1. North Carolina Soaring Association
Speed to Fly
Fly faster, turn tighter
Heinz McArthur
North Carolina Soaring Association
July 26, 2008

2. Agenda Glider polars, best L/D, minimum sink MacCready theory
Reichman approach
John Cochrane: “Just a Little More Speed”
Wil Schuemann: “The Price You Pay for MacCready Speeds”
Final glides
P1 notes

3. Polars

4. MacCready Theory
Goal: maximize average cross-country speed using optimal inter-thermal cruising speed

5. MacCready Theory MacCready speeds based on:
Glider performance
Sink rate between thermals
Expected average strength of next thermal
MacCready setting = Expected average strength of next thermal
MacCready setting = Minimum acceptable thermal strength

6. MacCready speeds
Then
Now

7. Reichman update Thermals tend to be stronger in the center
Weaker at the bottom and the top
MacCready setting
final climb = speed setting = initial climb

8. John Cochrane
During flight figure out/adjust the right level of confidence
“How much higher would I have to be in order to finish a minute sooner?”
This is the MacCready value
Take any thermal greater than the MacCready value; leave any thermal below the MacCready value.
Fly the speed ring setting corresponding to the current MacCready value.
MacCready value is the weakest thermal you would take for one circle. It is substantially less than the peak climb in the best thermal of the day.
As you get lower, take weaker thermals and fly slower.
As you get higher, leave weak thermals, stop only for stronger ones, and fly faster.

9. John Cochrane

10. John Cochrane

11. Wil Schuemann

12. Wil Schuemann

13. Wil Schuemann Schuemann’s conclusions
Moderate speed with little variation costs very little XC speed
Reducing MacCready intensity yields more time to think!!! And look outside
Increasing range may improve thermal selection
Slower flight makes air easier to assess

14. Final Glide -- DJ Notes Leave the last thermal
When you can fly the MacCready speed and reach the goal
Plus a safety margin
MacCready setting = Average of the last thermal
The one you’re in
Wind now a factor
Glide angle over the ground
Flatter with a tailwind
Steeper with a headwind
As is wing loading and bugs
Set your calculator accurately
Which requires practice

15. Final Glide -- DJ Notes Psychological Pressures
Glide angle visually flat in modern glas
Excessive sink might be encountered
Flying fast, loud, low
And the turbulence gets rougher lower
And the pilot’s IQ starts to fade
Tunnel vision/narrowed focus dangerous
Must fly the airplane to a safe landing, not just a good finish

16. Final Glide -- DJ Notes Soaring accidents on final glide
Waiting too long to thermal
Relying on Zero MacCready to ‘make it’
Off-landing without preparation, from low altitude
Analyze fields near the airport

17. Final Glide – J7 Notes
Start shifting mentally to ‘final glide mode’ as early as possible
Watch cloud picture as you go into final TP to decide which way to run home
Try a 1 McCready setting to decide when to go on final glide
On some days it makes sense to start below glide path if cloud picture indicates you can work your way up to glide path while mostly sinking!

18. Final Glide – J7 Notes
When on glide path, turn up McCready setting until you maintain glide path, fly as fast (slow) as you are directed
Connect with lift sources, cloud picture on course, pull up in lift
Overly aggressive flying puts you in a field!
Set your arrival altitude to ’ above home field elevation, go much later to 500’.
Allow for another margin if you are not sure of your final glide/wind calculations
Be prepared to see the goal airport at a very shallow angle, it looks as if you won’t make it

19. Final Glide -- XM Notes Set MacCready 3
Leave last thermal when final glide altitude achieved
On glide slope, continue MC speed
Under glide slope, slow down
Over glide slope, speed up

20. P1 notes Shifting gears Speed-to-fly vs thermal heights
Sam Giltner and the blue hole at Winter Haven
Speed-to-fly vs thermal heights
Do you pull up in lift, speed up in sink?
Do you follow the push-pull indicator?
Do you set the MacCready “ring”? When?
When do you start final glide? What speed?

21. Wrap up
“Deciding when to stop and when to leave, and achieving the best average climb rate, are the most important determinants of cross-country speed.”
-- John Cochrane

22. References Cross-Country Soaring: Helmut Reichmann
Cruising for Speed: Sam Zimmerman presentation, 2007 Perry Cross Country Racing Camp
Final Glides: Doug Jacobs presentation, 2007 Perry Cross Country Racing Camp
Glider Polars and Speed-To-Fly: Bob Wander
Just A Little Faster Please: John Cochrane
Preparation for Contest Flying: Herbert Killian, Chicago Glider Club presentation
The Price You Pay For MacCready Speeds: Wil Schuemann
Training for Cross-Country: Article by Helmut Reichmann

23. Glider Polars