Data Logging and Telemetry

Data logging and telemetry: ���tools for performance optimization Francesco Meschia

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

I fly F3J

F3J launch

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

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

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)

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…

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

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”)

Tools of the trade: data recorder

From  top  le*,  clockwise:  www.eagletreesystems.com,  www.sm-­‐modellbau.de,    www.rc-­‐electronics.org    

Launch Log

Al<tude  

Airspeed  

Data recorder: how to install?

Data recorder: a better installation

Data recorder: the pod

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!

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!

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

More data to analyze

Al<tude  

Airspeed  

Trac<on  

A picture starts to form…

…with more and more detail…

…and even more detail…

…discovering something new…

1st  “hump”  

2nd  “hump”  “ringing”  

…to answer old questions

Only  one  “hump”  

almost  no  “ringing”  

Towhook  moved  5  mm  a*  

Other optimization: the zoom

airspeed  50  m/s  

al<tude  gain  55  m…  yield  is  43%  only!    

Optimizing zoom with snap flap

Al<tude  gain  now  90  m!  

yield  70%  

same  airspeed,  50  m/s  

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!

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

DIY telemetry system

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

Finding minimum sink setup

too  steep…   trim  

up…  beOer  

maybe  too  

slow…  

trim  down…  perfect!  

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?

Radio gear current draw

Current  draw  

Al<tude  

Pull-­‐up  

Electric motor logging

Voltage  

Current  

RPM  

Efficiency  

Al<tude  

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)

Thank you / Q&A