Length diameter ratio for laminar pods

Laminar pods need to have low length/diameter ratio to get the benefits of laminar flow. Bruce Carmichael recommends length/diameter ratio of 3.33 in his book. I accidentally found also a pdf format article from web which talks about the same thing. You can get if from here:

www.aerorag.com/resource/aircraft/aerodynamics/carmichael/min_fus_drag_carmichael.pdf

Here is another document about the matter:
ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19860014381_1986014381.pdf