Aeronautical Terms beginning with C
Cabin Pressurization
A condition where pressurized air is forced into the cabin simulating pressure conditions at a much lower altitude and increasing the aircraft occupants comfort.
Calibrated Airspeed (CAS)
Indicated airspeed corrected for installation error and instrument error. Although manufacturers attempt to keep airspeed errors to a minimum, it is not possible to eliminate all errors throughout the airspeed operating range. At certain airspeeds and with certain flap settings, the installation and instrument errors may total several knots. This error is generally greatest at low airspeeds. In the cruising and higher airspeed ranges, indicated airspeed and calibrated airspeed are approximately the same. Refer to the airspeed calibration chart to correct for possible airspeed errors.
Cambered
The camber of an airfoil is the characteristic curve of its upper and lower surfaces. The upper camber is more pronounced, while the lower camber is comparatively flat. This causes the velocity of the airflow immediately above the wing to be much higher than that below the wing.
Carburetor
1. Pressure: A hydromechanical device employing a closed feed system from the fuel pump to the discharge nozzle. It meters fuel through fixed jets according to the mass airflow through the throttle body and discharges it under a positive pressure. Pressure carburetors are distinctly different from float-type carburetors, as they do not incorporate a vented float chamber or suction pickup from a discharge nozzle located in the venturi tube. 2. Float-type: Consists essentially of a main air passage through which the engine draws its supply of air, a mechanism to control the quantity of fuel discharged in relation to the flow of air, and a means of regulating the quantity of fuel/air mixture delivered to the engine cylinders.
Carburetor Ice
Ice that forms inside the carburetor due to the temperature drop caused by the vaporization of the fuel. Induction system icing is an operational hazard because it can cut off the flow of the fuel/air charge or vary the fuel/air ratio.
Cascade Reverser
A thrust reverser normally found on turbofan engines in which a blocker door and a series of cascade vanes are used to redirect exhaust gases in a forward direction.
Center Of Gravity(CG)
The point at which an airplane would balance if it were possible to suspend it at that point. It is the mass center of the airplane, or the theoretical point at which the entire weight of the airplane is assumed to be concentrated. It may be expressed in inches from the reference datum, or in percent of mean aerodynamic chord (MAC). The location depends on the distribution of weight in the airplane.
Center-Of-Gravity Limits
The specified forward and aft points within which the CG must be located during flight. These limits are indicated on pertinent airplane specifications.
Center-Of-Gravity Range
The distance between the forward and aft CG limits indicated on pertinent airplane specifications.
Centrifugal Flow Compressor
An impeller-shaped device that receives air at its center and slings air outward at high velocity into a diffuser for increased pressure. Also referred to as a radial outflow compressor.
Chord Line
An imaginary straight line drawn through an airfoil from the leading edge to the trailing edge.
Circuit Breaker
A circuit-protecting device that opens the circuit in case of excess current flow. A circuit breakers differs from a fuse in that it can be reset without having to be replaced.
Clear Air Turbulence
Turbulence not associated with any visible moisture.
Climb Gradient
The ratio between distance traveled and altitude gained.
Cockpit Resource Management
Techniques designed to reduce pilot errors and manage errors that do occur utilizing cockpit human resources. The assumption is that errors are going to happen in a complex system with error-prone humans.
Coefficient Of Lift
See Lift Coefficient.
Coffin Corner
The flight regime where any increase in airspeed will induce high speed mach buffet and any decrease in airspeed will induce low speed mach buffet.
Combustion Chamber
The section of the engine into which fuel is injected and burned.
Common Traffic Advisory Frequency
The common frequency used by airport traffic to announce position reports in the vicinity of the airport.
Complex Aircraft
An aircraft with retractable landing gear, flaps, and a controllable-pitch propeller, or is turbine powered.
Compression Ratio
1. In a reciprocating engine, the ratio of the volume of an engine cylinder with the piston at the bottom center to the volume with the piston at top center. 2. In a turbine engine, the ratio of the pressure of the air at the discharge to the pressure of air at the inlet.
Compressor Bleed Air
See Bleed Air.
Compressor Bleed Valves
See Bleed Valve.
Compressor Section
The section of a turbine engine that increases the pressure and density of the air flowing through the engine.
Compressor Stall
In gas turbine engines, a condition in an axial-flow compressor in which one or more stages of rotor blades fail to pass air smoothly to the succeeding stages. A stall condition is caused by a pressure ratio that is incompatible with the engine r.p.m. Compressor stall will be indicated by a rise in exhaust temperature or r.p.m. fluctuation, and if allowed to continue, may result in flameout and physical damage to the engine.
Compressor Surge
A severe compressor stall across the entire compressor that can result in severe damage if not quickly corrected. This condition occurs with a complete stoppage of airflow or a reversal of airflow.
Condition Lever
In a turbine engine, a powerplant control that controls the flow of fuel to the engine. The condition lever sets the desired engine r.p.m. within a narrow range between that appropriate for ground and flight operations.
Configuration
This is a general term, which normally refers to the position of the landing gear and flaps.
Constant Speed Propeller
A controllable pitch propeller whose pitch is automatically varied in flight by a governor to maintain a constant r.p.m. in spite of varying air loads.
Control Touch
The ability to sense the action of the airplane and its probable actions in the immediate future, with regard to attitude and speed variations, by sensing and evaluation of varying pressures and resistance of the control surfaces transmitted through the cockpit flight controls.
Controllability
A measure of the response of an aircraft relative to the pilot’s flight control inputs.
Controllable Pitch Propeller
A propeller in which the blade angle can be changed during flight by a control in the cockpit.
Conventional Landing Gear
Landing gear employing a third rear-mounted wheel. These airplanes are also sometimes referred to as tailwheel airplanes.
Coordinated Flight
Application of all appropriate flight and power controls to prevent slipping or skidding in any flight condition.
Coordination
The ability to use the hands and feet together subconsciously and in the proper relationship to produce desired results in the airplane.
Core Airflow
Air drawn into the engine for the gas generator.
Cowl Flaps
Devices arranged around certain air-cooled engine cowlings which may be opened or closed to regulate the flow of air around the engine.
Crab
A flight condition in which the nose of the airplane is pointed into the wind a sufficient amount to counteract a crosswind and maintain a desired track over the ground.
Crazing
Small fractures in aircraft windshields and windows caused from being exposed to the ultraviolet rays of the sun and temperature extremes.
Critical Altitude
The maximum altitude under standard atmospheric conditions at which a turbocharged engine can produce its rated horsepower.
Critical Angle Of Attack
The angle of attack at which a wing stalls regardless of airspeed, flight attitude, or weight.
Critical Engine
The engine whose failure has the most adverse effect on directional control.
Cross Controlled
A condition where aileron deflection is in the opposite direction of rudder deflection.
Crossfeed
A system that allows either engine on a twin-engine airplane to draw fuel from any fuel tank.
Crosswind Component
The wind component, measured in knots, at 90° to the longitudinal axis of the runway.
Current Limiter
A device that limits the generator output to a level within that rated by the generator manufacturer.
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