On Jun 8, 2:20*pm, Eric Greenwell wrote:
On 6/6/2010 7:29 PM, Bruce Hoult wrote: On Jun 7, 5:42 am, Gary *wrote:

In any event, much of this does run counter to the normal "racing"
protocol. E.g., Moffat's final turn at the top of a climb when it is
tightened and you accelerate across the thermal core before exiting.

I've never understood how you are supposed to do that. I'm *already*
circling as tightly as I can at the speed I'm flying!

Do you mean you are flying close to stalling? My glider, and many
others, climb better if flown about 5 knots above stall, so I can always
tighten my turn if I need to reposition my circle, or take evasive
action if another glider gets too close.

Of course I'm a similar amount over the stall speed, and can tighten a
little, but nowhere near the halving of the radius that would be
required to go through the center of the existing circle.

Flying at 45 knots with a 40 knot stall speed (at that G loading) only
gives you scope to increase the lift by 25%, not the 100% needed.

OTOH it's true that if you've only got a 30 degree bank angle then
rolling to 90 degrees bank without changing the AoA will halve the
initial turn radius (before you plummet and speed up). From a 45
degree bank you can only decrease the radius to 70% in this way. Maybe
it's enough.

Hmm. Rolling from 30 degrees to 60 degrees will decrease the turn
radius to 58% (pretty close to 50), but still leave half a G worth of
vertical lift. Or rolling from 30 degrees to 53 and also pulling 25%
more G would halve the turn radius while only accelerating downward at
0.25 G.

Yeah, maybe it's doable. But it will have to be good lift in there and
no one just ahead of and below you in the thermal (blind spot!) to hit
on the way out!