horizontal needle of the cross-pointer indicator (aircraft instrument). The horizontal needle of the cross-pointer indicator of the Instrument Landing System (ILS) shows the pilot the vertical position of the aircraft as it descends along the glide slope for an instrument approach.
If the horizontal needle is above the center mark, or doughnut, the aircraft is below the glide slope, and the pilot should fly upward. If the needle is below the doughnut, the aircraft is too high and should descend. The glide slope is sometimes called the glide path. See illustration for glide slope.
horizontal plane. A horizontal plane is one that is perpendicular to the gravitational field of the earth.
horizontal situation indicator. See HSI.
horizontal stabilizer (airplane control). The fixed horizontal surface on the tail of a conventional airplane. The horizontal stabilizer is usually adjustable in flight to vary the down-load produced by the tail. This allows the airplane to fly hands-off at any desired air speed.
horsepower. A measure of mechanical power equal to 33,000 foot-pounds of work done in 1 minute, 550 foot-pounds of work done in 1 second, or 746 watts of power.
One metric horsepower is equal to 75 meter-kilograms per second or 0.9863 English horsepower
horseshoe magnet. A permanent magnet formed in the shape of the letter U, the shape of a horseshoe. The poles of a horseshoe magnet are close together, and the magnetic flux between them is concentrated.
hose. A flexible fluid line. A hose may have threaded fittings installed in its ends for attachment to other fittings, or it may be slipped over a piece of rigid tubing and secured with hose clamps.
hot-blow forming (sheet metal forming). A method of forming sheet metal by forcing it into a die with argon gas whose pressure is computer-controlled to maintain the correct rate of strain of the metal.
hot dimpling (sheet metal construction process). A process used to dimple, or indent, the hole into which a flush rivet is to be installed. Some metals, such as magnesium and the harder aluminum alloys, cannot be dimpled cold because they are likely to crack. These metals must be hot dimpled.
Hot dimpling equipment consists of a pair of electrically heated dies with a pilot that goes through the rivet hole. The pilot is passed through the hole, and the heated dies are pressed together. The dies heat the metal enough to soften it and force it into the shape of the die. This is the proper shape for the rivet head.
hot section (gas turbine engine). The portion of a gas turbine engine that operates at high temperature. The hot section includes the combustors, the turbine, and the exhaust system of the engine.
hot section inspection (gas turbine engine maintenance procedure). The inspection of the hot section of a gas turbine engine.
hot spark plug (reciprocating engine ignition component). A spark plug with a long path for heat to travel from the nose core insulator to the spark plug shell. Because the heat must travel a long distance before it is transferred into the cylinder head, the nose core stays quite hot.
|
