AIRCRAFT LANDING AIRCRAFT LANDING GEARGEAR

LANDING GEARLANDING GEAR is a structure which installed on the aircraft for theis a structure which installed on the aircraft for the

ground and also ground and alsoallows the aircraft to land safely. Landing gear also allows the aircraft to land safely. Landing gear also provides mobility to theprovides mobility to theaircraft purpose to support the weight of the aircraft aircraft purpose to support the weight of the aircraft whiles it on ground or water.whiles it on ground or water.

Aircrafts require landing gear for taxiing, takeoff, and Aircrafts require landing gear for taxiing, takeoff, and landing. Initially aircrafts used skids as its landing gear. landing. Initially aircrafts used skids as its landing gear. Times after times, wheels were attached to the skids. Times after times, wheels were attached to the skids. Since that time, various arrangements have been used Since that time, various arrangements have been used for wheels and structures to connect them to the for wheels and structures to connect them to the airplane. airplane.

TYPES OF LANDING GEARTYPES OF LANDING GEAR

Conventional landing gearConventional landing gear Tricycle landing gearTricycle landing gearTandem landing gearTandem landing gear

Conventional landing gearConventional landing gear

consists of two wheels forward of the aircraft's consists of two wheels forward of the aircraft's center of gravity and a third small wheel at the center of gravity and a third small wheel at the tail. This type of landing gear is most often seen tail. This type of landing gear is most often seen in older general aviation airplanes. The two main in older general aviation airplanes. The two main wheels are fastened to the fuselage by struts. wheels are fastened to the fuselage by struts. Without a wheel at the nose of the plane, it Without a wheel at the nose of the plane, it easily pitches over if brakes are applied too easily pitches over if brakes are applied too soon. Because the tailwheel is castered--free to soon. Because the tailwheel is castered--free to move in any direction--the plane is very difficult move in any direction--the plane is very difficult to control when landing or taking off.to control when landing or taking off.

HistoryHistory

In early aircraft, a tail skid made of metal In early aircraft, a tail skid made of metal or wood was used to support the tail on or wood was used to support the tail on the ground. In most modern aircraft, a the ground. In most modern aircraft, a small, articulated wheel assembly is small, articulated wheel assembly is attached to the rearmost part of the attached to the rearmost part of the airframe in place of the skid. This wheel is airframe in place of the skid. This wheel is steered by the pilot through a connection steered by the pilot through a connection to the rudder pedals, allowing the rudder to the rudder pedals, allowing the rudder and tail wheel to move together. and tail wheel to move together.

AdvantagesAdvantages

tailwheel has less parasite dragtailwheel has less parasite drag less expensive to buy and maintain less expensive to buy and maintain Tailwheel aircraft are easier to man-handle on Tailwheel aircraft are easier to man-handle on

the ground and, due to their lower tail, they will the ground and, due to their lower tail, they will fit into some hangars more easilyfit into some hangars more easily

If a tailwheel fails on landing, the damage to the If a tailwheel fails on landing, the damage to the aircraft will be minimal. This is not the case in aircraft will be minimal. This is not the case in the event of a nosewheel failure, which usually the event of a nosewheel failure, which usually results in propeller damage. results in propeller damage.

DisadvantagesDisadvantages

Tail wheel aircraft are much more subject to "nose-over" Tail wheel aircraft are much more subject to "nose-over" accidents, due to main wheels becoming stuck in holes accidents, due to main wheels becoming stuck in holes or injudicious application of brakes by the pilotor injudicious application of brakes by the pilot

Conventional geared aircraft are much more susceptible Conventional geared aircraft are much more susceptible to ground looping. A ground loop occurs when directional to ground looping. A ground loop occurs when directional control is lost on the ground and the tail of the aircraft control is lost on the ground and the tail of the aircraft passes the nose, in some cases completing a full circle. passes the nose, in some cases completing a full circle. This event can result in damage to the aircraft's This event can result in damage to the aircraft's undercarriage, tires, wingtips and propeller. Avoiding undercarriage, tires, wingtips and propeller. Avoiding ground loops requires increased pilot training and skill.ground loops requires increased pilot training and skill.

Tail wheel aircraft are more difficult to taxi Tail wheel aircraft are more difficult to taxi during high wind conditions, due to the during high wind conditions, due to the higher angle of attack on the wings. They higher angle of attack on the wings. They also suffer from lower crosswind capability also suffer from lower crosswind capability and in some wind conditions may be and in some wind conditions may be unable to use crosswind runways or unable to use crosswind runways or single-runway airports.single-runway airports.

Conventional geared aircraft require more Conventional geared aircraft require more training time for student pilots to master.training time for student pilots to master.

TRICYCLE LANDING GEARTRICYCLE LANDING GEAR

Tricycle gear is the most popular landing Tricycle gear is the most popular landing gear arrangements. The tricycle gear arrangements. The tricycle undercarriage includes two main gears undercarriage includes two main gears just aft of the center of gravity and a just aft of the center of gravity and a smaller auxiliary gear near the nose.smaller auxiliary gear near the nose.

AdvantagesAdvantages It allows more forceful application of the brakes It allows more forceful application of the brakes

during landings at high speeds without causing during landings at high speeds without causing the aircraft to nose over.the aircraft to nose over.

It permits better forward visibility for the pilot It permits better forward visibility for the pilot during takeoff, landing, and taxiing.during takeoff, landing, and taxiing.

It tends to prevent ground looping (swerving) It tends to prevent ground looping (swerving) by providing more directional stability during by providing more directional stability during ground operation since the aircraft’s center of ground operation since the aircraft’s center of gravity (CG) is forward of the main wheels. The gravity (CG) is forward of the main wheels. The forward CG keeps the airplane moving forward forward CG keeps the airplane moving forward in a straight line rather than ground looping.in a straight line rather than ground looping.

TANDEM LANDING GEARTANDEM LANDING GEAR

is used for very large aircraft like the B-52 is used for very large aircraft like the B-52 bomber and the U-2 bomber and the U-2 reconnaissance/research aircraft. The reconnaissance/research aircraft. The main landing gear is in two sets that are main landing gear is in two sets that are located one behind the other on the located one behind the other on the fuselage. The tandem landing gear allows fuselage. The tandem landing gear allows the use of a highly flexible wing, but it may the use of a highly flexible wing, but it may also require the use of small wheels on the also require the use of small wheels on the tips of the wings to keep the wings from tips of the wings to keep the wings from scraping the ground. scraping the ground.

Another Types of Landing GearAnother Types of Landing Gear

QuadricycleQuadricycleUnconventionalUnconventionalBogeyBogey

QUADRICYCLEQUADRICYCLE Quadricycle gear are also very similar to the Quadricycle gear are also very similar to the

tricycle arrangement except there are four main tricycle arrangement except there are four main gear roughly equal in size and mounted along gear roughly equal in size and mounted along the fuselage. Like tricycle gear, the quadricycle the fuselage. Like tricycle gear, the quadricycle undercarriage also requires a very flat attitude undercarriage also requires a very flat attitude during takeoff and landing. This arrangement is during takeoff and landing. This arrangement is also very sensitive to roll, crosswinds, and also very sensitive to roll, crosswinds, and proper alignment with the runway. The most proper alignment with the runway. The most significant advantage of quadricycle gear is that significant advantage of quadricycle gear is that the plane's floor can be very close to the ground the plane's floor can be very close to the ground for easier loading and unloading of cargo. for easier loading and unloading of cargo. However, this benefit comes at the price of much However, this benefit comes at the price of much higher weight and drag than bicycle gear. higher weight and drag than bicycle gear.

UNCONVENTIONALUNCONVENTIONAL

Aircraft that have to land on water are Aircraft that have to land on water are fitted with skids rather than wheels.fitted with skids rather than wheels.These skids are the unconventional These skids are the unconventional landing gears for the aircraft. Somelanding gears for the aircraft. Someplanes had interchangeable skids and planes had interchangeable skids and wheels so that the plane could be usedwheels so that the plane could be usedto land both on land and on water. Other to land both on land and on water. Other than skids, skis and floats also thethan skids, skis and floats also theunconventional gears.unconventional gears.

BOGEYBOGEY Another type of landing gear is the use of multiple Another type of landing gear is the use of multiple

wheels per landing gear strut. It is especially common to wheels per landing gear strut. It is especially common to place two wheels on the nose strut of the tricycle place two wheels on the nose strut of the tricycle arrangement to provide safety and steering control in arrangement to provide safety and steering control in case of a tire blowout. This additional tire is particularly case of a tire blowout. This additional tire is particularly useful on carrier-based aircraft where two nose wheels useful on carrier-based aircraft where two nose wheels are a requirement. When multiple wheels are placedare a requirement. When multiple wheels are placedon the same gear unit, they are attached together on a on the same gear unit, they are attached together on a structural device called a bogey. The heavier the aircraft structural device called a bogey. The heavier the aircraft becomes, the more wheels are typically added to the becomes, the more wheels are typically added to the bogey to spread the plane's weight more evenlybogey to spread the plane's weight more evenlyacross the runway pavement.across the runway pavement.

Classification of Landing Classification of Landing GearGear

Non-Absorbing Landing gearNon-Absorbing Landing gear

Includes Rigid landing gear, Shock-cord Includes Rigid landing gear, Shock-cord landing gear, Spring landing gearlanding gear, Spring landing gear

    Rigid:  helicopters, sailplanes.  No flexing Rigid:  helicopters, sailplanes.  No flexing other than the structure.other than the structure.

    Shock cord system:  uses “Bungee” cordsShock cord system:  uses “Bungee” cords     Spring type uses spring steel (some Spring type uses spring steel (some

Cessna’s)Cessna’s)

Images of Non absorbing landing Images of Non absorbing landing geargear

**RIGID** *Shock cord* **spring type* **RIGID** *Shock cord* **spring type*

Shock-Absorbing Landing GearShock-Absorbing Landing Gear Dissipates landing energies by forcing fluid through a Dissipates landing energies by forcing fluid through a

restrictionrestriction This fluid generates heat, dissipated into the atmosphereThis fluid generates heat, dissipated into the atmosphere Two types:  Spring Oleo, and Air-Oil OleoTwo types:  Spring Oleo, and Air-Oil Oleo   Spring Oleo is history by nowSpring Oleo is history by now   Air Oleos are all very similar:  a needle valve restricts Air Oleos are all very similar:  a needle valve restricts

fluid flowfluid flow Air in the oleo holds the weight of the a/c on the groundAir in the oleo holds the weight of the a/c on the ground Air Oleos present in both retractable and fixed gearsAir Oleos present in both retractable and fixed gears

Images of shock-absorbing landing Images of shock-absorbing landing geargear

Spring oleo Air-Oil OleoSpring oleo Air-Oil Oleo

Fixed GearFixed Gear

Non retractable, usually bolted on to the Non retractable, usually bolted on to the structurestructure

  Often uses fairings or wheel pantsOften uses fairings or wheel pants

        Advantages:Advantages:         Lighter weightLighter weight         Least costlyLeast costly

Images of Fixed gearImages of Fixed gear

Retractable GearRetractable Gear

Designed to eliminate drag (the greatest Designed to eliminate drag (the greatest advantage)advantage)

Can be either fully or partially retractableCan be either fully or partially retractable Direction of retraction depends on airframe Direction of retraction depends on airframe

modelmodel Methods of retraction:  hydraulic, electric, Methods of retraction:  hydraulic, electric,

mechanical, pneumaticmechanical, pneumatic Critical area of aircraft maintenance for safety Critical area of aircraft maintenance for safety

reasons reasons

Images of Retractable landing gearImages of Retractable landing gear

Hulls and Floats Hulls and Floats 

Can be single float, or multipleCan be single float, or multiple Definition may include floating hulls (ex. “Lake” Definition may include floating hulls (ex. “Lake”

aircraft)aircraft) Floating hulls may only require wing tip floatsFloating hulls may only require wing tip floats Skis used for snow and ice (wood, metal, Skis used for snow and ice (wood, metal,

composites)composites) Skis are mounted on the same strut as tiresSkis are mounted on the same strut as tires

Hulls and FloatsHulls and Floats

ENDEND

LANDING GEARLANDING GEARCast of CharactersCast of CharactersJaysser FuentesJaysser FuentesJohnzel VasquezJohnzel Vasquez

Raffy ZaraRaffy ZaraInstructorInstructor Christopher LingaChristopher Linga

Stunt MenStunt MenALL AMT 4-1ALL AMT 4-1