Very interesting videos showing how F-35, C-17 and C-130 wheel are replaced. Landing gear is the undercarriage of an aircraft used for either takeoff or landing.
It was also formerly called alighting gear by some manufacturers, such as the Glenn L. Martin Company.
For aircraft, the landing gear supports the craft when it is not flying, allowing it to take off, land, and taxi without damage.
Wheels are typically used but skids, skis, floats or a combination of these and other elements can be deployed depending both on the surface and on whether the craft only operates vertically (VTOL) or is able to taxi along the surface.
Faster aircraft usually have retractable undercarriages, which fold away during the flight to reduce air resistance or drag.
As aircraft grow larger, they employ more wheels to cope with the increasing weights. The earliest “giant” aircraft ever placed in quantity production, the Zeppelin-Staaken R.VI German World War I long-range bomber of 1916, used a total of eighteen wheels for its undercarriage, split between two wheels on its nose gear struts, and a total of sixteen wheels on its main gear units — split into four side-by-side quartets each, two quartets of wheels per side — under each tandem engine nacelle, to support its loaded weight of almost 12 metric tons.
Multiple “tandem wheels” on an aircraft — particularly for cargo aircraft, mounted to the fuselage lower sides as retractable main gear units on modern designs — were first seen during World War II, on the experimental German Arado Ar 232 cargo aircraft, which used a row of eleven “twinned” fixed wheelsets directly under the fuselage centerline to handle heavier loads while on the ground.
Many of today’s large cargo aircraft use this arrangement for their retractable main gear setups (usually mounted on the lower corners of the central fuselage structure).