Thursday, March 3, 2011

Heavy Type - Colonial Expeditionary Force Part II

HOVERTANK -Whining Death
by Janne Kemppi

Janne's translation could use some work. Edits will be made as time allows. --GameThug

In 61st century the advancements in gas turbine technology and especially in neural computing needed in control systems has enabled Earth forces finally field air cushion vehicles that are known in commonly parlance as hovertanks. They have replaced wheeled and tracked vehicles in fighting units first in Human Concordat and later in NEC and CEF.

Hovertanks are logical follow-up of tracked tanks used in Earth for four millenia. Tanks have survived all that time because they have always embraced concept of highly mobile platform capable of carrying heavy weaponry that is well protected from threats of battlefield. Despite advances in technology this concept is still as valid as it has always been and now hovertanks fill the armies of Earth.

Hovertank construction is based on idea of flying on nap-of-the-earth within ground effect height. This phenomena happens when downwash created by air is fanned under hovertank and this creates a pressure buildup that will increase lift and reduce necessary power requirements compared to free hover above ground effect height.

Unfortunately the phenomena known as recirculation might negate ground effect or even increase the necessary lift (and power). Recirculation happens when machine is hovering within ground effect height over rough mobile surfaces like long grass or near vertical obstacles such as walls or the edge of wood. For quite long time only method to void problem of recirculation could be overcome only with bigger engine. This made system very unpractical because the performance was weaker than with comparable helicopters.

Hovertank technology did not really came into age until Human Concordat times when advances in gas turbines and lift fans technology made it practical. Still the system remained unpractical until neural networks and genetical algorithms were used in controlling the airflow of the system and negating most effects of recirculation. When power requirement of a hovertank hovering on its ground effect became at first similar and finally even better to those of a helicopter, it was adopted as extremely mobile universal ground vehicle capable of moving in all kinds of terrain.

The ground effect only affects close to the ground and huge power requirements of genuine flight with unlifting body makes their maximum flight height to be under 25 meters except when jets are used for very short jumps over obstacles like walls or ravines at extreme fuel consumption. Typically hovertank flies just 2 to 5 meters above ground.

Allthough the maximum flight height is very poor compared to real helicopters and aircrafts military did not consider it as a problem. Helicopters fly almost exclusively in NOE heights in battlefield to avoid enemy fire. Hovertanks could also do pop-up attacks like helicopters and their speed was superior to tracked tanks.

Hover vehicles have usually very poor aerodynamics because they are designed to fullfill functions of ground vehicles and thus they are slower than helicopters. However, the speed advantage helicopters had over hovertanks was not very high compared to superiority over tracked vehicles.

Final deciding factor was protection. Helicopters cannot be well armoured because their rotor blades and complex gearbox systems are extremely vulnerable to enemy fire. Fans of hovertanks no different from other gas turbines and are very vulnerable to foreign objects (especially long, thin objects can easily destroy engine blades). However, hovertank fans could have filters and be armoured (within reason) to withstand enemy fire and environmental effects. In addition hovertanks could carry turret and armour that was similar to those of wheeled and tracked combat vehicles. Military field tests showed they had a new weapon that would in their minds make both helicopters and ground vehicles obsolete.

However, all these capabilities did not came without penalty. Production costs were daylight robbery and fuel consumption was outrageous. Keeping hovertank force fighting capable required well trained technicians and learning all the systems necessary to fully use all the unique capabilities long and arduous pilot training. In a way, the ground forces basic combat vehicle had turned into as expensive and complex weapon system as air force jet fighters.

Personnel problem was first solved. Human Concordat had invented earlier GRELs as giant combat police men. They were bred to be massive and awe inspiring fighting machines capable of intimidating rioters into submission with sheer size. Now these huge men were issued to other branches that were suffering from poor morale and desertion. Complicated hover tanks seemed just suitable next specialisation for these fighters capable of learning perfectly use and maintenance of even most complicated weapon systems of military.

Technological complexity problem needed different approach. Costs were cut by making hovertank into a complete vehicle family. All hovertank models were based on same basic model and all variants would use as many common parts as possible.

Following collapse of HC NEC took over the cutting edge of hovertank design. Vehicle family concept was developed into even further by building the actual vehicle into a common weapon platform where armour, weaponry and command system modules could be installed according to campaign, battle or even mission. The modular construction made also the repairs in battlefield much faster as entire systems could be easily and rapidly changed. Actual repairs of broken parts were difficult and time consuming but they could be done in good time with well equipped workshops safely in rear.

Modules were mission specific and huge variety was available as new modules were added as technology advanced. CEF provided broad classification for all weapon systems to simplify commanding. For example Assault-class hovertank would carry extra armour in front and heavy particle accelerator as main weapon. This class was suggested for use against heavily armoured enemy tank forces in close combat. Commanders would often enchance their own units by issuing for example extra armour modules capable of defeating HEAT rounds if threat seemed to rely on weapons using HEAT rounds. This all would make hovertank in question still be within limits of "Assault" class.

The design factors of hovertank itself still follow the four basic tenets that have been used with armoured fighting vehicles for over four millenia. These tenets are mobility, firepower, protection and command.

Mobility of hovertank makes it possible to go into battle by itself and move quickly across dangerous battlefield with the fighting. Mobility also helps hovertank to avoid enemy fire. Typical modern hovertank has top speed of some 200 kilometers per hour while it flies at 2 to 5 meters over the ground.

Heart of hovertank is two spool augmented turbofans. Bypassing air from the low pressure compressor, or fan, past the rest of the engine to rejoin the hot core flow in the exhaust has better fuel economy at subsonic speeds. The fuel economy and power are improved by increasing the engine pressure ratio. The hovertank engines have much higher bypass ratio and higher pressure ratio (and better fuel economy) than multi mach capable heavy jet fighter engines. Engine efficiency is enhanced with wide chord blade design. This makes possible for engine to achieve high pressure with fewer stages of blading. Engine is also simpler and cheaper and its structure is tougher and system is able to withstand more battle damage.

Hovertanks use primary and secondary vectored thrust fans. Primary system is built around vehicle body and it is used to keep hovertank flying. Most of the power of two engines is reserved for that. However, engines have considerable excess power reserves in case hovertank must areas where ground effect might not be present. This reserve makes it possible for hovertank to actually hover high above ground but its poor aerodynamic shape would make it vulnerable to crosswinds and possibly accident.

Engines considerable power reserves are usually used to jump over obstacles. Hovertank typically flies for few seconds and could go over gullies or houses of hundreds of meters long. Jump capability is very useful in combat too as hovertank can do similar pop-up attacks as helicopters or for example rise for a few seconds above ground effect level to scout area with its sensors. Hovertanks ability to jump has been found to be very useful in hilly terrain and in battles amongst huge sand dunes Western Desert, where CEF could quite often jump across ridges to surprise unsuspecting enemies.

Secondary vectored thrust fans are smaller and equipped with afterburners. They are kept together with airflow controllers in front and back of hovertank. These wings and fans are used mainly for rapid manouvering while slow manouvers are done with nozzles of primary systems.

Hovertank is very agile beast within reason. High mass and high speed make hovertank (or any vehicle for that matter) clumsy at top speed but its powerful manouvering jets made it quite nimble compared to tracked tanks in combat.

Jet engines can increase their propulsion very quickly and their peak power outputs are high. This brute force approach is necessary as hovertank design and layout is not optimal for aerial manouvers. They are above of all meant for ground combat, which requires heavy armour and weaponry. Both requirements increase total weight which is comparable to heavy tracked main battle tanks. Thus hovertank requires huge engines which make it very big and boxy.

High fly weight means huge mass to control. As long as hovertank is flying in ground effect primary system power reserves can be used to help in manouvering. When all primary power is used to jump the tank becomes very big and very clumsy rock flying directly forwards. The problem goes only worse if weather is bad and thus jumping in stormy weather is allowed only in extreme emergencies.

Hovertanks fight in battlefield and therefore its mobility systems had to be well protected. Overall the armour of hovertank is comparable to any tracked heavy tank. A penetrating hit to one of side mounted jet engines typically cripples hovertank. Still the heavy armour protects them quite well.

Fans on the other hand are lightly armoured compared to rest of the vehicle because they need to move at all times. Fan protection remains a basic problem with hovertanks as a lucky hit may destroy fan with potentially catastrophic consequences. Some redundancy is constructed to system with neural network controls redistributing the workload if parts of system are inoperable but typical mobility kill is achieved with hit to fans.

The downward flow of air coming from fans is very hot and thus it is forbidden to stand or work directly below hover tank without IPS. This is a problem when moving in military bases or among friendly civilian population in peace time. In these situations hovertanks may use flexible skirt that enables them to direct some air directly under them and move like conventional hovercrafts. However, skirt using hovertanks are extremely clumsy because of their huge size and inability to use manouvering jets. In these situations CEF regulations stress calm mind, cautious defensive driving and taking others into consideration as hovertank pilots are not alone on road.

Most intriguing capability of hovertanks is their ability to be airdropped from shuttles and aircrafts. They can do this without any preparations as fans provide gentle and consistent deceleration. In military standpoint this enables CEF to drop a combat ready hovertank unit anywhere in the enemy territory without having to go through vulnerable bottlenecks like landing zones or airfields. This strategic mobility is much appreciated by CEF.

Despite this capability restraint is suggested here too. Drops can be initiated at extremely short notice but they can be very dangerous too. Any engine failures lead to catastrophic consequences adding casualties and descending unit is vulnerable to effects of weather and are sitting ducks to enemy fire. CEF suggests that drops zones should be designated into areas without effective air defence and absolute air superiority should be established. Orbital fire support should also be available.

Major weakness of hovertanks remains to be the outrageous fuel consumption. Especially jumping above ground effect height burns fuel in huge amounts. CEF recognized the fueling being Achilles heel of hovertank equipped units and attempted to minimize the problem with hovertanks carrying extra fuel in march or refueling them on the move. In addition highly mobile logistical units had rapid refueling and rearming assets.

Fuel considerations create unique tactical considerations to hovertank units. Their endurance in range is similar to most ground vehicles but their endurance in time at high speeds is much shorter. On the other hand this very speed enables them to move to battlefield and fly quickly to refuel and rearm and return in just ten or so minutes. In addition hovertanks could just shut down and sit in as long as necessary. Despite this hovertank units typically fight in short and very violent pulses over long distances appearing suddenly somewhere and as quickly then disappearing.

Hovertanks normally use liquid hydrogen as their fuel. It was chosen because of its high energy content in chemical reaction. Turbines can use also liquid oxygen or kerosene used by Terra Novan militaries or even alcohol but all these fuels reduce engine effectiveness and increase wear and tear and may even force to complete engine overhaul. Therefore these fuels are used only in extreme emergencies.

Hydrogen is extremely flammable and dangerous to handle but it is extremely easy to create from water with electricity. Since water is plentiful in habitable planets this capability eases fuel problems somewhat. Hydrogen related accidents are always very dangerous but they were thought to be worth much better engine performance and easier fuel supply.

Firepower enables hover tank to destroy the enemy forces and support friendly forces effectively at long ranges. Weaponry must also be easy to use and be capable of reacting against multiple simultaneous targets. Fire must also be effective in move and in all environments. Hover tank is much like a helicopter as a weapon platform. Recoilless weapons are preferred since heavy recoil slowed speed and platform could tremble lowering accuracy. On the other hand it was very stable platform as it did not had to worry terrain contours in move. Three dimensional stabilisation of weaponry was in general enough to ensure high accuracy.

Already in Human Concordat had directed energy weapons such as lasers, particle weapons and microwave projectors been used in widespread service. Since these weapons have been little used in Terra Nova and their widespread use by CEF was such a shock, a bit more comprehensive introduction might be in need. Laser (Light Amplification by Stimulated Emission of Radiation) is based on stimulated radiation principle postulated first by Albert Einstein in 1917 although first working laser was constructed in 1960. In practice laser works by warming a matter which moves additional energy to individual atoms and molecules. This additional energy causes electrons move from lower energy levels to much higher. After a few picoseconds electrons return to lower energy levels and releases a single energy kvant. This released energy kvant is called photon. In Stimulated emission the electrons do not return to lower energy levels randomly but return is caused by another kvant hitting atom. When kvant released with right energy hits to atom with additional energy, it does no more absorb the kvant. Instead atom moves to lower energy level releasing a kvant with same energy, phase and direction as kvant that hit the atom. By using this technique through lasered matter the number of identical kvants comes very high.

High energy lasers used by military affect in target with severe effects. For one they weaken the structure when temperature in hit location increases. Secondly the rapidly increasing temperature causes in target a shock wave that damages especially well structures with poor heat conductivity like glass and plastic. In addition the vaporization of matter in hit location causes X-ray radiation with could cause severe malfunctions in electronic systems. Finally even a beam with low energy can destroy electro-optical command and communication systems and cause blindness to unprotected personnel.

The principles of particle accelerators were first presented by various scientists in early 20th century and first workable particle accelerator was started in 1952. It is based on electrical properties of atomic particles such as neutrons, electrons and protons.

If electrical current moves through vacuum tube electrons move from cathode to anode. The release of electrons may be increased by heating the cathode with electrical current. If tube has some gas in it, the electrons ionize the atoms of gas forcing them to release new electrons. Electrical field in tube starts to also move these newly ionized electrons causing further ionization. This leads to electrical discharge in vacuum tube. If cathode has channels (holes) the system emits so called channel radiation. This radiation is made of particles. What particle is released depends on what gas was used in vacuum tube. For example with hydrogen gas the channel radiation is made of protons. Particles can then be guided with magnetic fields and accelerated with electrical fields to relativistic speeds and then released towards target.

The characteristics of particle accelerators are roughly same as comparable laser systems. They do have lesser range in atmosphere due beam attenuation and atmospheric turbulence causing ionization of beam. On the other hand they emit much more X-ray radiation and thus have much higher tendency to disrupt electronic systems. This is extremely useful capability in modern battlefield filled with electronics.

CEF main vehicle weapon family was commonly called as particle accelerator but officially they were Directed Energy Combination Weapons (DECW). They were based on combining lasers and particle accelerators. At first a laser would be fired to ionize the atmosphere. This would increase range of particle accelerator system that would be fired nanoseconds later through same beam.

DECW was tunable to match individual atmospheric conditions of each planet so it would always fire through suitable "window" in atmospheric conditions and ensure peak performance. In addition the particle accelerator could be switched off and all the energy released through laser system if necessary.

Like any weapon DECW had its advantages and disadvantages. As a beam weapon it did not need to take lead when firing at targets in ground battle. Then it had no detectable recoil which made it preferable to use them in hover tanks. In addition the combination system made single weapon capable of firing particle beams at short range targets and laser beams to medium ranges. This made it possible to switch to weapon with best performance at any given range. This all made DECW highly accurate weapon.

DECW did had severe disadvantages as well. As electronic system it was expensive. It was also difficult to repair in field conditions. The atmospheric and battlefield conditions like rain, fog and dust also reduced its effectiveness especially in long ranges. Power requirements were extremely high despite use of technically advanced superconducting magnets, capacitors and coils used. Actually highly destructive DECWs were not possible until materials that were superconducting in high temperatures were invented. Then the bulky cooling system could be done with and compared to old systems for example capacitors had several orders of magnitude higher capacity. In addition superconducting cables and coils no (in practice however a little) waste heat when electric current is lead through them.

Hovertank DECWs are recharged between shots from huge superconducting capacitor banks. Capacitor banks themselves could be recharged from any electric source but CEF usually changed entire capacitor banks because this could be done very quickly in battlefield. If there was time available generators carried by some logistics vehicles could be used to directly recharge the capacitors. Further redundancy was added by making it possible to recharge capacitors with hovertanks own engines. However, since fuel consumption was very high it was not encouraged.

Soldiers were not entirely happy with DECWs. They could only fire at line of sight targets and had no ability to fire specialized ammunition. DECW could also be fooled with countermeasures like aerosols and their effectiveness was weaker in long ranges. Since hovertanks should only carry recoilless weapons the logical choice to weapon designers for long range firepower was missile. They could carry all kinds of warheads, fly beyond effective laser ranges and hit targets without line of sight. Finally the launch recoil was negligible.

Either Light, Medium or Heavy Vehicle Missile System (LVMS, MVMS and HVMS respectively) were installed to every vehicle moving in battlefield. Numbers and size varied according to class and mission. For example anti-tank vehicles would carry massive battery of HVMS while workshop vehicles of logistics would be armed with just few LVMS missiles for self defence.

Common for all missiles was the use of vertical launch system in hover tanks. VLS was simply a row of launch silos constructed inside hover tank roof. Hermetically sealed containers with missiles were just inserted to these standardized silos. During the launch piping would allow exhaust gases of missile be ejected under the hover tank. Advantage of VLS was that it offered same 360 degree capability without heavy and potentially unreliable mechanical turrets or launchers.

Because VLS fires the missile directly upwards hover tank crews tilted their vehicle 4 degrees left so that the malfunctioning missile would not drop on top of them. Misfiring missiles and their containers were simply ejected from tank via floor exhaust gas tubes. It was truly idiot proof launch system.

Once fired missile would then turn towards target and start flying and attacking in selected height and attack profile. These could be chosen according to enemy defenses. For example low flying missiles were difficult to detect from ground clutter but high flying missiles had much smaller chances of accidentally hitting some tree branch before attack.

Attack profile was important because of variable target armour and defence system configurations in use. Diving missiles could hit targets usually weak roof while pop-up missiles would fly low to avoid detecting and then suddenly ascend and then descent in front of tank to provide more difficult targets for defensive systems. At times it was even better to just explode missile high above target or fly it in level into target.

VLS allowed firing any combination or any types of missiles from one to all of battery in a single volley according BISN, computers and commanders wish to any number of targets. This was necessary as amount of sheer fire in single volley could be increased so high it would overwhelm the defence systems. If enemies had no defense systems the shock effect of huge missile volley hitting multiple targets and destroying them simultaneously would demoralize enemy unit.

DECWs are very good in destroying hard targets such as vehicles and installations but they are not terribly good against soft area targets like infantry. CEF envisages soft target destruction as two layered system. Self defence against infantry trying to attack vehicle and offensive system for suppressing infantry. Self defence systems fell under category of protection which is very large subject by itself.

Most typical infantry suppression systems in assault class hovertank are automatic grenade launchers and aerosol flamers. Grenade launchers are simply enlarged machineguns that fire cannon sized grenades on direct fire or indirect fire to point targets or large area. Since these launchers can fire a large family of grenades the ammunition load can be tailored to meet variety of threats and environments. For example flechettes can be used against soft targets and always popular incendiaries for burning undergrowth and to flush infantry out. They could also be fired against targets without line of sight. This system replaced originally fielded machineguns and variety of automatic cannons.

Aerosol flamer is a very different system. It fires stored liquid that at first evaporates into aerosol gas. A high speed pump then ejects this fuel aerosol towards target. Concentration of aerosol next to hovertank is reduced by employing inert gas stream to remove premature ignition. Volatile liquid hydrocarbons (like butane) are most amenable fuels. It is easy to suspend them in air as aerosol cloud of required dilution. Aerosol flamers have similar ranges to vehicle flamethrowers they were construct to replace. Because the cloud is heavier than air it flows to tunnels, trenches and holes that infantry uses as cover. Above the target the cloud is ignited.

The power advantage of exploding fuel air mix is five times as high as with ordinary explosives. It is a pure blast weapon without fragmentation effect of conventional anti-infantry weaponry. Blast causes internal damage to human body. Effects of shock wave to human body are highly complex but greatest harm arises from the passage of shock wave through gas filled cavities of the body. Pulmonary damage is typical. Lungs are squeezed fiercely as the shock wave decelerates into the thoracic cavity. Bubbles of air may then be forced into blood circulation by collapsing lungs causing brain damage or rapid death that is typical to air embolism. There is often damage to abdominal organs too.

Probability of death is much higher with fuel air weapons than with conventional explosions and in addition infantry body armour does not offer good protection against blast making aerosol flamer very effective anti-infantry weapon. It can also be used against structures as relatively small overpressures have great effect on ships, aircraft, houses and in exploding minefields.

Modern battlefield is extremely dangerous place filled with anti-tank missiles, infantry anti-tank squads, indirect fire and drones. Vehicle Protection System (VPS) was designed to protect hovertank and take care all of those threats.

Protection is a very large concept and includes not just armour but also other factors like reducing observability, avoiding getting hit and if necessary to reduce the effects of a hit. VPS handled the protection needs of hovertank and was divided into two fundamental parts. They were passive and active systems.

Armoured protection forms the cornerstone of passive systems. Typical hover tank armour uses homogenous ceramics only on body itself. The armour proper is a combination of steel, ceramics, fibers and rubber layers. The armour is also modular allowing rapid change of damaged parts, tailoring the armour to match mission and to add new protection technology.

Deep beneath active multilayered armour was reactive element made of explosive plates. These explosive parts could not be destroyed with small explosive charge of tandem HEAT or with face hardened armour piercer. The layer was last line of defence and explosion direction had been configured to be 90 degree difference to position of armour plate. This crossing explosive jet caused "guillotine effect" offering excellent protection against both kinetic penetrators and HEAT rounds.

The armour is reinforced in key locations. These vital locations (like crew and fuel tanks) are also isolated from each other to increase damage control. Additional redundancy has been added with duplication and even triplication of some systems. Alternatives are also used so that in case some part is destroyed another part of system could take over its functions. For example computer system of hovertank had numerous separated parts, all which could take over entire combat if some part was destroyed. Protection could also be improved with careful design where layout of non essential parts was put around isolated and protected vital parts to increase armour.

Outer coating of tank is usually rough surfaced non magnetic mass. It is difficult to make magnetic weapons and thrown anti tank grenades to stick to this kind of surface. Surface painting is matt (to avoid reflections) camouflage (to reduce visibility) which naturally varies according to battlefield. In addition there are always camouflage nets which may used to camouflage stationary vehicle. CEF does not suggest attaching tree branches to camouflage nets because they might be accidentally sucked into engine intakes. Similarly caution is advised for personnel moving close to intakes.

Hovertanks must be able to fight in every environment and weather. This is taken into account already in design. It has heater and cooling system to interior to keep vital equipment running at peak performance. For desert operations air intakes have special filters that help keeping the dust away. Similarly materials choices take into account needs of preventing heat enlargement of jamming the mechanical systems in heat and cold. Specialized systems like electrical heating and pure oxygen tanks have also been connected to ensure engine startup in cold.

ABC warfare is constant threat with modern armies and CEF provides all its vehicles with a degree of protection. Coating material protects surfaces from acidic gases and hovertank is completely air tight with slight overpressure always kept inside to keep particles away. Specialized armour like layer of boron or some specialized plastics which absorb radiation are inserted to armour. Variety of warning systems inform use of ABC weapons. Environmental system of hovertank can keep it operating without any kind of contact to outside world for at least a week (and sometimes for month) but it is not completely circulatory system.

Main reason for crew to leave hovertank is for receiving orders and for rearming and refueling their vehicle. Commands can be relayed via BISN and rearming and refueling can be done with remotely controlled arm if environment is dangerous. This arm has wide variety specialized tools available and it is sometimes used to probe potentially dangerous objects outside hovertank.

The protection of tank is finalized with careful thinking put to minimizing silhouette (to make target smaller), design (to reduce radar cross section, and increase chances of hit ricocheting) and reduction of observable factors (like sound, heat, magnetic field, exhausts).

Even if hit would be achieved some steps could be taken to reduce their effectiveness. Modern tank ammunition causes damage with splinters and heat of kinetic penetrator or directed explosive charge. Splinters were dealt with compartmentalization of vehicle so that damage would be localized and wearing IPS to stop fragments.

Heat effect lead to fire that was extremely dangerous to hovertanks which carry hydrogen as fuel and ammunition of missiles and explosives. Fire protection systems can recognize starting liquid/aerosol or HEAT liquid metal flame in less than millisecond and extinguish it in less than 10 milliseconds with halon gas. This prevents severe damage to systems or burns to crew. If damage is crippling but not catastrophic and fire protection system does not work the crew is protected with IPS to survive fires. They can then either try to put out the fire with hand extinguishers or leave the hovertank without having to fear severe burns.

Catastrophic hit to engines would force hovertank to make either forced landing or just crash. Comfortable seats, seatbelts and air bags protected the crew from high speed or high altitude crashes. IPS gave also protection from neck injuries.

In emergencies hovertank might have to be evacuated. Therefore each crew member had her own hatch for quick evacuation. Rescuing wounded crew men was made easier with special carrying loops built-in in neck of IPS. Now crew could rise wounded quickly from tight hatches.

Finally crew would carry in their person the necessary survival equipment and personal weaponry to stay alive in battlefield and wait until their own forces would arrive to rescue them.

Active part of VPS consists of warning and jamming systems and active defenses. It integrates the sensors and systems into single automatic system that selects automatically or manually suitable countermeasures to each threat.

First the warning systems sweep the battlefield around hovertank. Passive systems are used most of the time because of active systems make hovertank easy to find. BISN provides also warnings to the system. When incoming projectile is found the active sensors are usually turned on to pinpoint its location. If missile flies past the vehicle countermeasures are not used but instead warning is issued to BISN. There are variety of sound (weapon noise) and light (muzzle flash) searching systems too but they are mostly useful for provide warning against infantry and infantry anti-tank weapons.

Assuming the projective is a threat the countermeasures must be initiated. Because of huge size of electromagnetic spectrum and amount of possible guidance systems the measures are equally numerous. Because not even GRELs are quick enough to use missile protection systems the computer typically takes it all over. One might have to use smoke screen (which has metal aerosol and can block several areas of electromagnetic spectrum), laser dazzler (which jams the laser guided weaponry), flares (which confuse heat seekers), noise jamming (to jam command guided weapons) or any or all combination of these or other systems.

Some of these passive systems have anti-infantry uses too in case of emergency. Flares are sometimes shot to make terrain burn in order to flush infantry out of there. Laser dazzler can increase its intensity and luminance so high it blinds infantry and destroys electro-optical devices. Smoke screen has carbon monoxide and tiny metal particles which make breathing through gas mask very difficult and might cause suffocation.

Countermeasures do not fool or stop all projectiles and as a rule they do not stop determined infantry trying to attack vehicle with satchel charges. To deal with these problems VPS switches to active defenses next.

Active defence part of VPS consists usually one or two weapon pallets.
Usually one was put on roof of hull or turret and another to hull glasis to give additional protection from threats emerging from front which was recognized to be most dangerous direction. Weapon pallet usually has a laser anti missile system.

When VPS finds out that countermeasures do not work it orders active defenses to fire. Laser system fires a string pattern of short pulses towards the missile. Usually a single hit is enough as missile fuel explodes or heated up electronics are confused. Missile system is not as efficient against massive kinetic energy objects such as field gun rounds but it can destroy them too but with lower degree of confidence. VPS uses as a rule its own laser capacitor banks but it is connected to capacitor banks of other weapon systems of hovertank so that this vital piece of equipment works under all circumstances.

VPS is very effective against infantry but since suppressive lasers are already available this weapon is usually kept in vital active defence role. However it can be used in similar capacity to those weapons.

Second duty of VPS laser system is aerospace defence. While DECWs and missile systems might be used against slowly moving air targets like helicopters and other hovertanks they are not effective against high speed targets like jet fighters. VPS can engage them since it can drop hypervelocity anti tank missiles. Since VPS range is small it is purely a defensive system and purpose built aerospace defense systems are built on their own platforms.

Infantry close attacks can be very dangerous to hovertanks and they often happen in jungles and urban fighting. Because VPS laser system is almost always used for anti missile defence and infantry suppression systems might be engaging targets at long ranges additional protection is needed. Hovertanks carry antipersonnel system which consists of bouncing directional charges.

System fires the charge to direction of threat and explodes it in correct range. The fragments are directed downwards to destroy enemy infantry in position and to minimize effect on own infantry although the fragmentation direction can be changed if necessary. This system has secondary function to shoot down missiles. It is not as accurate as laser system but may be used for shooting down kinetic energy rounds from tank guns and artillery rounds.

Command forms fourth factor of hovertank design. For CEF it means integration of all systems in hovertank to single unified weapon system capable of fighting with extreme effectiveness. For hovertank command consists of sensors to find the enemy, fire control systems to make sure weapons hit their targets, communications to inform what is happening and last but not least human operators who oversee this all.

Combat starts always with finding the enemy. Even more importantly sensors must be used so that enemy cannot get advantage of surprise and cause crippling losses before close combat starts. Most friendly weapon systems need also very accurate information before they can be used efficiently.

Crew is well protected and deep inside hovertank. Tiny vision slits and periscopes offer very poor view what is happening so crew relies in practice entirely to wide variety of active and passive sensors.

Human eye processes most of its information with eyes and similarly electro-optical systems using visible spectrum and beyond still form base of all military sensors. These systems use almost exclusively passive systems since active systems (like searchlights, ladars and active infrared systems) are very easy to locate in battlefield. These systems can only be used in short range line of sight targets but this is not major problem since most of the ground battle happen in line of sight anyways.

Modern electro-optical system can exploit normal light, infrared and ultraviolet radiation spectrums simultaneously. Sensors can increase the magnification and sensitivity if necessary. This way for example far away objects might be magnified and in night intensity and contrast amplified to make system a low light system. Vision is stereoscopic and accuracy is almost similar in day and night. Computer processes all the data from various spectrums and presents it in coherent picture of what is happening. For example smoke from burning tank would block vision entirely if seen just on visible spectrum. After processing Infrared part could pick up crew escaping from burning wreck and ultraviolent picture notice anti-tank missile launcher hiding under camouflage nets.

Purely optical systems (like oculars) are kept as backup systems only. Modern battlefield is so filled with lasers that chances of blinding are high if someone uses laser dazzler or just by accident. Filters provide some protection in friendly forces wavelengths but all and all CEF regulations suggest minimizing the risk by avoiding use of pure optical systems. If optical systems must be used, a eye patch should be employed to avoid loss of both eyes at the same time.

Use of electromagnetic energy is second important technology. Radar was most popular active system. Pulses of radio waves could be transmitted via some sort of antenna and then received back getting accurate location needed for weapons. Because emitting radar is very easy to locate too hovertanks often used system where one was transmitting and everyone else was receiving. Then the received data would be distributed by BISN to everyone else. This in effect turned entire unit into one huge phased array radar that could filter out jamming quite well with information processing.

If radars could not be used at all for some reason one could always just listen and process what information could be obtained. Since again all information could be distributed via BISN enemy location could be found out quite easily. This signal intelligence was crosschecked from huge library previously captured information of enemy emitters and system would come out with precise information of what and where it is. This system is very useful since range of passive detection is much longer than with active searching.

Third method of finding is based on magnetic fields. It is very effective in telling something is present but does not really where the enemy is. It is more of a warning system rather than effective sensor system.

Targets must be found out before they can be engaged and if one has to use sensors one has to usually expose oneself from safety of cover. This naturally means that danger of hovertank being also located and enemy fire is also high. CEF solved this problem with two approaches. First was to maximize cover when using onboard sensors and second was to exploit drone systems.

Sensors of hovertank are usually located on top of turret so that it exposed only a little bit of turret when using sensors. Advances of sensor systems have made even this dangerous so CEF fitted sensor package on top of manipulative arm. This arm was actually highly sophisticated mast that allowed sensor package raised five meters above hover tank turret giving it very good bird's eye view of things. In addition the sensor pod could be made very stealthy to avoid enemy reconnaissance. In practice hovertanks that were stationary or hovering in final reconnaissance before attack stayed in cover behind trees or hills or gullies using mast mounted sensors. As energy use of mast was miniscule when compared to movement and weapon systems it was practically always on even when hovertank was stationary and engines shut down.

Mast mounted sensors have same problem as with any weapon platform based system. It just cannot see beyond line of sight. Besides the earlier and longer range one gets warning or target information of enemy the better. BISN was obvious solution but everyone in CEF agreed that one could never have enough reconnaissance systems.

Assault class hovertanks carried usually one vehicle drone that hovertank crew would pilot in the patrol. This small flying drone could be launched from inside and recovered and inserted to its module with manipulative arm used in rearming. Vehicle drone was unarmed and carried only a reconnaissance package. Its flight speed was similar to helicopters and endurance was set to two hours. Because only a limited sized module could be carried it was very small and understandably very stealthy.

The advantage of drone was that it made reconnaissance of large areas very easy. Since its cost was nothing compared to hovertank drone could be sent to dangerous place to look what was happening so in case it triggered a trap valuable hovertank was not lost. Typical hovertank unit kept always at least few drones flying around the clock patrolling their surroundings.

Most feared ability of sensors lied in their ability to not just patrol and do reconnaissance but relay the information in real time to BISN. Both sensor pods and all drones carried target designators that made possible to guide semi-active guided munitions into targets. For example a drone could be sent to look behind suspicious hill. If it found enemy the data would be relayed through BISN to hovertanks that could fire their missiles without even seeing the enemy behind the hill. It could also be used to guide semi-active munitions from non BISN equipped artillery if necessary.

After target had been found it is usually engaged. At this moment the computerized fire control system takes over. Fire Control System (FCS) has to recognize targets, evaluate threats and guide weapon systems to destroy them. At first FCS has to make sure that contact is enemy before firing it because accidental shooting of friendly forces has very bad influence on troop morale. Contact evaluation employs image recognition (computerized shape recognition), IFF systems (usually when fighting with non BISN equipped troops), BISN information (gives accurate location of all friendly units) and vehicle navigational systems data (as a reference).

Rules of Engagement (ROE) information might also be included to contact evaluation. Some ROEs may for example forbade use of certain weaponry in certain situations and locations or forbade engaging some target types (such as civilian refugees). FCS follows these targets too and includes ROE status information so crew can evaluate if/how engage them. Similarly some physical locations have been declared free fire zones where anything moving will be destroyed without any kind of evaluation. Thus FCS ROE information is constantly updated according to situation. Crew can override or redo ROE settings if situation so warrants.

Once contact has been evaluated as valid target it will be tracked. FCS tracks automatically all targets, calculates firing solutions and arranges targets to engagement priority according to estimated threat level they form to hovertank or to mission hovertank is fulfilling.

Target list can be engaged either in automatic or manual. Some targets like incoming missiles and artillery rounds were automatically engaged as even GRELs were not fast enough to initiate countermeasures manually. Assault class hovertanks used manual engagement for some of situations but some applications (like aerospace defence) were already without human interaction.

Inherently slow reactions of human body have changed their role from actually using weapon system to supervision and commanding it. Hovertank unit battle is almost completely a war between fully automated weapon systems. Humans were still thought to be very necessary as their intelligence provides them inherent ability to comprehend a situation and learn new things in a way no artificial intelligence in Earth has yet matched.

Manual fire control uses so called "hunter-killer" system where all crewmen could look and fire at any targets they would deem necessary to destroy. The fire control system processes new targets and threats constantly during the firing enabling smooth selection to another target.

After human operator or FCS has made a decision to fire FCS will make final update to firing solution by taking into consideration several hundred factors varying from particle density of air to amount of heat enlargement the constant firing has caused to DECW systems.

Reaction time of typical hover tank is extremely short and first shot could be fired at target in less than a second from initial detection. With manual fire that time was less than five seconds.

War is more than just firing enemies and destroying them. One has to also relay information on both own and enemy status, intentions and actions. Reliable long range communications were absolutely vital to CEF because it could field only limited number of soldiers to fight in entire planet it would invade. It was also reliant to high technology weaponry that would not work efficiently without BISN.

Advanced telecommunications technology has enabled CEF to cram satellite communications to box a smaller than cellular phone. It did not need bulky and vulnerable dishes either. This made possible to construct BISN into worldwide system based on satellites.

Satellite systems offer practically secure and jamming free high capacity system but they have also a weakness. Satellites themselves are essential microwave relay stations that must remain operational all the time. They are very vulnerable to enemy anti-satellite missions. CEF recognized this problem and had huge stockpile of mass produced communications satellites and launch systems to replace destroyed ones and to add reliability to communications system.

Because communications were the critically important component of CEF fighting additional redundancy was added to system by providing hovertanks extensive radio equipment too. Secure frequency hopping microwave communications are used whenever possible to avoid jamming and interception. Radio equipment on hovertank is excellent even if it is just a backup system.

Final part of communications is security. All signals were coded so that even if transmissions were intercepted they would give enemy no advantage. Cryptographic systems and their advantages and disadvantages remain well guarded secret but amount of time and effort given to coding in CEF was extreme because of potential disaster if enemies could use BISN to their advantage.

Last but not least link in command concept of design and also most important part of hovertank is human. Although CEF has replaced most humans with GRELs these biological constructs are so humanlike the same concepts apply also for them. Human part of design means putting attention to ergonomics, then to information presentation to crew and finally how crew can act upon all of this.

Ergonomics is relatively unknown but vital part in military systems design. Poorly designed layouts and displays often might lead to misunderstanding with tired crew. This kind of slipping could have deadly consequences in combat.

In modern hovertank meters and gauges have been replaced with simple graphical displays. Manual knobs have been set logically so they are easy to find in heat of action and so on. All crewmen can use weapon systems without taking their arms from joysticks necessary for moving hovertank as all necessary buttons are attached to control sticks.

Crew sits in comfortable seats that have seatbelts and airbags in case of crashes. There is enough room to crew so that one is not cramped and can stay alert for whole time. Lights are adjusted to be comfortable to eye. Even colors of walls have been thought out. They are light so that even a tiny amount of light inside hovertank would give crew a slightly better chances of seeing in case of emergency. Ergonomy means in essence making everything in the cockpit work for crew and not wise versa.

Information displays have advanced considerably. Crew is surrounded by large graphic displays that show three dimensionally of what is happening around them as well as vital information in easy to understand way. This is however just a backup. The heart of hovertanks information presentation is helmets crewmen wear.

All information is directly fed from computers to helmet visor and ear phones giving out totally virtual reality. One can use direct feed of visual data of what is happening outside. This picture is then filled up with all information BISN, sensors and FCS represents giving a perfect view of carnage in battlefield. However, most of the GREL crews seem to prefer totally artificial picture where all data is processed and only directly militarily relevant information is presented.

Advantage of helmet presentation was that it gave out very clear picture what was happening. It also gives crew somewhat unreal
reality of battlefield where everything seems to be in perfect order despite death, smoke and confusion. Some critics say it turns battle into a videogame where crew might forget that "Game Over" for players would be their final.

In addition to information presentation hovertank also gives out suggestions for actions to pilot. As FCS lists out targets and evaluates threats it also plots out possible routes and ideas for fighting. This assistance program is based on use of relevant historical data of fighting against similar type of enemy and also based on exploiting weaknesses on enemy weapon systems. However, final decision and responsibility on course taken relied always on hands of crew.

Like all computer systems inside hovertank this complicated software was highly complicated piece of neural networking. Hovertank computing system was programmed to learn from its own experiences as it had been noticed that learning system could reach excellence performance in control systems like turbine air flow controls and stabilization.

Level of learning depended on unique user history of each hovertank. In this way every hovertank system was unique. Some GRELs reported of computer system having unique way of presenting and suggesting its information. Similar reports have been made about some Terra Novan Heavy Gears whose neural network system is based on architecture got from captured Earth computer control systems.

Once crew has been presented the relevant information of the battlefield and they made their decision it must be turned into reality. It is here where the action comes in. Joysticks are most relevant physical means but different needs mean that different systems like keyboard, control ball, VR gloves, voice, touch controls, eye movement and thought control could also be used as supplanting or replacing joysticks in variety of capacity. Which systems were used in each individual situation varied according to taste of crewmen.

For example thought control was usually used when selecting almost without conscious thought something from limited well remembered list. Keyboard was method of choice for writing reports and voice was efficient way to give out short orders.

One even did not have to be inside hovertank to command it. Crewmen leaving hovertank for example to repair some part that could not be accessed from inside panels or fixed with manipulative arm kept their helmets on. Crewman could then command hovertank and ask information from self diagnostics or use manipulative while she would be connected to inside with light fiber or wireless radio data link.

Similarly hovertank could also be taken over by another unit in battlefield. This master-slave remote control could be broken by human crew in slave tank at any time. This link was intended to aerospace defence systems where one hovertank could direct totally fire of entire platoon or troop on its own and it was installed to every command software. It was also very useful in training where master tank could take over if trained crew made bad error of judgment.

At times this was used to reactivate abandoned hovertank in battlefield to do something in remote control or leave it run on automatic for some reason. For example if crew had died hovertank could be commanded by master to fight or leave battlefield. Similarly half destroyed hovertanks left in battlefield could be ordered to awake at certain inputs or carry on some duty (like a bait or reconnaissance).

More exotic control systems were tested too. Direct connect between brains of GREL to hover tank computer was field tested. The actual connection was somewhat similar to use of cyberspines, cybernetic sensory organs and webblings all connected. Actual tests were extremely successful and cybered crew effectiveness was much higher than with ordinary GREL crew. However, the time needed to install the cybernetic equipment to a single host body was six months and final cost of system was staggering.

For Terra Novans the massive hovertanks and their high pitched whine were harbingers of inhuman legions of almost unstoppable GRELs. For Colonial Expeditionary Force it was just a vehicle, basic weapon platform, for their units. Despite their vast advantages they were not really ultimate and universal war machines capable of anything as cheap popular fiction has made them to be.

CEF never thought that hovertanks were end for itself. They were just a family of platforms that could carry their army with guns, infantry and everything else to battle faster than much more safely than with all the helicopters and wheeled and tracked vehicles.

In rational assessment hovertanks were outgrowth of more ordinary ground vehicles with advantages and disadvantages like any other system. When compared to ground vehicles they were just another combination of four basic tenets of armoured vehicle construction with vastly greater mobility compared to other ground vehicles.

It was this mobility that made CEF so deadly. Hovertanks could go anywhere they wanted and deliver a sudden unexpected blow to surprised Terra Novans. This mobility allowed CEF commanders to start and stop fighting almost when they wished and where they wished.

Still there were weaknesses to worry. Helicopters and hoppers were roughly as mobile (allthough more vulnerable) and could fight on even standing. Fast jets were also as dangerous to them as to any other ground vehicle. Their large sensor profiles, vulnerable fans and huge size made them difficult to hide compared to most ground vehicles too.

The real weakness was not found on battlefield. It was the very technological sophistication that made hovertanks so deadly in the first place. Cost of hovertank was similar to military jet, so too was the logistical effort needed in upkeeping. CEF ate up huge quantities of fuel, ammunition, supplies, spare parts and maintenance hours every day. With supply lines to factories in Caprice and Earth severed, CEF could simply not keep enough super tanks combat ready to make the difference.

No matter how skilled their commanders were, no matter how many tanks, gears or helicopters hovertanks destroyed, their every won battle was hollow. CEF always lacked that one last hovertank needed to reach the ultimate victory. Beaten Terra Novan armies could and would replace their losses and return back to battlefield to fight again. All this dragged campaign longer and longer and ate up more and more irreplaceable GRELs, hovertanks and supplies dwindling chances of CEF to achieve victory until in Baja the back of camel was finally broken. The end was inevitable.

After the war the hovertanks have become very rare sight. Attempts to copy the design by Terra Novans have largely been enormously expensive failures. Reasons have varied from poor engine fan technology to inadequate computer software. Expensive and ridiculed Scythe is epitome of some sort of Terra Novan success with hovertank design.

Only place where scores of hovertanks still roam is Port Arthur where remnants of CEF have reborn as totally new military force called Arthurian Korps. Lack of supplies and proper materials has hindered and slowed overhaul of hovertank force whose numbers are diminishing little by little.

The remaining hovertanks are used mainly for exterminating Rover bands in Western Desert but everyone agrees that Cavalry Brigade's hovertanks still represent awesome fighting power well respected by Terra Novans remembering the carnage of War of Alliance.

[Janne Kemppi] [Heavy Type]

The above article was archived from Heavy Type: A Heavy Gear Fan Fiction Website as part of the Hermes 72 Archive Project. It has been edited from its original form and is used without permission.

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