Different Types of Landing Gear Arrangements in the Aircraft Industry

Serving as the undercarriage of an aircraft, landing gear is used to support the vessel when it is not in flight, enabling it to take off, land, and taxi without damage. In general, wheeled landing gear is most commonly implemented, with skis or floats being used when flying over snow, ice, and/or water. However, skids are often used when flying over wetlands. High-speed aircraft tend to take advantage of retractable landing gear, which fold away during flight to reduce drag. To better understand why there are so many different types of landing gear arrangements in the aircraft industry, we will provide a brief overview of each and how they work. 

Most Common Landing Gear Arrangements 

Wheeled undercarriages are available in two configurations, conventional and tricycle types, both of which we will outline below. 

Conventional Landing Gear

Conventional landing gear, also called taildraggers, consists of two main wheels at the front of the aircraft and a single, smaller wheel or skid at the tail end. Common during the early propeller era, a taildragger arrangement allows more room for proller clearance. However, over time, conventional landing gear became less popular for being considered hard to use during landing and takeoff operations. In fact, this arrangement is unstable and requires special pilot training. 

Tricycle-Type Landing Gear

Tricycle-type landing gear, on the other hand, consists of two main wheels or wheel assemblies located under the wings, in addition to a third small wheel beneath the nose. For their overall reliability, this type of landing gear is frequently incorporated on most modern aircraft. If over-rotation occurs on take off, leading to a tail strike, a small tail wheel or skid/bumper can be added to this arrangement to prevent damage to the belly of the fuselage. In special cases, some aircraft models will feature tail-strike protection, common examples including the B-29 Superfortress, the Boeing 727 trijet, and the Concorde.

Tandem (Bicycle-Type) Landing Gear

A third arrangement, known as tandem or bicycle-type landing gear, has the main and nose gear situated fore and aft of the vehicle’s center of gravity, just under the fuselage and with outriggers on the wings. This arrangement is utilized when there is no convenient location on either side of the fuselage to attach the main landing gear or to store it when retracted. Some examples of models with tandem landing gear include the Lockheed U-2 spy plane and the Harrier jump jet. 

Quadricycle Landing Gear

Quadricycle landing gear is similar to their bicycle-type counterparts, with the exception that there are two sets of wheels that are laterally displaced in the fore and aft positions. One common example of this landing gear arrangement is found on the experimental Fairchild XC-120 Packplane which has a quadricycle gear located in the engine nacelles to enable unrestricted access to the underside of the fuselage, allowing for the attachment of a large freight container. 

Retractable Landing Gear 

To decrease drag during flight, retractable undercarriages are used, those of which lay flush into the wings and/or fuselage. If the wheels do not retract completely and partially protrude, this is called semi-retractable gear. It is worth noting that a majority of retractable landing gear is hydraulically operated, but some electrically operated and manually operated variations are also available. 

Conclusion 

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1. andrew paul
2. Posted on March 20, 2023
aviation