Luftwaffe Junkers Ju 87s, with fixed conventional landing gear.

Main and nosewheel undercarriage of a Qatar Airways Airbus A330

Wing and fuselage undercarriages on a Boeing 747, shortly before landing

main landing gear on a Antonov An-225

The dual tandem landing gear of a B-52 Stratofortress

Nosewheel undercarriage of a Airbus A380

Virgin Atlantic Airbus A340-600 landing. This airliner has an undercarriage on the fuselage belly, as well as on the wings.

In aviation, the undercarriage or landing gear is the structure (usually wheels) that supports an aircraft and allows it to move across the surface of the Earth when it is not flying. Junkers Ju 87 Stuka dive-bombers. ... Junkers Ju 87 Stuka dive-bombers. ... This or section does not cite its references or sources. ... Junkers Ju 87 G-2 (Royal Air Force Museum Hendon) Junkers Ju 87 G-2 (Royal Air Force Museum Hendon) Nazi propaganda image Air victory over Poland with an artistic vision of a Junkers Ju 87 The Junkers Ju 87 or Stuka was the best known Sturzkampfflugzeug (German: , literally plunging... The Piper Super Cub is a popular taildragger aircraft. ... The main undercarriage nosewheel of a Qatar Airways A330-300 (A7-ACA), on the approach to London (Heathrow) Airport, England. ... The main undercarriage nosewheel of a Qatar Airways A330-300 (A7-ACA), on the approach to London (Heathrow) Airport, England. ... Qatar Airways was the launch customer of the new Airbus A340-600HGW, showing the new Qatar Airways Livery Qatar Airways (Arabic: القطرية) is an airline based in Doha, Qatar. ... The Airbus A330 is a large-capacity, wide-body, medium-to-long-range commercial passenger airliner manufactured by EADS (Airbus S.A.S.). It was developed at the same time as the four-engined A340. ... Download high resolution version (1500x1125, 293 KB) Wing and fuselage undercarriages on a Boeing 747 landing at London Heathrow Airport, England. ... Download high resolution version (1500x1125, 293 KB) Wing and fuselage undercarriages on a Boeing 747 landing at London Heathrow Airport, England. ... The Boeing 747, commonly nicknamed the Jumbo Jet, is a long-haul, widebody commercial airliner manufactured by Boeing. ... Image File history File links Download high resolution version (536x620, 87 KB) Summary Antonov-225 Mria heavy lift transport - main landing gear. ... Image File history File links Download high resolution version (536x620, 87 KB) Summary Antonov-225 Mria heavy lift transport - main landing gear. ... The An-225 Mriya (Антонов Ан-225 Мрія, NATO reporting name: Cossack) is a strategic airlift transport aircraft which was built by Antonov, and is currently the worlds largest flying airplane. ... Image File history File links Download high-resolution version (1504x980, 280 KB) B-52 Stratofortress upon landing Source: http://www. ... Image File history File links Download high-resolution version (1504x980, 280 KB) B-52 Stratofortress upon landing Source: http://www. ... The Boeing B-52 Stratofortress is a long-range, jet strategic bomber flown by the United States Air Force (USAF) since 1954. ... Image File history File linksMetadata Size of this preview: 450 × 600 pixelsFull resolution (960 × 1280 pixel, file size: 561 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Undercarriage Metadata This file contains additional... Image File history File linksMetadata Size of this preview: 450 × 600 pixelsFull resolution (960 × 1280 pixel, file size: 561 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Undercarriage Metadata This file contains additional... The Airbus A380 is a double-deck, four-engined airliner manufactured by EADS (Airbus S.A.S.). It is the largest passenger airliner in the world. ... Image File history File linksMetadata Download high-resolution version (1802x1275, 376 KB) Virgin Atlantic Airbus A340-600 (G-VYOU) lands at London Heathrow Airport, England. ... Image File history File linksMetadata Download high-resolution version (1802x1275, 376 KB) Virgin Atlantic Airbus A340-600 (G-VYOU) lands at London Heathrow Airport, England. ... Virgin Atlantic Airways Ltd. ... Virgin Atlantic Airbus A340. ... MyTravel Airways Airbus A320 landing Landing is the last part of a flight, where a flying animal or aircraft returns to the ground. ... The fuselage can be short, and seemingly unaerodynamic, as in this Christen Eagle 2 The fuselage (from the French fuselé spindle-shaped) is an aircrafts main body section that holds crew and passengers or cargo. ... A Laughing Gull with its wings extended in a gull wing profile Aircraft wing planform shapes: a swept wing KC-10 Extender (top) refuels a trapezoid-wing F/A-22 Raptor A wing is a surface used to produce lift and therefore flight, for travel in the air or another... Aviation refers to flying using aircraft, machines designed by humans for atmospheric flight. ... Look up aircraft in Wiktionary, the free dictionary. ...

Overview

Landing gear usually includes wheels equipped with shock absorbers for solid ground, but some aircraft are equipped with skis for snow or floats for water, and/or skids or pontoons (helicopters). The force bearing on the axle has an eccentricity e with the point of contact to the rolling surface and exerts a moment about the contact point. ... Gasfilled Shock absorber. ... A shaped, twin-tip alpine ski. ... A DeHavilland Single Otter floatplane in Harbour Air livery. ... A pontoon boat, like this small pleasure boat, typically floats and balances by means of two pontoons oriented in the direction of travel. ... A helicopter is an aircraft which is lifted and propelled by one or more horizontal rotors consisting of two or more rotor blades. ...

Types of gear arrangements

Wheeled undercarriages come in two types: conventional or "taildragger" undercarriage, where there are two main wheels towards the front of the aircraft and a single, much smaller, wheel or skid at the rear; or tricycle undercarriage where there are two main wheels (or wheel assemblies) under the wings and a third smaller wheel in the nose. Most modern aircraft have tricycle undercarriages. Taildraggers are considered harder to land and take off, and usually require special pilot training. Sometimes a small tail wheel or skid is added to aircraft with tricycle undercarriage, in case of tail strikes during take-off. The Concorde, for instance, had a retractable tail “bumper” wheel (as delta winged aircraft need a high angle when taking off). Some aircraft with retractable conventional landing gear have a fixed tailwheel, which generate minimal drag and even improve yaw stability in some cases. The Piper Super Cub is a popular taildragger aircraft. ... A Cessna 152 with a tricycle landing gear Tricycle gear describes a kind of aircraft undercarriage, or landing gear, arranged in a tricycle fashion. ... Tailstrike is a term used in aviation. ... British Airways Concorde G-BOAB. Concorde G-BOAD on a barge beneath Verrazano Narrows Bridge in New York City in November 2003, bound for the Intrepid Sea-Air-Space Museum. ... The delta-wing is a wing planform in the form of a triangle. ... The word yaw can refer to: Yaw, the name for the Levantine god of chaos, rivers, the sea, and tempests; Yaw, an aeronautical and nautical term which indicates how far a craft is pointing away from its direction of travel due to rotation about its vertical axis. ...

Retractable gear

To decrease drag in flight some undercarriages retract into the wings and/or fuselage with wheels flush against the surface or concealed behind doors; this is called retractable gear.

A design for retractable landing gear was first seen in 1876 in plans for an amphibious monoplane designed by Frenchmen Alphonse Pénaud and Paul Gauchot. Aircraft with at least partially retractable landing gear did not appear until 1917, and it was not until the late 1920s and early 1930s that such aircraft became common. By then, aircraft performance was improved to the point where the aerodynamic advantage of a retractable undercarriage justified the added complexity and weight. An alternate method of reducing the aerodynamic penalty imposed by fixed undercarriage is to attach aerodynamic fairings(often called "spats" or "pants") on the undercarriage, with only the bottoms of the wheels exposed. 1876 (MDCCCLXXVI) was a leap year starting on Saturday. ... Alphonse Pénaud (1850–1880) was a major 19th century pioneer of aviation, inventor of the rubber powered model airplane and founder of the aviation industry. ... The 1920s is a decade that is sometimes referred to as the Jazz Age or the Roaring Twenties, usually applied to America. ... Face The 1930s (years from 1930–1939) were described as an abrupt shift to more radical and conservative lifestyles, as countries were struggling to find a solution to the Great Depression, also known in Europe as the World Depression. ... Victorian china fairings are small porcelain figurines ranging from about three inches (7. ...

Large aircraft

As aircraft grow larger, they employ more wheels to cope with the increasing weights. The Airbus A340-500/-600 has an additional four-wheel undercarriage bogie on the fuselage centreline. The Boeing 747 has five sets of wheels, a nose-wheel assembly and four sets of four-wheel bogies. A set is located under each wing, and two inner sets are located in the fuselage, a little rearward of the outer bogies. The Airbus A340 is a long-range four-engined widebody commercial passenger airliner manufactured by Airbus S.A.S. a subsidiary of EADS. It is similar in design to the twin-engined A330. ... A bogie is a wheeled wagon or trolley. ... The Boeing 747, commonly nicknamed the Jumbo Jet, is a long-haul, widebody commercial airliner manufactured by Boeing. ...

Unusual types of gear

Some planes use wheels only for take off and drop them afterwards to gain the improved streamlining without the complexity, weight and space requirements of a retraction mechanism. In this case, landing is achieved on skids or similar simple devices. Historical examples include the Messerschmitt Me 163 and the Messerschmitt Me 321. A related contemporary example are the wingtip support wheels ("Pogos") on the U-2 reconnaisance aircraft, which fall away after take-off and drop to earth usually killing someone; the aircraft then relies on titanium skids on the wingtips for landing. A Ryanair Boeing 737 takes off from Bristol International Airport, England Take off is the phase of flight where an aircraft transitions from moving along the ground (taxiing) to flying in the air (see flight), usually from a runway. ... The Me 163 Komet, designed by Alexander Martin Lippisch, was the only operational rocket-powered fighter aircraft during the Second World War. ... During the preparation for a possible invasion of Britain during World War II (called Operation Sealion), the Oberkommando des Heeres (OKH) required a cargo glider that would carry about 130 equipped soldiers because it was not possible to ship all the important weapons and goods by naval vessels. ... The Lockheed U-2, nicknamed Dragon Lady, is a single-seat, single-engine, high-altitude aircraft flown by the United States Air Force. ...

Landing gear on an Airbus A310

An unusual undercarriage configurations is found on the Hawker Siddeley Harrier, which has two mainwheels in line astern under the fuselage (called a bicycle or tandem layout) and a smaller wheel near the tip of each wing. On second generation Harriers, the wing is extended past the outrigger wheels to allow greater warloads to be carried. Image File history File linksMetadata Download high-resolution version (1200x1600, 867 KB) Daniel2986 05:40, 28 December 2006 (UTC) I, the creator of this work, hereby release it into the public domain. ... Image File history File linksMetadata Download high-resolution version (1200x1600, 867 KB) Daniel2986 05:40, 28 December 2006 (UTC) I, the creator of this work, hereby release it into the public domain. ... See also BAE Sea Harrier The Hawker Siddeley Harrier and the AV-8A are the first generation of the Harrier series, a successful close-support and reconnaissance fighter aircraft with V/STOL capabilities. ... Look up Tandem in Wiktionary, the free dictionary. ...

A multiple tandem layout was used on some military jet aircraft during the 1950s such as the Lockheed U-2, Myasishchev M-4, Yakovlev Yak-25, Yak-28 and the Boeing B-47 because it allows room for a large internal bay between the main wheels. A variation of the multi tandem layout is also used on the B-52 Stratofortress which has four main wheel bogies underneath the fuselage and a small outrigger wheel supporting each wing-tip. The B-52's landing gear is also unique in that all four pairs of main wheels can be steered. This allows the landing gear to line up with the runway and thus makes crosswind landings easier (using a technique called crab landing). Jet aircraft are aircrafts with jet engines. ... This does not cite any references or sources. ... The Lockheed U-2, nicknamed Dragon Lady, is a single-seat, single-engine, high-altitude aircraft flown by the United States Air Force. ... The Myasishchev M-4 Molot (Russian: Hammer, NATO reporting name Bison) is a four-engined strategic bomber, designed by Vladimir Myasishchev and developed by the Soviet Union in the 1950s to provide a bomber capable of attacking targets in North America. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Yak-28I The Yakovlev Yak-28 was a swept wing, turbojet-powered combat aircraft used by the Soviet Union. ... USAF B-47E Stratojet. ... The Boeing B-52 Stratofortress is a long-range, jet strategic bomber flown by the United States Air Force (USAF) since 1954. ... It has been suggested that Slip landing be merged into this article or section. ... A crab landing is method of landing an airplane in a crosswind. ...

For light airplanes, a landing gear which is economical to produce is a simple wooden arch laminated from ash, as used on some homebuilt aircraft. A recent addition to this type of gear is the fixed-gear RJ.03 IBIS canard homebuilt aircraft.

Steering

The steering mechanism used on the ground with wheeled landing gear varies by aircraft, but there are several general types of steering. Taildragger aircraft may be steered by rudder alone (depending upon the prop wash produced by the aircraft to turn it) with a freely-pivoting tail wheel, or by a steering linkage with the tail wheel, or by differential braking (the use of independent brakes on opposite sides of the aircraft to turn the aircraft by slowing one side more sharply than the other). Aircraft with tricycle landing gear usually have a steering linkage with the nose wheel (especially in large aircraft), but some allow the nose wheel to pivot freely and use differential braking and/or the rudder to steer the aircraft. Stern-mounted steering oar of an Egyptian riverboat depicted in the Tomb of Menna (c. ...

Some aircraft require that the pilot steer by using rudder pedals; others allow steering with the yoke or control stick. Some allow both. Still others have a separate control, called a tiller, used for steering on the ground exclusively. A tiller or till is a lever attached to a rudder post (American terminology) or rudder stock (English terminology) of a boat in order to provide the leverage for the helmsman to turn the rudder. ...

Rudder steering

When an aircraft is steered on the ground exclusively using the rudder, turning the plane requires that a substantial airflow be moving past the rudder, which can be generated either by the forward motion of the aircraft or by thrust provided by the engines. Rudder steering requires considerable practice to use effectively. Although it requires air movement, it has the advantage of being independent of the landing gear, which makes it useful for aircraft equipped with fixed floats or skis.

Direct steering

Some aircraft link the yoke, control stick, or rudder directly to the wheel used for steering. Manipulating these controls turns the steering wheel (the nose wheel for tricycle landing gear, and the tail wheel for taildraggers). The connection may be a firm one in which any movement of the controls turns the steering wheel (and vice versa), or it may be a soft one in which a spring-like mechanism twists the steering wheel but does not force it to turn. The former provide positive steering but make it easier to skid the steering wheel; the latter provide softer steering (making it easy to overcontrol) but reduce the probability of skidding the wheel used for steering. Aircraft with retractable gear may disable the steering mechanism wholly or partially when the gear is retracted.

Differential braking

Differential braking depends on asymmetric application of the brakes on the main gear wheels to turn the aircraft. For this, the aircraft must be equipped with separate controls for the right and left brakes (usually on the rudder pedals). The nose or tail wheel usually is not equipped with brakes. Differential braking requires considerable skill. In aircraft with several methods of steering that include differential braking, differential braking may be avoided because of the wear it puts on the braking mechanisms. Differential braking has the advantage of being largely independent of any movement or skidding of the nose or tail wheel.

Tiller steering

A tiller in an aircraft is a small wheel or lever, sometimes accessible to one pilot and sometimes duplicated for both pilots, that controls the steering of the aircraft while it is on the ground. The tiller may or may not be designed to work in combination with other controls such as the rudder or yoke. In large airliners, for example, the tiller is often used as the sole means of steering during taxi, and then the rudder is used to steer during take-off and landing, so that both aerodynamic control surfaces and the landing gear can be controlled simultaneously when the aircraft is moving at aerodynamic rates of speed.

Landing gear and accidents

Malfunctions or human errors related to retractable landing gear have been the cause of numerous accidents and incidents throughout aviation history. Distraction and preoccupation during the landing sequence play a vital role in the approximately 100 gear-up landing incidents that occurred each year in the United States between 1998 and 2003.^[1] A gear-up landing incident is an accident resulting from the pilot simply forgetting, or failing, to lower the landing gear before landing. Although rarely fatal, a gear-up landing is very expensive, as it causes massive airframe damage, and almost always requires a complete rebuild of engines, due to the propellers striking the ground and suffering a sudden stoppage if they were running on impact. Many aircraft between the wars - at the time when retractable gear was becoming commonplace - were deliberately designed to allow the bottom of the wheels to protrude below the fuselage even when retracted to reduce the damage caused if the pilot forgot to extend the landing gear or in case the plane was shot down and forced to crash-land. Examples include the Avro Anson and the Douglas DC-3. The contemporary Fairchild-Republic A-10 Thunderbolt II is similarily designed in an effort to avoid (further) damage during a gear-up landing, a possible consequence of battle damage. The Avro Anson was a twin-engine, multi-role aircraft that served with the Royal Air Force, Fleet Air Arm and numerous other air forces during World War II and afterwards. ... The Douglas DC-3 is a fixed-wing, propeller-driven aircraft, which revolutionized air transport in the 1930s and 1940s and is generally regarded as one of the most significant transport aircraft ever made (also see Boeing 707 and Boeing 747). ... The Fairchild-Republic A-10 Thunderbolt II is a single-seat, twin-engine jet aircraft designed to provide close air support (CAS) of ground forces by attacking tanks, armored vehicles, and other ground targets. ...

On September 21, 2005, JetBlue Airways Flight 292 successfully landed with its nose gear turned 90 degrees sideways, resulting in a shower of sparks and flame after touchdown. This type of incident is very uncommon as the nose oleo struts are designed with centering cams to hold the nosewheels straight until the weight of the aircraft compresses it. JetBlue Airways Flight 292 was a scheduled flight from Bob Hope Airport (BUR) in Burbank, California, to John F. Kennedy International Airport (JFK), in New York City. ... The Oleo Strut was a coffeehouse in Killeen, Texas, from 1968 to 1972. ...

Automatic Extension Systems

The Piper Arrow was originally fitted with a system that automatically extended the landing gear when certain power and flap settings were selected. The manufacturer issued an Airworthiness Directive for owners to disable this system. Pilots were found to be relying on this system to extend the gear in routine flight operations, rather than just as an emergency backup. If the gear failed to extended then the manufacturer was exposed to liability for the resulting gear-up landing. There were also concerns over unintentional gear extension incidents where pilots placed the aircraft in "bad-weather" (low-power setting, flaps down) configuration and inadvertently activated the gear extension system. Cherokee is the common name for the Pipers PA-28 family of aircraft models, which received its type certificate from the FAA in 1960 and is still under production by The New Piper Aircraft Company. ... An Airworthiness Directive (commonly abbreviated to AD) is a notification to aircraft owner/operators of a known safety issue with a particular model of aircraft, engine, avionics or other system. ...

Stowaways

Main article: Stowaway.

Unauthorized passengers have been known to stowaway on larger aircraft by climbing a landing gear strut and riding within the compartment. There are extreme dangers to this practice, including: A stowaway (also stoweaway) is a person who travels illegally, by airplane, bus, ship or train. ...

• Death from hypothermia or hypoxia, as the landing gear bays are not climate contolled or pressurized.
• Death from heat produced by the aircraft's wings and engines.
• Being crushed by the gear or bay doors if the bay is not large enough for the stowaway.
• Being caught by the tires and run over while climbing on or off a plane in motion.
• Falling off the strut, especially when it is extended after takeoff or before touchdown. This is exacerbated by the force of wind and aircraft velocity.
• Falling out of the bay should the doors open unexpectedly. This can be caused if the door mechanism cannot support the weight of the stowaway. Also, the stowaway may be asleep or unconscious when the gear is lowered for landing.

Yaguine Koita and Fodé Tounkara were stowaways who froze to death flying from Conakry, Guinea, to Brussels, Belgium, on July 28, 1999. Their bodies were later discovered in the aircraft's wheel bay. The boys were carrying a letter, written in imperfect French, which was widely published in the world media. Hypothermia refers to any condition in which the temperature of a body drops below the level required for normal metabolism and/or bodily function to take place. ... Hypoxia may refer to: Hypoxia (medical), the lack of oxygen in tissues Hypoxia or Oxygen depletion, a reduced concentration of dissolved oxygen in a water body leading to stress or even death in aquatic organisms This is a disambiguation page: a list of articles associated with the same title. ... July 28 is the 209th day (210th in leap years) of the year in the Gregorian calendar, with 156 days remaining. ... 1999 (MCMXCIX) was a common year starting on Friday, and was designated the International Year of Older Persons by the United Nations. ...

On May 9, 2004, two stowaways were severely injured when their flight, American Eagle Flight 1450 from Mayagüez, Puerto Rico to Luis Muñoz Marín International Airport in San Juan, Puerto Rico, crashed during landing. The stowaways were able to recover from the ordeal. May 9 is the 129th day of the year in the Gregorian calendar (130th in leap years). ... shelby was here 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ...

On June 8, 2005, the remains of a stowaway were found inside the wheel well of a South African Airways aircraft when it landed at John F. Kennedy International Airport, arriving from Johannesburg via Dakar, Senegal. June 8 is the 159th day of the year in the Gregorian calendar (160th in leap years), with 206 days remaining. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ...

Gallery

Hawker Harrier GR7 (ZG472). The two mainwheels are in line astern under the fuselage, with a smaller wheel on each wing Image File history File linksMetadata Download high resolution version (1633x1093, 654 KB) Hawker Harrier GR7 (ZG472) at Kemble Airfield, Gloucestershire, England. ... See also BAE Sea Harrier The Hawker Siddeley Harrier and the AV-8A are the first generation of the Harrier series, a successful close-support and reconnaissance fighter aircraft with V/STOL capabilities. ...

Landing gear on a private jet Image File history File linksMetadata Download high-resolution version (1944x2592, 2200 KB) Description: Landing gear on a private jet. ...

Space Shuttle Atlantis deploying its landing gear on return from earth orbit Image File history File links Download high resolution version (1500x1200, 1763 KB) Summary The Space Shuttle Atlantis returns to Earth after mission STS-30 landing at Edwards Air Force Base, CA. Source Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to... Space Shuttle Orbiter Atlantis (NASA Orbiter Vehicle Designation: OV-104) is one of the fleet of space shuttles belonging to the U.S. National Aeronautics and Space Administration (NASA). ...

Airbus A380 landing gear Image File history File linksMetadata Download high-resolution version (2016x1512, 1011 KB) Summary Airbus A380 Photographer: Florian Lindner camera: Panasonic DMC-FZ3 lens: Built-in shutter speed: see EXIF lens aperture: see EXIF date: see EXIF Licensing File links The following pages on the English Wikipedia link to this file... The Airbus A380 is a double-deck, four-engined airliner manufactured by EADS (Airbus S.A.S.). It is the largest passenger airliner in the world. ...

External references

1. ^ http://asrs.arc.nasa.gov/callback_issues/cb_292.htm

• Alphonse Pénaud website
• FAA Website