"Todd Pattist" wrote in message
...
(Chris OCallaghan) wrote:

I'm a little confused by who is writing what and to whom, but each
person has their own peculiar theory of thermalling. Hal was
interested, as best as I could tell, in maximizing his climb. The
approach I suggested gets you into the better lift as quickly as
possible, and establishes a new "center" for others in the thermal to
join.

I'm as interested as you in getting to the new center
quickly, but here is the scenario: you and I are at the same
altitude on opposite sides of a turn, and you are on the
weak side, I'm on the strong side. I desperately want to
turn tighter so I can stay in the lift and skip the weak
lift you're in. I'm going to tighten as much as I can and
still be clear of you .

The problem is that you suggested tightening first on the
weak side, then opening up. Aside from the fact that I don't
see much advantage in tightening on a weak side, if you
tighten, I can't tighten, as that puts us both head on if
you don't open up. Since most pilots will tighten in strong
cores, when I see you tighten, I've got to consider that
you're mistaken as to the location of the core.

We have the same problem if you're on the strong side, and
I'm on the weak. If I use your method of tightening in the
sink, you can't safely tighten in the strong lift because
I've turned into the space you need.

Bottom line, when we're at the same altitude, some
cooperation will be both safer and better for both of us.
We'll get the lift cored faster if we tighten in lift, not
sink.
Todd Pattist - "WH" Ventus C
(Remove DONTSPAMME from address to email reply.)

I went back and plotted the glider paths to scale using turn math. My
suggestion to reduce the bank by 15 degrees at the weakest point works
perfectly and creates no problem even if the pilot opposite tightens his
turn in the strongest lift. This isn't my idea, I think it was Klaus
Holighaus who originally wrote about it.

It's a bit counter-intuitive but an 8-second 180 degree turn at reduced bank
will place you in perfect position to tighten up in the core, or at least
you will have moved the turn center directly toward the strongest lift.
It's also much easier to keep track of other gliders at a lessened bank.
The small control deflections required are very efficient.

Violent maneuvering to center the core has several disadvantages. It's very
draggy to fly with large control deflections, it's harder to do the mental
dead reckoning to keep track of the direction to the stronger lift and it
risks collision with possibly unseen gliders.

To summarize, at the weakest point of the turn, lessen the bank by exactly
15 degrees (45 to 30 for example) and then hold that bank and airspeed for
180 degrees of turn and then increase the bank again to 45. This moves the
circle center roughly one turn diameter in the direction of the stronger
lift. It's a very gentle maneuver and it is easy to do. It just takes some
patience to stick with it through the 180 turn.

Bill Daniels