Aviation Glossary

The glossary of terms, acronyms, and definitions used in the aviation industry. Letter – ALetter – BLetter – CLetter – DLetter – ELetter – FLetter – GLetter – HLetter – ILetter – J and KLetter – LLetter – MLetter – NLetter – OLetter – P Letter – Q Quartersawed wood. Wood sawed from a tree … Read more

Wake. The high-velocity stream of turbulent air behind an operating aircraft engine. Wankel engine. See rotating combustion (RC) engine. Warp clock. An alignment indicator included in a structural repair manual to show the orientation of the piles of a composite material. The ply direction is shown in relation to a reference direction. Warp threads. Threads … Read more

Vapor lock. A condition in which vapors form in the fuel lines and block the flow of fuel to the carburetor. Vapor pressure. The pressure of the vapor above a liquid needed to prevent the liquid evaporating. Vapor pressure is always specified at a specific temperature. Variable displacement pump. A fluid pump whose output is … Read more

UDF engine. Un-ducted Fan™. The trade name registered by General Electric for a type of ultra-high-bypass turbofan engine that drives one or more wide-blade propellers that have between eight and twelve blades. These blades, which are not enclosed in a duct or shroud, are very thin, have wide chords, and are highly swept back in … Read more

TACAN (Tactical Air Navigation). A radio navigation facility used by military aircraft for both direction and distance information. Civilian aircraft receive distance information from a TACAN on their DME. Tachometer. An instrument that measures the rotational speed of an object. Tack coat. A coat of finishing material sprayed on the surface and allowed to dry … Read more

Saddle gusset. A piece of plywood glued to an aircraft structural member. The saddle gusset has a cutout to hold a backing block or strip tightly against the skin to allow a nailing strip to be used to apply pressure to a glued joint in the skin. SAE. Society of Automotive Engineers. A professional organization … Read more

Rack-and-pinion actuator. A form of rotary actuator where the fluid acts on a piston on which a rack of gear teeth is cut. As the piston moves, it rotates a pinion gear which is mated with the teeth cut in the rack. Radial bearing load. The load on a bearing perpendicular to the shaft on … Read more

P-lead. Primary lead. The wire that connects the primary winding of a magneto to the ignition switch. The magneto is turned off by grounding its P-lead. Packing. A seal between two parts where there is relative motion. Paint. A covering applied to an object or structure to protect it and improve its appearance. Paint consists … Read more

Oblique shock wave. A pressure wave that forms on a sharp-pointed object when air flows past it at a supersonic speed. Octane rating. A system used to rate the antidetonation characteristics of a reciprocating engine fuel. Fuel with an octane rating of 80 performs in a laboratory test engine the same as the fuel made … Read more

N1. A symbol representing the rotational speed of the low-pressure compressor in a dual-spool gas turbine engine. N2. A symbol representing the rotational speed of the high-pressure compressor in a dual-spool gas turbine engine. NACA cowling. A long-chord cowling used over a radial engine. The forward portion of this cowling has an aerodynamic shape that … Read more