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Exercise 10

STALLING

CFS Gliding Examiners © 2009

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1. To monitor speed and prevent the stall

2. To recover from the stall with minimum height loss.

AIMS

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REDUCED G• Reduced g results in a sensation of weightlessness similar to going over a hump-backed bridge

• Occurs when the aircraft pitches down

• The sensation stops when the aircraft stops pitching

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Why does a stall occur ?

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Relativeairflow

Chord line

15°Angle of Attack (AoA)

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At high AOA, turbulent airflow overthe wing breaks away…

…reducing lift…

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…and resulting in dramatic height loss

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HEIGHT

AIRFRAME

SECURITY

ENGINE

LOCATION

LOOKOUT

HASELL ChecksTo be carried out before intentionally stalling

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The 4 symptoms of the full stall are:

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…caused by turbulenceover the tailplane

1. Airframe buffet…

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2. Nose pitches down…

…even though the control columnis held fully back

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3. Possible wing drop

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4. Increased sink

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So the symptoms of the full stall are:

Airframe buffet

Nose may pitch down

Possible wing drop

Increased sink

(but not all symptoms are present at each stall)

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Standard Stall Recovery(SSR)

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Move the control columncentrally forward…

…to select the recovery attitude(approximately the 60 kt approach attitude)

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Wait for 50 kt

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Level the wings with co-ordinated controls (if necessary)

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Select the normal gliding attitude

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So the STANDARD STALL RECOVERY is…

Control column centrally forward to select the recovery attitude

Wait for 50 kt

Level wings (if necessary)

Select normal gliding attitude

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The Steep Stall

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Should the stall occur from a steep entry attitudeThe nose may pitch below the recovery attitude

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To recover from a steep stall,

use the

STANDARD STALL RECOVERY

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The Shallow Stall

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Should the stall occur froma very shallow entry attitude…

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…and a wing drop is less likely

…the nose may not pitch down at all…

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To recover from a shallow stall, use the

STANDARD STALL RECOVERY

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Stall in a Turn

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Should a stall occur while in a turn……there is a likelihood that the wing will drop further

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To recover from a stall in the turn, use the

STANDARD STALL RECOVERY

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If you attempt to raise the downgoing wing with aileron

before achieving 50 kt,

you will make the you will make the situation worsesituation worse

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Stall Prevention

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There are 4 signs of theapproaching stall

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1. Attitude is higher than it should be

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2. Speed is low (because attitude is wrong)

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3. Noise level is reduced because speed is low

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4. Controls less effective because speed is low

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So the 4 signs of the approaching stall are:

Attitude higher than it should beSpeed is low because attitude is wrongNoise level is reduced because speed is lowControls less effective because speed is low

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To prevent the stall:

Monitor speedMonitor speedIf speed is incorrect, adjust attitudeIf speed is incorrect, adjust attitude

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On the approach to land:

• Wrong attitude may not appear abnormal• Reduced noise masked by airbrake• During a stable approach control inputs are small and reduced effectiveness may go unnoticed• The only indication of the approaching The only indication of the approaching stall is reducing airspeedstall is reducing airspeed

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To prevent the stall on the approach:

Monitor speedMonitor speedIf below approach speed:• Close airbrake• Adjust attitude to regain approach speed• When approach speed regained, select airbrake as required• Continue approach, monitoring speedContinue approach, monitoring speed

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THE END

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??Any QuestionsAny Questions

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