crimping tool (electrical wiring tool). A special tool used to install crimp-on terminals on the ends of electrical wires. The tool is designed to exert enough pressure that the barrel of the terminal is squeezed into the strands of the wire to form a strong, low-resistance attachment.
crimp-on terminals (electrical wire terminals). Terminals which are attached to the end of an electrical wire for the purpose of connecting the wire to a terminal strip or component, or for splicing the wires. The terminals are attached to the wire ends by squeezing the terminal into the strands of the wire. No solder is used.
crinkle finish. A type of finish formed by a special paint in which the surface dries in a series of wrinkles.
The paint used to make a crinkle finish contains special ingredients that cause the surface to partially dry before the paint below the surface dries. As the subsurface paint dries, it shrinks and pulls the surface into a series of wrinkles. Crinkle finish is used on instrument panels to give a tough, attractive finish that does not reflect light.
critical altitude (aircraft reciprocating engine specification). The maximum altitude under standard atmospheric conditions at which an aircraft reciprocating engine can deliver its rated horsepower.
14 CFR Part 1: “The maximum altitude at which, in standard atmosphere, it is possible to maintain, at a specified rotational speed, a specified power or a specified manifold pressure. Unless otherwise stated, the critical altitude is the maximum altitude at which it is possible to maintain, at the maximum continuous rotational speed, one of the following:
(1)
The maximum continuous power, in the case of engines for which this power rating is the same at sea level and at the rated altitude.
(2)
The maximum continuous rated manifold pressure, in the case of engines, the maximum continuous power of which is governed by a constant manifold pressure.”
critical angle of attack (aerodynamics). The highest angle of attack at which air passes over an airfoil in a smooth flow. At angles of attack greater than the critical angle, the air burbles, or flows in a disturbed pattern, and lift is lost.
The critical angle of attack is sometimes called the stalling angle of attack.
critical compression ratio (compression-ignition engine). The lowest compression ratio of a compression-ignition engine that allows a specific fuel to be ignited by compression ignition.
critical coupling (electrical transformers). The coupling between the windings of a transformer that transfers the maximum amount of energy. Critical coupling is also known as optimum coupling.
critical engine (aircraft operation). The engine of a multiengine airplane which would cause the most difficulty in maintaining control if it failed in a critical condition of flight, such as on takeoff. 14 CFR Part
1: “The engine whose failure would most adversely affect the performance or handling qualities of the aircraft.”
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