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4. Stall warning
5. Control buffet
Considerations:
Manoeuvres
- When pulling out of a dive, applied back pressure, AoA, L hence LF.
- The stall speed in a manoeuvre can be calculated using
VNS = VS LF
- In addition to that, the load factor in a turn can be calculated using
LF = 1 / Cos(AoB)
eg. In a steep turn: AoB = 60 LF = 2g so, VNS = 62KIAS
A stall occurs at an AoA, not an IAS
Actual Stalled Flightpath
Attempted 3G
Pullout
Planned
Flightpath
Increased
Stall Speed
1G 2G 3G 4G
2.0
1.8
1.6
1.4
1.2
1.0
“g” load
RMIT Flight Training Stalling
RMIT Instructor Rating Mass Briefs Issue 1 /2004 Page 6 Brief 8
Weight
- As weight increases, lift must also increase. When both aircraft achieve
the critical angle the heavy aircraft must fly at increased IAS to produce
the additional lift required.
CoG
- Forward movement of the CoG will increase the strength of the nosedown
couple between lift and weight as a result increase the amount of
downforce required on the tailplane
- In effect this increase of downforce is similar to an increase in weight and
therefore a forward CoG will lead to an increased stall speed.
Ice
- Ice disturbs the streamline airflow causing earlier separation.
- Also W, which requires L hence VS.
L
L
W
W
16o 16o
40 kt 44 kt
RMIT Flight Training Stalling
RMIT Instructor Rating Mass Briefs Issue 1 /2004 Page 7 Brief 8
Flap
- Lowering flap increases the aerofoil’s camber and AoA for the same
attitude. Therefore at the same AoA (ie. critical angle) the flaps allow the
aircraft to fly at IAS with a lower nose attitude.
- With flap, more lift is generated on the inboard portions of wing (closer to
CoG), reducing lateral stability and becoming more susceptible to a
wingdrop.
Power
- Slipstream re-energises the airflow over the inboard sections of the wing,
delaying separation. Also the vertical component of thrust assists in
counteracting the weight.
- Like flaps, the wingtip may stall first (due less airflow) causing a wingdrop.
Stability in the Stall
- Reduces the angle of incidence on wingtip compared to the wing root.
- Ensures the wing root stalls first providing control buffet on the elevator
and a more stable stall.
16o 16o Relative Airflow
High Nose Attitude Lower Nose Attitude
Thrust
TH
TV
Smaller AoA
Relative Larger AoA
Airflow Cross-Section
at Wing Tip
Cross-Section
at Wing Tip
RMIT Flight Training Stalling
RMIT Instructor Rating Mass Briefs Issue 1 /2004 Page 8 Brief 8
Air Exercise:
Pre-Stalling Checks
- Height sufficient to recover by 3000ft
- Hatches/Harnesses secure.
- Engine Temperature & Pressure.
- Location – not above a populated area.
- Loose articles secure.
- Lookout (360 turn)
Entry
- Pick a reference point (maintain with rudder not ailerons)
- Retard throttle, maintaining height.
- Note previously discussed symptoms.
Stall
- Nose pitches down.
- Note height loss
Recovery
- Lower nose to horizon.
- Speed increases through 65KIAS, full power.
- Climb out.
Wing Drop Recovery
- Apply opposite rudder to stop yaw.
- Lower nose to unstall attitude.
- Passing 65KIAS, full power.
- Climb out.
Airmanship:
- INADVERTANT STALLS SHOULD NEVER OCCUR!
- Lookout (conduct 90 turn after each stall).
- Smooth co-ordinated control input – especially during recovery.
- Correct Handover/Takeover procedure.
- Monitor engine gauges.
Stalling Mass Brief
Aim
• To discover the aerodynamic principles and
factors of a stall. Considering the approach
to a stall, recognition of the symptoms, and
how to recover with minimum height loss in
varying configurations.
Application
– High AoA / Low IAS Operations
– Take-off and landing
– Inadvertent stall recovery
Overview
• Aim
• Revision
• Definitions
• Principles
– Stalling
• Considerations
• Air Exercise
• Airmanship
• Review
Revision
• Aerofoil and Lift
Airspeed
Lift
Revision
Drag
Induced Drag
Parasite drag
TOTAL DRAG
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