Tricycle landing gear, the arrangement that puts a single nose wheel in front of two main wheels set well aft, has become the most common type found on today's runways. Standard general aviation aircraft like the Cessna 172 are equipped with this layout because it provides stability on the ground, gives the pilot better forward visibility, and reduces risk of nose-over during braking. The nose wheel allows steering through the rudder pedals, while the level cabin floor created when the airplane is parked simplifies loading and offers easy access to the fuselage and cabin. Although the system is more intricate and therefore more expensive than the older tailwheel alternative, its benefits have made it the dominant configuration since the post-war years, tracing a lineage that runs from modified Cessna 170s to virtually every new light aircraft rolling off production lines today.
What is a tricycle landing gear?
Tricycle gear is a type of aircraft undercarriage which features two main wheels, and it includes a single one/two-wheeled front undercarriage under the cockpit.
A landing gear employing a front-mounted wheel is called tricycle landing gear. The design with a third wheel on the nose is referred to as a tricycle gear. Three wheels include two main wheels located under the fuselage and a third wheel typically located near the nose of the aircraft. When the third wheel is located on the nose it is called a nosewheel.
The airplane's centre of gravity is slightly forward of the main gear, so the nose wheel at the front provides steering control through mechanical linkage designs or castering. Because the cabin floor is horizontal when the airplane is on the ground, forward visibility is boosted for the pilot.
What is the function of tricycle landing gear?
The primary function of tricycle landing gear is to mitigate the impact of landing by absorbing and dissipating kinetic energy. During ground operations the two main wheels located under the fuselage, together with the nose wheel, support the entire weight of the aircraft and facilitate smooth movement through taxiing, takeoff and parking while the nose wheel provides steering control through castering or mechanical linkage designs. By positioning the main wheels close to or slightly behind the center of gravity, tricycle gear keeps the aircraft naturally level on the ground and less likely to tip over and easier to steer. The level stance of the tricycle arrangement gives an unobstructed view and shortens landing distance through more effective braking.
What are the differences between tricycle and conventional landing gear?
The principal difference between a tricycle and a conventional landing gear lies in the relative position of the third wheel. Conventional landing gear, called tailwheel or taildragger, carries a small skid or wheel at the tail behind the two large main wheels, so the center of gravity is aft of the main gear. Tricycle gear reverses the arrangement: the small wheel moves to the nose, the mains stay slightly aft, and the center of gravity sits slightly forward of the main wheels in the so-called Delta configuration. This forward-shifted CG makes tricycles more stable because the aircraft sits level and the mass is closer to the mains than in a tailwheel aircraft.
Directional control on the ground is different. Taildraggers swivel about the long lever arm of the tailwheel, making them less susceptible to weathervaning at low speed when rudder power is low, yet they demand constant footwork to prevent the characteristic ground loop. Tricycles are less susceptible to directional control problems during landing roll because the nose wheel, steerable or free-castering, keeps the fuselage aligned without pilot input.
Weight, drag, and cost differ. Two wheels weigh less than three, and the tailwheel assembly is smaller and simpler than a nose gear, so they tend to be lighter, faster, and cheaper to buy and maintain. Tricycles are normally fixed - either rigid or with the front wheel retracting into the nose - adding mechanism weight but gaining propeller clearance and reducing stone damage.
Shifting from taildragger to tricycle gear is almost impossible owing to firewall and nose gear attachment differences, while the reverse, though slightly easier, still carries extra structural weight.
Pilot workload differs. Tailwheel aircraft typically require extensive training because incidents occur in the form of ground loops. Tricycle aircraft allow student pilots to learn ground handling with less risk, which is why modern pilots usually start in Cessnas and Pipers before transitioning to taildraggers.
What are the parts of a tricycle landing gear?
The tricyle landing gear is made up of five major structural parts: the wheel, shock absorber, the brake system, turning system, and the undercarriage retraction system. The nose wheel is one of three wheels comprising the landing gear system. It is located beneath the aircraft's nose or forward fuselage and supports the aircraft's weight while providing nose wheel steering control through either castering or mechanical linkage designs. Nose wheel steering allows tight turns and provides very effective ground handling. It is linked to the rudder pedals, making the nosewheel steerable and responsive. The rake angle for the nose gear of a tricycle landing gear must not exceed 25, otherwise, porpoising occurs and a high elevator deflection is required for rotation during takeoff.
What are the advantages and disadvantages of tricycle landing gear?
The advantages of tricycle landing include better forward vision due to a lowered cockpit. Having the main wheels behind the center of mass reduces the risk of a ground loop, providing better ground handling. Tricycle aircraft are generally easier to handle in the air, especially when landing. They are less vulnerable to crosswinds and are easier to control as the altitude required to land on the main gear is the same as when flaring the aircraft. Improved forward vision is a consideration in the final stages and on the ground.
The steerable nosewheel, linked to the rudders by cables or rods, allows precise directional control while taxiing, and the configuration provides better forward vision, giving the pilot an unobstructed view of the runway and taxiways. When the gear is made retractable, the high-speed-drag advantage of retraction far outweighs the modest weight penalty, so overall aerodynamic efficiency rises in cruise.
The disadvantages are fewer but noteworthy. The nose wheel requires careful handling to prevent damage from heavy landings or sharp turns on rough pavement, and the added steering mechanism increases parts count, weight, and maintenance. Fixed tricycle installations create more parasitic drag than a simple tail skid, while retractable systems add complexity and cost. Because the main gear lies behind the center of mass, a hard brake application lifts the tail slightly, so pilots must manage braking energy judiciously.
What are the typical applications of tricycle landing gear in aircraft?
Tricycle landing gear is widely utilized in various types of aircraft, from small trainers like the Cessna 172 to large airliners like the Airbus A320. Commercial airliners like Boeing 737 and Airbus A320 are equipped with tricycle landing gear. General aviation includes many light aircraft, training planes, personal aircraft, and business jets that feature tricycle landing gear. Almost all jet-powered aircraft have been fitted with tricycle landing gear to prevent the blast of hot, high-speed gases from causing damage to the ground surface. Even the largest Antonov An 225 has the same tricycle arrangement, albeit with 32 wheels to handle its weight. Tricycle gear is widely utilized in military aircraft. Tricycle landing gear biplanes are rare because biplanes are built light, and the heavy engine cannot have much distance to the center of gravity, making the nose-wheel arrangement impractical.
What was the first aircraft to use tricycle landing gear?
Very early Antoinette planes had primitive tricycle gear, and Alberto Santos-Dumont replaced skids with small bicycle wheels on his 14-bis model plane in 1906. Waldo Waterman's 1929 tailless Whatsit was one of the first to have a steerable nose wheel, and Fred Weick's homebuilt W-1A of 1934 was one of the first aircraft to employ tricycle landing gear.
During World War II the Heinkel firm began building airframe designs meant to use tricycle undercarriage systems. The Heinkel He 280 pioneering jet-fighter demonstrator series and the Heinkel He 219 twin-engined night fighter of 1942 used this layout. The fifth prototype of the Me 262 was fitted with fixed tricycle landing gear, and from the sixth prototype onward the type received fully retracting tricycle gear. The Douglas DC-4 was the first large commercial aircraft to incorporate this approach, ending the era in which tailwheels dominated airliner design.
Jim GoodrichPilot, Airplane Broker and Founder of Tsunami Air
Expert behind this article
Jim Goodrich
Jim Goodrich is a pilot, aviation expert and founder of Tsunami Air.
