Landing gears are the unsung heroes of aviation, quietly ensuring every journey begins and ends on solid ground. Their design and functionality are key to a smooth ride, from taxiing to touchdown.
Let’s get into a deeper look at the different types of landing gear!
Table of Contents
Major Types of Landing Gears
There are three major types of landing gears used in light aircraft: Tail Wheel (Conventional), Tricycle, and Retractable. Each type has its own unique features, advantages, and disadvantages, which we’ll explore in the following sections.
Tail Wheel (Conventional)
Tail Wheel, also known as conventional landing gear, is characterized by two main wheels located under the aircraft’s fuselage and a third wheel positioned at the tail.
This arrangement is commonly found in older aircraft or those designed for rough terrain because of its increased stability during ground maneuvering.
Pros:
- Better performance on rough or soft surfaces
- Lower drag and weight compared to tricycle gear
Cons:
- Increased difficulty during ground maneuvers due to decreased forward visibility
- Higher risk of a ground loop (uncontrolled ground maneuver)
Tricycle
The Tricycle landing gear is the most popular type of landing gear in use today. It consists of two main wheels under the fuselage and a third wheel at the nose of the airplane. This design offers better stability during takeoffs, landings, and ground operations.
Pros:
- Improved forward visibility during ground maneuvers
- Easier handling on ground due to shorter distance from center of gravity to nose wheel
- Lower risk of ground loops compared to tail wheel
Cons:
- Increased drag and weight compared to tail wheel gear
- Decreased performance on soft or rough terrain
Retractable
Retractable landing gear provides the best of both worlds by combining the advantages of tail wheel and tricycle gear. When not in use, this type of landing gear is retracted into the aircraft’s fuselage or wings, reducing drag and improving overall performance.
Pros:
- Improved aerodynamic efficiency due to reduced drag
- Better fuel efficiency compared to fixed landing gear
Cons:
- More complex and heavier system, increasing maintenance requirements
- Higher risk of landing gear failure due to additional mechanical components
Components and Terminology
Here is an overview of the major components and terminology related to landing gears in light aircraft:
- Undercarriage: The structural framework that supports the aircraft while it is on the ground, which includes the landing gear.
- Main Wheels: The primary wheels of an aircraft’s landing gear that support the load and provide rolling capabilities.
- Nose Wheel/Tail Wheel: The third wheel in tricycle or tail wheel configurations, which helps provide balance and stability during ground operations.
- Skid: An alternative to wheels, skids are found in some aircraft types (such as helicopters) and provide support to the aircraft while on the ground without the need for rolling capabilities.
- Struts: Structural components that connect the undercarriage to the aircraft’s fuselage, transferring the weight and loads from the wheels to the aircraft’s primary structure.
- Control: A system that allows the pilot to steer the aircraft on the ground, often involving the connection between the rudder pedals and the landing gear.
What’s The Big Deal About Tail Wheel Landing Gear?
The tail wheel landing gear, also known as taildragger or conventional landing gear, is a type of aircraft undercarriage that features two main wheels forward of the aircraft’s center of gravity and a small wheel or skid supporting the tail.
Advantages
Tail wheel landing gear has several advantages compared to other types:
- Lighter weight: Due to its simpler design, taildragger is generally lighter than tricycle and retractable landing gears.
- Lower cost: As a less complex system, tail wheel landing gear tends to be less expensive to manufacture and maintain.
- Better ground clearance: Tail wheel-type landing gear provides better ground clearance for the propeller, making it suitable for operating from unimproved airstrips or grass fields.
- Greater rudder control: In taildraggers, the main landing gear is located near the aircraft’s center of gravity, which makes it easier for pilots to maintain rudder control during takeoff and landing rolls.
Disadvantages
However, tail wheel landing gear also has some drawbacks:
- Limited forward visibility: The nose-up attitude of tail wheel-type aircraft on the ground can hinder the pilot’s forward visibility, making taxiing, takeoff, and landing more challenging.
- Ground loops: Taildraggers are more prone to ground loops due to the position of the main gear relative to the center of gravity, which can cause the aircraft to swerve or spin if not properly controlled.
- Nose gear damage risk: In case of a hard landing or botched takeoff, tail wheel-type landing gear can cause more stress and potential damage to the nose gear, as the impact energy is transferred through the main gear and onto the nose.
And Tricycle Landing Gear?
Tricycle landing gear is a type of aircraft undercarriage arranged in a tricycle fashion, consisting of a single nose wheel in the front and two or more main wheels slightly aft of the center of gravity. This configuration is the most widely used on aircraft due to its ease of takeoff, landing, and taxiing.
Advantages
One of the main advantages of tricycle landing gear is its improved forward visibility. The position of the nose wheel lowers the cockpit, providing the pilot with better vision compared to a taildragger aircraft, where the vision is elevated and partially blocked by the aircraft nose2.
Tricycle landing gear also offers better ground handling, as the main wheels are located behind the center of mass, reducing the risk of a ground loop. This configuration allows for differential braking, making it simpler to steer the aircraft on the ground using the main landing gear brakes. Some tricycle-type landing gear also features a steerable nose wheel, providing enhanced control during taxiing.
Disadvantages
Despite the numerous benefits, tricycle landing gear does have some drawbacks. One of these is the increased vulnerability to crosswinds during takeoff and landing. The aircraft’s nose wheel can make it harder to maintain directional control when confronted with strong crosswinds.
Another disadvantage is the increase in aircraft weight and complexity, especially with tricycle-type landing gear that includes a retractable or steerable nose wheel. This additional weight can reduce an aircraft’s payload capacity and, in some cases, its fuel efficiency.
Retractable Landing Gear
Retractable landing gear mainly started gaining popularity in the 1930s among military and civilian aircraft. However, they are not commonly used in small, low-performance planes due to added weight and complexity. There are three main types of retractable landing gear: electrical, hydraulic, and manual.
Advantages
One of the key benefits of retractable landing gear is the improved aerodynamics. By retracting the gear into the aircraft’s fuselage, the aircraft generates less drag, which leads to increased efficiency and speed.
This also helps in reducing fuel consumption during flight. Retractable landing gear also reduces the need for external fairings and cowlings, streamlining the overall design of the aircraft.
Retractable landing gear systems incorporate various safety devices to ensure proper operation. They typically come with gear alignment units and warning devices, such as indicator lights or alarms, to notify the pilot if the landing gear is not locked in the required position.
Some aircraft even have emergency extension mechanisms to lower the gear if the primary retraction system fails.
Disadvantages
Although retractable landing gear offers several advantages, there are some drawbacks. The added complexity of the retraction mechanisms can lead to a higher likelihood of system failures. This increased level of complexity also means that retractable landing gear generally requires more maintenance, which can be costly.
Specialized Landing Gears
Skis for Snow and Ice
Aircraft operating in snowy or icy environments may be equipped with skis as an alternative to wheels, allowing them to land on non-paved runways, such as frozen lakes or snow-covered fields.
Skis can be fitted to both tail wheel and tricycle landing gear configurations. These specialized landing gears enable light aircraft such as sailplanes and bush planes to operate in remote and challenging terrains.
Floats for Water Operations
For aircraft operating on water, floats are used in place of traditional wheels. Floats, also known as pontoons, are typically found on seaplanes, replacing the standard landing gear to allow these aircraft to land and take off from water surfaces.
Float configurations generally come in two main types, single and twin float. A single float is mounted centrally under the aircraft, while twin floats are mounted on either side of the fuselage.
Helicopter Skids
Helicopters often utilize skids as their landing gear. Skid landing gears are simple, lightweight, and effective for helicopters. They are horizontal beams with a slight upward curve towards the end, supporting the helicopter’s weight on the ground.
This design helps distribute the aircraft’s weight evenly and makes it relatively easy for helicopters to land on uneven terrain, which is particularly beneficial in emergency situations or rescue missions.
Amphibious Aircraft
Amphibious aircraft are versatile planes designed to operate on both water and land. They combine the features of floats and wheeled landing gears to allow seamless transition between various environments.
These specialized aircraft may have retractable wheels integrated into their pontoons, or use a tricycle landing gear configuration with a separate set of floats mounted on the aircraft. Amphibious aircraft are useful for search and rescue missions, as well as providing transportation to remote areas with limited infrastructure.
Landing Gear Systems and Controls
Shock Absorbing Equipment
Shock absorbing equipment is crucial in light aircraft to ensure smooth landing and taxiing experiences. The most common types of shock absorbers used in light aircraft are oleo-pneumatic struts and leaf springs.
Oleo-pneumatic struts consist of an oil chamber and a gas chamber, which work together to absorb and dissipate the energy from the impact during landing. Leaf springs, on the other hand, are typically made of steel or composite materials and flex to absorb shock.
Steering Systems
Steering systems in light aircraft primarily consist of two types: tail wheel and tricycle. Tail wheel systems, also known as conventional landing gear, have a third wheel positioned at the tail of the aircraft and are steered using a combination of rudder inputs and differential braking.
On the other hand, tricycle systems have a nose wheel, which can be steered directly through a mechanical linkage, or indirectly using the rudder pedals. Some light aircraft with retractable landing gear feature a castering nose wheel, which allows the wheel to turn freely and be steered using differential braking.
Wheel and Brake Assemblies
Light aircraft landing gears are typically equipped with wheel and brake assemblies. The main components of a wheel assembly include the wheel hub, tire, and wheel bearings. Most light aircraft use disc brakes, which consist of a disc, calipers, and brake pads.
The brake system can be controlled either mechanically through cables, or hydraulically using hydraulic fluid.
- Wheel hub: Houses the wheel bearings and provides support for the tire
- Tire: Provides contact between the aircraft and the ground, and absorbs shocks
- Wheel bearings: Reduce friction between the wheel and the axle
- Disc brakes: Provide stopping power by clamping the brake pads onto the disc
Mechanical and Hydraulic Systems
Landing gear systems in light aircraft may utilize a combination of mechanical and hydraulic systems to control the extension and retraction of the gear, as well as the application of brakes.
Mechanical systems often involve a series of cables, levers, pushrods, and gears, while hydraulic systems use hydraulic fluid under pressure to transmit force through cylinders and actuators.
The choice between mechanical and hydraulic systems depends on factors such as aircraft size, complexity, and operating requirements. Most smaller light aircraft opt for mechanical systems, as they are simpler and less expensive, whereas larger or more complex aircraft may benefit from the smoother, more precise control offered by hydraulic systems.
Here’s A Bit of Historical Context About Aircraft Landing Gear
Early Landing Gear Designs
In the early days of aviation, landing gear systems were quite simple and not as advanced as the ones we see today. The tail wheel, tricycle, and retractable landing gears all have their origins in these early designs.
The tail wheel landing gear, also known as the conventional landing gear, was widely utilized in early aircraft designs as it provided better ground handling. One of the notable examples of this type of landing gear is the Yakovlev Yak-15, a jet fighter in use after World War II.
Tricycle landing gear, on the other hand, has a single nose wheel in the front and two or more main wheels slightly aft of the center of gravity. This configuration provides improved handling during takeoff, landing, and taxiing, making it the most widely used arrangement in modern aircraft. Notable examples include the Vickers VC.1 Viking, a British airliner, and the Heinkel He 178, the world’s first jet-powered aircraft.
As aviation technology progressed, the demand for faster and more efficient aircraft increased, leading to the development of retractable landing gears. Retractable gears not only improved aerodynamics but also allowed aircraft to carry heavier payloads and achieve higher speeds.
A few prominent examples utilizing retractable landing gear include the Supermarine Attacker, a British jet fighter, and the Messerschmitt Me 262, the world’s first operational jet-powered fighter aircraft.
Larger aircraft, like military bombers, and specialized planes such as the U2 spy plane, also embraced the adoption of modern landing gear systems to accommodate varying mission requirements and improve operational efficiency.
Final Thoughts
Tail wheel, tricycle, and retractable gears each bring their own flair to the runway, tailored for different tastes in performance and style. Whether it’s the classic poise of a tail wheel, the balanced grace of a tricycle, or the sleek efficiency of retractable gear, there’s a fit for every flight.
In the skies of innovation, retractable landing gears carve paths for speed and efficiency, marrying old-school charm with cutting-edge technology. Yet, no matter the type, each gear plays its part in the ballet of aviation, ensuring safety and performance go hand in hand. As we taxi back to the hangar, it’s clear: landing gears are the quiet custodians of the skies, pivotal in every takeoff and landing, making every journey possible.
