Last year, 1995, the United States Marine Corps began trials of a modified LVTP7 amphibious APC with a rather interesting Power plant; A gas turbine-driven electric generator of some 750 thousand watts of power production. Electric current from this generator drives two engines on the tracks and two aquajet water drives, replacing the Diesel engine and standard Hamilton Jets. Even including the mass of the complex cooling fans required for the gas turbine, the weight is precisely the same as what has been removed, and in fact the situation for the engine now becomes more flexible; the lighter fuel storage system required has improved the performance of the vehicle by around ten percent in speed.
This is a vindication of the 1990 study by the US Department of Defence that predicted the day of the “ All-Electric Tank “ was within sight; An armoured fighting vehicle in which locomotion, weapons and defences are driven by electricity. This is not Sci-Fi, in the sense of ray-guns, but Science Fiction that becomes Science Fact, and it has some very interesting effects on wargaming.
Firstly, Electric weapons; Obviously, some readers will think of lasers, but at this moment the battlefield laser is a very poor weapon. Current lasers are low-powered and incapable of lighting a cigarette let alone penetrating any armour thicker than human cell membranes. The last is, however, a legitimate target for today’s targeting lasers – Instead of their usual role of range finding, these can blind troops either temporarily or permanently. Research on this is very quiet, as it strays into the Geneva Convention on incapacitating weapons; More useful are lasers made to dazzle other optical sensors on missiles and targeting systems. The requirements of a laser capable of even anti-personnel use would at the moment be met by a generator of 900 kilowatts, which will not be seen before the start of the next century.
The armament of the “All-Electric Tank” will probably be an Electromagnetic Rail Gun or Mass Driver Cannon, which is in essence a giant solenoid. A solenoid is a coil of wire that can have a current passed through it, turning it into an electromagnet. Any conducting object is propelled down the hollow of the coil, and with a force related to the strength of the charge in the wire coil. Not a new idea – Coil guns were built in 1845 to throw steel rods, and were suggested for the Spanish-American war and World War Two. These weapons have not been competitive due to the lack of strong lightweight magnets and power supplies. With the advent of non-metallic magnets and superconducting materials i.e., substances that conduct electricity with low resistance and thus avoid the loss of flow caused by the production of heat in the conducting material. The idea is used more successfully today; In Arizona, a 3 Megawatt (3 million Watt) Mass driver has been built to test the launching of satellites via the Jules Verne method. Although not designed as a weapon, the figures give a good idea of the performance of this breed – A sixty kilogram projectile can reach Mach 9 muzzle velocity from the 18 metre “breech “ length of coil. Scaling this down to size; using the inverse square law for magnetism, a six kilogram shell with contemporary chemical gun velocity would require a two-metre coil operating at 500 Kilowatts (and with the same sort of technology it could be built today). Consider though that the projectile would be suspended in a magnetic field and therefore travel along the barrel virtually without friction Smaller projectiles could be delivered at higher velocity for the same input of power, and thus with more impact force. Damage would he produced by the hole punched through various systems by the projectile, since the magnetic field would mean that a fused explosive round might be risky to use; the fuse could be triggered by the intense magnetic field. Simple iron-alloy ball or shaped shot may be used by these weapons. One advantage to this is that no longer will chemical explosive be stored in the vehicle making it safer for the crew. Damage to such a vehicle would be just that, to the vehicle not the personnel. Another is that while the coil diameter will be larger for heavier powered guns (i.e., with larger magnets for heavier weapons), the internal “calibre “ could be made the same for all the weapons in the unit. (E.g., for tanks, tank-hunters and infantry fighting vehicles in a combined force imagine the logistical problem of the 120mm, 155mm and 80mm guns with various warheads. What if we replaced these with one size of case-hardened Tungsten-Steel ‘Ball bearing’ fired at a range of velocities?) A big simplification of the Quartermaster’s traditional struggles! For such weapons in armour rules the number of ammunition points per vehicle could be at least doubled; which would reduce the need to resupply the force and conserve rounds to clear targets.
Secondly, a number of defensive systems can be used by an AFV with electric power as an integral feature. One useful feature is the Martin-Marietta microwave mine clearing system; a bumper-shaped microwave antenna that can trigger mine fuses at ranges of around 6 metres and using about 45 kilowatts. Wave goodbye to the drag from mine dozing blades on tanks and specific minesweeping MBT’s. Microwave radio projectors can also be used to scramble the sensors of incoming missiles and intelligent munitions, such as the British Merlin 8lmm mortar round with its 50% kill ratio (due to optical targeting sensors in the bomb itself). If the modern tank is to survive, such devices are not luxuries but necessary in the face of increasingly more sophisticated weapons such as these. The electronic jamming devices currently used by modern aircraft may yet be fitted to such AFVs as this, which in rules systems will require a kind of “saving throw” against the guidance abilities of the weapon in question.
Thirdly the fuel situation changes. Gas turbine engines burn a variety of gaseous fuels, e.g., Methane (Natural gas), Propane or even Butane (Lighter fuel). Also Turbines do so with efficiency greater than that of internal combustion engines working on LPG or similar. Of course this is just to turn the generator, rather than directly operate the tracks as in the M1A1 Abrams. So any direct generating system could replace the turbine; One candidate for the near future, say until the year 2010, is the fuel cell or it’s relative the Hydrodynamic Turbine. Fuel cells are basically a kind of battery, combining chemicals that react to make a flow of electric current. Research into spacecraft power systems has improved this a hundred-fold since the bulky devices that caused the Apollo 13 crisis. They are now considered as future automotive power plants, running on hydrogen and oxygen, producing water as their by-product (exhaust). Nitrogen and oxygen fuel cells are also possible, and as such gases are relatively common and fairly easily converted to liquids; refuelling vehicles can combine storage, transport and refining into two or three portable units.
In the future, Hydrodynamic turbines, or to give them their correct name, Magneto-hydro-dynamic turbine systems, are a likely replacement for standard high-powered Diesels. These work on a very interesting but obscure fact that when fuels are burnt at high temperature and pressure, and within a magnetic field a current begins to flow within the magnet. (As if it was part of a conventional electric motor.) This current can be drawn off and used with no loss due to friction like on conventional generators. However, due to the heat involved metal magnets lose their magnetism very quickly, so ceramic magnets are needed to cope with the heat. Such alloys of porcelain and metals are just now becoming easier to make and show great promise in this use, leading to purely gas-driven electric vehicles.
Obviously, modern armour rules as they stand cannot include such new developments in technology, but the outline here gives broad hints for changes required. It might be interesting to pit Third World forces armed with present day weapons against a UN force with such upswept hardware to compare the practical with the brand-new.
David Stuckey – BSc. – AATB No.1 June 1996.