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59 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What is meant by matter? |
Anything that occupies space and has weight. |
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What are three basic physical states in which matter can exist? |
Solid, liquid or gas. |
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What is meant by pressure? |
Force that acts on a unit of area. |
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What is the standard sea level atmospheric pressure expressed in inches of mercury and in pounds per square inch? |
29.92 inches of mercury or 14.69 pounds per square inch. |
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What characteristics of the atmosphere determines the speed of sound? |
it's temperature |
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What is meant by the fulcrum of a lever |
The point about which the level rotates. |
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Give an example of a first class lever, a second class lever, and a third class lever? |
First class lever a seesaw Second class lever a wheelbarrow Third class lever a hydraulically retracted landing gear. |
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What is the formula used to find the amount of work done when an object is moving across the floor? |
Work = Force x Distance. |
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What determines the mechanical advantage of an arrangement of ropes and pulleys? |
The number of ropes that support the weight. |
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What determines the mechanical advantage of a gear train? |
The ratio between the number of teeth on the drive gear and the driven gear. |
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What is meant by the resonant frequency of an aircraft structure? |
The frequency that produces the greatest amplitude of vibration in the structure. |
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What is the principle upon which ultrasonic inspection is based? |
The resonant frequency of a material, The frequency of a known sound material is compared with the resonant frequency of a material on the test to indicate the presence of a fault. |
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What are two types of fluids? |
Liquid and gaseous |
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What is meant by density of a fluid? |
The mass per unit volume of the fluid. |
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What effect does the increase in temperature of a condensed gas have on its pressure? |
When the volume of the gas remains constant, an increase in its temperature increases its pressure. |
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What is meant by the specific gravity of a fluid? |
The ratio of the density of the fluid to the density of pure water. |
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What effect does an increase in the volume of a gas have on its temperature if it's pressure remains constant? |
As the volume of the gas increases and it's pressure remains constant, the temperature decreases |
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What effect does increasing pressure of a confined gas have on its temperature? |
It increases its temperature. |
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What is the difference in the fluids used in a hydraulic system and those used in the pneumatic system? |
Hydraulic system uses incompressible fluids, while the pneumatic system uses compressible gases. |
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What effect on density altitude is caused by an increase in air temperature? |
Increase in temperature results in the decrease in density and the density altitude of increases. |
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What effect does an increase in density altitude have an engine performance? |
Increasing attitude density results in decreasing engine performance. |
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What effect does high humidity have on a piston engine performance? |
Because water vapor is less dense than dry air, thus high humidity decreases the density of the air. The less dense air decreases engine performance. |
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What does the specific gravity of the electrolyte of lead acid aircraft battery indicate? |
The amount of acid relative to the water in the electrolyte, and this is an indication of the state of charge of the battery |
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How much force is produced by 1,000 PSI of hydraulic pressure acting on a piston with an area of 20 square inches? |
20,000 pounds (1000psi x 20in square) |
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How many cubic inches of fluid is forced out of a cylinder by a piston with an area of 20 square inch when the Piston moves 5 inches? |
5 x 20=100 cubic inches |
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What will happen to the pressure of a confined gas if the temperature of the gas is increased? |
Pressure will increase. |
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What is meant by a temperature of absolute zero? |
The temperature at which all molecular movement stops. |
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What is the Celsius equivalent of a temperature of 50° f |
10° c |
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What are three methods of heat transfer? |
Conduction, convection and radiation. |
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What is meant by the absolute humidity of the atmosphere |
The actual amount of water that is in a given volume of air. |
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What causes ice to change into liquid water? |
The absorption of heat energy. |
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What happens inside a solid material when it absorbs heat energy? |
Molecules within the material moves faster. |
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What is the basic unit of heat in the English system? |
British Thermal Unit (BTU) |
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At work would one BTU of heat energy perform? |
778 foot pounds of work |
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What is the basic unit of heat in the metric system? |
Calorie |
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How much heat energy is in a small calorie? |
The amount of heat energy that will raise the temperature of 1 g of water to 1° c. |
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How much heat energy is in a large calorie? |
The amount of heat energy that will raise the temperature of 1 kg of water to 1° c. |
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What is the first law of thermodynamics? |
Heat energy can neither be created nor destroyed, it can only be changed in its form. |
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What is the second law of thermodynamics? |
Heat energy can only flow from one body having a high temperature to another body having a lower temperature. |
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What is an example of heat transfer by conduction? |
Removal of heat energy from an engine cylinder by air flowing over its surface. |
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What is an example of heat transfer by convection? |
The uniform heating of air in a room by a floor heater. Whereby the heat air rises and force the cooler head down so it can be heated by conduction. |
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What is an example of heat transfer by radiation? |
The heating of the earth's surface by heat transmitted through space from the Sun. |
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Why do metals expand when they are heated? |
As heat is absorbed, the electrons move faster and expand their orbits in the molecules of the metal. |
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What is meant by density of air? |
The weight of a given volume of air. |
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What is meant by relative wind with regard to an airfoil? |
The direction the wind strikes and Airfoil. |
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What is meant by the angle of attack? |
The acute angle formed between the chord line of an airfoil and the direction the air strikes the airfoil. |
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What is meant by the critical angle of attack? |
The highest angle of attack at which the air passes over the airfoil in a smooth flow. The point at which the airflow breaks away and becomes turbulent. |
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What is meant by the stagnation point of an airfoil? |
The point on the leading edge of the airfoil at which the air flow separates, some flowing over the top and some at the bottom. |
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What is the difference between speed and velocity? |
Speed is the rate at which an object is moving. Velocity is the vector quantity that expresses the rate and the direction an object is moving. |
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What is meant by air density? |
The mass of air in a given volume |
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What is meant by weight? |
A measure of the force of gravity acting on a body |
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What is meant by thrust? |
A forward aerodynamic Force produced by a propeller, a fan or a turbo jet engine as it forces a mass of air to the rear of the airplane. |
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What is meant by drag? |
The aerodynamic force acting in the same plane as the relative winds striking an airfoil. Drag acts in the direction opposite to that of thrust. |
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What is meant by autorotation in helicopter? |
The aerodynamic force that causes a helicopter rotor to spin with no engine power applied to the rotor system. |
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What is meant by dissymmetry of lift produced by a helicopter rotor? |
The difference in lift between the two sides of the rotor disc when the helicopter is in the forward flight. |
The side with the advancing blade produces the greater lift because the forward speed adds to the rotor speed. And the side with the retreating blade produces less lift because the forward speed subtracts from the rotor speed. |
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What is meant by a blade stall of a helicopter rotor? |
A condition in flight in which the retreating blade is operating at an angle of attack higher than will allow for the air to flow over its upper surfaces without turbulence. |
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What is meant by transitional lift in a helicopter? |
The additional lift produced by a helicopter rotor as the helicopter changes from hovering to forward flight. |
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What is meant by Brown effect in helicopter flight? |
An increase in lift when a helicopter is flying at an altitude of less than half the rotor span. This increase is produced by the effective increase in the angle of attack caused by the deflection of the down washed air. |
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What is meant by ground resonance in a helicopter? |
The destructive vibration that occurs when the helicopter touches down roughly and unevenly. |
The shock throws a load into the lead lag hinges of the rotor blades and causes them to oscillate about this hinge. And if the frequency of this oscillation is the same as the resonant frequency of the fuselage, the energy will cause the helicopter to strike the ground hard with the opposite skid or wheel. If corrective action is not taken immediately, ground resonance can destroy the helicopter. |
