I went back to the reference for the flow equations, and the Hagen-
Poiseuille equation is described for laminar flow conduits, not flat
plate turbulent flow. The reference I used is on blood flow within
arteries and veins (hemodynamics). There are references to turbulence
effects where vessels narrow (as through stents or valves), but the
book's detail is lacking on the topic.
Thank you, Richard Vance, for pointing this out, otherwise my oversight
might lead others astray. By presuming the 4th power relationship, I
used a very, very (that's "very" to the 2nd power) conservative bleed
hole diameter increase (approx. 25%) to speed up my damper pneumatic.
It worked well -- just dumb luck, based on my incorrect assumptions.
I'm lucky that the natural laws and my assumptions were not reversed,
or I'd now be wondering why my pedals are so easy to push.