1. XC 2: Flying Further and Faster

2. The Plan The polar curve and performance Flying Further – maximising the glide Flying faster – in theory In practice – rules of thumb Final glides Technology

3. Performance

4. Polar Curve

5. Different Gliders

6. Flying Further

7. 49/1.62 = 30.3 Glide Ratio at max LD

8. 34/1.85 = 18.4 20 kt Headwind

9. 62/1.55 = 40.0 15 kt Tailwind

10. 60/4.2 = 14.3 2 kts Sink

11. 57/11.2 = 5.1 6 kts Sink & 30 kt Headwind

12. Flying Faster

13. Assumptions: Climb by circling i.e. cover no distance while climbing. Thermal strength is constant with altitude. Thermal strength is known in advance (!)

14. x Caution: Algebra Ahead

15. V = Airspeed S = Rate of Sink (negative) C = Rate of Climb (positive) During the glide we fly distance e with loss of height h in time t 1 We then climb h in time t 2 (1) Total time, t = t 1 + t 2 (2) Average speed, V av = e / t (3) Altitude loss in glide, - h = S t 1 (4) Altitude gained while climbing, h = Ct 2 (5) Gliding time, t 1 = e / V (6) Combining 3 and 4: t 2 = t 1 (- S / C ) (7) Substitute for t 2 from (1): t - t 1 = t 1 (- S / C ) (8) Substitute for t 1 from (5): t = ( e / V )(1- S / C ) (9) Substitute for t from (2): e / V av = ( e / V )(1- S / C ) => V av / V = C /( C - S ) h e

16. Climb of 2kts V av / V = C /( C - S )

17. As our expected rate of climb increases we fly faster. But how much faster?

20. Climb or Glide?

21. Climb of 2kts

23. 2 Kt 6 Kt 15:20 7:30 18:19 13:21 14.49

24. So much for Theory...

25. Rules of Thumb Final Climb = Speed Ring = Initial Climb (Reichmann/Comté) Do I have enough height to get to a (probably) better climb yet? (Chris Rollings) MIAROC – Minimum Instantaneous Acceptable Rate of Climb (Platypus)

26. A Typical Flight 4 Kt 5 Kt 4 Kt 5 Kt 4 Kt 3 Kt 5 Kt 6 Kt 5 Kt 4 Kt 5 Kt 4 Kt

27. 5 Kt 8 Kt 0.1 Kt -2 Kt A Typical BRITISH Flight 0 Kt ? ! ****!

28. Final Glides

29. The Final Climb 4 Kt ?

30. When to Begin? Set McCready to 4 Kts How much more height do I need to arrive home at my chosen safety margin? Remember the wind Keep updating as the climb rate changes When no more height is needed then go!

31. On Glide (or not) If you're getting above glide then increase the McCready setting If you're getting below glide then reduce it and/or take another climb

32. That Safety Margin How far is it? What are conditions like on track? What is the performance of the glider? What is the McCready setting?

33. Having Finished Do remember to... Put the wheel down Dump any ballast Attempt some sort of reasonable landing Not crash