Quote:
Originally Posted by Isaac Zachary
(1) A certain level of practicality is needed, therefore a certain level of interior space for cargo and passengers.
(2) There are four general ways of increasing or decreasing interior volume, roof height, floor height, width, and length, as well as door and wall, roof, floorboard and engine bay thicknesses (related to, but not exclusively, crumple zones)
(3) Taking any shape and making it wider or taller in order to increase interior space to an acceptable amount increases cross-sectional area and therefore increases drag.
(4) Increased length does induce a small amount of surface friction against the fluid (air) but usually makes up for it by allowing more gradual curves.
(5) Once you reach a Cd of 0.04 then increasing the length will induce greater drag but not near as much as increasing the height or width to the same interior volume mainly due to increased cross-sectional area.
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1) 'practicality' has turned out to be highly subjective.
2) yep!
3) 'acceptable' gets back into the 'subjective zone .'
4) Yes, and it's the gentle curves which protect the boundary layer and provide the pressure recovery which reduces the pressure drag, the major drag component.
5) Yep, although, I'd qualify Cd 0.04, as the basic body drag one would derive, lets say, the Cd 0.08 body from, which would grow to Cd 0.13 when wheels were added, then reduced to, say, Cd 0.10 or 0.09 when the same wheels were faired into the body.