Re: Do-it-yourself drag calculation
OK for a back of an envelope calculation, but still over simplified. Dynamic pressure is proportional to the square of the velocity. Drag is proportional to the square of the velocity ONLY if the drag coefficient is constant.
For something that would have highly seperated/turbulent airflow, like a motorcycle and rider, drag coefficient will increase with velocity, probably very sharply after some speed. Drag increase due solely to the increase in dynamic pressure is small compared to the increase in drag due to increased flow seperation (i.e. increasing drag coefficient).
As a result, you will be underestimating the effect of aerodynamic drag with your method.