If you’ve ever wondered where the fuel is stored in a plane, you may be surprised to learn that a commercial airplane stores its fuel in its wings.
“Wet wings” as they’re known is a popular fuel storage strategy because it’s economically efficient.
While commercial planes store fuel in their wings, it’s more common for military planes to store fuel in tanks in the aircraft itself.
4 Reasons Why Fuel is Stored in the Wings
Aircraft fuel is stored in their wings because it’s the most convenient and cost-saving option for airlines.
More specifically, though, fuel is stored in an airplane’s wings for the following reasons.
1. Weight and Balance
It’s vital for airplanes to have a proper center of gravity.
That center of gravity can be unbalanced if the fuel is allowed to move in the plane’s body.
Fuel stays stably in the wings because there is no room for the fuel to move.
Evenly distributing the fuel in the wings is an effective way to maintain a plane’s center of gravity.
Airlines employ loadmasters that decide where cargo should be stored on a plane.
2. Storage Room
Commercial airplanes are designed to carry the largest payload possible.
A plane’s payload consists of its passengers, luggage, and cargo.
In almost any plane, the top half of the plane holds passengers. The bottom half contains the cargo. Only the plane’s wings are left for storing fuel.
The wings of an airplane are watertight like a car’s separate tank, so they’re ideal for storing fuel.
Spars are even built between the wing’s sections to prevent the fuel from sloshing.
The spars contain holes that let the fuel pass through at slow rates.
3. Structural Integrity
Aircraft wings generate lift for the aircraft to fly.
For this reason, the most stress is placed on an airplane’s wings during takeoff.
Having fuel stored in its wings helps prevent a plane’s wings from flexing, which is what would happen if a plane’s body was heavy, but its wings were light.
Having heavier wings during takeoff reduces the stress on wings and keeps the plane’s weight more evenly balanced.
Therefore, it’s logical for an airplane’s wings to be used for fuel storage.
4. Cost Savings
It was only in the 1950s that wet wings were widely adopted by the aviation industry.
Engineers at this time realized that wet wings would improve takeoff and help with developing overall lighter aircraft.
Having wet wings reduced the need for having a fuel tank entirely, which resulted in substantial cost savings for aircraft manufacturers.
These cost savings weren’t due just to aircraft manufacturers not needing to construct fuel tanks either.
Not having fuel tanks anymore meant that aircraft could now increase the amount of cargo and the number of passengers they could hold, thereby maximizing profit.
Once the practical benefits of increased storage because of using wet wings was discovered, it was not long before all aircraft were manufactured with wet wings to take advantage of reduced costs and maximizing profit.
Where is Fuel Stored in Fighter Jets?
Unlike commercial airplanes, fighter jets store fuel in fuel tanks installed behind the pilot’s seat.
Some fighter jets may have extra fuel tanks, known as auxiliary fuel tanks, that are externally attached to the aircraft.
These external fuel tanks are even designed to be jettisoned after use, but they are rare.
That being said, it’s not impossible for the fuel tank of fighter jets to also be stored within their wings, but that’s rare.
To prevent fuel from sloshing around and moving when the plane performs high-speed maneuvers, fighter jets use negative gravity friendly designs.
Types of Aircraft Fuel Tanks
Typically, aircraft will use one of the three types of fuel tanks:
- Rigid Removable
Integral Fuel Tanks
Integral tanks are constructed within an aircraft.
For example, the wet wing design used in commercial aircraft is a type of integral fuel tank. Integral fuel tanks cannot be removed from the aircraft.
Inspection of integral fuel tanks is conducted using inspection panels.
Almost all large aircraft use integral tanks because of the aforementioned economic advantages of doing so.
Rigid Removable Fuel Tanks
Rigid removable fuel tanks are attached to an aircraft in a special compartment.
Rigid removable tanks are constructed from metal, and they can be removed for inspection, replacement, and repair purposes.
Rigid removable fuel tanks are often used by smaller aircraft, since they’re designed for aircraft that don’t depend on the fuel tank for providing structural integrity.
Bladder Fuel Tanks
Bladder fuel tanks, which are also known as fuel cells, are rubberized fuel bags attached to the plane.
The bladder is rolled and installed into this compartment via an access panel.
Usually, metal buttons will be attached to secure the bladder in its place.
Bladder tanks are typically used for light aircraft like small turboprops and helicopters.
How Much Fuel Does a Plane Use?
A plane’s fuel consumption depends primarily on its size, type, model, and flight duration.
Generally speaking, the larger an aircraft is, the more the payload, and therefore, the more fuel it can carry.
Large commercial planes have the highest fuel mileage of any type of plane.
A large commercial plane, like the Boeing 747 for example, uses approximately 4 liters or 1 gallon of fuel every second of operation.
Over a 10-hour flight, a Boeing 747 would use over 150,000 liters or 36,000 gallons of fuel.
The Boeing 747 burns nearly 5 gallons of fuel per mile or 12 km of distance traveled.
Related: How Much Fuel Does a Plane Use?
How Do Planes Refuel?
Most planes will refuel at airports where fuel providers use fuel trucks parked underneath the plane’s wings to fuel them.
The truck driver will connect a hose to the aircraft’s wings and pump kerosene fuel at 2,400 liters per minute or 634 gallons per minute.
At this rate, it could take between 15 and 20 minutes to refuel an aircraft.
Sometimes, two trucks will be simultaneously employed to fuel a larger plane faster.
There are some aircraft, particularly military aircraft like fighter jets that can be refueled in the air.
Air refueling involves a hose being connected to a tanker plane.
In conclusion, civilian passenger planes store fuel in their wings because it’s economically advantageous. Military planes mostly store their fuel in tanks behind the pilot seat.