thermal acquisition and centeringwhen to stay and when to leave • never fly through the same bad...
TRANSCRIPT
Thermal Acquisition Thermal Acquisition and Centeringand Centering
How to Have Fun
Soaring Cross Country
Finding and Centering Lift Finding and Centering Lift
• The most important skill for successful cross country soaring
• Cannot be learned without soaring cross country
How Do You Find LiftHow Do You Find Lift
• Look for it in as many places as you can
• Fly through areas where it is most likely to be
Required Equipment?Required Equipment?
• Audio variometer• Total energy probe• The seat of your pants
Considerations of DistanceConsiderations of Distance
• Long range considerations…20 miles– Choosing your course
• Medium range considerations…5 miles– Sampling individual thermals
• Close range considerations…1 mile– Finding the core
Long Range… Long Range… Choosing Your CourseChoosing Your Course
• Terrain• Clouds• Off-course deviations
Medium Range…Medium Range…Thermal SourcesThermal Sources
• The crest of ridges• High ground• Thermal contrasts
Sampling ThermalsSampling Thermals
• Minimize energy loss while cruising• Optimize your opportunity to find the
best thermals• Sample many, use a few• Connect the dots• Wifferdiddle
Thermal IndicatorsThermal Indicators
• Clouds• Other gliders• Haze domes on blue days• Dust devils
Close Range…Close Range…Finding the CoreFinding the Core
• Other gliders in the thermal• Professionals nearby• Darker areas of cloud• The side of the cloud that has been
working• The firm feel of a core
The Lift Profile of a ThermalThe Lift Profile of a Thermal
Approaching a ThermalApproaching a Thermal
• Keep speed up through sink• Slow down a little as lift increases• Don’t turn too soon, wait for upsurge• Turn toward lifted wing• When you feel it, center it
Bank Angle and AirspeedBank Angle and Airspeed
• Bank steeply…normally 45 °• Fly 20% faster than minimum sink
– 42 kts min sink is 50 kts at 45 degrees
• Fly shallower and slower only in large smooth areas of lift
Centering MethodsCentering Methods
• 1- Decrease bank as climb increases
• 2- Increase bank as climb decreases
• 3- Combine 1 and 2
Blue ThermalsBlue Thermals
• Look for thermal triggers• Look for streeting along the wind line• Turn into the wind
Thermal EtiquetteThermal Etiquette
• Enter a gaggle without causing a disturbance
• Fly predictably• Keep your eyes out of the cockpit• Don’t turn your inside other ships unless
well clear• Avoid a “double-blind” situations
Thermal EntryThermal Entry
Re-Acquiring LiftRe-Acquiring Lift
• Common cause is falling out the downwind side
• Fly into the wind to re-acquire
When to Stay and When to Stay and When to LeaveWhen to Leave
• Never fly through the same bad air twice!
• Don’t waste time in weak lift• Leave when the rate of climb decreases
– But only if you have a high probability of finding a better thermal