Amateur Aerodynamics

Aerodynamics Matter Regardless How Fast a Car Goes The claim: Drag only matters if you go above a certain speed. 45 mph/50 mph/55 mph/60 mph—take your pick, as the critical speed depends entirely on the person reporting this myth. The reality: People who repeat this claim are telling only part of the story—as is true of many, if not all, of these misconceptions. To see why, we need to go back (again) to some fundamentals of fluids in motion.   If you’ve ever taken a college physics class, you might remember something called the “Bernoulli equation.” This equation describes the relationship between internal energy, potential energy, and kinetic energy in a fluid—not just a fluid in motion, but any (incompressible) fluid (e.g. the “hydrostatic equation” is the Bernoulli equation simplified for a static fluid). By definition, the specific volume, v , of an incompressible fluid must remain constant, allowing us to divide out volume, V , and convert the energy terms into pressures. Because