Fuel is a necessary component for the movement of any vehicle, including airplanes. However, airplanes have the unique challenge of maintaining large amounts of fuel while there is light during their flight. As a result, aircraft engineers have designed intricate fuel cells within the structure of the aircraft body called integral fuel tanks. These fuel storage tanks offer ample storage without losing aerodynamics.
Features of integral fuel tanks
Integral fuel tanks are unique in their structure as they are part of the overall form of support for the aircraft. These fuel tanks are built into the aircraft’s frame. As a result, the tanks cannot be removed for maintenance or replacement. Engineers must strategically place tanks within the aircraft structure, taking into account the weight balance of the fuel, as well as the overall fuel volume needs.
Placement on the wing
The placement of the fuel tank determines its type or shape. Most of the integral fuel tanks reside in the wings. Each wing has two fuel tanks. The tanks fill the open space between the upper and lower wing surfaces. The fuel tank closest to the fuselage of the plane is almost a perfect square, it has more space due to the width of the large wing. As the wing narrows towards the tip, another fuel tank fills this small space in the shape of an elongated rectangle.
Some planes require larger fuel reserves, especially for long-haul trips across the oceans. These aircraft add types of integral fuel tanks along the belly of the fuselage, or below. Similar to wing tanks, the tank’s placement on the belly resides within the permanent body frame of the fuselage, preventing any access to the fuel tank. Additionally, the tail of the aircraft can house a small integral fuel tank for further storage. These types of tanks vary in design and shape, depending on the overall construction of the aircraft and the engineering of the manufacturer.
According to Lockheed Martin, integral fuel tanks offer the best fuel efficiency for transportation. The fuel tanks are not centralized in one area, this causes the aircraft to have an extreme imbalance. Structural tanks balance fuel throughout the body of the aircraft to stabilize the fuselage structure. In particular, the fuel in the wing and belly tanks has to travel a short distance to supply power to the aircraft engine, increasing fuel distribution efficiency.
All types of integral fuel tanks must be accurately sealed. Since they are part of the structural framework of the aircraft, repairing a leak is extremely difficult. During fabrication, workers should verify that tanks are free of small openings before permanently installing mounts, to avoid costly fuel leakage.