It’s a common misconception that airplanes have isolated fuel tanks — similar to those found in automobiles. With the exception of certain all-electric models, most airplanes store fuel. They burn this fuel with air to power their respective engines and achieve forward momentum. Most airplanes, however, use integral fuel tanks rather than traditional fuel tanks.
What Are Integral Fuel Tanks?
Integral fuel tanks are specialized areas within an airplane’s body that are used to store fuel. Also known as wet wings, they aren’t separated or isolated fuel tanks. Instead, integrated fuel tanks consist of internal aircraft structures that are fitted to safely hold fuel.
Common structures used for integral fuel tanks include the following:
- Wing skins
- Wing ribs
- Front and rear spars
- Stringers
- Access panels
How Integral Fuel Tanks Are Designed
Integral fuel tanks are designed with sealant to withstand the otherwise corrosive nature of aviation fuel. The structure interior is carefully sealed to create a safe environment in which fuel can be stored. Integral fuel tanks, though, don’t have their own dedicated walls. Instead, they use the walls of the structure in which they are “integrated.”
Most integral fuel tanks have specialized ports through which fuel is loaded. Known as filler ports, they are typically found on the wing or fuselage. Filler ports are used to refill the tanks by pumping fuel into the sealed tank interior.
During flight, boost pumps move fuel from the tanks to the engines. The fuel will typically pass through one or more filters that remove impurities.
Why Airplanes Use Integral Fuel Tanks
You might be wondering why airplanes use integral fuel tanks. They offer several advantages over traditional fuel tanks, one of which is increased fuel storage. Airplanes contain hollow body sections for structural support. Rather than leaving these sections empty and unused, engineers seal them so that they can store fuel. This design allows airplanes to carry more fuel, which in turn allows for longer flight ranges and fewer refueling stops.
Another reason airplanes use integral fuel tanks is weight reduction. Every pound of weight increases an airplane’s fuel consumption while subsequently reducing its overall efficiency. Traditional fuel tanks require their own walls and supporting structures like brackets. Integral fuel tanks eliminate the need for these items, resulting in a lower weight.
Integral fuel tanks don’t just offer weight reduction; they offer better weight distribution as well. Fuel is distributed throughout the airplane’s body, such as its wings. This design helps to counter some of the forces acting on the airplane during flight, allowing for better handling and performance.
