An aircraft ground carriage (also "ground power assisted takeoff and landing concept") is a

landing gear Landing gear is the undercarriage of an aircraft or spacecraft that is used for taxiing, takeoff or landing. For aircraft, it is generally needed for all three of these. It was also formerly called ''alighting gear'' by some manufacturers, s ...

system connected to the ground, on which

aircraft An aircraft ( aircraft) is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or the Lift (force), dynamic lift of an airfoil, or, i ...

can take off and

land Land, also known as dry land, ground, or earth, is the solid terrestrial surface of Earth not submerged by the ocean or another body of water. It makes up 29.2% of Earth's surface and includes all continents and islands. Earth's land sur ...

without their aircraft-installed landing gear. The technical feasibility of the ground carriage is being investigated by two research groups. In 2013,

IATA The International Air Transport Association (IATA ) is an airline trade association founded in 1945. IATA has been described as a cartel since, in addition to setting technical standards for airlines, IATA also organized tariff conferences tha ...

included the technology into their "Technology Roadmap";

Airbus Airbus SE ( ; ; ; ) is a Pan-European aerospace corporation. The company's primary business is the design and manufacturing of commercial aircraft but it also has separate Airbus Defence and Space, defence and space and Airbus Helicopters, he ...

pursues the concept as part of its "Future by Airbus” strategy.

Advantages and functionality

The aircraft-installed landing gear and related structures and systems account for 6 to 15 per cent of the empty weight of an aircraft, but it is only required on the ground for takeoff and landing as well as for

taxiing Taxiing (rarely spelled taxying) is the movement of an aircraft on the ground, under its own power, in contrast to towing or pushback (aviation), pushback where the aircraft is moved by a tug. The aircraft usually moves on wheels, but the term ...

and parking. During cruise flight, it is carried along as unused

ballast Ballast is dense material used as a weight to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within ...

. An aircraft without landing gear could therefore require 8 to 20 per cent less fuel in flight. Furthermore, landing gears are one of the most expensive

aircraft systems Aircraft systems are those required to operate an aircraft efficiently and safely. Their complexity varies with the type of aircraft. Aircraft software systems Aircraft software systems control, manage, and apply the subsystems that are engaged ...

and complex in operation and maintenance. Finally, less noise is emitted when the drag of the undercarriage is omitted during approach and the engines are switched off while taxiing on ground. A ground carriage provides the means for an aircraft to takeoff and land without carrying an own aircraft-installed landing gear. Instead, the aircraft is equipped with much lighter interfaces, which connect to the ground carriage. Every

airport An airport is an aerodrome with extended facilities, mostly for commercial Aviation, air transport. They usually consist of a landing area, which comprises an aerially accessible open space including at least one operationally active surf ...

approached by aircraft without landing gear must operate at least one ground carriage. In addition, alternate airports must be available if an airport is closed due to bad weather or a system failure. For emergency landings outside of

runways In aviation, a runway is an elongated, rectangular surface designed for the landing and takeoff of an aircraft. Runways may be a human-made surface (often asphalt, concrete, or a mixture of both) or a natural surface (grass, dirt, gravel, ...

, unsuitable flooring or unpaved ground cannot absorb the high wheel loads. Therefore, the landing gear of heavy long-haul aircraft in emergency landing on unsuitable ground is often not extended, since it would otherwise sink into ground first and then bend or break off.

Related Concepts

The precursor of the aircraft ground carriage is the jettisonable or detachable landing gear, wherein the aircraft takes-off from a cart, which is then released and eventually lands on skids (IE: SNCASE Baroudeur). It was used on all operational examples of the Messerschmitt Me 163B ''Komet'' with its jettisonable twin-wheel "dolly" main gear — its conventional arrangement included a semi-retractable tailwheel on the ''Komet's'' rear fuselage — and the first eight prototypes of the Arado Ar 234 "Blitz", which all used a jettisonable tricycle-gear arrangement "trolley" design. The glider Schleicher Ka 1, which was built in the 1950s, also had a droppable landing gear. A Sea Vampire Mk.21 landed with retracted landing gear on an aircraft carrier with flexible rubber decks for testing purposes. The Rockwell HiMAT

unmanned aerial vehicle An unmanned aerial vehicle (UAV) or unmanned aircraft system (UAS), commonly known as a drone, is an aircraft with no human pilot, crew, or passengers onboard, but rather is controlled remotely or is autonomous.De Gruyter Handbook of Dron ...

used skids for landing. The idea of the aircraft ground carriage is finally related to the

aircraft catapult An aircraft catapult is a device used to help fixed-wing aircraft gain enough airspeed and lift for takeoff from a limited distance, typically from the deck of a ship. They are usually used on aircraft carrier flight decks as a form of assist ...

, especially with the

Electromagnetic Aircraft Launch System The Electromagnetic Aircraft Launch System (EMALS) is a type of electromagnetic catapult system developed by General Atomics for the United States Navy. The system launches carrier-based aircraft by means of a catapult employing a linear in ...

, which is currently under development.

GroLaS

"GroLaS" (Ground-based Landing gear System) is an aircraft ground carriage system which is being developed since 2008 by a

Hamburg Hamburg (, ; ), officially the Free and Hanseatic City of Hamburg,. is the List of cities in Germany by population, second-largest city in Germany after Berlin and List of cities in the European Union by population within city limits, 7th-lar ...

-based company in cooperation with the

Technical University of Hamburg-Harburg The Hamburg University of Technology (in German ''Technische Universität Hamburg'', abbreviated TUHH (HH as acronym of Hamburg state) or TU Hamburg) is a research university in Germany. The university was founded in 1978 and in 1982/83 lecturin ...

and the

German Aerospace Center The German Aerospace Center (, abbreviated DLR, literally ''German Center for Air- and Space-flight'') is the national center for aerospace, energy and transportation research of Germany, founded in 1969. It is headquartered in Cologne with 3 ...

. Currently, the setup of a small scale demonstrator is envisioned, the full scale system is planned to be ready for market entry in 2035. The focus of the GroLaS study starts with long-haul

cargo aircraft A cargo aircraft (also known as freight aircraft, freighter, airlifter or cargo jet) is a fixed-wing aircraft that is designed or converted for the carriage of cargo rather than passengers. Such aircraft generally feature one or more large door ...

. In a first implementation of the system, the world's major cargo airports and corresponding alternate airports have to be equipped. The costs for an airport are expected to be 500 million euros. GroLaS is patented in Europe, the USA and China. A model in 1:87 scale, which was built in 2013, was exhibited at the Berlin Air Show in 2014. GroLaS consists of a slide which speeds up and slows down by means of a maglev system installed on both sides of the runway. Thus, the conventional runway remains and enables a dual usability of conventional aircraft and of aircraft without installed landing gear. Upon landing, the slide automatically accelerates the mounted ground carriage to the approaching speed of the aircraft before touchdown and adjusts its position longitudinally and laterally to the aircraft. Pins located on the ground carriage couple into corresponding aircraft installed interfaces. Takeoff and landing are less susceptible to side winds due to a

yaw angle The Euler angles are three angles introduced by Leonhard Euler to describe the Orientation (geometry), orientation of a rigid body with respect to a fixed coordinate system.Novi Commentarii academiae scientiarum Petropolitanae 20, 1776, pp. 189� ...

adjustment. The braking energy is converted into electrical energy, which can be used to support the aircraft engines during takeoff. The braking distance is shortened, and there is no

reverse thrust Reverse or reversing may refer to: Arts and media *Reverse (Eldritch album), ''Reverse'' (Eldritch album), 2001 *Reverse (2009 film), ''Reverse'' (2009 film), a Polish comedy-drama film *Reverse (2019 film), ''Reverse'' (2019 film), an Iranian cr ...

required. For taxiing, the ground carriage can be decoupled from the slide to remain underneath the aircraft.

GABRIEL

"GABRIEL" ("Integrated Ground and on-board system for support of the Aircraft Safe Takeoff and Landing") is a research project to develop an aircraft ground carriage started in 2011 by a consortium of several European universities, companies and institutions. The proposed aircraft ground carriage moves on its own electromagnetic rail system and not on a conventional runway. The pins for attaching to the ground carriage are installed on the aircraft and the aircraft needs to synchronize laterally to the position of the ground carriage, which is a different approach compared to the GroLaS-concept. Parallels are the longitudinal and yaw angle synchronisation and, that the electrically driven ground carriage is designed demountable from the slide for taxiing.

References

External links