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PHILADELPHIA GLIDER COUNCIL

PHILADELPHIA GLIDER COUNCIL. PGC. XC Soaring Lift Sources. Ken Kochanski 2/21/2004. PHILADELPHIA GLIDER COUNCIL. PGC. Prerequisites. Skepticism of Weather Forecast(ers) Verified TE Compensation Audio Variometer - A Must !!! Proper CG Location for Thermalling Logical neat panel

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PHILADELPHIA GLIDER COUNCIL

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  1. PHILADELPHIA GLIDER COUNCIL PGC XC Soaring Lift Sources Ken Kochanski 2/21/2004

  2. PHILADELPHIA GLIDER COUNCIL PGC Prerequisites • Skepticism of Weather Forecast(ers) • Verified TE Compensation • Audio Variometer - A Must !!! • Proper CG Location for Thermalling • Logical neat panel • Proficient Speed and Bank Control L&R

  3. PHILADELPHIA GLIDER COUNCIL PGC Thermal Formation • Insolation warms surface features • Sheltered warmed air accumulates • Inertia/surface tension constrains • Trigger mechanism releases thermal • Rises through unstable atmosphere • Cu form … with sufficient moisture Reichmann:Cross Country Soaring

  4. PHILADELPHIA GLIDER COUNCIL PGC Thermal Structure • Strong rising core surrounded by sink • Narrow, disorganized and weaker low • Stronger and wider with altitude • Weaker approaching cloud-base (?) • 600’ - 1000’ diameter at altitude • Limited lifespan … and steady state • Multi-core and other Forms • Rotation (?)

  5. PHILADELPHIA GLIDER COUNCIL PGC 200 FT 8 KT 6 KT 4 KT 2 KT 0 KT -2 KT 1,000 FT March 30th, 2000 Fire-induced Cumulus Cloud Tom Warner shot air photo in Northern Nebraska Lift Cross Section

  6. PHILADELPHIA GLIDER COUNCIL PGC Height/Cu Forecast • Thermal/Cu Height goes up during day • Drying air can suppress afternoon cu

  7. PHILADELPHIA GLIDER COUNCIL PGC Finding Thermals • When you’re high … fly the sky • Cu, wisps, haze domes • Birds, debris, gliders • When you’re low … look below • Terrain, junk yards, hay fields, heat source • Smoke, crop movement, flags, debris • Spacing is related to convection depth • Mark and return to excellent thermals

  8. PHILADELPHIA GLIDER COUNCIL PGC Thermal Entry/Exit • Plan entry at least a mile ahead • Transition sink at cruise speed • Trade cruise speed for altitude • Join gaggle safely • Occupy visible position • ‘Moffit’ exit through center if safe

  9. PHILADELPHIA GLIDER COUNCIL PGC Centering Techniques • Don’t turn too soon • 270 degree correction to search • Toward lifted wing/yaw string swing • Tighten in surge • Minimum smooth control movements • Search/Adjust constantly • Can’t climb/center? … you’re not alone

  10. PHILADELPHIA GLIDER COUNCIL PGC Thermalling Speed/Bank • Goal: Attain highest climb rate • Libelle bank/sink/diameter comparison Diagonal Screws Horizontal for 45 Deg. Bank

  11. PHILADELPHIA GLIDER COUNCIL PGC Evaluating Thermals • Evaluate in every climb from tow • Identify lift chars and operating band • Thermal core relative to cloud base • Ground shadows for size and distance • Look at Cu size/shape/cycle during cruise WinPilot PRO -Climb Maximizer Page

  12. PHILADELPHIA GLIDER COUNCIL PGC Speed To Fly • MacCready sets min. value for next thermal • Reichmann says set for start/end of climb • Plus you have to reach next thermal • 70 – 100 mph typical in East (2–4 kts) • Slow down in lift … Speed up in sink

  13. PHILADELPHIA GLIDER COUNCIL PGC Optimization • Correct MacCready value selection • Stepped MacCready operating bands • Minimize Thermal Entry/Exit Losses • Course Deviation • Dolphin flight

  14. Stepped MacCready John Cochrane – Fly A Little Faster Please

  15. PHILADELPHIA GLIDER COUNCIL PGC Entry/Exit Losses John Cochrane – Fly A Little Faster Please

  16. PHILADELPHIA GLIDER COUNCIL PGC Course Deviations • 30 Degree Deviation = 15% • Distance Increase • A 3 Mile 30 Deg. Deviation @ 80 Kts • ‘costs’ 20 seconds • At MacCready 3 … this is an even • trade if you gain 100’

  17. PHILADELPHIA GLIDER COUNCIL PGC Cruise/Dolphin Flight • Netto Variometer helpful • Slow up to low cruise speed range • S-turn to explore • Thermal … or accelerate in lift • Course deviations to lift • Cloud shadows for bearing/distance

  18. PHILADELPHIA GLIDER COUNCIL PGC DIY Climb/Speed Calcs • 150 Mile Course = 5 Mile Climb @ 30:1 • 5 x 5280’ = 26,000’ – 5,000’ AGL Start • 20,000’ climb @ 200 fpm = 100 Minutes • 150 miles @ 70 mph = 130 Minutes • 3:50 for 150 Miles = 40 MPH • Use SeeYou for analysis of your flight

  19. PHILADELPHIA GLIDER COUNCIL PGC Cloud Streets • Wind > 15 knots + stable cap layer • Excellent lift … and awful sink • Spacing 3x Convection Depth • Potential Lee Waves over top • 30 degree course deviation OK • 90 degree transition between streets • Use ‘blue’ extension of street • Turn-point access/exit strategy Drawing: A Met Guide For Beginners – Tom Bradbury

  20. PHILADELPHIA GLIDER COUNCIL PGC Blue Days • Stable or dry/drying air • Thermals as frequent and as strong • Follow terrain - high, dry, sun-facing • Turn crosswind in heavy sink • More dependence on gaggles • Haze domes may appear in afternoon

  21. PHILADELPHIA GLIDER COUNCIL PGC Shifting Gears • Has the air changed in the last 10 minutes? • Shift down (or up) for declining conditions • Up-shift in improving air or after trouble • Can’t climb/center? … you’re not alone

  22. PHILADELPHIA GLIDER COUNCIL PGC Low Altitude Saves • Field selected and appraised • Radio volume down/off • Additional airspeed • Turn immediately in lift • Don’t leave below 2000 feet AGL • 600 FPM down = 200 feet in 20 seconds

  23. PHILADELPHIA GLIDER COUNCIL PGC Ridge Running • Ridge sites/camps best initial experience • Wind Speed and Direction Important • Ridge Shapes/Orientation/Gaps • Wave and Thermal Suppression • Crotch Strap and No-Hands “P” System

  24. PHILADELPHIA GLIDER COUNCIL PGC Ridge Thermals • Favor Upwind side of ridge • Often rough/strong … with small cores • Initial turns always away from ridge – 8’s • Circle when > 200 feet above ridge top • 1000 FPM down = 330 feet in 20 seconds • Ridge thermal can suppress weak ridge • Have a field or retreat plan

  25. PHILADELPHIA GLIDER COUNCIL PGC Wave/Rotor • Typically After Cold Front – U/S/U • Lennies … Rotor Clouds … or None • Terrain or atmospheric generators • Parallel to Ridge – 1st, 2nd, N Cycles • Interference Patterns – Peaks/Nulls • Inter-day Wavelength Changes • Rotor/Thermal Entry

  26. PHILADELPHIA GLIDER COUNCIL PGC Wave Entry/Flying • Wave Induced Cumulus • Climb upwind side of rotor • Transition through windows • Fly directly upwind … or crab • Cold, O2, Visibility Issues

  27. PHILADELPHIA GLIDER COUNCIL PGC Other Lift Sources • Sea Breeze Fronts • Temp or Moisture Frontal Systems • Thunderstorms/Dust Devil • Gap Roll/Obstruction Waves • Magic Lift

  28. PHILADELPHIA GLIDER COUNCIL PGC Reading/Research • Moffat – Winning on The Wind • Reichmann – XC Soaring • Knauff/Wander/Bradbury • Internet – Many Resources

  29. PHILADELPHIA GLIDER COUNCIL PGC Mark … Good Finish !!! Ken Kochanski

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