Advanced Aerodynamics

Fundamental Flight Maneuvers

• Straight and Level

• Turns

• Climbs

• Descents

Four Aerodynamic Forces

• Lift

• Thrust

• Drag

• Weight

• When are they in equilibrium?

Four Aerodynamic Forces

• In steady-state or unaccelerated straight and level flight

• What happens when you initiate a climb?

Four Aerodynamic Forces

• Lift briefly exceeds weight.

• Rearward component of the Lift adds to drag

• Upward component of Thrust is called the Lift of Thrust

Four Aerodynamic Forces

• Once the climb is established, the forces are again balanced

Lift

• Which of Newton’s laws of motion are used to describe lift?

Lift

• Second law of motion says that a force results whenever a mass is accelerated F = ma

• Third law states for every action there is an equal and opposite reaction

Bernoulli’s Principle

• As the velocity of a fluid increase, its internal pressure decreases

• High pressure under the wing and lower pressure above the wing’s surface

Lift• In what direction does lift act?

• Perpendicular to the relative wind

• Drag acts parallel to the flight path in the same direction as the relative wind

Lift

• Angle of incidence

• Angle of attack

• Washout

Lift Equation

• L = CLV2S

• If the angle of attack and other factors remain constant and airspeed is doubled lift will be four times greater

Controlling Lift

• What are four ways commonly used to control lift?

Controlling Lift

• Increase airspeed

• Change the angle of attack

• Change the shape of the airfoil

• Change the total area of the wings

Angle of Attack

• Directly controls the distribution of pressure acting on a wing. By changing the angle of attack, you can control the airplane’s lift, airspeed and drag.

Angle of Attack

• Angle of attack at which a wing stalls remains constant regardless of weight, dynamic pressure, bank angle or pitch attitude.

Angle of Attack

• When the angle of attack of a symmetrical airfoil is increased, the center of pressure will remain unaffected.

Angle of Attack

• At high angle of attack, pressure increases below the wing, and the increase in lift is accompanied by an increase in induced drag.

Flaps

• What are the four types of flaps found on general aviation aircraft?

Flaps

• Plain

• Split

• Slotted

• Fowler

Leading Edge Devices

• Slot

• Slats

• Leading Edge Flaps

Drag

• Induced drag is a by-product of lift and is greatly affected by changes of airspeed.

Wing Planform

• Name several wing shapes and their advantages?

Wing Planform

• Elliptical - Excellent load distribution for high-G maneuvering and low drag for high speeds

• Rectangular - stall first at root, least expensive

Wing Planform

• Tapered - Favorable stall characteristics with good load distribution, saves weight

• Delta - supersonic flight

Wing Planform

• How do you find the Aspect Ratio of an airplane?

Wing Planform

• Found by dividing the wingspan by the average cord.

• What is a typical aspect ratio for typical training aircraft?

• Gliders?

Wing Planform

• Gliders - 20 to 30

• Training Aircraft - 7 to 9

Wing Planform• What is sweep?• A line connecting the 25% cord points of all

the wing ribs which is not perpendicular to the longitudinal axis of the plane is said to be swept

• The sweep can be forward but most are back

Wing Planform

• What is a device that is used to block or diffuse wing tip vortices?

Wing Planform

• Winglets

• Winglets can increase fuel efficiency at high speeds at altitudes by as much as 16 to 26%

Ground Effect

• Where is ground effect found?

Ground Effect

• Within one wingspan of the ground

• An airplane leaving ground effect will experience an increase in what kind of drag?

Ground Effect

• Induced Drag

• Induced Drag is only about half of its usual value when the wing is at 10% of its span above the ground

Drag

• What kind of drags rate of increase is proportional to the square of the airspeed?

Drag• What kind of drags rate of

increase is proportional to the square of the airspeed?

• Parasite Drag

• What kinds of drag make up parasite Drag

Drag

• Form Drag - based on the shape of the plane, how well streamlined and amount of frontal area.

Drag

• Interference Drag - created when the airflow around one part of the airplane interacts with the airflow around another.

• Skin Friction Drag - surface friction

Total Drag• The sum of the induced drag and

the parasite drag.

• Total drag is lowest at the airspeed which produces the highest ratio of lift to drag

L/Dmax

Total Drag

• Best power-off glide range

• Greatest Range

High Drag Devices

• Spoilers

• Speed Brakes

Spoilers

• What are the advantages of using spoilers?

Spoilers• Rapid descent without reducing power,

engine stays warm• Maintain normal descent speed• Help slow to landing gear extension

speed• Descent rapidly through icing • Stay at high altitudes longer

Thrust

• Opposes drag. If greater than drag, the airplane is accelerating

• A pound of Thrust must be available for each pound of drag.

Thrust

• Power is the rate at which work is done. It takes less power to do the same amount of work at a slower rate.

Propeller Efficiency

• High angle of attack at root, low angle of attack at tip

• Elliptical planform

• High Aspect ratio

Max Level Flight Speed

• Intersection of the Power or Thrust required curve with the Power or Thrust available curve.

Load Factor

• Ratio between the lift generated by the wings at any given time divided by the total weight of the airplane.

Load Factor

• What is the relationship between a heavily loaded airplane and stall speed compared to a lightly loaded airplane?

Load Factor

• A heavily loaded plane stalls at a higher speed than a lightly loaded airplane.

• It needs a higher angle of attack to generate required lift at any given speed than when lightly loaded.

Calculating VA

• VA2 = VA W2 / W1

• VA2 = Maneuvering speed ( at this weight)

Calculating VA

• VA = Maneuvering speed at Maximum weight

• W2 = Actual Airplane Weight

• W1 = Maximum Weight

V-G Diagram

• Relates velocity to load factor

• Applies to one airplane type

• Valid for a specific weight, configuration and altitude

Aircraft Stability

• Static Stability

• Dynamic Stability

Aircraft Stability

• Longitudinal Stability

• Stable in pitch or stable about the lateral axis

• Motion of the plane controlled by the elevators

Aircraft Stability

• Achieved by locating the center of gravity slightly ahead of the center of lift

• Need a tail down force on the elevator

Aircraft Stability• Lateral stability• Return to wings level following a

roll deviation• Dihedral

–Low wing aircraft have more• Sweep

Aircraft Stability

• Sweep may be used when dihedral would be inappropriate such as in an aerobatic airplane that needs lateral stability while inverted

Aircraft Stability

• Directional Stability

• Vertical tail and sides of the fuselage contribute forces which help to keep the longitudinal axis aligned with the relative wind.

Flight Maneuvers

• Straight and Level

• To maintain altitude while airspeed is being reduced, the angle of attack must be increased

Flight Maneuvers• Climbs

• Transitioning to a climb, angle of attack increases and lift momentarily increases

–Thrust acts along the flight path

Climb Performance

• Decreases with altitude

• Absolute Ceiling

• Service Ceiling

Turns

• What force turns an airplane?

Turns

• The horizontal component of lift.

• Load Factor and Turns

• The relationship between angle of bank , load factor, and stall speed is the same for all airplanes

Turns

• Rate and radius

• Steeper bank reduces turn radius and increases the rate of turn, but produces higher load factors

Turns

• A given airspeed and bank angle will produce a specific rate and radius of turn in any airplane

• Adverse Yaw

Stalls

• Angle of attack

• Power-on stalls

• Power-off stalls

• Accelerated stall

Stalls

• Secondary stall

• Cross-controlled stall

• Elevator trim stall

Stalls

• Total weight, load factor, and CG location affect stall speed

Spins• Incipient spin

• Fully developed spin

• Spin recovery

• What type of spin can result if the CG is too far aft and the rotation is around the CG?

Spins

• Flat Spin

• Spin Recovery

Spin Recovery

• Throttle to idle

• Neutralize the ailerons

• Determine the direction or rotation

• Apply full opposite rudder

Spin Recovery

• Apply forward elevator

• As rotation stops, neutralize the rudder

• Gradually apply aft elevator to return to level flight

One of the main functions of flaps during the approach and landing is to.

A. decrease lift, thus enabling a steeper-than- normal approach to be made.B. decrease the angle of descent without increasing the airspeed.C. provide the same amount of lift at a slower airspeed

One of the main functions of flaps during the approach and landing is to

C. provide the same amount of lift at a slower airspeed

Which is true regarding the use of flaps during level turns?

A. The raising of flaps increases the stall speed.B. The lowering of flaps increases the stall speed.C. Raising flaps will require added forward pressure on the yoke or stick.

Which is true regarding the use of flaps during level turns?

A. The raising of flaps increases the stall speed.

A rectangular wing, as compared to other wing planforms, has a tendency to stall first at the

A. center trailing edge, with the stall progression outward toward the wing root and tip.B. wing root, with the stall progression toward the wing tip.C. wingtip, with the stall progression toward the wing root.

A rectangular wing, as compared to other wing planforms, has a tendency to stall first at theB. wing root, with the stall progression toward the wing tip.

By changing the angle of attack of a wing, the pilot can control the airplane'sA. lift, airspeed, and CG.B. lift and airspeed, but not drag.C. lift, airspeed, and drag.

By changing the angle of attack of a wing, the pilot can control the airplane'sC. lift, airspeed, and drag.

The angle of attack of a wing directly controls theA. amount of airflow above and below the wing.B. angle of incidence of the wing.C. distribution of pressures acting on the wing.

The angle of attack of a wing directly controls theC. distribution of pressures acting on the wing.

The angle of attack at which a wing stalls remains constant regardless of

A. dynamic pressure, but varies with weight, bank angle, and pitch attitude.B. weight, dynamic pressure, bank angle, or pitch attitude.C. weight and pitch attitude, but varies with dynamic pressure and bank angle.

The angle of attack at which a wing stalls remains constant regardless ofB. weight, dynamic pressure, bank angle, or pitch attitude.

The need to slow an aircraft below VA is brought about by the following weather phenomenon:

A. Turbulence which causes a decrease in stall speed.B. High density altitude which increases the indicated stall speed.C. Turbulence which causes an increase in stall speed.

The need to slow an aircraft below VA is brought about by the following weather phenomenon:C. Turbulence which causes an increase in stall speed.

Stall speed is affected byA. angle of attack, weight, and air density.B. weight, load factor, and power.C. load factor, angle of attack, and power.

Stall speed is affected byB. weight, load factor, and power.

The stalling speed of an airplane is most affected byA. variations in airplane loading.B. variations in flight altitude.C. changes in air density.

The stalling speed of an airplane is most affected byA. variations in airplane loading.

An airplane will stall at the same

A. airspeed regardless of the attitude with relation to the horizon.B. angle of attack and attitude with relation to the horizon.C. angle of attack regardless of the attitude with relation to the horizon.

An airplane will stall at the same

C. angle of attack regardless of the attitude with relation to the horizon.

In a rapid recovery from a dive, the effects of load factor would cause the stall speed toA. not vary.B. increase.C. decrease.

In a rapid recovery from a dive, the effects of load factor would cause the stall speed toB. increase.

Recovery from a stall in any airplane becomes more difficult when itsA.elevator trim is adjusted nosedown.B.center of gravity moves forward.C.center of gravity moves aft

Recovery from a stall in any airplane becomes more difficult when itsC.center of gravity moves aft

(Refer to figure 2.) Select the correct statement regarding stall speeds.

A. Power-off stalls occur at higher airspeeds with the gear and flaps down.B. In a 60° bank the airplane stalls at a lower airspeed with the gear up.C. Power-on stalls occur at lower airspeeds in shallower banks.

(Refer to figure 2.) Select the correct statement regarding stall speeds.C. Power-on stalls occur at lower airspeeds in shallower banks.

Refer to figure 2.) Select the correct statement regarding stall speeds. The airplane will stall

A. 10 knots higher in a 45° bank, power-on stall, than in a wings-level stall.B. 10 knots higher in a power-on, 60° bank, with gear and flaps up, than with gear and flaps down.C. 25 knots lower in a power-off, flaps-up, 60° bank, than in a power-off, flaps-down, wings-level configuration.

Refer to figure 2.) Select the correct statement regarding stall speeds. The airplane will stallB. 10 knots higher in a power-on, 60° bank, with gear and flaps up, than with gear and flaps down.