Untitled Quiz

Forces Acting on an Aircraft

• Thrust: Force propelling aircraft forward, generated by engines and propellers
• Drag: Opposes forward motion, categorized as:
  • Induced Drag: Generated by lift-producing components (wings)
  • Parasite Drag: Non-lift-related drag, including form drag and skin friction
• Lift: Upward force opposing weight, generated by wings through air pressure differences
• Weight: Downward force due to gravity, pulling the aircraft towards Earth

Lift

• Bernoulli's Principle: Faster airflow over the wing's curved surface creates lower pressure above, lifting the aircraft
• Newton's Third Law: Deflecting airflow downwards results in an upward lift force
• Factors Affecting Lift: Air density, velocity, wing surface area, and angle of attack. Higher velocity and larger wings increase lift

Drag

• Induced Drag: Caused by wingtip vortices, prevalent at slow speeds and high angles of attack
• Parasite Drag: Increases with speed, consisting of form drag (caused by shape), skin friction, and interference drag
• Ground Effect: Reduced drag near the ground as wingtip vortices are restricted

Thrust

• Generated by propellers or jet engines, overcomes drag
• Adjusting thrust controls airspeed

Weight

• Acts through the center of gravity, balancing lift
• Improper distribution affects flight stability and performance

Couples

• Formed when forces like weight, lift, drag, and thrust act at parallel but separate points, creating turning moments
• Weight ahead of lift causes nose pitch down
• Drag above thrust causes nose pitch up

Wing Design

• Airfoil Camber: Affects lift, deeper camber providing higher lift but more drag
• Planform: Shape of the wing from above, affecting lift and stall characteristics (rectangular, tapered, elliptical, delta)
• Aspect Ratio: Ratio of wingspan to chord length influencing induced drag. Higher aspect ratios reduce drag
• Angle of Incidence: Fixed angle between wing chord line and airplane's longitudinal axis, optimized for efficient cruising

Axes of the Airplane

• Longitudinal Axis (Roll): Controlled by ailerons, affecting banking and rolling movements. Lateral stability
• Lateral Axis (Pitch): Controlled by elevators, affecting nose-up or nose-down movements. Longitudinal stability
• Vertical Axis (Yaw): Controlled by the rudder, affecting left or right yaw movements. Directional stability

Stability

• Affected by weight distribution, wing design, and control surface location
• Dynamic Stability: Aircraft's ability to return to steady flight after disturbance. Poor balance between forces leads to instability

Propeller Effects

• Torque: Propeller rotation causes a left-turning tendency countered by the rudder
• P-Factor: Asymmetric thrust at high angles of attack causes yawing
• Slipstream: Spiraling air from the propeller striking the tail causing yaw. Corrected with trim tabs or rudder

Climbing and Gliding

• Climbing: Achieved by increasing angle of attack and applying power. Steady rate of climb establishes equilibrium.
• Gliding: Controlled descent without engine power, using angle of descent and balance of lift, drag, and weight. Best glide speed maximizes range.

Turns

• Lift is divided into vertical and horizontal components
• The horizontal component acts as centripetal force, turning the airplane
• The vertical component must be increased by pulling back on controls to maintain altitude

Spiral Dives

• Steep, descending turn with excessive nose-down attitude
• Rapidly increasing airspeed and rate of descent
• Characteristics: Excessive angle of bank, rapidly increasing airspeed, rapid descent
• Differences from Spins: Airspeed continuously increases in spiral dive, remains low and constant in a spin
• Dangers: Risk of structural damage, high load factors during recovery
• Recovery: Close throttle, level wings, ease out of dive, resume straight and level flight

Airspeed Limitations

• V_S (Stall Speed): Minimum speed for maintaining steady flight
• V_A (Maneuvering Speed): Maximum speed for safe abrupt control deflection or operation in turbulence. Decreases with reduced weight
• V_FE (Flaps Extended Speed): Maximum speed permissible with flaps extended
• V_NO (Maximum Structural Cruising Speed): Maximum safe speed for normal operations, designed for structural integrity in turbulent air
• V_NE (Never Exceed Speed): Maximum speed for safe operation in smooth air, preventing structural failure

Stalls

• Factors Affecting Stalls: Weight, center of gravity, turbulence, turns, flaps, surface contamination (frost or ice)
• Stall Recovery: Lower nose, increase airspeed, return to stable flight conditions

Spins

• Aircraft enters autorotation after stalling, characterized by simultaneous yaw, roll, and pitch around a spin axis
• Stages of a Spin: Incipient Spin (stall to establishing spin), Developed Spin (stabilized with predictable rates), Recovery (breaking the spin)
• Recovery Procedure: Idle power, neutralize ailerons, apply full rudder opposite spin, push control column forward, neutralize rudder and level wings once rotation stops

Pitot-Static Instruments

• Airspeed Indicator: Uses pitot and static sources
• Altimeter: Uses only static source
• Vertical Speed Indicator: Uses only static source
• Pitot Tube: Has three openings
  • Pitot source: Measures total pressure
  • Static source: Measures static pressure
  • Third opening: Equalizes pressures during pre-flight checks
• If Pitot System is Blocked:
  • Airspeed Indicator: Over-reads in climb, under-reads in descent
  • Altimeter: No effect
  • Vertical Speed Indicator: No effect
• If Static System is Blocked:
  • Airspeed Indicator: Under-reads in climb, over-reads in descent
  • Altimeter: Freezes at current reading
  • Vertical Speed Indicator: Stays at 0

Gyroscopic Instruments

• Rotor rotating at high speed in a universal mounting (gimbal)
• Types: Attitude Indicator, Heading Indicator/Directional Gyro, Turn Coordinator
• Powered by: Vacuum, positive air pressure pump, or battery (electrical source)
• Principles:
  • Rigidity in Space (Gyroscopic Inertia): Tendency of rotating object to remain in its plane of rotation
  • Gyroscopic Precession: Force applied to a spinning gyroscope causes reaction 90 degrees away in the direction of rotation

Attitude Indicator

• Also Known As: Artificial Horizon
• Function: Provides artificial horizon reference when natural horizon is obscured
• Gyroscopic Property: Inertia (rigidity in space)
• Power Source: Usually vacuum, some electrically driven
• Shows: Degrees of pitch (nose up/nose down) and wing bank angle

Attitude Indicator Limitations

• Requires at least 4" of suction for operational speed
• Acceleration Error: Sudden acceleration causes "pitch up," deceleration causes "pitch down"

Heading Indicator

• Mounted vertically, spins about its horizontal axis
• Errors: Subject to precession errors, causing drift
• Corrections: Gyro needs regular resetting using magnetic compass

Turn Coordinator

• Combination of a turn indicator and a slip/skid indicator