# Shared Flashcard Set

## Details

Pilots License Chapter 1 Section 5
Forces Acting On The Airplane in Flight
20
Aerospace Engineering
Not Applicable
05/22/2012

Term
 Lift
Definition
 The upward-acting force that opposes weight. Lift is produced by the dynamic effect of the air acting on the wing and acts perpendicular to the flight path through the wing's center of lift.
Term
 Weight
Definition
 The combined load of the airplane itself, the crew, the fuel, and the cargo or baggage. Weight pulls the airplane downward toward the center of Earth because of the force of gravity. It opposes lift and acts vertically downward through the airplane's center of gravity.
Term
 Thrust
Definition
 The forward force produced by the engine/propeller. Thrust opposes or overcomes the force of drag. As a general rule, it is said to act parallel to the longitudinal axis.
Term
 Drag
Definition
 The rearward, retarding force that is caused by disruption of airflow by the wing, fuselage, and other protruding objects. Drag opposes thrust and acts rearward and parallel to the relative wind.
Term
 Four principal airfoils on an airplane
Definition
 The wing The propeller The horizontal tail surfaces The vertical tail surfaces
Term
 Bernoulli's Principle
Definition
 States in part that "The internal pressure of a fluid decreases at points where the speed of the fluid increases." Other words, high speed flow is associated with low pressure, and low speed flow is associated with high pressure.
Term
 How is Bernoulli's Principle applicable to an airplane wing?
Definition
 It is designed and contructed with a curve or camber. when air flows along the upper wing surface, it travels a greater distance in the same period of time (i.e. faster) than the airflow along the lower wing surface. The pressure above the wing is less than it is below the wing, which generates a lift over the upper curved surface of the wing.
Term
 Newton's Third Law of Motion (For every action force there is an equal and opposite reaction force)
Definition
 Due to the angle of incidence/angle of attack, the lower surface of the wing deflects air downward, which causes and upward force.
Term
 Several factors that help to generate the amount of lift
Definition
 Speed of the wing through the air Angle of attack Planform of the wing Wing area Air density
Term
 Weight
Definition
 Force caused by gravity accelerating the mass of the airplane toward the Earch and is expressed in pounds. CG(Center of Gravity) is the imaginary point on the plane where all weight is considered to be concentrated.
Term
 Relationship between weight and lift
Definition
 Lift is required to counteract the airplane's weight, which acts dowward through the airplane's CG. When lift force equals weight force the plane is at equillibrium. If lift becomes less than weight, the airplane loses altitude. vice versa The heavier the plane, the more lift is required
Term
 What produces thrust?
Definition
 The propeller, acting as an airfoil, produces the thrust that drives the airplane through the air. It receives power from the engine and displaces a large mass of air to the rear. In order to maintain a constant airspeed, thrust and drag must remain equal. If thrust is less than drag, the airplane will slow down until its airspeed is insufficient to support it in the air.
Term
 Drag
Definition
 Acts parallel to, and in the same direction as, the relative wind. Every part of the airplan exposed to the air while the airplane is in motion produces some resistance and contributes to drag. Two types of drag- Induced drag and parasite drag
Term
 Induced drag
Definition
 The undesireable but unavoidable by-product of lift
Term
 Parasite drag
Definition
 The resistance of the air as the airplane passes through it Can be further classified into form drag, skin fraction, and interference drag
Term
 Factors that affect parasite drag
Definition
 The more streamlined an object, the less the parasite drag The more dense the air moving past the airplane, the greater the parasite drag The larger the size of the object in the airstream, the greater the parasite drag As speed increases, the amount of parasite drag increases as the square of the velocity.
Term
 Form Drag
Definition
 Caused by the frontal area of the airplane compenents being exposed to the airstreams Streamlining an object will redude form drag
Term
 Skin Friction
Definition
 The type of parasite drag that is most difficult to reduce. No surface is perfectly smoothl even machined surfaces, when inspected through magnification, have a ragged, uneven appearance.
Term
 Interference drag
Definition
 Caused by interference of the airflow between adjacent parts of the airplane, such as the intersections of wings and tail sections with the fuselage.
Term
 Frost
Definition
 Forms when the temperature of a collecting surface is at or below the dew point of the adjacent air, and the dew point is below freezing. Can make it difficult to fly and take off.
Supporting users have an ad free experience!