Aerolab: A Sneak Peak at GoldenCheetah's Upcoming Virtual Wind Tunnel

gcAs GoldenCheetah prepares for its upcoming release, I wanted to keep you all posted about the development of the virtual elevation module, Aerolab.  Aerolab is not currently in Golden Cheetah, but I’m hoping it may eventually find its way there.   There’s tons of work still to be done, but at least we now have a prototype that works.

To recap, Aerolab is a tool for estimating the coefficient of rolling resistance (Crr) and the aero coefficient of drag (CdA) of a bike/rider combination.  It does this by  reverse-engineering an elevation curve from power data using Newton’s Second Law.   With the help of Justin Knotzke, I’ve put together some of Greg Steele’s ideas into a very preliminary tool.

Here’s a sneak peak of Aerolab.   It’s not perfect, as a quick glance will tell you, but it’s starting to take shape.  Below is a screenshot of  an actual iBike ride.  The green curve is the actual elevation profile, while the blue curve is the derived virtual elevation curve.  Slider controls govern the values of Crr, CdA, rho, and total mass.


The Aerolab Module in Golden Cheetah

A first release will limit itself to only a manual solver mode, where the user tweaks all the parameters by hand to obtain the desired elevation curve. Future releases will include an “AUTOSOLVE” mode that uses VE’s Newton solver to automatically find the right parameter values of Crr and CdA.

That’s it for now. Stay tuned for lots more updates and maybe someday that this will see the light of day in Golden Cheetah!

5 comments to Aerolab: A Sneak Peek of GoldenCheetah’s Upcoming Virtual Wind Tunne

  • Robert

    Very nice. The first couple of years I did this was no more complicated than what you have here (though your implementation is far slicker, of course) so I’d say even in its current state it could be useful.

    As currently implemented, are you using an entire file or can you specify a segment of a file? I typically mark interesting segments with the interval markers so I just work with interval X, but the other way to do this is to be able to mark a segment post hoc.

    Sometimes it’s helpful to adjust the axis scaling or to add a horizontal reference line or two.

    I work with the PT so I alway set eta, the overall drivetrain efficiency factor, at 1.0. If I used a Quarq or SRM or some other device I’d allow for drivetrain loss.

  • It looks great Andy! Getting this available will be awesome, and really encourage development! And drive GC adoption for sure.

  • Lanier

    This looks awesome! Keep up the good work. Once you get this out I’ll definitely give GC a try.

  • [...] Montrealer, and all around good guy Andy Froncinoni has create a Virtual Wind Tunnel for all you TT and Tri Freaks.  It created quite a stir on some mailing [...]

  • john

    is there a quick guide on how an idot like me can do a general interpriation of the graph ?

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