Sunday, May 18, 2008

Aero test - helmets - final

[b]Final results for helmet test 1:[/b]

OK, after a lot of analysis, playing with different stats and error methods here are the final results for Helmet Aero test 1 between the Specialised Decibel, Giro Advantage 2 and Limar Crono 05.

I've also readjusted the data to take into account that the rolling resistance should be the same for all groups of data (since it was... same wheels/tyres for every test). This was done by plotting all the helmet data collected as one series and generating a combined linear trend to get the rolling resistance offset, and using that combined offset for each dataset. (Google Wattage group was some use after all).

The graph also plots the amount of error (SE) for each set of data (plotted as +SE/-SE). (These are the little black bars extending from each data point). At slower speeds the error from each data point overlap the other trend lines (not what we want), but at higher speeds this is not the case (this is what we want).

The graph plots force against the velocity (speed) squared in order to get a linear line, no easy way to force the data through the same rolling resistance offset otherwise.
This means it's harder to read, so the results below are included in the easy to digest format that shows how much time you could expect to save, and your time on the course.

[b]Feedback[/b]

Now does anyone want to participate in Helmet test no 2, which should be able to test a much wider variety of aero helmets (providing we get loaner donations of lids for a week or so).
I'd also be interested in anyone else with a proper power meter (SRM/powertap) that would like to help run tests, can't hurt to have some different riders have a crack at the test protocol either (plus you'll get good info on your drag profile that might allow you to go faster with a few tweaks). And finally, if anyone has got any strings with indoor velodromes, now would be a good time to let us know!

[b]
Results: At 200 watts: 0 degrees yaw (ie a calm day).[/b]

[code]

KM......Decibel...Advantage2...Chrono
Av KMH.....35.5......36.1......36.9

time on course (hh:mm:ss)

KM......Decibel...Advantage2...Chrono
20......0:33:48...0:33:14...0:32:31
40......1:07:36...1:06:29...1:05:02
90......2:32:07...2:29:35...2:26:20
180.....5:04:14...4:59:10...4:52:41

time savings over using Decibel (hh:mm:ss)

KM......Decibel...Advantage2...Chrono
20......0:00:00...0:00:34...0:01:17
40......0:00:00...0:01:07...0:02:34
90......0:00:00...0:02:32...0:05:46
180.....0:00:00...0:05:03...0:11:33[/code]


[img]http://www.efirst.com.au/rob/fishboy/HelmetTest1FinalErrors.GIF[/img]

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