If I look at my '27's polar and assume it takes about
0.25 nm to execute a pullup, I get less than 25 feet
of difference due to the higher sink rate at redline
for the unballasted case (at 154 kts the ballasted
L/D is 19 and unballasted L/D is 14).

This doesn't count for the losses associated with the
Gs of the transition to the pullup, but I would think
that you'd generate more induced drag to change the
(vertical) direction of the heavier glider.

I, too, have always flown with the belief that ballasted
gliders would get more altitude on a pullup from the
same speed - but I can't come up with any aerodynamic
or physics rationale to support it.

9B

At 04:00 15 September 2003, Kilo Charlie wrote:
I just entered this thread so apologize if having not
read all the posts
this has been mentioned already. Let me quote Helmut
Reichmann from Cross
Country Soaring pp 63-64:

'Starting in contests with full water ballast is always
a good idea. If the
run through the gate is made at high speed, heavier
sailplanes will gain
more height than light ones in the subsequent pullup'.

Although I find it impossible to argue with the math
presented might it be
that we are oversimplifying things? With all due respect
a modern sailplane
is a long way from a rock or pendulum. I'm certainly
not an engineer but
have flown for long enough and have done enough high
speed pullups at the
finish and on course to feel fairly certain that the
altitude gained is
substantially greater. But even more to the point
if you don't believe this
then was Reichmann wrong? Maybe the translation was
poor? Geez my bubble
is bursting! Send help!

Casey Lenox
KC
Phoenix