Landing gear

Landing gear is the undercarriage of an aircraft or spacecraft that touches the ground when parking, taxiing, taking off, or landing. It keeps the main body of the plane, called the fuselage, safely above the surface to prevent damage. Most planes have wheels for landing gear, though some use skids or floats depending on where they fly—such as over water or snowy terrain.

Early airplanes had fixed landing gear that stayed out during flight, creating drag and limiting speed. Modern aircraft usually have retractable landing gear that folds up inside the body when not needed. This improves aerodynamics, allowing planes to fly faster and more smoothly.

Landing gear must be very strong to support the weight of the plane and absorb the shock when it touches down. It is usually arranged in a tricycle layout with three sets of wheels—one in front and two in back—or sometimes in other special designs. This design is essential for keeping flights safe.

Specialized companies like Safran Landing Systems, Collins Aerospace, and Héroux-Devtek make landing gear for many different types of aircraft. For spacecraft and rovers, landing gear only supports the vehicle after it has landed and during movement on the surface.

Aircraft

The landing gear is the undercarriage of an aircraft, used when parking, taxiing, taking off, or landing. It represents a small portion of the aircraft's weight and cost but is important for maintenance. A well-designed wheel can support heavy loads and last for many years.

There are different types of gear arrangements. Conventional landing gear, also called "taildragger," has two main wheels toward the front and a smaller wheel at the rear. Tricycle landing gear has two main wheels under the wings and a third smaller wheel at the nose. Most modern aircraft use tricycle gear because it is easier to land and take off. Some aircraft have retractable gear, which folds up into the wings or fuselage to reduce drag during flight.

Landing gear also includes shock absorbers to help absorb the impact when the aircraft touches down. Larger aircraft often have multiple wheels and thicker runways to support their weight. Some special aircraft, like those that land on water, have different types of gear, such as floats or skis.

Spacecraft

Landing gear is not commonly used on most launch vehicles, which take off straight up and are not reused. However, some special vehicles, like those that land vertically after a short flight or spaceplanes that land like regular airplanes, do have landing gear.

In the 2010s, private companies started making reusable rockets. For example, SpaceX built test rockets with landing gear to practice vertical landings. Their Falcon 9 and Falcon Heavy rockets have special, lightweight landing legs that pop out to touch down safely. The newest rocket being developed, Starship, is planned to have landing legs on both its first and second stages, which would be a first for such vehicles. Spacecraft meant to land on places like the Moon or Mars may also have landing gear, such as legs or air bags, to help them settle safely.