However, in actual fact, the difference in the glide distance due to the change in Reynolds number (and associated drag reduction) is likely going to be so small that it would be nearly impossible to measure, let alone for you to see in an operational environment.
One might think so, but I'm not sure that's the case. Skin friction drag coeffients vary as Re^(-1/2) for a laminar boundary layer and Re^(-1/5) for a turbulent one.
A 20% increase in weight gives a 10% increase in best glide speed, and therefore in Re. So that's a 2 to 5% reduction in skin friction drag, or a 1 to 2.5% reduction in total drag.
Compare that to simply getting the glide speed wrong. All else equal, a 10% pilot deviation from best glide speed (i.e. the speed that puts you at the minimum of the drag curve) causes only a 2% increase in total drag. I think that the continual whining of my old instructor to "nail the glide speed" suggests that 2% is important.
[ 19 July 2001: Message edited by: bookworm ]