[4] 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.
For emergency landings outside of runways, unsuitable flooring or unpaved ground cannot absorb the high wheel loads.
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.
[12] GroLaS consists of a slide which speeds up and slows down by means of a maglev system installed on both sides of the runway.
[5] "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.
[9] Parallels are the longitudinal and yaw angle synchronisation and, that the electrically driven ground carriage is designed demountable from the slide for taxiing.