28 february 2008don puttock1 use of airbrakes and approach control
TRANSCRIPT
28 February 2008 Don Puttock 1
Use of Airbrakes and Approach Control
28 February 2008 Don Puttock 2
Airbrakes and spoilers
• Airbrakes create additional drag.
• The further out they moved, the greater the effect.
28 February 2008 Don Puttock 3
Airbrakes and spoilers
The high drag reduces the glide performance
28 February 2008 Don Puttock 4
Airbrakes and spoilers
ASK13 (in still air)
•Airbrakes closed 25:1
•Airbrakes open 6:1
28 February 2008 Don Puttock 5
Airbrakes and spoilers
Speed limiting?
• Few gliders have truly speed limiting airbrakes
• Many limit the speed to below Vne in a 45° dive or less.
• For some gliders the dive angle is less than 30°
28 February 2008 Don Puttock 6
Airbrakes and spoilers
The extra drag can cause a decay in airspeed.
Steady 55kt
Steady 55kt
To maintain speed the aircraft must adopt a new attitude.
No Airbrake 38:1 Full Airbrake 8:1
28 February 2008 Don Puttock 7
Airbrakes and spoilers
Opening the airbrakes often have an effect on pitch.
Brakes Closed Brakes OpenASK13
28 February 2008 Don Puttock 8
Airbrakes and spoilers
Opening the airbrakes often have an effect on pitch.
Brakes Closed Brakes OpenGrob 103
The pitch change is type dependent
28 February 2008 Don Puttock 9
Airbrakes and spoilers
The loss in lift caused by opening the airbrakes increases the stalling speed
A point worth remembering with a ballooned landing
28 February 2008 Don Puttock 10
Airbrakes and spoilers
Airbrakes on some gliders will “suck” open
Hold the “Blue” lever firmly and once unlocked do not let go, resist any tendency for them to move uncommanded,
28 February 2008 Don Puttock 11
Airbrakes and spoilersOpening the Airbrakes in high g redistributes the wing bending loads
Lift DistributionLift Distribution
28 February 2008 Don Puttock 12
Airbrakes and spoilers
Spoilers disrupt the airflow causing a reduction in lift
The spoilers are normally opened against a spring –let go and they close
Spoiler
Wing
28 February 2008 Don Puttock 13
Airbrakes and spoilers
Tailchutes increase the drag dramatically
28 February 2008 Don Puttock 14
Airbrakes and spoilersTrailing edge brakes
Can have a rapid and pronounced effect on speed and pitch
28 February 2008 Don Puttock 15
Approach Control
28 February 2008 Don Puttock 16
Approach Control
Purpose of the approach
• To intercept and maintain a 2/3 airbrake approach.
• To maintain airspeed through the wind gradient.
• To “round out” at a desired location.
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Approach Control
• Advantages----opportunity to adjust in both directions
• Clearing obstacles/landing short.
28 February 2008 Don Puttock 18
Approach Control
Scraping in over the fence with zero brake is not safe.
Creeper approach---no margin for error
28 February 2008 Don Puttock 19
Approach Control
• Effect of the wind on approach path
28 February 2008 Don Puttock 20
Approach Control
Effect of wind gradient on speed
It why we have additional speed for our approach.(1.4Vs+ ½ wind)
28 February 2008 Don Puttock 21
Approach Control
Selecting a reference point
28 February 2008 Don Puttock 22
Approach Control(Normal)
28 February 2008 Don Puttock 23
Approach Control(Normal)
28 February 2008 Don Puttock 24
Approach Control(Normal)
28 February 2008 Don Puttock 25
Approach Control(Normal)
28 February 2008 Don Puttock 26
Approach Control(Normal)
ES
Normal approach
28 February 2008 Don Puttock 27
Approach Control(wrong)
28 February 2008 Don Puttock 28
Approach Control(wrong)
28 February 2008 Don Puttock 29
Approach Control(wrong)
28 February 2008 Don Puttock 30
Approach Control(wrong)
28 February 2008 Don Puttock 31
Approach Control(wrong)
ES
Approach looks right but speed decaying
28 February 2008 Don Puttock 32
Approach Control(wrong)
28 February 2008 Don Puttock 33
Approach Control(wrong)
28 February 2008 Don Puttock 34
Approach Control(wrong)
28 February 2008 Don Puttock 35
Approach Control(wrong)
28 February 2008 Don Puttock 36
Approach Control(wrong)
ES
Approach looks right but speed increasing
28 February 2008 Don Puttock 37
Approach Control(Undershoot)
28 February 2008 Don Puttock 38
Approach Control(Undershoot)
28 February 2008 Don Puttock 39
Approach Control(Undershoot)
28 February 2008 Don Puttock 40
Approach Control(Undershoot)
28 February 2008 Don Puttock 41
Approach Control(Undershoot)
ES
Undershooting
28 February 2008 Don Puttock 42
Approach Control(Overshoot)
28 February 2008 Don Puttock 43
Approach Control(Overshoot)
28 February 2008 Don Puttock 44
Approach Control(Overshoot)
28 February 2008 Don Puttock 45
Approach Control(Overshoot)
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Approach Control(Overshoot)
ES
Overshooting
28 February 2008 Don Puttock 47
Approach Control
• Top Tips
• Longer approaches give you time to settle.
• Airbrakes change your rate of descent
• Attitude (via the stick) gives you airspeed.
• Make few adjustments to the airbrakes---consider before acting.
• Select a reference point (RP)
28 February 2008 Don Puttock 48
Approach Control(Normal)
28 February 2008 Don Puttock 49
Approach Control(Normal)
28 February 2008 Don Puttock 50
Approach Control(Normal)
28 February 2008 Don Puttock 51
Approach Control(Normal)
28 February 2008 Don Puttock 52
Approach Control(Normal)
28 February 2008 Don Puttock 53
Approach Control(Normal)
ES
Normal approach