Current tanks 3.5 generations are M1A2 Abrams SEP, Leopard 2A5,T-80UM, Challenger and Leclerc etc.
The future tanks (4. generation) are already in development. I will now talk about western tanks. The 4. gen tanks will be smaller, lighter (around 56
tons). They will problably have 3 man crew located in hull and unmanned (and smaller) turret with autoloader. The conceptional drawing :
As you can see it is slightly smaller with low-siluete unmaned turret. Another concept is "semi turret tank" whre the turret is just the canon. The
amunition is auto-loaded from the hull. This is "expeditional Hawk tank" form GM/Cadillac
There was also no-turret-tank in consideration but it was rejected (the only one no-turret-tank is Swedish STRV-103).
The FMBT (future main battle tank) must be very agile. The speed must be at least 100 km/h on road, or 80km/h (terrain). It will probably have
diesel-engine. Gas turbine was modern in 80ites but the current diesels (like EUROPACK) are equally powerful but they need only half amunt of fuel
when comparing to gas turbine. The engine will be located in front hull (like by Merkava).
The armor will contain only small amount of steel, mostly only lighter materials like titanium,aluminium or composites. The British want to create no
metal armour, they want use termohardened polymeres witch should increase the resistance by 300%. The ERA (explosive-reaction armor) will be aalso
used. Another defensive systems witch will be used are active defense systems like current russian Shtora (ATGM jamming) and ARENA ( small rocket
projectiles combined with small radar used to destroy incoming ATGM misiles - interesting but also very dangerous for infantry-I think this is the
reason why ARENA type devices are not in western considered for western FMBTs- at least for now).
ARENA pictures (those red things):
Cannon - yet it is not clear what gun will the FMBT use. There are 2 main opinions :
1. larger (140mm) caliber = very powerfull, but you can carry fewer rounds
2. more powerfull smaller caliber (120 or even back to 105mm!) canons = electrothermalchemical gun - diskused on other WEPONRY thread, or liquid
propellant. Both have their pros an cons - liquid propellant need complicated loading system and ETC cannon creates high temperatures.
So this was 4th gen. and 5th generations projects are laready also running. This tank should apear around 2020.
As you can see tank is smaller and lower. Crew is only two man and tank can be also controled by radio signals. AET (all-electrical tank) should have
electo-engine power should be produced by solar panels or recieved from satelites. The composite armor is rienforced by a EM field witch should
deformate incoming rounds or misiles. The turret carries 6 barrel EM gun (3 barrels for 38mm anti infantry explosive rounds, and 3 25mm armour
piercing rounds). In the rear hull is place for vertical launched ATGMs or 3 soldiers. The problem witch need to be solved before this sci-fi thing
comes into production are how to concentrate the required energy for EM field and EM gun in such small space.