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Can an aircraft that is not stalled be in a spin?
No. Both stall and yaw must be present to spin
Define spin axis
Aerodynamic point around which stall and yaw forces act to sustain spin rotation
Define poststall gyration
- Aerodynamic forces during stall that result in movement around the pitch, roll and yaw axes
- Can introduce yaw and spin entry
- Higher the airspeed - greater the poststall gyration tendency
- Lower the airspeed - Less the poststall gyration tendency
What is the key factor affecting the intensity of poststall gyrations?
The airspeed at the time of stall
What is the definition of angle of attack (AOA)?
The angle between the chordline and the relative wind
In a spin, which wing will have the higher AOA, up-going (outside wing) or down-going (inside wing)?
Down-going (inside) wing
What is the cause of autorotation in a spin?
Unequal lift and drag forces acting on each wing
How does pitch affect spins?
Lower the pitch results in higher rotation rate
If stalled and yawed, an aircraft pulling positive or negative G's, would enter a inverted spin?
Negative G's + stalled and yawed= inverted spin
- Nose will pitch up
- Lesser vertical component of drag acting on tail
- Rotation rate slows, then, increases
- Nose will pitch down
- Larger vertical component of drag acting on the tail
- Rotation rate increases, then, decreases
How does anti-spin rudder aid in recovery?
Slows rotation and decreases AOA
Would an aircraft spinning with the stick other than full aft be in an accelerated or unaccelerated spin?
Anytime the aircraft is spinning with the stick other than full aft, the spin is accelerated
- Caused by maintaining full up elevator while holding anti-spin rudder
- Characterized by lowering of the nose and spin direction reversal
- Caused by maintaining pro-spin rudder and moving stick forward of neutral
- Characterized by immediate increase in nose-down pitch and increased roll rate
Lighter aircraft spin characteristics
- Faster spin entry
- Increased oscillations
- Faster recovery
Heavier Aircraft spin characteristics
- Slower spin entry
- Less oscillations
- Slower recovery
For any given power setting, stall speed varies inversely with pitch attitude:
- Low pitch attitude=higher stall speed=faster entry with more oscillations
- High pitch attitude=slower stall speed=slower entry with fewer oscillations
Flying at a given pitch attitude, stall speed varies inversely with power setting:
- Low power setting=higher stall speed=faster entry with more oscillations
- High power setting=slower stall speed=slower entry with fewer oscillations
- Stabilizes at lower pitch
- Stabilizes slower with more oscillations
- Rotation rate increased
- Stabilizes at higher pitch
- Stabilizes faster with less oscillation
- Rotation rate decreased
What causes the variance in left and right spin characteristics?
Gyroscopic effect of the propeller
How does the introduction of yaw affect the lift and drag of a stalled wing?
Causes asymmetrical lift and drag between the outside and inside wing
What is the main aerodynamic factor affecting spins?
Conservation of angular momentum
How can a progressive spin be entered?
By maintaining full aft stick while applying and holding anti-spin rudder