Quote:
Originally Posted by Piwoslaw
Those numbers look much better. When I was doing my coastdowns a while back I noticed that passing cars had the greatest effect on the results - one truck going the opposite direction could nullify the whole test run  |
There is really big margin of error however, with only three runs I get lot of variation with even 1kph difference, I need to do more tests and use GPS, speedometer is not enough accurate and as error in speedometer is not same all the time it can throw results off by good amount.
Also need to find more level road.
I did test and watched videos again, inputted data again and now I got cd 0.24 when using speedometer numbers, did same yet another time but used corrected values, not sure if corrected values were right and got cd 0.56.
So even smallest error can cause huge effect and one needs to really make that at least 6 runs and with gps it would be lot easier to get correct speed, update rate of 1 second in gps should be enough for testing too, so perhaps next evening I can do bit better, also wind should be more calm then, it was not big but certainly enough to affect last time.
One way to improve accuracy would be to do 12 runs and just average two same way runs to table so one would get double accuracy, well at least in my mind.
Either way, all measured cost downs are good when comparing to runs done with mods, just that mods still need to be made and installed, but soon :P