Transcript THERMALLING BASICS - Soaring Association of Canada

THERMALLING
(and how to avoid landing out)
• Other possible titles:
“How I landed out over 50 times.”
“50 Farming families I’ve met.”
“ S.W. Ontario walking tours.”
Purpose
• Improve your soaring skills.
• By learning from the mistakes of others.
• Reach the point where you enjoy cross
country soaring.
• Give you some insights into current
thinking about cross country.
• Pass along your new skills and insights to
fellow pilots.
The Need for Speed
• All cross country flights are a race against time.
• Essential to understand the importance of a
superior climb rate as compared to high interthermal speed.
(Any fool can fly fast!)
• Thermal activity – weak in morning and late
afternoon – requires tactical adjustments.
• Late in the day – STAY HIGH!
First Cross Country
• The 50 km. task is easy – in a modern
glider – assuming decent weather
conditions..
• 6,000 feet msl. at SOSA – York Soaring is
in the bag.
• The biggest barrier you face is the
psychological fear of cutting the apron
strings.
YOUR OBJECTIVE
• Badge flying is NOT a competition.
• Your purpose is to COMPLETE THE
TASK.
• Who cares if you complete a 300km. flight
in 4 hours or 6 hours?
• You should ! Higher speed requires mental
discipline and courage.
• Yet, enjoy the experience – the journey is
just as important as the achievement.
The Big One – 300km.
• Junior glide ratio is 34:1 at fairly high airspeed.
• Most modern fiberglass gliders are in the 33:1 to
37:1 range. Astir, Libelle, Junior, Std. Cirrus.
• “Even” a 1-23, 1-34 or a 1-35 are capable of
300 km. + +
• The key – good thermalling skills and adequate
planning.
• Conclusion – 300 km. flight is possible on many
“average” soaring days in S.W. Ont.
PLANNING
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Check lists.
Weather forecast?
Declaration.
Water*, Food.
Pee system.
Map preparation – do not
rely on GPS.
• Course line?
• Key radio frequencies.
* Top priority for safety!
• Know how to operate
your instruments –
vario, computer, radio
etc.
• Can you reach
everything?
• Weather shaping up per
forecast?
• Take your time – let the
day develop.
• Get input from qualified
pilots.
• Be positive – don’t get
psyched out!
The Big Day
• Once airborne, get a feeling for the day.
• How do actual conditions compare to the
forecast?
• Thermal strength and ease of connecting.
• Wind shear – at what height?
• Operating band*– thermals consistent above
2,500 feet or higher?
• Resist the pressure to start too early!
*Note – operating band will change as the day
develops.
Thermal Indicators
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Other gliders – most times.
Birds – hawks and seagulls.
Dust “devils” – ploughed fields.
Debris – plastic bags, hay, small cars.
Slopes, ridges, hills, towns, factories
etc.
• Fires – often quite small but powerful.
• Remember the rule ……
Thermal Indicators
• WHEN HIGH …..
Use clouds or haze domes.
• WHEN LOW…..
Use terrain features.
On overcast (overdeveloped) days fly to
areas of sunshine.
Common Thermalling Errors
• Look outside – keep your head out of the
cockpit!
• Use the audio function.
• Use ALL your senses.
• Speed control – fly attitude – fear of
stalling?
• Angle of bank – fear of stalling?
• How do I calculate my bank angle?
Calculate my bank angle?
• Airspeed – you know.
• # seconds to complete 360°
turn – you know.
• Gives you approximate
angle of bank.
Circling Time in Thermals
Bank
angle
30°
35°
40°
45°
40 knots
45 knots
50 knots
55 knots
23 sec.
26 sec.
29 sec.
31 sec.
19 sec.
21 sec.
24 sec.
26 sec.
16 sec.
18 sec.
20 sec.
22 sec.
13 sec.
15 sec.
16 sec.
18 sec.
Circling Time in thermals
• Better pilots typically fly at 45 to 55 knots
@ 19 – 23 seconds per turn.
• If you are wandering around at 20 degree
angle of bank – you cannot thermal
efficiently.
• Good training – Blanik @ 42 knots –
around 19 to 20 seconds.
• Caution – remember laminar flow … you
can also thermal too slowly.
Common Thermalling Errors
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Turning too soon when you enter a thermal.
Banking at high speed : 60 knots + +.
Chasing the vario – remember vario lag.
Ignoring the yaw string.
Rough control movements once established in
the thermal.
• Entering thermals at high speed.
• Leaving thermals at high speed.
Common Thermalling Errors
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Taking every thermal.
Thermal “love in” – the last to leave?
Follow the mob or lead?
Team flying – single file or spread out?
On blue days it is essential that all gliders
on a task spread out.
“Average” thermal strength
• Typical flight computer – average thermal
strength based on:
– Start of climb?
– Last 10 seconds?
– Last 20 seconds?
– Last minute?
– Duration of flight?
– Computers have given us greater insight into
achieved speeds.
Average thermal strength
• Typically based on the past 20 to 30
seconds.
• That is why a 4 knot day really turns out to
be a 1.7 to 2.0 knot day when you analyze
the data.
• Beware of optimistic radio calls – “5 knots
here.”
Thermal strength* in knots
*(Assuming 4 turns to center)
Height
gained
1,000
ft.
2,000
ft.
5,000
ft.
1 knot
climb
0.7
2 knots 4 knots 6 knots
climb
climb
climb
1.1
1.5
1.8
0.9
1.7
2.9
3.8
1.0
1.9
3.4
4.8
Cruising between Thermals
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This should be a very busy time for you.
How fast to fly?
How slow?
Go left?
Go right?
Fly through the blue hole ahead?
Avoid the overcast on course line?
Catch up with that LS 8 ahead?
Cruising between thermals
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How FAST should I fly?
If I fly too fast, what happens?
If I fly too slowly, what happens?
The good old days of “pure”
MacCready ring settings.
Impact of Conservative Ring
Setting
Thermal
Strength
4 knots
Achieved!
6 knots
Achieved!
8 knots
Achieved!
# 2 setting
costs you:
3%
6%
9%
# 4 setting
costs you:
0
1%
3%
# 6 setting
costs you:
1%
0
1%
Impact of Conservative Ring
settings
• If you set the MacCready ring at “0”
• How much performance/time do you lose?
• Answer – 20%........ Leading to a high
probability of an out-landing!
• Why?
• Reduces your thermal search area.
• Limited amount of thermal activity during
the day – you run out of time.
Thermal Probability
S.W. Ontario*
1 mile
5 miles
1 knot
20
90
2 knot
10
61
4 knot
5
30
6 knot
2
10
* Standard class glider.
10 miles
99
84
52
18
KEY LESSON
• IT TAKES TIME TO CENTER THERMALS!
• A “good” pilot will take FOUR turns to core a
thermal. That is 120 seconds, 2 minutes – a
long, long time, going nowhere!
• A really superior pilot will center the thermal in
two turns. Time saved during a 20 thermal flight?
• 10 minutes!!
• An “average” pilot may NEVER center the
thermal.
How to read Clouds
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Depth of cloud – vertical development.
Shape, Texture, Curl over.
Solid, dark base.
Firm profile – not fuzzy.
Cloud shadow. (Overdevelopment?)
Growing clouds, Mature clouds and dissipating
clouds.
• Learn to recognize the differences!
• Beware of towering Cu.
How to Read Clouds
• Rule of thumb – 1 in 3 clouds working.
• Thermal height is proportional to distance
between thermals.
• 8,000’ cloud base – thermals far apart, lots
of sink.
• 3,000’ cloud base – thermals close
together, not much sink.
• Thermal cycles - try to get in phase with
growing clouds.
While you are thermalling…..
• Read the sky ahead.
• Pick out growing cloud(s) – have more
than one option!
• Avoid blue holes!
• Select best course line based on cloud
layout.
• If you deviate – try to deviate upwind.
Between Thermals
• Blue holes - course line deviations. How
far ? Remember your objective!
• Upwind or downwind?
• Cloud shadow.
• Overdevelopment – how to handle?
• Cloud streets – visible and not so visible.
• Sink streets – be decisive – act quickly.
• Blue days – sunglasses.
Between Thermals
• Lake effect.
• Turn point in blue air – what to do?
• First – decide how far you have to fly in
blue air.
• Second – climb as high as possible.
• Slow down and be patient.
• Work weak lift in blue air – particularly
after turn point- wind at your back.
Course deviations
• Remember your mission !
• A 30° course deviation causes you to fly
15% further.
• At 80 knots, 3 miles and 30° deviation
costs you 20 seconds.
• If you gain a mere 100 feet, you are better
off than the blue hole puncher.
Course Deviations
(The Tortoise and the Hare)
• High personal confidence in my
thermalling ability.
• Shortest distance (best speed) between
two points? Straight line ?
• Flying with others showed that the most
effective way to fly between two points is
frequently made by deviating under
“wimpy” lift.
Effective Inter-thermal Flying
• Fly with purpose! Don’t let the thermals
push you around
Effective Inter-thermal Flying
• When you feel lift always slow down
and turn into it
• Anytime you can climb while flying
straight on course is advantageous
Turn point Tactics
• Take upwind turn point……….. LOW.*
• Take downwind turn point…… HIGH.
*( Within reason, of course!)
• Bartell – “ a 2 knot thermal going
downwind is as good as an 8 knot thermal
going upwind.”
Key Points
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Read clouds carefully.
Enter and leave thermals correctly.
Turn tightly.
Be selective with thermals you take.
Use conservative MacCready settings.
Speed up by slowing down between
thermals.
• Be flexible!
Thermalling Rules
• First glider in thermal establishes direction
of turn.
• When joining a thermal do NOT interfere
with other gliders.
• Keep yourself visible to other pilots in the
thermal.
• If you are climbing faster than other gliders
– you must not impede other pilots
• Maintain a good lookout at all times.
Psychological Factors
• The importance of flexibility - learn to
adjust your pace.
• At 7,000 feet ignore weak lift.
• At 2,000 feet take anything!
• High = Fast
• Low = Slow
• Be patient – a 1.5 knot thermal at 1,200
feet may be a 4 knot thermal at 3,000 feet
Psychological Factors
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Develop stamina – both physical and mental.
Fight the urge to “do something”. Be patient!
Avoid follow the leader – fly your own flight.
Fight the urge to “catch up” – the need for
companionship.
• Remember your objective – finish the task
safely.
Psychological Factors
• The need for companionship – follow the
leader often puts your brain in neutral.
• Think for yourself – avoid the herd
mentality.
• The other guy is just a dumb as you are.
(Most of the time, anyway!)
Psychological Factors
• Don’t get sucked in by higher performance
gliders.
• Be realistic about your gliders
performance:
Astir versus Ventus
Hornet versus LS 6
LS 6 versus Nimbus 3
• McMaster strategy – optimize your gliders
performance envelope.
Airport Hopping
(Airport hoping?)
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Seductive for the low time pilot.
Pros and cons. Silver distance – o.k.
Dangerous for longer flights?
Your energy and concentration is on the next
airport and NOT on weather reading.
• Actually slows your speed dramatically.
• Many airstrips are very narrow!
• Target fixation – final glides…. The mind stops
working!
PRACTICAL STEPS
• The importance of weak days.
• Use 1 knot thermals around the field.
• Work on low saves around your Club.
(Just brief the Duty Instructor!)
Work on stamina.
• Release early. The Tow pilot creed – “if he
fails to release in lift, he must want sink”.
Summary
• Develop thermalling skills – particularly on weak
days.
• Constant angle of bank, constant airspeed.
• Tight turns !
• CONSERVATIVE ring setting.
• Make haste slowly and steadily.
• Read the sky ahead.
• Avoid blue holes.
• Work on long inter thermal glides – 15 to 20km.
• Lead – don’t follow.
• Have fun!
Recommended reading list
• Soaring Cross Country
• New Soaring Pilot
Irving
• Winning 11
• The Platypus Papers
• Meteorology for glider pilots
• Transition to gliders
Reichmann
Welch &
Moffat
Bird
Wallington
Knauff
Recommended Reading List
• A comprehensive reading list will be
e-mailed along with a copy of this
presentation.
E-mail address:
[email protected]