Originally Posted by TomK
The Bowlus....APPEARS to be about as streamlined as anything that is actually inhabitable and practical. To taper any slower, there would be a long unusable space that would add more length, but not much more capacity.
The problem is that if was made more aerodynamic, many people would think it looked less aerodynamic - all that 'eye training' on supposedly aerodynamic shapes like the VW.
The Bowlus would be better if the back end tapered more slowly and just stopped at the same length in a flat bulkhead - a Kamm tail, as suggested by Herr (Professor?) Kamm back in the 1930s and still in use today on low drag shapes like the Toyota Prius or the GM EV-1 (the lowest drag production vehicle).
Incidentally my personal rule of thumb is that airflow can stay attached to a body that tapers up to about 15 degrees from the horizontal or straight-ahead. More than about 15 degrees or almost any sharp change in taper and the flow won't stay attached and any body behind that will be doing no good.
If you have your own wind tunnel you can do better than this, but then if you have your own wind tunnel, nothing I write would tell you anything new.......