LESSON 8 GROUND (aerodynamics)

Weight (heavier) stall

1. aircraft weight increases, more lift is needed 2. AOA increased to produce more lift 3. wing is closer to critical AOA, reaches stall speed sooner (faster speed)

3 types of parasite drag

1. form 2. skin friction 3. interference

Chord line

An imaginary straight line from the leading edge to the trailing edge of an airfoil.

Load Factor

ratio of the aerodynamic force on the aircraft to the gross weight of the aircraft

overbanking tendency

when entering a turn, the outside wing travel faster than inside wing, it produces more lift than inside wing, causes overbanking tendency

dihedral - if turbulence causes airplane to roll

1. airplane will sideslip 2. relative wind strikes lower side of lowered wing due to dihedral 3. generates more lift on lowered wing, bringing plane to level flight

Adverse Yaw

A condition of flight in which the nose of an airplane tends to yaw toward the outside of the turn. This is caused by the higher induced drag on the outside wing, which is also producing more lift.

Camber

A measure of the curvature of the airfoil.

spiraling slip stream

Backward flow of air which wraps around the airplane due to the propeller. hits left side of vertical stabilizer=yaw to left

Vx

Best angle of climb (altitude/distance)

Vy

Best rate of climb (altitude/time)

p-factor

Descending blade takes a larger bite of air (right side) than the ascending blade. causes yaw to left

turning skid describe the vectors how do you correct for it

During a skid, the aircraft is turning too fast for the bank angle, and yaws into the turn. excess centrifugal force over the horizontal lift component. brick slides to outside of turn, step on brick. reduce rate of turn, or increase the bank or both

Yaw is controlled via

Rudder (vertical stabilizer)

Longitudinal Stability

Stability about the airplane's lateral axis; pitching tendency.

Lateral stability

Stability about the airplane's longitudinal axis; rolling tendency.

Directional stability

Stability about the airplane's vertical axis; yawing tendency.

Two types of stability

Static-initial tendency of an object to return to equilibrium when displaced dynamic-the tendency over time of an object to return to equilibrium when displaced

Angle of Attack

The acute angle between the direction of the relative wind and the chord of an airfoil.

turning slip describe the vectors how do you correct for it

The nose of the aircraft yaws to the outside of the turn, and the aircraft's banked too much for the rate of turn. horizontal component of lift is greater than centrifugal force brick moves to inside of turn, step on brick. decrease your bank, or inc the ROT

Stall speed is affected by

Weight, load factor, and power.

gyroscopic precession

a force applied to a spinning object is felt 90 degrees in plane of rotation pitch down=force to the left=yaw to left

what creates a spin?

a stall and a YAW (SKID!!!)

Roll is controlled via

ailerons (wings)

controllability

aircrafts ability to respond to pilot control inputs

Manuverability

aircrafts ability to withstand load factor

Relative wind

airflow that is parallel and opposite of the flight path of the airfoil

Camber line

amount of curvature of the wing. Imaginary line runs halfway between upper and lower surfaces of the wing.

define load factor

any force applied to an aircraft to deflect its flight from a straight line produces a stress on its structure - the amount of this force is known as LOAD FACTOR

Why is a propellor twisted? what part of the blade moves the slowest

because the root of the blade spins much slower than the outer portion. Twisting the blade makes it meet the air at about the same angle across its entire length. This provides the most thrust and the least drag.

Do we have differential or frise ailerons?

combination frise-aileron that moves up has small portion below the wing (helps with adverse yaw) differential-aileron that moves up deflects at a larger angle than the aileron that goes down

How does a propellor generate lift

creates downwash and is directed rearward to propel the airplane forward

Parasite drag

drag that does not contribute to lift generation; drag caused by landing gear struts, cooling intakes, antennas, rivet heads, etc.

Pitch is controlled via

elevator (on the horizontal stabilizer)

Keel effect

high wing airplanes have more weight below wings - heavier body of aircraft acts like pendulum keeping the airplane from rolling

The airplane is balanced by the _______ ______ creating a tail downforce to counteract the nose down tendency caused by location of CG relative to the CP

horizontal stabilizer

Tail downforce

horizontal stabilizer acts as an upside-down wing airfoil that produces aerodynamic force downward using the same principles as any airfoil

Phases of spin

incipient developed recovery

parasite drag does what when velocity is increased?

it increases (squared)

in steady, unaccelerated flight, the four forces...

lift = weight and thrust=drag

Four forces of flight

lift, weight, thrust, and drag

with forward loading/CG, ____ trim is required in most aircraft to maintain level cruising flight. how does this affect wing loading/stall speed?

nose up increases wing loading and increases stall speed/higher AOA

slip

opposite rudder/aileron the upper wing stalls first (fuselage blocks upper wing)

name the four turning tendencies

p-factor spiraling slip stream gyroscopic precession torque

what compensates for yawing?

resultant sideslip causes air to strike the surface area behind the CG increases pressure on one side which corrects the yaw

skid

same rudder/aileron input the lowered wing blocks the air from the LOWER wing so it enters a spin if stalled

Dihedral

slight upward angle of the wings from root to tip increases lateral stability (rolling) When you turn, your horizontal component of lift turns into a lift vector in direction of turn. Causing you to slip to where you turn. To combat this, dihedral is used. Allows the side-slipped wing to generate more lift (relative wind comes from the side of the turn and generates more lift to return the AC to straight and level)

Weight is concentrated at...and is ___ the center of pressure

the aircrafts CG, forward the center of pressure

Angle of incidence

the angle between the chord line and the aircraft's logitudinal axis

what compensates for the overbooking tendency?

the deflection of the opposite aileron

L/D max

the point that provides the best glide. any deviations will cause an increase in drag and dec in lift

Induced drag

the resistive force that is produced via the generation of lift

Does a change in AOA change the center of pressure?

yes high AOA, CP moves forward low AOA, CP moves aft