Yes, you’re right — headwinds look like a hill for VE. And if you turn around and go back with the same wind as a tailwind, you don’t quite get back to the same elevation as you start, because it’s a quadratic term, not a linear term.

No, the CdA will be over-estimated. If you know how much the headwind added to the virtual elevation profile, you might account for it. If you had a constant headwind, for example, your VE should look like it was rising, rather than level. So a levelled VE curve would over-estimate your CdA. Although I’ve only looked at it a bit, probably Adam Haile’s virtual work method might be helpful if you can guesstimate how much headwind you had.

In Aerolab, the actual elevation profile looks as it should – very flat, but the VE profile looks like a mountain (if I set the beginning and ending points to the same elevation. I think this is correct – the headwind appears as a climb, but thought I’d check.

Also, will a CdA derived from this ride have any relation to reality?
Tom

Thanks for using Aerolab.

You definitely should try to flatten out the VE curves. A secondary problem is that as barometric pressure drifts, air density does, too. Aerolab currently only supports a constant-in-time air density model.

When I get the aero sensor finished, I will be turning my attentions to making Aerolab use it, and to making Aerolab more usable. My “todo” list includes:
1) interval selection
2) loop and out-and-back superimposed graphs
3) yaw variation in CdA

If you have any other ideas, please send them.

Cheers,

Andy

If so, it might be useful to have correction variable for the “actual” elevation curve to flatten it out (pre autosolve when it comes) given that so many of us rely on barometric measurements for this.

All in all, this is a great tool and I can’t wait to start doing comparison runs.

Thanks,

ted

First, thank you for trying Aerolab and Golden Cheetah. I really enjoy it when people use it!

I can get a patch in to Gareth Coco and will advise you when it is ready. How much altitude do you need?

Yes, air density (rho) is in play. You will need to compute this number separately, though, for the moment. Just get this spreadsheet (http://wattage.googlegroups.com/web/AeroTestRegressionMethod.xls?gda=BsD0zU4AAADBQWgbxXm8ObOsS_5kgCiKjiTwanbFfdNRAC-m6qynLUwWsjcy0CO1TJi0Wr-ZM0QBSF_SSboI6Zq6zbdDj1pJ47Cl1bPl-23V2XOW7kn5sQ) and go to the “Air Density” tab and fill things in. It’s easy!

Cheers,

Andy

On a related thought, does air density come into play in the calculation too? (I would assume it must) If so, a range able to include Colorado passes would allow this variable to be set too.
–Ian

The sliders are good for rough estimates but it would be good to be able to type in specific values so you can vary CdA by o.oo1 and Crr by 0.00001

It would also be useful to be able to plot more than 1 run so different conditions could be compared.

Chris

Notes:
1. X-axis is labeled Distance but it’s pretty clearly time.
2. Inputting values in the Crr/Cda/Rho/Total weight text boxes causes the values to go haywire.
3. Would be helpful to be able to zoom in on an interval