Spinning Flashcards
What is spinning
Pitching/Rolling/Yawing around vertical axis without input
Stages to a spin
Incipient
Fully developed spin
Recovery phase.
Incipient Spin
Aircraft stalls and autorotates.
Initial roll and settle nose down
Recovery:
- Centralise the controls
Starts - When ac begins to autorotate
Ends - First full turn through 360 degrees
Autorotation
After the stall but prior to the spin
Definition: Occurs after the stall but before the spin fully develops. Ac pitches/roll/yaws around a vertical axis without control inputs
Both wings are stalled but one is more deeply stalled than the other
Inside wing has less lift and more form drag
Ac roll and yaw towards the drag
Due to yawing cp behind CG nose will rise
One wing is stalled more than the other - both are stalled
Fully developed spin
Stable flight conditions no control inputs needed to maintain
Steady yawing rolling pitching flight
Recovery Phase from fully developed spin
Close power (remove torque forces from propeller)
Apply full opposite rudder in opposite direction
Push control column central forward
Spiral Diver (Difference from spin)
Airspeed increasing/ G force increasing/Nose further below horizon
Forgetting to level wings before trying to pull out of a dive
CG Position on Spinning
Forward CG - Steeper spin (easier to recover from)
Aft CG - Flatter spin (relative airflow is vertical)
AC characters for a flat spin
Low aspect ratio wings
Inboard engines
Mass concentrated on longitudinal axis
Pro Spin Controls
Forced autorotation from pilot
Full up elevator and full rudder at the stall
Buffet (Aerodynamic Warning)
Turbulent wake from air flow over TE over elevators
Reliable indicator on approach to stall
Stall strips on LE to encourage earlier flow separation
Aerodynamic symptoms at the stall
Intense buffet
Increase aerodynamic noise
Wing drop
Abrupt nose down pitch (Rapid forward CP)
Flapper Switch (Artificial stall warning system)
Mounted on LE
Stagnation point moves down and aft
Once stagnation point behind flapper airflow pushes on it
Horn alarm in cockpit
AOA Vane (Artificial Stall warning system)
Rotates around own axis and measure relative to ac longitudinal axis
Fixed Probe (Artificial Stall Warning)
2 ports which detect angle
Pressure differences sensed at each port and fed back to determine AOA
Rotating probe (artificial stall warning)
Servo motor drives probe around until 2 pressures equal and then calculates wings AOA
“Pitch Eyebrow”
Max safe pitch up angle on PFD
Advantage of Artificial warners
Independent of pitot systems so any blockage in pitot system does not impact warning systems
Power on vs Power off stall
Propeller AC:
High pitch angle means thrust vector pointing downwards contributing to lift reducing the stall speed
Slipstream from propeller increases lift reducing stall speed
Jets:
Under wing engines thrust line below ac CG full power pitch up couple
Recovery of stick pusher
Announce
Disengage autopilot
Apply nose down elevator
Nose down trim
Reduce thrust
Roll
Autorotation cause of roll and yaw
Difference in values of CL and CD for each wing that causes roll and yaw
Effect of CG position on spin
Further forward CG = steeper spin
Further aft CG = flatter spin (difficult to recover)
Mass along lateral axis will….
Spin with large amount of roll
Less yaw and a steeper pitch attitude
(Less sweepback/full tanks/engines mounted outboard)
Mass along longitudinal axis
Will spin flatter
(High aspect ratio/inboard engines)
Spiral Dive Recovery
Close power level/air brakes/level wings and ease out of dive
Incipient Spin Recovery Action
Retard the throttle to idle
Ailerons neutral
Apply full opposite rudder to rotation of spin (look at turn needle)
Apply forward elevator
Recover from dive
Spiral Dive
High static directional stability but low lateral stability
Small sideslip directional stability restore but weak dihedral effect lags behind
Possible cause for auto recovery of aeroplane after the stall
The angle of incidence of the wing is larger than the angle of incidence of the horizontal stabiliser (negative)
