carguychris Fifth gear

Join Date: Feb 2005 Location: Richardson, TX Posts: 2,093

Quote: SignOfZeta Originally Posted by I don't find this hard to believe at all. Aero is in the little things as much as the overall shape. The narrow, pointed bumper tends to push air to the sides and into the front wheelwells (Awla mentions this).

The narrow, pointed bumper pushes air downwards and make it "pile up" under the car, where it interacts with the mechanical bits underneath.

The hood-to-windshield angle is not optimal.

Those nifty-looking round mirrors force air inwards towards the doors where it interacts with air flowing along the sides of the car. This is why the NB's mirrors have a sharp edge and slant outwards to push air away.

The rear-end styling is gently curved, which makes air coming over the top of the car and around the sides and form vortices. From an aerodynamic perspective, it's better for a car to "just end", with sharp edges at the rear corners to keep the air separated. IIRC the NA Miata wasn't designed in a wind tunnel, it was designed to look good and emulate the flowing looks of classic sports cars. FWIW many designers of 50s and 60s classics were attempting to make the cars aerodynamic by emulating the flowing looks of WWII and early postwar airplanes, but most of them didn't have access to wind tunnels and didn't understand that aerodynamics is fundamentally different in ground effect (i.e. the zone where the flow around an object is influenced by its proximity to the ground). Consequently, they made several fundamental errors, such as directing lots of air downwards under their cars, and seriously screwed the aerodynamics up in many cases.



BTW don't feel too bad, the Cd of a Datsun 240Z is 0.44.



Mandatory disclaimer: I am not an aerospace engineer, nor do I play one on TV. +1. I wish I could find the thread, but IIRC there was a thread posted some years back about the Miata's aero problems. Some things I seem to remember:IIRC the NA Miata wasn't designed in a wind tunnel, it was designed to look good and emulate the flowing looks of classic sports cars. FWIW many designers of 50s and 60s classics were attempting to make the cars aerodynamic by emulating the flowing looks of WWII and early postwar airplanes, but most of them didn't have access to wind tunnels and didn't understand that aerodynamics is fundamentally different in ground effect (i.e. the zone where the flow around an object is influenced by its proximity to the ground). Consequently, they made several fundamental errors, such as directing lots of air downwards under their cars, and seriously screwed the aerodynamics up in many cases.BTW don't feel too bad, the Cd of a Datsun 240Z is 0.44.I am not an aerospace engineer, nor do I play one on TV. __________________

I know the above comment is highly biased and filled with stereotyping but so what, it's just not that important. - Greasyman, 2/27/07