AE103 Flashcards
What is equilibrium flight?
Equilibrium flight is any constant airspeed flight condition with balanced forces and moments.
What happens to air density as the temperature of air is increased while pressure remains constant?
a. Density decreases
1) Gas Law
Where is the fluid velocity the greatest? Where is fluid velocity the least?
a. In a streamtube with incompressible flow, air density and mass flow rate are constant. Therefore,
b. (Area X Velocity) POINT A = (Area X Velocity) POINT B = Area X Velocity) POINT C
c. Point C - Greatest fluid velocity
d. Point A - Least fluid velocity
In the streamtube below, where is the fluid static pressure the greatest? Where is fluid static pressure
the least?
a. Total pressure is constant along all points along a streamtube with incompressible flow. Since Point C has the greatest fluid velocity, Point C will have the largest dynamic pressure.
b. Using the Bernoulli Equation: PT = PS + 1⁄2 ρV2 or PT = PS + q, we find:
c. Point A – Greatest static pressure (lowest dynamic pressure)
d. Point C – Least static pressure (highest dynamic pressure)
What are the differences between true altitude, pressure altitude, and density altitude?
a. True Altitude: Actual height above mean sea level (MSL)
b. Pressure Altitude: Height above standard datum plane (29.92 in. Hg)
c. Density Altitude: Pressure altitude corrected for temperature
What are the characteristics of spanwise flow and chordwise flow over a wing?
a. Spanwise flow does not create lift
b. Chordwise flow produces lift
Which aircraft has a higher aspect ratio, a C-5 or an F-18?
The C-5 has the higher aspect ratio
What are the definitions for wing taper, sweep angle, dihedral angle, and angle of incidence?
a. Taper
b. Sweep angle
c. Dihedral (anhedral) angle
d. Angle of incidence
What is the center of gravity of an aircraft and how does it differ from the aerodynamic center?
a. Center of gravity (CG) - Point where all weight is concentrated
b. Aerodynamic center - Point where all the aerodynamic forces are acting
What are the three aircraft axes?
a. Longitudinal axis or roll axis
b. Lateral axis or pitch axis
c. Vertical axis or yaw axis
What hazards are encountered if an aircraft is operated with excessive weight or the aircraft center of
gravity out of limits?
a. Excessive weight
b. CG too far aft
c. CG too far forward
What is aerodynamic force and which of the four major forces acting on an aircraft in-flight are
aerodynamic forces?
a. Aerodynamic force: Force that results from pressure and friction distribution over an airfoil
b. Lift - Aerodynamic force
c. Drag- Aerodynamic force
What are the relationships of these four major forces during takeoff?
a. Forces are unbalanced
b. Thrust is greater than drag
c. Lift exceeds weight at liftoff
d. Forces balance when constant airspeed wings-level flight is achieved
How does a wing generate lift?
a. Airflow accelerates over a wing’s curved surfaces
1) Decreases static pressure below atmospheric pressure above and below the airfoil
2) Produces lifting force on top and bottom of wing
b. On positively cambered airfoil static pressure above airfoil less than below airfoil
1) Lower static pressures on top of airfoil creates lifting force that pulls wing upward
What two methods can the pilot use to change the coefficient of lift of an aircraft’s wing?
a. The pilot can change the coefficient of lift by changing:
1) Angle of attack
2) Shape or size of the airfoil
What is total drag?
a. Total drag is the aerodynamic force component parallel to and in the same direction as the relative wind.
b. Sum of parasite drag and induced drag
c. Drag equation
D=1/2pV^2SC_D
What causes induced drag?
a. The production of lift
1) Note that as velocity increases induced drag decreases
What is ground effect and how does it affect landing?
a. Reduction in wing downwash
b. Occurs within one wingspan of ground
c. Creates “floating effect”
What is the relationship between shaft horsepower, thrust horsepower, and propeller efficiency?
a. Shaft horsepower (SHP): Engine output
b. Thrust horsepower (THP): Propeller output
c. Propeller efficiency: THP/SHP
What are the effects of weight and altitude on the thrust required and power required curves?
a. Increased weight: Shifts curves up and to the right
b. Increased Altitude
1) TR curve shifts to the right
2) PR curve shifts up and to the right
What is the major aerodynamic effect experienced by the aircraft when the landing gear is lowered in-
flight?
Parasite drag increases, resulting in increased total drag and thrust required.
What are the differences between true airspeed (TAS), groundspeed (GS), indicated airspeed (IAS), calibrated airspeed (CAS), and equivalent airspeed (EAS)?
a. Indicated airspeed (IAS): Read on airspeed indicator; measure of dynamic pressure
b. Calibrated airspeed (CAS): IAS corrected for instrument error
c. Equivalent airspeed (EAS): CAS corrected for compressibility
d. True airspeed (TAS): Relative to the airmass
e. Groundspeed (GS): Relative to the ground; TAS corrected for wind
What is the difference between a symmetric and a cambered airfoil?
a. Symmetric: MCL and chordline are the same
b. Positively cambered airfoil: MCL above chordline
What are the definitions for angle of attack, pitch angle, and angle of incidence?
a. Angle of attack (AOA): Angle between relative wind and wing chordline (includes the angle of incidence)
b. Pitch angle: Angle between the horizontal and aircraft longitudinal axis
c. Angle of incidence: Preset angle attack of the wing
Why does parasite drag increase and induced drag decrease with increased airspeed?
a. Parasite drag is dependent upon the amount of air flowing over, around, and between surfaces. When airflow increases, parasite drag increases.
b. Induced drag is created by the production of lift and is proportional to aircraft AOA. Unless the aircraft is in high G flight, AOA decreases with increased airspeed, therefore induced drag decreases.
When does maximum excess thrust occur for any aircraft in-flight?
a. Maximum thrust excess occurs when the difference between thrust available and thrust required (total drag) is the greatest.
b. Max thrust excess for a propeller-driven aircraft occurs at an airspeed slower than L/DMAX airspeed.
Does the maximum power excess for a prop aircraft occur at a velocity slower than, equal to, or faster
than LD_max airspeed?
a. Maximum power excess occurs when the difference between power available and power required (total drag X velocity) is the greatest.
b. Max power excess for a propeller-driven aircraft occurs at L/DMAX airspeed.
What are the definitions of force, work, and power?
a. Force: Push/pull
b. Work: Force x distance
c. Power: Work/unit of time
