Aerodynamics Reivew

Force

Push or pull exerted on a body (F=ma)

Mass

Quantity of molecular material

Density

Mass/Volume

ρ

Moment

Force applied a distance from a fulcrum

Weight

Force toward the earth (gravity) on a mass

Kenetic Energy

Energy of Motion

What happens to air density and temperature as altitude increases?

Both Decrease

What atmospheric properties affect pressure?

Density and Temperature

P = ρRT

What is total pressure

Dynamic (caused by movement) + Static (random movement)

True Altitude

Actual height above MSL

Pressure Altitude

Height above a standard datum plane

Density Altitude

Pressure altitude corrected for temperature

Indicated Airspeed

Airspeed from ASI

(DIfference between Pt and Ps)

Calibrated Airspeed

IAS corrected for instrument error

Equivalent Airspeed

CAS corrected for compressability

True Airspeed

Speed through Air Mass

Groundspeed

TAS corrected for Winds

Mach Number

TAS/Speed of Sound

Critical Mach Number

Speed where there is first evidence of local supersonic flow

What happens to TAS and Mach Number in a constant IAS climb

Both will increase

(Tas\~ 3knots per 1000ft)

What are the three airplane axes, what motions are about them, and what flight con?

Lateral = Pitch → Elevator

Longitudinal = Roll → Aileron

Vertical = Yaw → Rudder

Wingspan

Distance from wingtip to wingtip

Chordline

Infinite line from leading edge to trailing edge

Chord

Width of the wing

Average Chord

Average of all cords

Wing area

Wingspan times average chord

Aspect Ratio

Wingspan / Average Chord

(greater aspect ratio = harder to manuver)

Angle of Incidence

Angle between Chord Line and longitudinal axis

Dihedral angle

Upward slope of wing viewed from head on

Relative Wind

Airflow experienced by aircraft/airfoil (opposite of flight path)

Angle of Attack

Angle between relative wind and chord line

Flight Path

Path through air

Pitch Altitude

Angle between longitudinal axis and horizon

Mean Camber Line (MCL)

Line halfway upper and lower surface of airfoil

Positive Camber

when the MCL above chrod line

Aerodynamic Center

Point on chord line where changes in aerodynamic aerodynamic forces take place

(engineers be rounding)

Spanwise Flow

Parallel to leading edge

Chrodwise Flow

Perpendicular to leading edge

How are lift, weight, thrust, and drag related in level unaccelerated flight?

Lift = Weight

Thrust = Drag

How are lift, weight, thrust and drag related during the takeoff roll?

Lift < Weight

Thrust > Drag

What is the center of gravity?

Point where all weight is concentrated

What are the results of the CG being too far aft or too far forward?

AFT: Tail heavy, tendency to pitch up

Forward: Nose heavy, tendency to pitch down

What is the Lift equation?

L = 1/2 ρ V^2 CL S

Changing which factor is the lift equation effected by the most

Velocity

How can a pilot change lift?

AOA + Velocity

(can also change camber with flaps)

What are the two parts of the aerodynamic force due to airflow over the wing?

Lift and Induced Drag

What is total drag?

Parasyte + induced

What are the 3 types of parasyte drag

form, friction, interference

What happens to parasite drag and induced drag as velocity increases?

parasite : increases

induced : decreases

Which parasite drag is the difference between static pressure of the leading and trailing edges?

form

Which parasite drag is turbulent airflow in the boundary?

friction

which parasite drag is due to mixing airflows between components?

interference

Describe the effects on lift and drag caused by raising or lowering flaps

Lowering to T/O: More lift with a little bit of drag

Lowering to LDG: More lift and More drag

What drag increases as Gs increase?

Induced

What is L/D max?

Lowest point on total drag curve

What effects does lowering the gear have on drag?

It increases parasite drag

At what velocities is induced drag greatest?

slower

If weight increases, how is equilibrium flight maintained?

AoA or Velocity must increase

What is thrust and shaft horsepower?

Thrust = propeller output

Shaft = engine output

What is propeller efficiency?

THP/SHP

ability to convert engine output to thrust

What factors affect thrust available?

PCL Position

Altitude

Airspeed

Due to prop efficiencies, how does Pa change with velocity?

Decreases

Thrust required

(Tr) thrust to overcome drag

Power required

(Pr) Power to produce Tr

Excess thrust

Difference between Ta and Tr

Ta > Tr

Excess power

Difference between Pa and Pr

(Pa > Pr)

What is the relationship between velocity, Tr and Pr

Tr decreases to L/Dmax, then increases

Pr decreases to an Airspeed below L/Dax then increases

What is the result of PA being greater than PR?

Acceleration or Climbing

What effect does a change in configuration have on Ta, Tr, Pa, Pr?

Ta and Pa is unaffected

Tr and Pr is increased

What factors increase takeoff or landing roll?

What factor has the greatest effect?

Increased: weight, altitude, temperature, humidity, tailwind

decreased: headwind

\
Most effect: weight

Max rate of climb (Vy)

Airspeed to get the most altitude in the least amount of time

Max angle of climb (Vx)

Airspeed to get most altitude in least distance

Best glide speed

L/Dmax

power off range airspeed: 125 KIAS minimum

Max range

Max distance for a set amount of fuel

Max endurance

Max time airborne of a set amount of fuel

What is LRC (long range cruise)

Airspeed above max range that gives 99% max range

(sacrifice a bit of range to go faster)

What factors decrease both max range and max endurance

More weight

Dirty configuration

decreased altitude

increased temperature

What factors change groundspeed, but has no effect on TAS?

Headwind / Tailwind

What factors decrease glide range?

Dirty Configuration

Unfeathered Propeller

Lower altitude

Greater Headwind

Lesser Tailwind

Where does max range for a propeller aircraft occur

L/Dmax on Pr curve

Where/What is the region of reverse command

The part of the Pr curve where decreased airspeed requires increased power

Left of max endurance on Pr curve

What is critical Mach?

Airspeed where the first evidence of supersonic flow

What is Slipstream Swirl?

Left yaw resulting from prop airflow past rudder

What is the correction for slipstream swirl

Right rudder

\`What causes P-factor

Ascending + Descending produces different thrust due to different AOA

@asymetric prop thrust

What is propeller torque

Roll opposite of prop rotation

Contrast slip and skid

Slip: not enough rudder (ball same side)

Skid: too much rudder (ball opposite side)

Why must back pressure be added in a turn

Increase total lift

vertical component = weight

Why must power be increased during a turn

Increased AoA → increased induced drag and Tr → more power

What is turn rate?

Rate of heading change (deg/sec)

What two things determine turn rate and radius?

Velocity and bank angle

Limit load factor

Max load without damage

Ultimate load factor

Max load without failure

Maneuvering speed

Max speed where abrupt control inputs will not cause damage

Asymmetric Gs

Pulling Gs with ailerons or rudder deflection

T-6 asymmetric load limits

\-1.0 to 4.7

T-6 symmetric load limits

\-3.5 to 7.0

How will an increase in bank angle for a level turn change the required Gs?

Increase required Gs

What is dynamic stability?

Displacement over time after a disturbance (oscillation)

Describe a PIO

Pilot and longitudinal stability corrects for oscillations simultaneously around lateral axis