EUGC Training Talk

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Stalling and Spinning

• EUGC Training Talk
• Wednesday 18th October 2006

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Horizontal fuselage datum
Chord
Span
Attitude
Flight path
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Relative airflow
Flight path
Chord line
Horizontal fuselage datum
Angle of incidence
Angle of attack
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• For AoA less than the critical angle lift is
  proportional to AoA.
• Beyond the critical angle lift reduces with AoA
  and drag increases rapidly.

CL
AoA
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(No Transcript)
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• Stalling depends only on the angle of attack
  exceeding the critical angle.
• This can happen at any airspeed given a
  sufficiently high load factor.
• Load factor increased by turning, vertical
  acceleration, winch launch.
• Example in a 2G turn
• L1 ½?CLV12 L2 ½ ?CLV22 L2 2L1
• V2 V1v2
• So if the 1G stalling speed is 37kts, for
  example, the stalling speed in a 2G turn will be
  52kts.

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Recovery

• Stall caused by too high an AoA.
• Therefore recovery is to reduce to AoA.
• Rate of acceleration/decrease of AoA depends on
  attitude.
• Therefore amount of forward movement required
  depends on attitude.
• Failure to lower nose sufficiently results
  inlow/no acceleration risk of another stall.

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Symptoms

• Attitude nose high
• Low airspeed
• Airflow noise
• Buffeting
• Changing effect of controls
• Stick position
• Elevator fails to raise the nose

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Mushing Stall
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Hammerhead Stall
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Stall off a Launch Failure
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Spinning

• Glider is asymmetrically stalled
• Pitching, rolling and yawing simultaneously
• Low airspeed
• High rate of descent

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Unusual attitude Rapid rotation High rate of
yaw Rapid descent Low IAS Low and steady
G Laughter from back seat
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Spin Recovery

• Full opposite rudder
• Centralise the ailerons
• Pause (not normally necessary in gliders)
• Move the stick forwards until the rotation stops
• Centralise the rudder
• Recover from the dive