|
Hi Guys,
So far in my coast down testing, there are about twenty runs to crunch numbers on. The maximum speed for the runs was 60 mph.
For the record, the vehicle is a 2000 Insight, of stock weight, smoothing under-body panels, and tires pumped to 50 psi.
The twenty runs have been mostly on the way to work where there is a mile long stretch that is not too beat and rippled due to low temps.
I had the day off and spent quite a bit of time coming up with a math model to duplicate the actual coast down numbers.
*If* this was done correctly, then the Insight consumes:
About 67% of it's gas at 55 mph from air drag
And the remainder (33%) is rolling resistance due to drive train.
Aerohead may be able to substantiate this with his past experience. However the math model matches the real world data extremely well with this mix of aero drag and rolling resistance.
__________________________________________________ _________
EDIT (01-09-10 based on Aerohead's data in another post):
The coast down testing clearly shows that a single constant or Crr (coefficient of rolling resistance) is a good approach for modeling the effect of rolling resistance versus overall vehicle drag.
However, it should be noted that Crr, while being a constant, does not imply that rolling resistance is static, or unchanging. Rather it is dependent upon the velocity of the vehicle under test, and is linear in fashion. As the vehicle speed increases, the rolling drag of the vehicle increases by the same proportion.
All of the runs so far have been in winter conditions, so the effect of temperature on the Crr can not be determined until the temperatures rise.
__________________________________________________ _________
Jim.
|