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

Hey Chris,

I used the factory polar to estimate altitude loss
at redline with and without ballast. The difference
over 0.25 nm was 26' (105' - 79'). As you bleed off
airspeed the difference in sink rate declines, so the
actual difference in altitude loss should be less than
25' - maybe more like 15'.

This ignores G-related losses, which should be low
if the Gs are low (i.e. not too radical a pullup).
Of course too gradual a pullup and you don't get maximum
altitude gain because the parasite drag will accumulate.

9B





At 23:00 15 September 2003, Chris Ocallaghan wrote:
Andy,

see my notes earlier in the thread. There's not much
penalty for
pulling from high speed so long as you don't go to
too quickly to high
AOA (bigger penalty in induced drag). 2g to 30 degrees
nose up is
typical. The you ease off to 1g until you start push
gently to
attitude at your desired exit speed.

Did your calculations include the losses to friction
throughout the
manuever? Your altitude difference seems a little too
low. I would
expect about a 20 to 30 foot difference for a pull
from 100 knots to
60 knots, ie, a normal 'test the strength of the core'
pull up.

At any rate, if we get any decent weather, I'll be
sure to make some
runs with a lighter glider and tender the real world
results.

The original poster was looking for some real world
feedback. Right
now all I can offer is that when ridge soaring, if
I have water and
another 27/V2 is empty, I'll outpace him by at least
10 knots on a
hundred mile-per-hour day. Roughly 10 to 12 percent
more speed at the
same sink rate/drag. A big spoonful of pure, sweet
hubris.