In aerodynamics, the zero-lift drag coefficient. is a dimensionless parameter which relates an aircraft's zero-lift drag force to its size, speed, and flying altitude. Mathematically, zero-lift drag coefficient is defined as. , where. is the total drag coefficient for a given power, speed, and altitude...

Alternatives to pyrexIf the object is stationary or is moving at a constant velocity, the vectors should graphically add up to zero. If the object is accelerating, the sum of the vectors should produce a vector in the same direction as the acceleration. Writing down the sum of the forces. Identify direction of every force and of acceleration.

Note that the drag coefficient decreases with the Reynolds number, and it becomes almost a constant (C D = 0.4) for a Reynolds number between 10 3 and 2×10 5. As the Reynolds number increases (Re > 2×10 5 ), the boundary layer becomes thinner in the front of the sphere and begins its transition to turbulent.