Ask the Editors: The Physics of Our Gas Tanks
Proven with time.
This is a very interesting question because while we don’t often realize it, liquid is heavy. A full 3 gallon gas tank adds 25-pounds of weight compared to an empty one. Worse still, this weight isn’t even fixed but rather moves fore and aft, and side to side thanks to the principle of inertia.
If our machine’s fuel tank happened to be located closer to the wheels, these tugs as fuel shifts around could actually affect the ATV’s handling. Additionally, the machine would handle differently based on how much fuel you happened to be carrying at any given moment.
Its centralized location upon the frame’s strongest member isn’t accidental. ATVs, especially early on, borrowed heavily from road-going motorcycles; where years of trial and error resulted in the design that more or less still lives on to this very day.
You are close in suggesting a lower center of gravity is crucial for handling but engineers go a step further still by not just lowering the gravitational rotation point but centralizing it too- we call this “canter of mass”. Without getting overly technical, the gist of it is this: the further away from the center of a machine, the more of an impact weight will have on a machine’s handling. If the concept sounds overly theoretical, imagine the difference between putting a 25-pound sack of potatoes on your lap when you ride versus hanging it off your left handlebar. The further it is from center, the more you’re going to be fighting it when in motion.
Lastly there is one other consideration that you are probably not taking into your reasoning that you can be certain the manufacturers are – a gas tank is, at its most basic, a bomb. You have a capsule filled with highly explosive fluid and vapor. Things like the routing of hot exhaust pipes, friction of moving chains/ drive shafts, and the risk of damage in a collision are all taken very seriously when designing a machine.
