On Feb 13, 5:54 pm, "J. Nieuwenhuize"
wrote:
All excessive speed that's left means spilled time... When you plan to
finish at 500' it's faster to leave early and make a (McReady) slow
glide to the finish line than to make a fast and low dash, which only
causes excessive drag. Of course it's very boring to ease back at 500'
instead of screaming alone with the crops hitting you're fuselage..

No disagreement, but if you need to carry some extra altitude for
safety (typically 500 to 1000 extra feet out here in the US SW), it is
faster to convert that altitude to speed when you realize that you
have the finish made safely. With a 500' at one mile finish, you want
to finish at 501 ft, and whatever speed that gives you. With a 50'
finish line, you would want to descend gradually and just hit 51 ft at
the line. While it sure is fun running in in ground effect (just
don't do it over people or things!) it isn't faster, at least with US
50 ft finish rules, since you would have to pull up to get across the
finish.

But as you say, diving down into ground effect specifically to extend
a glide will not help - better to just glide at L/D max to ground
effect, then float as long as possible. This is due to the energy
loss in the dive due to the pushover, pullout, and higher parasitic
drag at higher speed. Difference is small, but measurable.

Kirk
66