How is it that CT with that triangular shape specifically designed for aerodynamics, has worse CD than Rivian which is a traditional shaped truck ?
Source: I’m a mechanical engineer and pilot and therefore have taken several fluid dynamics and aero classes, but do not claim to be an aero expert:
Sharp angles cause separation of the airflow at the angle, which indices turbulence and increases induced drag.
Stainless is less smooth than a painted surface, so there are some losses there due to body material choice.
The inability to do a lot of curvature on the body prevents you from following the airflow, which again induces separation at the surface, turbulence, and induced drag.
Cyber is longer, which increases Cd.
All the angular wheel arches, etc are less ideal than a gradually curved surface.
Cybertruck still has a vertical (but slightly curved) front fascia.
Wiper is not concealed out of the airflow. It’s probably better to have the wiper there than not, given the flat panels, to help guide airflow around the edge of the windshield, but not as good as a concealed wiper with more complex body panels that can guide airflow better.
Frontal area is NOT part of the Cd equation, but is a factor in total drag *force*.
The tonneau cover has to be a big contributor to the good numbers as it prevents air over the roof from backfilling into eddies in the low pressure truck bed area. But the tonneau cover is still ribbed, so will induce some turbulent airflow over it.
Frankly, it’s great that the CT’s drag coefficient is as close to the Rivian’s as it is.