A lot of on line physics and engineering calculators are suspect and many get pulled as soon as I present them as being "interesting" or "fun." (I never diss a free calculator.)
The drag on a sphere calculator below is probably OK but they leave it to you to figure out the exponent.
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I start out using something I know like the drag force on a car going55 mph. Then I work my way down to the order of magnitude of concern.
Bret Cahill