Today we’ll look at passenger aircraft and examine where they store all that fuel. Unlike a car that you fill up until full (or whatever your budget allows), deciding how much fuel to load into an aircraft is a complicated matter. Flight planners calculate the amount of fuel an aircraft will need based on several factors. These variables include distance, weight, cruising altitude, wind velocity, and air temperature. Added to this is taxi burn, which is the fuel used to get to and from the runway. And of course, adding a little extra just in case of a diversion or emergency.
By not carrying more fuel than is needed for the trip, airlines can save vast amounts of money as they are not operating with unnecessary weight. With some long-haul flights, the amount of fuel needed can account for a third of the aircraft’s weight, which means that it needs to be stored in such a way so as not to throw off the plane’s center of gravity. The best place to do this on modern passenger planes is to store the fuel in the wings.
Weight and Balance
Weight and balance are essential considerations when it comes to creating an aircraft’s center of gravity. The seating arrangement is also a factor, as we have found out with the Airbus A321neo and A320neo. Under certain circumstances, both planes tend to pull their nose up after certain severe maneuvers. To compensate for this, Lufthansa now blocks the sale of the last row of seats on this aircraft.
Airlines also have loadmasters who decide where cargo is placed based on volume and weight. When it comes to heavy fuel, evenly distributing it between the wings helps to maintain aircraft balance.
Commercial airliners are built to carry as much payload as possible. The payload includes passengers, luggage, and cargo. If you took a cross-section of the plane, you would see that the bottom half is for carrying freight and the upper half for passengers. This leaves the virtually hollow wings as a perfect place to store the fuel. Similar to a car with a separate fuel tank, the wings on aircraft are watertight and designed to hold aviation fuel. Having spars built between sections of the wing also stops the fuel from sloshing around. These spars have holes in them that let fuel pass through but at a much slower rate.
We should also note that the while wings are the most common fuel storage area for commercial aircraft, the A320 family of aircraft have options to install additional fuel storage in the aft cargo hold.
All aircraft rely on their wings to create lift, with the most stress being put on the wings during takeoff when the plane is at its heaviest. Putting fuel in wings helps stop them from flexing, which would occur if you had a heavy aircraft and light wings. Engineers discovered that having heavy wings actually put less stress on them as the weight of the plane is more evenly balanced.
All of this means that storing fuel in the wings is not only a great way to save space, but also a smart way of putting less pressure on the wings’ integrity. Clearly, a win-win for everyone.