Control is achieved through an independent tiller in the flight deck. Figure 7. A nose wheel steering tiller located on the flight deck. The main gear on a tricycle-type landing gear arrangement is attached to reinforced wing structure or fuselage structure. The number and location of wheels on the main gear vary. Many main gear have two or more wheels.
Figure 8. Dual main gear of a tricycle-type landing gear. Multiple wheels spread the weight of the aircraft over a larger area. They also provide a safety margin should one tire fail. Heavy aircraft may use four or more wheel assemblies on each main gear. When more than two wheels are attached to a landing gear strut, the attaching mechanism is known as a bogie. The number of wheels included in the bogie is a function of the gross design weight of the aircraft and the surface type on which the loaded aircraft is required to land.
Figure 9 illustrates the triple bogie main gear of a Boeing Figure 9. Triple bogie main landing gear assembly on a Boeing The tricycle-type landing gear arrangement consists of many parts and assemblies. A main landing gear of a transport category aircraft is illustrated in Figure 10 with many of the parts identified as an introduction to landing gear nomenclature. Figure Nomenclature of a main landing gear bogie truck. Fixed and Retractable Landing Gear Further classification of aircraft landing gear can be made into two categories: fixed and retractable.
Many small, single-engine light aircraft have fixed landing gear, as do a few light twins. This means the gear is attached to the airframe and remains exposed to the slipstream as the aircraft is flown. As the speed of an aircraft increases, so does parasite drag. Mechanisms to retract and stow the landing gear to eliminate parasite drag add weight to the aircraft.
On slow aircraft, the penalty of this added weight is not overcome by the reduction of drag, so fixed gear is used. As the speed of the aircraft increases, the drag caused by the landing gear becomes greater and a means to retract the gear to eliminate parasite drag is required, despite the weight of the mechanism. A great deal of the parasite drag caused by light aircraft landing gear can be reduced by building gear as aerodynamically as possible and by adding fairings or wheel pants to streamline the airflow past the protruding assemblies.
A small, smooth profile to the oncoming wind greatly reduces landing gear parasite drag. The thin cross section of the spring steel struts combine with the fairings over the wheel and brake assemblies to raise performance of the fixed landing gear by keeping parasite drag to a minimum. Wheel fairings, or pants, and low profile struts reduce parasite drag on fixed gear aircraft. The gear features pontoons for water landing with extendable wheels for landings on hard surfaces.
A similar system is used to allow the use of skis and wheels on aircraft that operate on both slippery, frozen surfaces and dry runways. Typically, the skis are retractable to allow use of the wheels when needed. Figure illustrates this type of landing gear. Three basic arrangements of landing gear are used: tail wheeltype landing gear also known as conventional gear , tandem landing gear, and tricycle-type landing gear.
Tail wheel-type landing gear is also known as conventional gear because many early aircraft use this type of arrangement. The main gear are located forward of the center of gravity, causing the tail to require support from a third wheel assembly. A few early aircraft designs use a skid rather than a tail wheel. This helps slow the aircraft upon landing and provides directional stability.
The resulting angle of the aircraft fuselage, when fitted with conventional gear, allows the use of a long propeller that compensates for older, underpowered engine design. The increased clearance of the forward fuselage offered by tail wheel-type landing gear is also advantageous when operating in and out of non-paved runways. Today, aircraft are manufactured with conventional gear for this reason and for the weight savings accompanying the relatively light tail wheel assembly.
Directional control is maintained through differential braking until the speed of the aircraft enables control with the rudder. A steerable tail wheel, connected by cables to the rudder or rudder pedals, is also a common design. Pontoons Explained This Cessna Caravan uses pontoon landing gear. There are two basic Pontoon designs, single float and twin float. Using a single Pontoon allows for operations in rougher waters, but is bulkier.
Twin float Pontoon Gear use two Pontoons in place of the main gear. While this increases versatility, it also increases weight and complexity. Some designs utilize ski-only gear, in which the wheels are replaced by skis. These are mostly used during the winter when there is deep, freshly fallen snow.
The first powered plane ever, the Wright Flyer, took off from a track and used skis to land. Conclusion Airplanes are meant to operate in the sky, but they still need to get around on the ground, hence the invention of the Landing Gear. Pontoons are used by planes that want to land on water, as they allow flotation. Landing Gear Types 4.
They include tricycle, tail-wheel, pontoons, and skis, learn more here. Share on Facebook. Joel N. A former owner of a Cessna and a current partner in a C Cardinal, Joel is a private pilot with hours. His writings have been featured on sites such as Good Men Project and Plane and Pilot magazine, to name a few. Joel holds a degree in Aerospace Engineering, and his interests include space, aviation history, and astronomy. Whether you need a prototype or large runs for your assembly line, you can rely on AMI for rapid delivery and short lead-times.
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