Performance World Class design proposal

Bruce Hoult wrote:
In article ,
"Pete Reinhart" wrote:

Mark,
A most thoughtful metric.
It might lead to a very interesting way of valueing the gider market as
opposed to $perL/D.

Of course this is just L/D at 80 knots, with his 300 fpm cutoff being
an L/D of about 26.6:1 and an LS4 being 25:1.

It appears that you need (-ve) flaps to get as low as 300 fpm, but then
there are lots of missing interesting gliders. The Discus and ASW28 may
prove me wrong, for example.

Getting lower fpms seems to also have at least one downside
too: higher stall speed. I personally would like something
like a Russia AC-4c, with a fairly low stall speed, but
with ballast too. Short wings and slow stall speed when I want it
are good. I wonder about getting one with a motor and
then just putting a big water bag in the hatch instead

30 knot stall vs. 40 knot stall is
900 vs. 1600 energy units at landing.
Almost twice as much energy to dissapate at touchdown.

Once the unballasted stall speed of a glider gets past
40 knots, I'd be a little hesitant to be "happy'
about the great penetration...
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Mark J. Boyd