Quantifying aero and tyre
performance using ChassisSim.
Introduction
• Quantifying tyre and aero performance is key
to engineering a race car.
• This is thought to be impossible ...
Linking Data to the simulator – Creating a
monster file
• A monster file is constructed from a single flying lap.
• This i...
Modelling Aerodynamics
CLA, CDA, and aero balance – The metrics of
Aerodynamics
• Downforce - CLA, Drag – CDA and aero balance can be
defined as,...
Using Race data to construct the Aeromap
• When a car is run on the race track it returns a thin sliver of
the aeromap
• I...
Aeromap Test procedure
• The following is suggested as a test matrix.
Run No Setup
1 frh0 and rrh0 + baseline rear wing
2 ...
Using the Aero Modelling toolbox
• You create monster files from each of these runs.
• You then open the Aero toolbox in C...
Tyre Modelling
The ChassisSim V3 Tyre Model –
Formulation
• The mathematical formulation of the tyre model is shown
below
 
 
   ...
The ChassisSim Tyre Model quick start
• This is all summarised in the ChassisSim tyre model quick start.
• This is what yo...
Using the ChassisSim tyre quick start
• Adjusting the init long multiplier.
• Sample camber values
Car Type Lat Camb sensi...
The ChassisSim tyre force modelling toolbox
• This is the ChassisSim Tyre force Modelling toolbox
• Works off doing track ...
Creating advanced tyre models
• Step – 1 – Create the 2D Model.
• Step – 2 – Optimise camber and slip settings
• Step – 3 ...
What to expect
• The end result of ChassisSim Tyre modelling.
Conclusion
• Modelling tyres and aero from Race data can be done.
• It’s just a matter of procedure and being patient.
• P...
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Determining Aero and Tyre models of race cars from data using ChassisSim

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It is often thought to be very difficult or impossible to extract the aerodynamic and tyre properties of the race car from data. In this seminar Danny Nowlan the Director of ChassisSim Technologies will show you how this can be done using the motorsports multi body vehicle simulation program ChassisSim. What will be shown is common place throughout the ChassisSim community that spans vehicles as diverse as open wheelers, sportscars, touring cars and GT cars.

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Determining Aero and Tyre models of race cars from data using ChassisSim

  1. 1. Quantifying aero and tyre performance using ChassisSim.
  2. 2. Introduction • Quantifying tyre and aero performance is key to engineering a race car. • This is thought to be impossible from race data. • However it is done on a daily basis using ChassisSim. • We’ll discuss the how and why.
  3. 3. Linking Data to the simulator – Creating a monster file • A monster file is constructed from a single flying lap. • This is exported at 50 Hz from your logger. • Using the monster file you can. • Construct the circuit properties • Perform Baseline modelling. • A monster file looks something like this, 0 6564 -0.02 0.05 -6.21 -3.3 23.17 28.62 -0.1 100 231.7 1.305 6612 -0.1 0.25 -6.9 -3.95 21.52 25.94 -0.1 100 231.7 2.606 6588 -0.05 0.25 -6.2 -3.71 20.69 24.08 -0.1 100 231.6 3.908 6600 -0.33 0.19 -5.13 -2.63 20.72 24.93 -0.1 100 232.2 5.209 6564 -0.05 0.25 -3.98 -1.62 21.77 26.46 -0.1 100 231.8
  4. 4. Modelling Aerodynamics
  5. 5. CLA, CDA, and aero balance – The metrics of Aerodynamics • Downforce - CLA, Drag – CDA and aero balance can be defined as, AeroRAeroF AeroF xD AeroRAeroF ZL FF F awf V Drag CAC V FF CAC        2 2 2 1 2 1   • Keep this in strict SI Units. Forces are in N, speed in m/s, and density kg/m3 .
  6. 6. Using Race data to construct the Aeromap • When a car is run on the race track it returns a thin sliver of the aeromap • If you don’t have ride height sensors these can be inferred by, t S m k F w  i i m s i w MR x d  2 2 43 0 21 0 dd rhrh dd rhrh rr ff    
  7. 7. Aeromap Test procedure • The following is suggested as a test matrix. Run No Setup 1 frh0 and rrh0 + baseline rear wing 2 frh0 and rrh0 + d_rrh + baseline rear wing 3 frh0 and rrh0 + 2*d_rrh + baseline rear wing 4 frh0 and rrh0 + 3*d_rrh + baseline rear wing 5 frh0 – d_rrh and rrh0 + baseline rear wing 6 frh0 + d_rrh and rrh0 + baseline rear wing 7 frh0 and rrh0 + baseline rear wing 8 frh0 and rrh0 + baseline rear wing + 2 holes 9 frh0 and rrh0 + baseline rear wing + 3 holes • Just to clarify the nomenclature we have, frh0 = Baseline front ride height as specified in the starting setup. rrh0 = Baseline front ride height as specified in the starting setup. d_rrh = delta rear ride height. d_frh = delta front ride height.
  8. 8. Using the Aero Modelling toolbox • You create monster files from each of these runs. • You then open the Aero toolbox in ChassisSim • This generates a file called aero_analysis_results.dat
  9. 9. Tyre Modelling
  10. 10. The ChassisSim V3 Tyre Model – Formulation • The mathematical formulation of the tyre model is shown below             MAXzcambTCTZx MAXzcambMTFyTZy TMaxTZT TZMAX TZzcambMTMTMax FFTFSRfnF FFCTFfnF MTFfnM TFfnF TFfnFCM      ,,, ,,, ,, ),( ),(, _ _     • For the time being we will focus on the lateral and longitudinal forces. However the same techniques can be applied to self aligning torque. • Effectively this represents an approximation that is put into a lookup table.
  11. 11. The ChassisSim Tyre Model quick start • This is all summarised in the ChassisSim tyre model quick start. • This is what you are going to use to refine the results.
  12. 12. Using the ChassisSim tyre quick start • Adjusting the init long multiplier. • Sample camber values Car Type Lat Camb sensitivity Long Camb sensitivity Open Wheeler 3 2 GT car 2 2 Sedan 0.5 – 1 0.5 - 1
  13. 13. The ChassisSim tyre force modelling toolbox • This is the ChassisSim Tyre force Modelling toolbox • Works off doing track replays comparing actual to simulated lateral acceleration from looking at race data.
  14. 14. Creating advanced tyre models • Step – 1 – Create the 2D Model. • Step – 2 – Optimise camber and slip settings • Step – 3 – Tune in temperature characteristics in tyre properties • Step – 4 – Create the 3D Tyre model.
  15. 15. What to expect • The end result of ChassisSim Tyre modelling.
  16. 16. Conclusion • Modelling tyres and aero from Race data can be done. • It’s just a matter of procedure and being patient. • Prepare the monster file and put in your setup. • Aero – run the test matrix and then use the Aero modelling toolbox. • Tyre modelling – tyre quick start and then use the tyre force modelling toolbox.

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