Why Do Airliners' Nose Wheels Retract Forward?

There are various reasons for employing the forward-retracting nose gear design.

Modern commercial aircraft are equipped with hydraulic retractable landing gears. The retraction system utilizes pressurized hydraulic fluid to actuate various linkages to raise and lower the gear. When the pilot commands the landing gear in the "up" position, hydraulic fluid is directed into the gear line.

The fluid flows through sequenced valves and down-locks to the gear-actuating cylinders. The system incorporates a hydraulic reservoir to contain excess fluid and features electrical gauges to determine the system fluid level. Each gear has two limit switches installed, one dedicated to extension and one to retraction.

On most commercial aircraft, the main landing gear is retracted rearwards or sideways while the nose gear is retracted forward into the fuselage. The nose gear is much smaller and has fewer wheels than the main landing gear. Unlike the main gear, there is usually no braking mechanism in the nose gear. That means the gear structure and system are much lighter. As such, it is prone to stronger vibrations due to the aerodynamic drag incurred during flight.

When the aircraft takes off, the forward retracting design forces the gear to overcome the air resistance. This is easier to do since the air cart is at relatively lower speeds. When lowering the gear at a higher speed, the aerodynamic force assists the downward movement, thereby preventing the gear from experiencing excessive stress. A rear-retracting design may be more advantageous during stowing. However, inward forces would impose significant stress on the gear during extension.

The structural members are designed such that they carry the load of the nose gear assembly away from the forward door. The forward retracting design acts as a fail-safe system as part of the safety mechanism on commercial airliners. In the event of an in-flight hydraulic malfunction (or failure) of the nose gear system, the gear is more likely to be extended downwards in the direction of the flow.

On most airliners, the nose door can be opened manually during a hydraulic malfunction, allowing the gear to experience gravity extension. The oncoming aerodynamic force aids in putting the gear in place. The gravity-pull in a rearward design could be prevented by the drag the aircraft experiences during flight.

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Upon touchdown, the forward-retracting design bear high mechanical loads incurred on the nose gear system. The air resistance has minimal or no effect on the gear system when it is locked in a lowered position. The mechanical and aerodynamic loads can compromise the rear-retracting locking mechanism or result in a complete collapse of the nose gear. It is noteworthy that many military aircraft use a rear-retracting nose gear mechanism with a locking knee for added structural support.

The forward retraction design maximizes the cargo space by utilizing the space in front of the fuselage. The Russian Tupolev Tu154 and Tu134 use the rear-retracting nose gear design, which takes up much of what could be the cargo space. Notably, the rear-retracting design was inherited from older Russian airplanes that allowed the space for the glass nose seating navigator just beneath the cockpit.

What are your thoughts on the forward-retracting nose gear design? Tell us in the comments section.

Writer - Omar is an aviation enthusiast who holds a Ph.D. in Aerospace Engineering. With numerous years of technical and research experience under his belt, Omar aims to focus on research-based aviation practices. Apart from work, Omar has a passion for traveling, visiting aviation sites, and plane spotting. Based in Vancouver, Canada