Quote:
Originally Posted by 3-Wheeler
Hi Jim,
I think you are close, but over calculating just how much power is required.
If you look at the post here...
http://ecomodder.com/forum/268030-post22.html
... you'll see that rolling drag is not proportional to speed. Therefore, the hp requirement does not go up as quickly as the cube of the velocity, but is close.
It also means that you should be able to get a reduction in Cd easier than the classic V^3 equation would lead one to believe.
Hope this helps, Jim. |
Actually, the equation from Phil that I worked with only considers the drag or hp needed to overcome wind resistance. Click his link in my post. I did click through to your link on rolling resistance and looked at your data. From extrapolation of your average curve, it looks like the rolling deacceleration at around 50 MPH would be around .2 M/s^2, and rising with speed. So the power to support that rolling resistance would make matters worse by that amount, I think
Maybe I have the direction wrong, but doesn't seem so.
In any case, it is a daunting task to raise the lean burn threshold by Cd reduction alone, since changing frontal area(A) is mostly unavailable. I don't see us ever getting to a CdA of 2.74ft^2 from a stock value of 5ft^2.
All very interesting to contemplate. Thanks for your post
