Maybe I am missing something,but can anybody tell me why Soviet armor in particular have external fuel tanks as seen 0n T-34,T-55 even modern T-72,T-80's.Also I have seen pictures of German and Allied tanks with racks of jerry cans attached to the vehichles.Did they go into battle with these,or were the cans and tanks armored,if not I would think that this could make a tank vunerable even to small arms fire,couldnt the tank be destroyed by a hit on these extra cans or external tanks much like a molotov cocktail?

I can't say about German or US equipment but the Russian tanks were Diesel weren't they? That would have eliminated the chance of explosion, wouldn't it?

Well, in the Soviets' case, all their tanks since about 1940 have been diesel. Diesel fuel isn't particularly dangerous unless it is under pressure. Seriously, you can take a can of diesel and drop a lit match into it without it blowing up or even burning. The M10 TD crews used to use this little nugget to tease the new guys. They'd drop a lit match in a fuel tank and watch the new guys dive for cover thinking the TD would blow up.

The Soviets (now Russians) are still trying to keep their tanks cheap and small, so they elect to put the fuel outside the armor envelope so that the volume of the tank is smaller, thus less armor is needed, thus the weight is kept a lot lower. Recent history suggests this is not a great design priority bt whatever

As for the gas-powered Germans, the really big stacks of jerricans you see on, say, DAK tanks were probably only carried in secure areas. But a few gas cans on the outside of a tank seem to be relatively safe. Remember the crew is on the other side of the armor.

Alled and German tanks of WWII did carry cans of gas on them duirng long road marches where contact with opposing forces was not expected. This gave them the ability to move a longer distance without waiting for the supply support.

The Russians mounted external diesel tanks on their WWII tanks to increase the range of their combat vehicles. Yes, the external fuel tanks could be damaged from small arms fire and artillery fragments. However, the range of Russian tanks with the external fuel tanks was over 200 miles. In WWII this was long distance for a tank to go on a tank of fuel.

The Russians did recognize that the external fuel cells had to have something done. The solution was to have the rear drums be dropped by the tank driver with a switch that could later be picked up by the support unit. The T-55 and T-62 also had fuel cells on the fenders of the tanks. These were supposed to be removed prior to combat (the rear drums stayed on until contact with the enemy). For some reaason the Soviet advisors to the Syrians and Egyptians either did not tell, show or say to the Arab tankers to remove the fender fule cells. Some of the Arab tanks had sand bags over the fuel cells to protect them from artillery fragments. The Israelis would call for air burst over the Arab tanks and then fire WP main gun rounds on the leaking fuel flowing on the Arab T-55's and T-62's which did cause the diesel fuel to burn.

The fuel cells and drums give the Russian tanks a range of over 300 miles. Most NATO tanks with diesel engines would get from 200 - 300 miles.

One of the primary reasons the Soviets used external tanks on their armor was that their logistical model called for a unit to attack until it's stores and manpower were depleted. The unit then allowed a second echelon unit to pass through to continue the atttack. Eventually the first unit was consolidated or disbanded (depending of remaining strength) and fed back into the attack. The Soviet tactical doctrine called for only reinforcing success. Units that couldn't advance were left to die on the vine.