Ever wonder how retractable landing gear works? With the exception of small private airplanes and commuter airplanes, most airplanes don’t have fixed landing gear. Instead, they have retractable landing gear. Their landing gear systems are concealed within the belly of their fuselage during flight. When it’s time to land, the pilot will then lower the airplane’s landing gear. Here’s a breakdown of how retractable landing gear works.
The Purpose of Retractable Landing Gear
Retractable landing gear offers more than just aesthetic benefits; it reduces drag while subsequently improving fuel efficiency.
When an airplane’s landing gear remains down during flight, it will generate more drag. The landing gear will be exposed to the airstream. As the moving air strikes the landing gear, it will create an aerodynamic force that goes against the airplane. This force is known as drag. By pulling up and retracting the landing gear, however, airplanes can achieve a more aerodynamic shape that minimizes drag and maximizes fuel efficiency.
Retraction System
While there are different configurations for retractable landing gear — tricycle, taildagger, bicycle, etc. — they all require some type of retraction system. The retraction system is the mechanism that pulls the landing gear into the belly of the airplane’s fuselage.
The most common retraction system is hydraulics. Airplanes with hydraulic landing gear leverage pressurized fluid, known as hydraulic fluid, to raise and lower their respective wheels. The pilot can flip a switch to direct the hydraulic fluid to the airplane’s landing gear. As the hydraulic fluid moves through the landing gear, the wheels will extend down in a locked position.
In addition to hydraulic retraction systems, there are electric retraction systems. This alternative type of retraction system doesn’t rely on pressurized fluid. Instead, it uses electricity to raise and lower the airplane’s wheels. Electric retraction systems essentially convert electricity into mechanical power that moves the wheels up and down.
While not as common as hydraulic and electric, there are some airplanes with manually operated landing gear. After taking off, the pilot must raise the airplane’s wheels manually — typically by turning a knob or using some other instrument. When preparing to land, the pilot must perform a similar process to manually lower the wheels.
In Conclusion
Retractable landing gear is characterized by its ability to be raised or lowered. This is typically achieved via hydraulics or an electrically powered system, though some airplanes use a manually operated retraction method.
