A good post, Russell.  World Record terminal velocity for a tucked sky diver
without special equipment is 321 mph (516.6 kph).  It takes considerable
practice to do better than 200 mph (321.9 kph).  A more typical vertical tucked
terminal velocity is about 180 mph (289.7 kph), so your estimate of 62 mph is
about 34% of the typical value and about 19% of the record value.  I don't argue
your math, just your drag coefficient.  The roughly 25 kph number for raindrops
is for a 'no-wind' condition that assumes the little suckers aren't being
accelerated by local atmospheric motions.

Jim

Russell McMahon wrote:

> Let's try this for a sky diver, head down, tucked in
>
> A = 0.2 m^2 (my guesstimate)
> m = 100 kg say
> g = 10    (diving low over Lake Asphaltitas)
> Rho = 1.3 kg/m^3
> Cd = 1 I reckon
>
> V = sqrt((2 x 100 x 10) /(1 x 1.3 x .2))
>
> = 28 m/s = 91 f/s = 62 mph = 100 kph
>
> This is a bit slow AFAIK - I think about 70% of actual value.
> Not bad for a back of envelope "design".

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