Ami - the .09 was a nominal value based on CFD analysis and a scale tunnel test which had a perfect surface (I personally think the scale was too small).... In reality, the cD is probably double that if not more
The key thing to remember with velomobiles is that at the relative low speeds these thins travel at (less than 40mph - realistically cruising in the 20mph range) ... Designing for laminar flow isn't the most ideal as environmental forces have a rather large effect. Incoming flow is, for the most part, already turbulent. Of course, over a long distance - every watt saved is good thing... But for short trips, it's a compromise.
That said, even the current speed record holder has a relatively short tail end. The widest part of the diablo 2 is right at the shoulder area (and he's crammed in there
).
