Conventional landing gear
Conventional landing gear, or tailwheel-type landing gear, is an aircraft undercarriage consisting of two main wheels forward of the center of gravity and a small wheel or skid to support the tail. The term taildragger is also used.
A Cessna 150 converted to taildragger configuration by installation of an aftermarket modification kit
Tailwheel detail on a Tiger Moth biplane
Like many attack helicopters, the AgustaWestland Apache has a tailwheel to allow an unobstructed arc of fire for the gun.
Douglas DC-3, a taildragger airliner
Landing gear is the undercarriage of an aircraft or spacecraft that is used for taxiing, takeoff or landing. For aircraft it is generally needed for both. It was also formerly called alighting gear by some manufacturers, such as the Glenn L. Martin Company. For aircraft, Stinton makes the terminology distinction undercarriage (British) = landing gear (US).
The retractable main landing gear of a Boeing 747
Conventional/taildragger Piper Cub
Tricycle Cessna 152
Bicycle AV-8B Harrier