Retractable Gear Systems

The first evidence of a retractable landing gear design was in Europe circa 1911, but a working example didnt show up on aircraft until after WWI. As airplanes got heavier and faster, meanwhile, airport infrastructure-which mainly consisted of an open field and a windsock- couldnt keep up. As a result, some of the fastest airplanes in the 1920s and 1930s were seaplanes, even with the aerodynamic drag their floats imposed. By the time WWII erupted, the latest airplanes were equipped with retractable landing gear, even if in a conventional, taildragging configuration. Still, many long-range, multi-engine airliners of the day were seaplanes.

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Sunday, March 17, 2019 at 12:00 AM ET

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Key Takeaways:

Retractable landing gear evolved from early 20th-century designs to significantly reduce drag and improve aircraft performance, becoming standard by WWII.
Modern retractable gear systems utilize diverse power sources (electric, hydraulic, manual) and incorporate critical safety features such as alternate extension mechanisms, warning systems, and on-ground switches to prevent accidental retraction.
Reliable operation hinges on diligent maintenance and rigorous pilot adherence to checklists and procedures, as pilot error is the primary cause of gear-up landings; in emergencies, specific protocols exist to maximize survival, often recommending a gear-up landing on a paved runway over a partially extended configuration.

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The first evidence of a retractable landing gear design was in Europe circa 1911, but a working example didn’t show up on aircraft until after WWI. As airplanes got heavier and faster, meanwhile, airport infrastructure—which mainly consisted of an open field and a windsock— couldn’t keep up. As a result, some of the fastest airplanes in the 1920s and 1930s were seaplanes, even with the aerodynamic drag their floats imposed. By the time WWII erupted, the latest airplanes were equipped with retractable landing gear, even if in a conventional, taildragging configuration. Still, many long-range, multi-engine airliners of the day were seaplanes.

Boeing and Lockheed, among others, introduced retractable gear in the 1930s, although many manufacturers didn’t fully enclose the main gear. In an eloquent statement of what the engineers thought about the reliability of retractable landing gear, they sometimes designed the system so the wheels would still roll, and protect the fuselage and engine nacelles, when landed gear-up. Thankfully, the technology has improved since then, if not the pilots.