• 170 likes • 556 Views
EUGC Training Talk Wednesday 18 th October 2006. Stalling and Spinning. Horizontal fuselage datum. Chord. Span. Attitude. Flight path. Relative airflow. Flight path. Chord line. Horizontal fuselage datum. Angle of incidence. Angle of attack.
E N D
EUGC Training Talk Wednesday 18th October 2006 Stalling and Spinning
Horizontal fuselage datum Chord Span Attitude Flight path
Relative airflow Flight path Chord line Horizontal fuselage datum Angle of incidence Angle of attack
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
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 = ½CLV12 L2 = ½ CLV22 L2 = 2L1 V2 = V1√2 So if the 1G stalling speed is 37kts, for example, the stalling speed in a 2G turn will be 52kts.
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. Recovery
Attitude – nose high Low airspeed Airflow noise Buffeting Changing effect of controls Stick position Elevator fails to raise the nose Symptoms
Spinning • Glider is asymmetrically stalled • Pitching, rolling and yawing simultaneously • Low airspeed • High rate of descent
Unusual attitude Rapid rotation High rate of yaw Rapid descent Low IAS Low and steady G Laughter from back seat
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