic which greatly increases the effectiveness of a given thickness of armor is spacing. That is, having a space - an air gap or a lightweight filler material - between layers of armor. This is especially effective against shaped charges, but also helps against kinetic energy penetrators and simple explosive charges. One way to design this into a suit of powered armor is to have the actuation work through an orthotic frame exoskeleton, with the hard armor bolted on over this. The user of the suit wears what is essentially a thick, multi-layer bodystocking, inside the orthotic frame. One of the layers of the undergarment is kevlar or some other ballistic fiber. This would protect the wearer from spalling and from many of the projectiles which manage to penetrate the outer layer.

     Other layers of this undergarment would have other properties. For instance, the outermost could be a hydrogel, which would flash explosively into steam when contacted by the jet from a shaped charge, acting like reactive armor to disrupt it. The soft body armor and padding underneath would absorb most of the shock. Yes, the wearer would be injured by this; but much less so than if the portion of the jet which penetrated the outer armor actually made contact with the body inside. The primary use, though, would be to act as padding, helping to protect against explosive shocks, falls and such.

     Strength Amplification: This would more reasonably be called strength augmentation. The idea here is not to create a walking bulldozer, but to allow the wearer to carry weapons and equipment far beyond the capacity of the unaugmented foot soldier, without hindrance. The control system would measure and compare the exertion of the wearer to the resistance being experienced, and boost the force until the object moves or the suit reaches its limit. The actuators could be of several types, and a single design would probably use two or more of these, at least in a suit using our current level of technology.

     Using off-the-shelf or slightly modified available technology, the best bet would be a combination of hydraulic pistons and turbines, and electric motors. However, even with a great deal of clever design, and powerful computers controlling the actuators, the resulting motions would not accurately mimic those of a living creature, and in a suit you want natural movement. Hydraulic systems give great strength, but are bulky and just don't work as smoothly or quickly as muscle. Electric motors - especially modern digitally controlled ones - do better, but using conventional motors means converting rotary motion to linear. This would add bulk, weight and complexity. There are linear electric motors but they generally don't provide much force for the weight or volume.

     To provide natural, organic movement you need something which operates in much the same manner as muscles themselves. A crude version of this already exists: fibers which contract when electric current is applied to them, or when exposed to a certain chemical. These are already being proposed for use in manipulators on space probes (such as the Mars Pathfinder follow-on) and underwater vehicles. An advanced electroelastic fiber would be ideal for a suit of powered armor. These fibres could be aligned to mimic the natural pattern of muscle fibers, easing control problems and helping reproduce natural movement.

     Another new technology which might be used for actuation is MEMS (Micro Electro-Mechanical Systems). This uses a development of current integrated circuit construction technology to combine mechanical elements, sensors, actuators, and electronics on a common silicon substrate. Using this, the actuation of a suit could be achieved through surrounding the wearer with millions of tiny machines which move with respect to each other. (The current version of Marvel Comics' Iron Man suit uses this concept. Someone is paying attention. ;-)

     Controlling Movement: Candidates for control systems in a current technology suit include myoelectric sensors (which detect nerve signals to the muscles); piezoelectric force detectors and other pressure sensors; and fluidic position sensors and repeaters. (These last would operate in much the same way as the power steering in your car.) The best bet with current technology would be the myoelectric sensors. They are small, simple, and relatively inexpensive. However, without implanting the wires they would only detect signals to muscles at the surface of the body, just under the skin. Better would be a combination of two or more of the systems listed, for greater flexibility of response and for redundancy.

     Near-term future should be able to provide a system which is far better than any of these. Something capable of non-intrusively detecting activity in the motor area of the brain would be ideal. A SQUID (Superconducting Quantum Interference Device) array detects the minute magnetic fields produced by brain electrical activity. Units now available fill a small room and have moderately good resolution of only one small area of the brain at a time. If this technology advances as rapidly as microcomputers have in the past twenty years, then by 2020 a unit which can monitor in detail the entire motor and speech areas of the brain will fit in an oversized helmet. The suit would literally read its operator's mind, responding directly to the brain's commands to move, and accepting subvocalized instructions. This concept was actually studied by the US military, in 1985.

     To interpret these signals and use them to direct the suit would almost certainly require a neural net computer. The wearer would start out operating the suit with one or more of the other detection systems mentioned above, performing simple tasks. The neural net would compare the brain's motor center activity with the result (the suit would certainly have built-in position and force sensors), and build operative pathways. Soon the neural net control system would take over, with the backup system going to standby. With each use the computer would learn better ways of performing, continually learning and optimizing itself. (As you might guess, at least this part of a suit of powered armor would be very individual.)

     Once the neural net computer in the control system is taught how to correlate the brain's signals with the body's physical movement, controlling the suit would feel as natural as operation of the wearer's own limbs. The SQUID array reads the intended movement from the motor area, the computer interprets the commands to the muscles and send commands of its own to the electroelastic fibres, which move the suit just ahead of the wearer's limbs. Since all the load of the suit and its burdens are taken up by the actuators before the wearer needs to exert any force, moving the suit feels effortless. Weight and inertia both are compensated for.

     General Suit Control: Having a suit of powered armor simply act as a beast of burden would be a waste. It already contains sophisticated computer equipment, and a surplus of power most of the time. Circuitry is light, and hardware to provide an interface between user and computers not much heavier. At the very least the suit should have miniature versions of the sensor and communications gear in today's AFVs.

     Of course, this presents the problem of operating the additional equipment, with the hands occupied with weapons and other gear. Radio transmissions can be voice-activated, but what about the radar? The night vision display? The thermal IR?

     First and foremost, we need to make the suit's operations as automatic as possible. If ambient light fades, the faceplate becomes an LCD screen with built-in backlighting. Or perhaps the image is scanned onto the inside of the faceplate by three-color lasers. Control of the equipment is not through knobs or buttons but through verbal commands, or subvocalized commands, through the SQUID array. (For the sake of brevity, I'll assume that from here forward.) The suit's parser would have a large vocabulary, and flexible grammar. If the wearer subvocs Select grenades, HE. Stream three to target. Fire. the suit will rotate the grenade launcher magazine to the proper type of grenade, and launch three of these rapid-fire at the target the wearer has designated with a cross hair. (More below on aiming.)

     This parser does more than just interpret the user's instructions for weapons' use. If the user wants to communicate with the wearer of another suit who is in a better position to attack, he says aloud "Sam, put three HE grenades in that clump of bushes over there." The suit will automatically relay this to the appropriate member of the squad by radio or ultrasound, but not itself perform the action. As an added bonus, Sam's helmet display will show a crosshair of the sender's color, letting him know exactly where to shoot.

     This sort of methodology is already being developed for combat aircraft. The computers handle the minutiae, leaving the pilot to fly and fight. Any command input not directly related to these activities - and many which are - are given vocally. For instance, saying "Godseye" tells the computer to superimpose a synthesized overhead view of the battle area onto the HUD, allowing a pilot momentarily free of combat to quickly learn what's going on. If the pilot sees a target then all that's needed is to say "Select (appropriate missile)", target the enemy threat and squeeze the trigger. No need to look away from the action, or manually flip switches. The pilot is the boss, the computers the faithful and talented servants.

     In this respect the wearer of a suit of powered armor is like the commander of a crack team of highly-trained men who obey most orders without question. And like a member of a crack team, the suit will ask for clarification when the order isn't clear or confirmation when a command will put the wearer or a friendly at risk. And, yes, much of the development work for a suit of powered armor will involve developing algorithms for such functions.

     Sensor Gear: Current sensors used in military operations include electromagnetic sensors ranging from visual, through near-visual (UV and near IR), through heat (far infrared) and millimetric (very far infrared), to radio frequency (radio and radar). Sound sensors are available in both active (pinging sonar) and passive (selective amplification and pattern matching, including listening-only sonar, as well as seismic) types. For the near future, we can mostly expect refinements of these systems, though magnetometers (or magnetic anomaly detectors), ground penetrating radar and such might be added. Some sort of tactile repeater for the hands and feet would also be very useful to let the wearer know what is being handled or stepped on; such haptic systems are already under development for computer games and remote manipulators. Phased array radar can be fitted into the helmet, providing a rapid-scan, multi-frequency radar capability. Seismic sensors can detect movement of heavy objects (such as enemy armor) nearby, and even provide some indication of direction. Atmospheric analyzers could provide information on exhaust fumes and outgassing of various materials, perhaps even allowing identification of individuals by scent! (There are in existence devices which can detect airborne chemicals in far smaller quantities than even the best bloodhound is capable of scenting. These currently work with only one or a few chemicals at a time, lacking by orders of magnitude the flexibility of even a human nose. However, much work is underway on this technology and major results should be forthcoming in the next few years.)

     Even more sensors could be remote from the suit, relaying information through spread-spectrum radio encoding. All the sensor types built into the suit could be scattered around, planted manually, dispersed by artillery shells or grenades, or air-dropped ahead of an advance. Also available would be data from mobile units; rovers, swimmers, and flyers. (Reconnaissance drones smaller than most model airplanes, complete with TV imaging, are already being developed.) Suits can also network, sharing data. This can be combined with what is sent by the remote sensors to create a gestalt image of much greater scope and detail than what any one suit could perceive.

     Such networking is already in use. For instance, the F-14 has a very impressive radar, and a dedicated communications system which sends the information from this to other planes and the home carrier. It also receives information from other sources. An F-14 can shoot a target beyond the range of its own radar by - as just one example - using data from an AWACS to tell the missile where the target is. This capability would also be useful with suits of powered armor.

     The biggest disadvantage of such a flood of information is that it could be overwhelming if not handled correctly. That problem is discussed in the next section.

     Ergonomics: This includes more than just making the suit comfortable and having it move in a smooth, natural way. Information overload is a major potential problem. How do you provide the soldier with the data needed to survive and fight in a way that is quick, natural and easy to interpret? There comes a point where it is impossible to sort out what is vital from the chaff. And then there's the problem of handling the suit's offensive equipment. Each of these suits would have several weapons of different types to choose from. How do we make using them not only easy, but as intuitive as possible?

     The problems involved with presenting the accumulated data in a way which doesn't confuse the operator is very important. The HUD (Heads Up Display) technology used in modern military aircraft is already more advanced than most of what is described in fiction. (Of course, this could simply be due to writers avoiding those details so as to not lose their audience.) It is also already being used in tanks and AFVs.

     As mentioned before, an important resource available to the user of a suit of powered armor is computer capacity. That can be used to predigest much of the incoming info, and present it in a way that is easy to accept. For instance, we can have a computer convert the data from sensors into a format which a human can react to instinctively. This goes beyond simply having what the outside directional microphones in the helmet pick up repeated to stereo speakers in the helmet.

     The human auditory system is pretty good at quickly and accurately determining the direction and range of a sound source. So, let's have the suit provide some radar information in synthesized stereo. For example, the wearer hears a sliding whistle (familiar from hundreds of war movies) and immediately knows not only that there's an incoming projectile, but from the pitch whether it is a grenade, a mortar round or a cannon shell. And have a pretty good idea of whether it will land over there, or right here. Since a helmet will block outside sounds pretty well, signals from external stereo pickups will also be presented this way, as noted above. So if an enemy soldier steps on a twig, the suit wearer will automatically know the source of the sound is back and to the left. Many other types of information could also be presented in this way. No need to read words on a display, or track down and consciously interpret a blinking light or flashing symbol. Additionally, communication between suits - through radio links, ultrasound or normal sound - would use this same set-up. You know the person talking to you is over there.

     On top of these non-verbal cues, the suit can also provide information through synthesized speech, something already done in commercial aircraft and planned for future combat aircraft. Hearing a voice say "Minefield ahead." could be very useful under the right circumstances.

     Some information is best presented visually, and some control methods work very well when linked to vision. Modern attack helicopters track where the gunner is looking - head and eye - and point the chin turret the same direction. Information from other sensors provide range, wind drift and so forth, and the system automatically corrects the aim. Generally, the gunner knows the exact target the gun is on because there's a glowing cross hair superimposed on his field of vision. So, a target is spotted, the gunner "looks" the cross hairs onto it and squeezes the trigger.

     This procedure would work fine for something like a backpack grenade launcher, but would need to be modified for weapons which are manually aimed. You don't want the wearer to fight the suit moving his limbs to bring the weapon on target. With manually aimed weapons, having the suit place the cross hairs where the projectile would hit, given the current orientation of the active weapon, is a much better option. The wearer simply swings the rifle, missile launcher or whatever around until the cross hair is on what needs to be attacked, and squeezes the trigger. The suit compensates for wind, distance, slope and the particular characteristics of the weapon. And that brings us to the subject everyone's been waiting for.

     Armament: Naturally, powered armor needs weapons. Lasers are an obvious choice, and with power supplied by the suit there are several off-the-shelf industrial and research lasers which could be adapted without much trouble. The problem is that there are too many things - accidental and deliberate - which can reduce the effectiveness of a laser. And what happens if - while you're hosing a bunker or tank - the enemy's laser-sensing countermissile tracks the beam back to the source? Coherent light weapons may have some use on the battlefield of the future, but projectiles using kinetic energy and/or chemical explosives seem like better choices for a long time to come.

     Current weapons which can be adapted for use by powered armor include machineguns, grenade and rocket launchers, a powerful but otherwise conventional rifle (such as one of the .50 caliber semi-auto target rifles on the market) and so on. The near future developments bring improved versions of all these, plus a couple of new devices. Magnetic accelerators are often used in fiction, but too many people describe them as "railguns." While the railgun is an important research tool, it has to be rebuilt after every few shots, making it impractical as a weapon. (Railguns currently under development will do better at this, but the details are - naturally - classified.) A better alternative for many uses would be the coilgun. The US military is already working on several weapons using this technology. The great advantage of magnetic accelerators is that they produce a very high muzzle velocity. Since inert projectile effectiveness against hard targets is more closely related to kinetic energy than momentum, you want a lightweight projectile moving at high speed, rather than a big one moving slowly. The coilgun can provide this.

     Another new weapon is the ram accelerator, or (as I like to call it) ramshell launcher. The basic technology was originally developed as a way of sending small payloads high into the atmosphere without the use of a sounding rocket. More recently, it has been studied as well for weapons. Essentially, the projectile in its smoothbore launcher is an inside-out ramjet. Vaporized fuel (such as butane or methane) is injected into the bore ahead of the projectile, forming a fuel-air mixture. A small propellant charge starts the shell moving and as the fuel squeezes past the moving projectile the flash ignites it. The muzzle velocity is about the same as for a low-end coilgun, and the weapon doesn't use any suit power since it is chemically fueled. The weapon version is also recoilless, since the jet goes out the open back of the launch tube. Using estimated near-term performance, a projectile from a 40mm ramshell launcher - moving at perhaps 6000 meters per second and using a depleted uranium penetrator - would punch completely through the bow armor of an M1 Abrams main battle tank.

     However, the ramshell launcher has an enormous signature, with a fireball erupting from each end. This not only makes using it very noticeable, it is unlikely that the weapon would be fired by someone not already wearing protective gear. The weapon would also be large - measuring perhaps three meters long - and mass over seventy kilos. Handling such an awkwardly long, heavy object is less of a problem with the suit doing the work, but this would still be a specialty weapon, with perhaps one per squad. The ramshell launcher would provide the operator with the punch of a four-inch gun with a rate of fire of about one shot per three seconds.

     The forte of the ram accelerator is momentum, dealing a hammer blow instead of a needle-focus punch. This is less likely to penetrate armor than a smaller, higher-velocity projectile, but you don't need penetration if you can create a vigorous spalling action. Weapons designed to do this have been around since the Second World War. The blow - usually from a squash-head explosive charge - sends a shock wave through the armor which causes flakes to fly off the far side. These bounce around inside the tank or bunker at supersonic velocity, shredding the occupants. The technique is less effective against composite armor than homogenous, but it still works.

     An important force multiplier is making weapons usable automatically by the suit. Small to medium sized weapons could be placed on a steadymount, similar to the device used for making steady walking camera shots. These could of course be manually controlled by the simple expedient of grabbing the weapon and swinging it around. However, by adding actuators at the hinges, you can also have the suit's computer direct the weapon(s) so mounted, to act while the human operator is otherwise occupied.

     In addition to gun-like weapons, the suit could have other weapons mounted directly on the backpack. These would be controlled by the suit at the user's discretion, with no manual control. Grenade launchers, missile launchers and so forth are good candidates. The user could pick up the appropriate "pipper" from the edge of the faceplate display with his eyes, look at the target and think "fire." (Naturally, arming and other preparation would take place first.)

     While it is unlikely that any military force would allow the suit to take the initiative in firing a weapon, some automatic responses would probably be programmed in. For instance, antimissile fire. Place a coilgun on a steadymount, and have the suit programmed to use it if the operator isn't. When the suit detects an incoming projectile - missile, grenade or artillery shell - it can direct the coilgun to fire on this. Other actions - such as performing counterbattery fire or returning small arms fire - would be handled by the suit upon permission being granted by the wearer.

     If the coilgun is busy, the suit selects a grenade full of separate, tiny explosive charges, rotates the magazine so that type is in the ready position, and launches as many as needed to fill the air with enough flak to stop the incoming projectile.

     Longer-term prognostication about weapons is extremely difficult, and this piece is already quite large. I'll save that sort of speculation for later columns.

     Power Source: The energy to operate the suit must come from somewhere, and it would almost certainly be entirely electrical. Above I mentioned a small rotary engine, driving a generator (plus a hydraulic pump if the suit has hydraulic actuators). Other power sources now available include fuel cells, MHD generators and small gas turbines. For the near future there would be improved versions of all these plus the possibility of fission or fusion generators. Such power supplies would require some sort of buffer to take care of short term, high-power demands. Modern candidates for power storage include such options as exotic, high-density batteries. However, since charge and discharge would both need to be rapid, the best way to do this would be with a superconducting loop. Currently this requires cooling the loop to liquid nitrogen temperatures, but room temperature superconductors are a few degrees nearer every year.

     Even if high-temperature superconductors remain out of reach, very small, high-efficiency cryogenic refrigerators are already almost an off-the-shelf item. The main uses are in satellites and space probes, so these have to be lightweight, efficient and reliable. There should be little trouble in making them small and rugged enough to cool a loop of superconducting material to liquid nitrogen temperature in a powered armor suit's backpack.

     Getting Around: You can't build armor to withstand every weapon, not even for a main battle tank. (Remember the cavalry officer mentioned above?) Mobility is therefore important, and in fact has been the subject of several major research efforts. The reason the M-1 Abrams can lay a patch in second is that it has a turbine engine, making it not only very fast but giving it quite respectable acceleration. And talk about brakes! One maneuver taught drivers of these tanks is a full-speed sliding stop through locking the treads. Whoah!

     With the control and actuation systems which should be available within twenty years, the operator of powered armor would be able to run at least as fast in the suit as out of it, and jump farther than normal. This may not be enough, but it is a start.

     Many of the powered armor suits from fiction have had some means of flight, usually jump jets or rockets. These produce a high thrust for a short duration, allowing the suit to travel tens to hundreds of meters in a very short time, as well as gain a temporary altitude advantage in combat. In some cases true flight is possible. Unfortunately, both rockets and jets produce significant heat and noise signatures, and tend to raise a cloud of dust and debris on takeoff and landing.

     There is an alternative, something much better for this use than either jets or rockets. Shrouded fans, driven by electric motors designed to provide high output for short durations, would be nearly ideal. There is almost no heat signature from such a system, much less noise than from either alternative mentioned above, and even the dust raised is less, since the downblast is spread over a larger area. This system would require a sizeable amount of power in brief pulses, but that could be supplied by one or more superconducting loops, as described above. The blades could windmill during descent, not only partially recovering the energy spent but slowing the suit, in much the same way as a maple seed pod or an autogyro makes a gentle landing. In the last part of the descent the motors power up again, cushioning the landing.

     People think of suits of armor in general as being cumbersome. They needn't be. I recently saw a video in which an Armorer at the British Royal Armory Museum gave a demonstration of just how nimble someone in armor could be. Wearing mixed plate and chain, typical of a foot soldier's rig from a certain period and complete with weapons, this man repeatedly turned cartwheels. With the strength augmentation and sophisticated control systems of a suit of powered armor, a soldier wearing one might be more nimble than an equivalent soldier in normal field gear.

     Impractical Features: Okay, now what are some of the features of fictional powered armor suits that are not practical? High heel boots for one. (This a reference to a popular series of animated programs in Japan.) Anything that transforms, for another. (More anime.) Melee weapons, such as swords, axes, and chainsaws, are downright ridiculous, except under certain, very unlikely circumstances.

     On the Other Hand: Shields are often used with fictional suits, and are actually quite practical for powered armor combat. They allow the operator to add protection with less weight than is needed to upgrade the entire suit, and can be discarded quickly in the event more mobility is needed. A properly designed shield could even be used as a wing, to extend powered jumps.

     An implement something like a giant crowbar (or a wrecking bar or "spud" bar) would also be handy. It could be used for breaking into areas where use of explosives wouldn't be advised, such as bunkers where there may be hostages. And, in the improbable instance of needing a melee weapon, it would serve nicely as a quarterstaff. No energy swords required.

     The most important feature of all, of course, is proper application. You can't build a suit of armor that will provide as much protection as a main battle tank. Not even with ring carbon. Because a suit is light enough that an explosion or impact which would only stun the occupants of a tank will pulp the wearer of a suit of powered armor. And even the best tank in the world can be destroyed by the proper combination of common household items.

     It is better to think of a squad of soldiers in powered armor as armored infantry which is both always armored and always dismounted. If the military keeps this in mind, and uses the suits properly, they will revolutionize combat.

      My thanks to Dr. John Brantley for telling me about ring carbon armor.

     This document is Copyright 2002 Rodford Edmiston Smith. Anyone wishing to repost it must have permission from the author, who can be reached at: stickmaker@usa.net