1010 Test 2 CHP 7

Four forces of flight

-weight

-lift

-drag

-thrust

Lift

Acts perpendicular to the relative wind

Drag

Force that opposes motion and parallel in direction of relative wind

-consists of

+induced drag (caused by lift)

+parasite drag (all other drag)

+total drag (sum of parasite and induced drag)

Weight

-directly opposes lift in straight and level flight

+constructed of lightweight materials (aluminum, composite construction)

Thrust

-force that propels the aircraft forward

+goal to design an engine with lits of thrust and weighs little

+more speed, more lift, less drag

Theory of lift

-lift is the force that directly opposes the weight of an airplane and holds it in the air

-lift is a mechanical aerodynamic force produced by the motion of the airplane through the air

Camber

immediately behind the leading edge, upper and lower camber

+positive camber curves away from centerline

+negative camber moves towards centerline

Bernoulli’s Principle

-high velocity airflow results in decreased pressure

-as a fluid’s speed increases, pressure within the fluid decreases

+air moves faster over top of the wing than under the bottom

+low pressure on top of wing, higher pressure on bottom

Newton’s Third Law

-for every action, there is an equal and opposite reaction

+the airflow bending around the cambered wing exerts a downwash which causes lift

+airflow striking bottom of wing causes lift

Wing tip vortices

High pressure below the wing spills over the low pressure on the top of the wing

Density

-a measure of air molecules per cubic unit

+three determinants of density

1) temperature

2) pressure

3) water vapor

+density affect all parameters of flight (takeoff distance, climb gradient, speed, fuel burn)

Standard lapse rate in temperature

-2 degree celsius dropped per 1000 feet risen

-3.5 degree farenheit dropped per 1000 feet risen

+std temp 59 degree farenheit/15 degree celsius

Standard lapse rate in pressure

-1 inch of mercury dropped per 1000 feet risen

+std pressure 29.92’ Hg

Air flow

-as an object moves through the air, there is a flow pattern around it

1) laminar

-smooth flow is more desirable (laminar)

Stall

Separation and burbling of the upper surface flow at greater than the critical AOA that destroys lift

Aerodynamics

Study of air in motion

-aero

+air is a fluid

-dynamics

+refers to motion

Leading edge

Part of the airfoil that meets the air first

Chord

Imaginary line that connects leading edge to trailing edge

Trailing edge

Where the upper and lower camber come together at the rear of the wing

Angle of attack

Angle between relative wind and airfoil chord

-angle created at takeoff

-higher AOA generally makes more lift to an extent