I wish I'd never got into this...

THANK YOU UDO!!!
I think your sim. has the rights equations planted within it's
program!!!!
I am the one who started this debate. Quite fun uh!!! For your info.
,since
french is mother tongue, I posted the same question on a French forum.
Hell
is raised over the pound too. But the balance is in favour of a tie (
no
advantage to the ballasted). We stated than any difference less than 50
feet
is a tie. (That,s what you can read on your alti. with minimum
precision).
Must of people rely on their intuition on this side " If
it's twice as heavy, it has twice the energy, and it will
coast to twice the height, since the same drag force is
acting to deplete it's kinetic energy reservoir of twice the
size.
" Do not forget that the heavy glider has a bigger job to do and its is
exactly equivalent to the extra energy!!!!!
More thoughts for your intuition
1. will you need a bigger force to change the direction of travel of a
heavier object than a light one.
2. Intuitively, the wings of the heavy will bend more. Is the force
needed
to bend the wings translate in lost enrgy for the glider?
More for your consideration, better L/D is no advantage when your nose
is
pointed to the zenith. Lifts acts perpendicular to axis, it is actually
pulling you away from optimal trajectory.
Lastly, using the original data, if the heavy glider go say 75' (25m)
higher, it takes (100kgs*9.81 m/s2*25 m= 25 000 Joules of energy to do
that
job. So conversely, it is the extra job done by drag (....what
else...)on
the dry glider. I cannot fit this in any equation!!!!MAGIC!!!!!!
BravoQuebec


"Udo Rumpf" a icrit dans le message de
...
I am not able to comment on the math questions,
instead I used the simulator.
I used the ASW27 model with and without water.
I selected a trim speed in both cases (empty and full) of 180 km/h
flaps stayed in original position through out the manoeuvre.
The pull ups were with max stick deflection till an optimum
trajectory
for
both gliders was achieved.
Once the trajectory was established the glider was allowed to
fly/coast to the top.
The results over many test runs showed a 12% advantage on average for
the
unballasted Glider.
Regards
Udo




While Udo doesn't state the numerical value of the difference, I bet it's
only 30-40 ft.

you are correct. it works out to about 39 feet.

Udo