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 = CLV2r/2 S
• 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-thannormal 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 the
B.
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's
A.
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's
C.
lift, airspeed, and
drag.
The angle of attack of a wing
directly controls the
A.
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 the
C.
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 of
B.
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
by
A.
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
by
B.
weight, load factor,
and power.
The stalling speed of an
airplane is most affected by
A.
variations in airplane
loading.
B.
variations in flight
altitude.
C.
changes in air density.
The stalling speed of an
airplane is most affected by
A.
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 to
A.
not vary.
B.
increase.
C.
decrease.
In a rapid recovery from
a dive, the effects of
load factor would cause
the stall speed to
B.
increase.
Recovery from a stall in any
airplane becomes more
difficult when its
A.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 its
C.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 wingslevel 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 poweroff, flaps-down, wings-level
configuration.
Refer to figure 2.) Select
the correct statement
regarding stall speeds.
The airplane will stall
B.
10 knots higher in a
power-on, 60° bank, with gear
and flaps up, than with gear
and flaps down.