physics question about pull ups

On Jun 7, 7:20*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.

--
Eric Greenwell - Washington State, USA (netto to net to email me)

After doing the math on sink rate versus bank angle I realized that
there is a reason why I am always 50-100 feet lower than everyone else
- I always circle at 45 degrees of bank. In fact you should bank as
shallow as possible while staying in the strong lift. Between 30
degrees of bank and 45 degrees the sink rate goes up a lot so you best
be sure that the core is really so small that you need to give up the
extra sink rate to circle tight.

On the tightening up to go through the core, even if your are racked
up tight you can usually bank and yank even tighter if you are willing
to accept a little downward acceleration since you won't be able to
produce enough lift to maintain steady flight. This may in fact be
exactly what you are looking to do if you believe there is a REALLY
strong core and strong sink beyond the edge of the lift. Your sink
rate will go up to a couple of knots, so the core needs to be worth
the extra inefficiency and you have to want to accelerate to scoot
through the sink, otherwise it's all a waste of energy. I don't
generally do it as I more often find widespread lift at the top of a
climb.

9B