Quote:
Originally Posted by abcdpeterson
If I understand correctly that would make sense. a gentle / rounded transition before starting the 22 degree incline is needed. Correct?
I can see in the photo the transitional portion is, and then the 22 degree incline portion.
I am not sure what is being shown with the graph at the bottom.
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The values along the bottom,reflect the ratio of the boattails length,as compared to the diameter of the body.At the far left,with "zero" boattail,there is zero drag reduction.---------As you move to the right on the graph,the length of the tail is increasing as compared to the diameter.If you follow all the way to the right,you're at the point where the tail comes to a point,a full boattail.------------ From the Cd values,you'll notice that drag continues to drop as you lengthen,with the curve kind of flattening out as you near the full tail.This is why many will suggest that the law-of-diminishing-returns would have you chop the tail,well short of it's full length.Dr.Kamm and Dr. Korff suggested that we chop it off at the point where the wake area would be 50 % of the vehicles Frontal Area,to help with manuevering in traffic and parking.For racing and record vehicles,they don't have to contend with these issues,so they're more free to run the full enchilada.