Early in my soaring education I was fortunate enough to share a coffee with
Helmut Reichman, who kindly signed my copy of Cross Country Soaring

In the conversation I mentioned that the benefit from his advice in CCS to

'always cross the start line with your sailplane at max speed and max
gross*, pull up to your anticipated/estimated climb derived McCready speed
for that wing loading, glide to your first climb where you dumped ballast to
your anticipated ideal wing loading for the day'

was practically all derived from the cruise to the first thermal

After some discussion we agreed that in the real world of 1G pull ups the
only benefit was that obtained by a heavier sailplane due to its lower sink
rate at higher speeds during the time it took to decelerate from initial
cruise to exit cruise (say 130 kts to 80kts) and then its lower sink rate
during the time it took to reach the first climb at the estimated McCready
speed.

A quick calculation gives a deceleration time 5 seconds and an average
lower sink rate 2ft/sec giving a benefit of 10ft

Wow, what a lot of hot air expended to find that, in a pull up the heavier
glider will always end up higher but by such a small amount as to make this
debate an intellectual exercise

*at the time with ground based observed start lines this meant crossing a
3000ft start line as close to VNE as you dared, definately not PC today, hey
JJ?

"Todd Pattist" wrote in message
...
"szd41a" wrote:

An empty motorless 500 kg boat is drifting on a river. Current is moving
at
2.5 m/s, so is the boat. How many H.P has the boat?

I think you want to ask how much HP it takes to move the
boat. The answer would be "None." The boat is not rising
against gravity, and not storing potential energy. It is
not moving relative to the water and not dissipating energy
in the form of fluid drag. It's the same as a drifting
balloon at constant altitude.
Todd Pattist - "WH" Ventus C
(Remove DONTSPAMME from address to email reply.)