formal cosmos
you can light any a helicopter on fire (open flames) with 5 shots from small arms ( 5.45 or 556) Tracer ammo into a fuel tank, and as little as 1 round to start a slow fire ( Black burning smoke) I think this is feeding into a Hollywood myth. Tracers are not true incendiary rounds even if they have a small degree of incendiary effect to illuminate the projectile.
In contrast to a helicopter, directly shooting a fuel tank of a American or soviet truck required 16 tracer rounds to get complete open flames, so their fuel tanks are much less combustible for some reason.
Consider the fact most military ground vehicles are running on Diesel and Helicopters on jet fuel ( kerosene) which are less flammable then gasoline.
If a burning match or a lighter flame struggle to cause Diesel and Kerosene to burn from direct contact then similarly tracers would unlikely be able to ignite such fuel with such ease.
https://www.youtube.com/watch?v=JhfXG_0uKX4
An additional consideration is that there is a difference to Fuel being spilled on a surface exposed to oxygen vs a sealed fuel tank which means it doesn't have exposure to fresh oxygen from an external environment which further makes it more difficult to cause an open fire from shooting a fuel tank. Typically fuel tanks only have a higher chance of igniting if they are close to empty.
In most cases shooting a fuel tank with tracers should result in tank leaking. If by some chance a fuel tank does catch fire it would be more likely to have a chance for a small fire that would eventually suffocate and put itself out, rather then the entire vehicle being entirely engulfed in flames and burning the people in the vehicle to death.
wary kindle
