muzzle energy from the gun to improve range, accuracy and armour penetration. The most mature future gun technology is the electrothermal-chemical gun. The XM291 electrothermal-chemical tank gun has gone through successful multiple firing sequences on a modified American M8 Armored Gun System chassis. To improve tank protection, one field of research involves making the tank invisible to radar by adapting stealth technologies originally designed for aircraft. Improvements to camouflage or and attempts to render it invisible through active camouflage, which changes according to where the tank is located, are being pursued. Research is also ongoing in electromagnetic armour systems to disperse or deflect incoming shaped charges, as well as various forms of active protection systems to prevent incoming projectiles (RPGs, missiles, etc.) from striking the tank. Mobility may be enhanced in future tanks by the use of diesel-electric or turbine-electric series hybrid drives—first used in a primitive, gasoline-engined form with Porsche's Elefant German tank destroyer of 1943—improving fuel efficiency while reducing the size and weight of the power plant. Furthermore, advances in gas turbine technology, including the use of advanced recuperators, have allowed for reduction in engine volume and mass to less than 1 m3 and 1 metric ton, respectively, while maintaining fuel efficiency similar to that of a diesel engine. In line with the new doctrine of network-centric warfare, the 2010s-era modern battle tank shows increasing sophistication in its electronics and communication systems. The future of tanks has been challenged by the proliferation of relatively inexpensive anti tank guided missiles and rockets during the Russo-Ukrainian War. Design The three traditional factors determining a tank's capability effectiveness are its firepower, protection, and mobility. Firepower is the ability of a tank's crew to identify, engage, and destroy enemy tanks and other targets using its large-caliber cannon. Protection is the degree to which the tank's armour, profile and camouflage enables the tank crew to evade detection, protect themselves from enemy fire, and retain vehicle functionality during and after combat. Mobility includes how well the tank can be transported by rail, sea, or air to the operational staging area; from the staging area by road or over terrain towards the enemy; and tactical movement by the tank over the battlefield during combat, including traversing of obstacles and rough terrain. The variations of tank designs have been determined by the way these three fundamental features are blended. For instance, in 1937, the French doctrine