Chapter 3 - Aerodynamics
Within what Mach range does transonic flight regimes usually occur?
.75 to 1.20 Mach.
If an aircraft with a gross weight of 2,000 pounds were subjected to a total load of 6,000 pounds in flight, the load factor would be
3 Gs.
For significant benefit, wing sweep must be at least
30 to 35 degrees.
Aerodynamic braking is only effective up to approximately
60 to 70% of touchdown speed.
A bank angle of 15 degrees will increase induced drag by about
7%.
What true airspeed and angle of attack should be used to generate the same amount of lift as altitude is increased?
A higher true airspeed for any given angle of attack.
How can an airplane produce the same lift in ground effect as when out of ground effect?
A lower angle of an attack.
What is the result of a shock-induced separation of airflow occurring symmetrically near the wing root of a sweptwing aircraft?
A severe moment or "Mach tuck."
Why do some airplanes equipped with inbox/outboard ailerons use the outboards for slow flight only?
Aerodynamic loads on the outboard ailerons tend to twist the wingtips at high speeds.
What flight condition should be expected when an aircraft leaves ground effect?
An increase in induced drag requiring a high angle of attack.
Upon which factor does wing loading during a level coordinated turn in smooth air depend?
Angle of bank.
At what Mach range does the subsonic flight range normally occur?
Below .75 Mach.
During a skidding turn to the right, what is the relationship between the component of lift and centrifugal force?
Centrifugal force is greater than the horizontal lift component.
What effect does the leading edge slot in the wing have on performance?
Changes the stalling angle of attack to a higher angle.
Why must the angle of attack be increased during a turn to maintain altitude?
Compensate for loss of vertical component of lift.
What is the free stream Mach number which produces first evidence of local sonic flow?
Critical Mach number.
What is the highest speed possible without supersonic flow over the wing?
Critical Mach number.
What effect, if any, does altitude have on a Vmc for an airplane with unsupercharged engines
Decreases with altitude.
What is the effect on total drag of an aircraft if the airspeed decreases in level flight below that speed for maximum L/D?
Drag increases because of increased induced drag.
Which of the following is considered a primary flight control?
Elevator.
What is a difference between the fowler flap system and split flap system?
Fowler flaps produce the greatest change in pitching moment.
At which speed will increasing the pitch attitude cause an airplane to climb?
High speed.
Which is a purpose of leading-edge slats on high-performance wings?
Increase lift at relative slow speeds.
Which is a purpose of a leading-edge flaps?
Increase the camber of the wing.
What is the relationship between induced and parasite drag when the gross weight is increased?
Induced drag increases more than parasite drag.
What is the movement of the centre of pressure when the wingtips of a sweptwing airplane are shock-stalled first?
Inward and forward.
What is the reason for variations in geometric pitch along a propeller or rotor blade?
It permits a relatively constant angle of attack along its length when in cruising flight.
How does the stall speed (KCAS) vary as you climb from sea level to 33,000 feet?
It remains relatively unchanged throughout the climb.
Which of the following is considered an auxiliary flight control?
Leading-edge flaps.
If no corrective action is taken by the pilot if the angle of bank is increased, how is the vertical component of lift and sink affected?
Lift decreases and the sink rate increases.
What is load factor?
Lift divided by total weight.
When are inboard ailerons normally used?
Low-speed and high speed flight
When are outboard ailerons normally used?
Low-speed flight only.
What are some characteristics of an airplane loaded with the CG at the aft limit?
Lowest stall speed, highest cruise speed, and least stability.
What is the purpose of an elevator trim tab?
Modify the downward tail load for various airspeeds in flight eliminating flight-control pressures.
Describe dynamic longitudinal stability.
Motion about the lateral axis.
What is the purpose of a control tab?
Move the flight controls in the event of manual reversion.
Identify the type stability if the aircraft attitude tends to move farther from its original position after the controls have been neutralized
Negative static stability.
Identify the type stability if the aircraft attitude remains in the new position after the controls have been neutralized.
Neutral longitudinal static stability.
Which direction from the primary control surface does a servo tab move?
Opposite direction.
What is a characteristic of longitudinal instability?
Pitch oscillations becoming progressively greater.
Identify the type stability if the aircraft attitude tends to return to its original position after the controls have been neutralized
Positive static stability.
What is the purpose of an anti-servo tab?
Prevent a control surface from moving to a full-deflection position due to aerodynamic forces.
What is the primary function of the leading edge flaps in landing configuration during the flare before touchdown?
Prevent flow separation.
What is the relationship of the rate of turn with the radius of turn with a constant angle of bank but increasing airspeed?
Rate will decrease and radius will increase.
What is the purpose of a servo tab?
Reduce control forces by deflecting in the proper direction to move a primary flight control.
What is the purpose of flight spoilers?
Reduce lift without decreasing airspeed.
For which purpose may flight spoilers be used?
Reduce the wings' lift upon landing.
Which is a purpose of ground spoilers?
Reduce the wings' lift upon landing.
Which direction from the primary control surface does an elevator adjustment trim tab move when the control surface is moved?
Remains fixed for all positions.
Which direction from the primary control surface does an anti-servo tab move?
Same direction.
How can the pilot increase the rate of turn and decrease the radius at the same time?
Steepen the bank and decrease airspeed.
What is the principal advantage of a sweepback design wing over a straightwing design?
The critical Mach number will increase significantly.
What procedure is recommended for an engine-out approach and landing?
The flightpath and procedures should be almost identical to a normal approach and landing.
Which engine is the "critical" engine in a twin-engine airplane?
The one with the center of thrust closest to the centerline of the fuselage.
What effect does an increase in airspeed have on a coordinate turn while maintaining a constant angle of bank and altitude?
The rate of turn will decrease resulting in no changes in the load factor.
What is one disadvantage of a sweptwing design?
The wingtip section stalls prior to the wing root.
On which type of wing are flaps most effective?
Thick wing.
What characteristic should exist if an airplane is loaded to the rear of its CG range?
Unstable about the lateral axis.
How does Vs (KTAS) speed vary with altitude?
Varies directly with altitude.
What affects indicated stall speed?
Weight, load factor, and power.
Under what condition should stalls never be practiced in a twin-engine airplane?
With one engine inoperative.
Generally, the turning performance of an airplane is defined by
aerodynamic and structural limits at low altitude.
A turbojet airplane has an increase in specific range with altitude, which can be attributed to three factors. One of those factors is
an increase in proportion of velocity versus thrust required.
What will be the ratio between airspeed and lift if the angle of attack and other factors remain constant and airspeed is doubled? Lift will be
four times greater.
Upon landing, spoilers
function by increasing tire to ground friction.
Swept wings
increase the critical Mach number.
The stall speed of an airplane
is affected by weight and bank angle.
Precise roll control using a rudder on a transport category airplane
is difficult and therefore not recommended.
The primary purpose of high-lift devices is to increase the
lift at low speeds.
By changing the angle of attack of a wing, the pilot can control the airplane's
lift, airspeed and drag.
An airplane loaded with the CG aft of the rear-CG limit could
make it more difficult to flare for landing.
Ground spoilers used after landing are
more effective at high speed.
When compared to plain flaps, split flaps
produce only slightly more lift, but much more drag.
Swept wings causes a significant
reduction in effectiveness of flaps.
For a given angle of bank, the load factor imposed on both the aircraft and pilot in a coordinated constant-altitude turn
remains constant regardless of airspeed changes.
During a turn with constant power
the aircraft nose will pitch down.
If the boundary layer separates
the wing is about to stall and stop producing lift.
