1. Data logging and telemetry:
tools for performance optimization
Francesco Meschia

2. I fly gliders
• Since 2000
• Slope soaring since 2003
• FAI F3J since 2006
• Team manager for the F3J Italian team in 2007,
2008, 2011
• Team pilot for the F3J Italian team in 2009
• FAI F5J since 2011

3. I fly F3J

4. F3J launch
• Man-on-man competition (6-15 pilots)
• No winches!
• Two-men tow with monofilament line (500 ft)
• Incredible amount of energy!

5. F3J launch tenets
• You don’t launch high, you lose
• You don’t launch fast, you lose
• You don’t launch strong, you lose your friends
– towmen, that is

6. F3J Launch Optimization: why?
• “We’ve been watching the German guys
closely, our planes don’t launch nearly as
strong as theirs do – we need to understand
why, quick!” (G.Gallizia, 2008, after the F3J
Eurotour France contest)

7. F3J Launch Optimization: what?
• Three simple things we can play with
– launch camber
– elevator preset
– towhook position
• Can’t be that hard, huh?
– well, it turns out it is…

8. F3J launch optimization: how?
• Need to set a goal
• Need to measure the outcome
• Need to analyze how the parameters
influence the outcome
• Need to find a path to improve

9. Measure to know
• Optimization goal is to extract maximum
energy in the shortest time
– time is easy to measure
– how to measure energy?
• Energy at the end of the launch comes in two
forms:
– gravitational potential energy (i.e. “how high”)
– kinetic energy (i.e. “how fast”)

10. Tools of the trade: data recorder
From
top
le*,
clockwise:
www.eagletreesystems.com,
www.sm-­‐modellbau.de,
www.rc-­‐electronics.org

11. Launch Log
Altude
Airspeed

12. Data recorder: how to install?

13. Data recorder: a better installation

14. Data recorder: the pod

15. Data reduction and analysis
• Just altitude and airspeed – ok for end state
only
• Need something more if we want to
understand what’s going on
• How does energy “flow” from towing system
to plane?
– towmen pull line, line pulls plane
– wait! the line!

16. The importance of the towline
• Energy goes into line and from line into model
• Line stretches with tension
– it is essentially a spring
– it is the main “mode” of energy transfer
• We need a way to measure line tension!

17. Line tension transducer
• Suitable load cell manufactured by a French
modeler (www.xerivision.com)
• Attaches to the towline, hooks onto the
towhook
– cable brings analog signal to data logger,
disconnects upon release

18. More data to analyze
Altude
Tracon
Airspeed

19. A picture starts to form…

20. …with more and more detail…

21. …and even more detail…

22. …discovering something new…
“ringing”
2nd
“hump”
1st
“hump”

23. …to answer old questions
almost
no
“ringing”
Only
one
“hump”
Towhook
moved
5
mm
a*

24. Other optimization: the zoom
airspeed
50
m/s
altude
gain
55
m…
yield
is
43%
only!

25. Optimizing zoom with snap flap
same
airspeed,
50
m/s
Altude
gain
now
90
m!
yield
70%

26. Wait! all this is not telemetry
• True, but…
– data collection comes first
• Real-time telemetry is a useful addition
– potentially, another game changer
– not allowed by FAI rules, except for safety
• Good for training
– the pilot should not be looking at a display
– audio or buddy relay is to be preferred
• Great for team training!

27. UniLog and telemetry
• Available for Graupner, Multiplex, Jeti
• Of course I fly Futaba
• Needed to invent something myself
– well, almost: the actual inventor is W. Korosec
• 2.4 GHz, Bluetooth protocol radio link from
UniLog to UniDisplay

28. DIY telemetry system

29. Telemetry as a team project
• 3 complete units were built
• Used in team training sessions
• Data are received directly into PC
• Real-time or deferred analysis possible
– real time: finding best “float”
– deferred: launch setup

30. Finding minimum sink setup
too
steep…
trim
up…
beOer
trim
maybe
down…
too
perfect!
slow…

31. Further possibilities
• Angular position sensors available
– allow AoA and sideslip measurement
• Direct servo/receiver current draw
measurement
• In electric sailplanes/models
– current, voltage, input power
– RPM, output power, efficiency
– climb performance (m/(s*W)), (m/mAh)
• Live onboard video feed?

32. Radio gear current draw
Altude
Current
draw
Pull-­‐up

33. Electric motor logging
Voltage
Current
Efficiency
Altude
RPM

34. Wrapping up
• Real-time, deferred analysis, all is good
• Measuring and collecting data over time is key
– a way to compare, understand, improve
– sharing within a team is equally important
– real improvement is possible
• New radios are arriving with telemetry
– integrated display of telemetry data
– sound and speech synthesis (readout, vario,
alarms)

35. Thank you / QA