Wiktionary
n. 1 (context electricity English) A (usually unwanted) current that flows between two points that are meant to be at the same potential, but are not. 2 (context aviation English) A sudden, potentially damaging turn made by an aircraft while on the ground, owing to user error or adverse weather conditions. vb. (context aviation English) To suffer such a manoeuvre.
WordNet
n. a sharp uncontrollable turn made by an airplane while moving along the ground
Wikipedia
Ground loop may refer to:
- Ground loop (electricity), an unwanted electric current that flows in a conductor connecting two points inadvertently having different potentials
- Ground loop (aviation), the rapid circular rotation of an aircraft in the horizontal plane while on the ground
- Ground-coupled heat exchanger, an underground heat exchanger loop that can capture or dissipate heat to or from the ground
In an electrical system, a ground loop or earth loop is an equipment and wiring configuration in which there are multiple paths for electricity to flow to ground. The multiple paths form a loop which can pick up stray current through electromagnetic induction which results in unwanted current in a conductor connecting two points that are supposed to be at the same electric potential, often, but are actually at different potentials.
Ground loops are a major cause of noise, hum, and interference in audio, video, and computer systems. They do not in themselves create an electric shock hazard; however, the inappropriate connections that cause a ground loop often result in poor electrical bonding, which is explicitly required by safety regulations in certain circumstances. In any case the voltage difference between the ground terminals of each item of equipment is small. A severe risk of electric shock occurs when equipment grounds are improperly removed in an attempt to cure the problems thought to be caused by ground loops.
In aviation, a ground loop is a rapid rotation of a fixed-wing aircraft in the horizontal plane ( yawing) while on the ground. Aerodynamic forces may cause the advancing wing to rise, which may then cause the other wingtip to touch the ground. In severe cases (particularly if the ground surface is soft), the inside wing can dig in, causing the aircraft to swing violently or even cartwheel.
In powered airplanes, the ground loop phenomenon is predominantly associated with aircraft that have conventional landing gear, due to the center of gravity being positioned behind the main wheels. It may also occur with tricycle landing gear if excessive load is applied to the nosewheel, a condition known as wheel-barrowing.
If the aircraft heading is slightly different from the aircraft's direction of motion, a side force is exerted on the wheels. If this force is in front of the center of gravity, the resulting moment rotates the aircraft's heading even further from its direction of motion. This increases the force and the process reinforces itself. To avoid a ground loop, the pilot must respond to any turning tendency quickly, while sufficient control authority is available to counteract it. Once the aircraft rotates beyond this point, there is nothing the pilot can do to stop it from rotating further.
Ground loops occur when the aircraft is moving on the ground—either taxiing, landing, or during takeoff. Ground loops can damage the undercarriage and wingtips of an aircraft. Several extreme incidents of ground loop have resulted in fatalities.
Ground loops may occur when landing on muddy ground, wet pavement, or frozen surfaces, especially if there are puddles or patches. They may also occur when an aircraft departs a paved surface: for example, after an engine failure in multi-engine airplanes produces asymmetric thrust. Another common cause is failure of a tire or wheel brake, causing a loss of directional control. They also commonly occur without outside influence, due entirely to pilot error.
In gliders, ground loops can also occur because there is only a single main wheel near the center of gravity, and because the long wings are close to the ground. Any tendency to touch a wingtip to the ground while moving must be quickly counteracted. The leverage from the long wings can apply great stress to the rear fuselage, sometimes breaking the tail boom, especially on T-tail gliders.
Pilots may decide to execute a ground loop deliberately, usually as a last resort before hitting an immovable object, as in the case of China Airlines Flight 605 for example. In this case it may be a better option to dissipate energy by damaging the wings of the aircraft to protect the occupants seated in the fuselage.
Usage examples of "ground loop".
Occasionally she heard the controlled murmur of the air-to-ground loop.
There was no sound at the press stand, save the barking crackle of the PA's air-to-ground loop.
The subject within the ground loop was a dancing outline on the screen.
Either that or it was partly touching that stone or whatever, to which it was connected, and it created a ground loop.
Brim struggled with the controls, helplessly watching the scout slide into a ground loop, then the hull ricocheted from a flat outcropping of desert rock and somehow wobbled level, trailing a long column of dirty black smoke that thinned and disappeared as Ursis calmly manipulated the N-ray mains and extinguished the fires.
Evidently the engine and wings had been removed, possibly because of a ground loop or some other operational accident.
He did one ground loop inadvertently, which, but for the smooth ice, would probably have scuffed a wing off the ship.