Landing gear is designed to support the load of the aircraft for surface operations several types exist, designed for the intended operation or desires performance. The landing gear typically consists of three wheels:
Two main wheels (one located on each side of the fuselage), A third wheel positioned either at the front or rear of the airplane.
When the third wheel is located on the tail, it is called a tail-wheel, and the design is referred to as conventional gear When the third wheel is located on the nose, it is called a nose-wheel, and the design is referred to as a tricycle gear Aircraft can also be equipped with floats for water operations or skis for landing on snow.
Types of Landing Gear:
There are several types of landing gear which fall into four main categories:
A- Conventional (tail-wheel) Gear
B- Tricycle Gear
Conventional (tail-wheel) Gear:
Landing gear employing a rear-mounted wheel is called conventional landing gear Tail-wheel (Conventional)] Tail-wheel landing gear aircraft have two main wheels attached to the airframe ahead of its Center of Gravity (CG) that support most of the weight of the structure.
Allows adequate ground clearance for a larger propeller More desirable for operations on unimproved fields.
With the CG located behind the main gear, directional control of this type aircraft becomes more difficult while on the ground If the pilot allows the aircraft to swerve while rolling on the ground at a low speed, he or she may not have sufficient rudder control and the CG will attempt to get ahead of the main gear which may cause the airplane to ground loop Lack of good forward visibility when the tail-wheel is on or near the ground These inherent problems mean specific training (FAR 61.31) is required in tail-wheel aircraft.
Landing gear employing a front-mounted wheel is called tricycle landing gear Tricycle landing gear aircraft have two main wheels attached to the airframe behind its CG that support most of the weight of the structure, Additionally, a nose wheel will typically provide some sort of nose wheel steering control.
It allows more forceful application of the brakes during landings at high speeds without causing the aircraft to nose over It permits better forward visibility for the pilot during takeoff, landing, and taxiing It tends to prevent ground looping (swerving) by providing more directional stability during ground operation since the aircraft’s CG is forward of the main wheels The forward CG keeps the airplane moving forward in a straight line rather than ground looping.
One or more pontoons, or floats, are mounted under the fuselage to provide buoyancy By contrast, a flying boat such as the Consolidated PBY Catalina, uses its fuselage for buoyancy Either type of seaplane may also have landing gear suitable for land, making the vehicle an amphibious aircraft.