Rounding a turnpoint in sink

Right. That clarifies what you meant. By 'turnpoint',
the way I used it in the question, I meant the point
that you actually have to round physically, whether
it be the near edge of a cylinder or the centre or
whatever.

Good - you don't generally think about the turnpoint
as a fixed point in a racing task where you get credit
for distance within the cylinder - at least I don't.
You would think about it as a fixed point for record
flying.


Yes, all this is clear. This could perhaps be summed
up
by saying that to fly beyond the TP would only be worth
it if you find significantly stronger lift there than
you will along the task after the turn.

Yup. The trick is having a sense for how much stronger
the expected lift needs to be given the distance and
sink rate and whether you're getting credit for the
extra distance flown. I went 0.5 mi and 1.5 mi past
the far side of turn cylinders in contest tasks this
summer (with no sink involved). In the first case I
expect I broke even overall, in the second case it
was a losing proposition.

9B

Sous l'emprise d'une subite inspiration le 22/07/2004 03:22, Andy
Blackburn transcrivit ce que suit :

FAI AST racing tasks have a one mile radius (2 mile
diameter)around the turnpoint so you can either cut
short by a mile or go long by a mile so the total range
of distances is +/- two diameters or 4 miles.


Perhaps in some countries racing tasks have such large a radius, but
FAI/IGC don't. They have a 500 m radius, and no extra distance is
counted if you fly further than 500 m before the turn point.

--
Denis

R. Parce que ça rompt le cours normal de la conversation !!!
Q. Pourquoi ne faut-il pas répondre au-dessus de la question ?

What makes competing so fun is everything you've left out!

Which way is the wind blowing?

Is the potential lift source inside the 1 sm turn raduis?

How far is the gaggle behind me?

What is my current altitude above the ground, and when did I pass the
last lift or potential source of lift?

How much altitiude did I lose since leaving the last known source of
lift?

Were there other sources of lift, or was this the only one availble?

Is it likely I'll fall below the bottom of the height band before
finding lift agian?

But now to answer your question...

Assuming that I have flown an appreciable distance to the turnpoint
without seeing any other lift source, I go to the one I can see, even
if it is a little outside the 1sm turn area. If it proves useless, I
take a differnt line back, keeping an eye out for markers from the
following gaggle.

As far as turning around is concerned, I pull and roll simultaneously,
but not without keeping a good lookout. After all, the gaggle may not
be so far behind as I'd like to think. (More likely they are climbing
in the 10 knot thermal I missed.)

CV wrote in message ...
Let's imagine the following scenario:

You are flying a comp and eager to win. This far you are really
doing well on today´s task.

You had a good climb some distance back and have left the main
gaggle behind. It looks like you might be in the lead. Now you
are approaching the second turnpoint and are bombing along
through the sink at, say 90 kts, roughly according to the
chosen McCready setting.

Now, when you reach the turnpoint, you need to turn 180 degs
and head back in the opposite direction. The turnpoint is in
the middle of a largish area of heavy sink.

What is the most effective technique for making the turn ?

a. Tight turn at the current speed (90 kts) and carry
on according to McCready.
b. Slowing down to thermalling speed, turning tight and
accelerating back to 90 kts. This would end up being
a kind of chandelle-like maneuver since you'd be
pulling up sharply, turning while still in the climb,
and diving in quick succession.
c. A half loop with a roll on top. OK, I suspect this
might be theoretically best, but let's suppose you
rule this out due to a load of loose objects in the
cockpit: maps, pen, camera, sandwiches, drinking
water etc. and you are not really into advanced
aerobatics anyway.
d. Carrying on for half a mile (or a mile ?) past the
turnpoint where a cloud is building and you expect
to find lift to turn in.
e. Anything else.

CV

Our resident flight software coders could add ellipsis to the map display to
show how strong lift would have to be for an off-course excursion to the
ellipse from the present position to pay off. Say +2 and +4 knot ellipsis
above the current McCready setting.

Bill Daniels

"Andy Blackburn" wrote in message
...
Right. That clarifies what you meant. By 'turnpoint',
the way I used it in the question, I meant the point
that you actually have to round physically, whether
it be the near edge of a cylinder or the centre or
whatever.

Good - you don't generally think about the turnpoint
as a fixed point in a racing task where you get credit
for distance within the cylinder - at least I don't.
You would think about it as a fixed point for record
flying.


Yes, all this is clear. This could perhaps be summed
up
by saying that to fly beyond the TP would only be worth
it if you find significantly stronger lift there than
you will along the task after the turn.

Yup. The trick is having a sense for how much stronger
the expected lift needs to be given the distance and
sink rate and whether you're getting credit for the
extra distance flown. I went 0.5 mi and 1.5 mi past
the far side of turn cylinders in contest tasks this
summer (with no sink involved). In the first case I
expect I broke even overall, in the second case it
was a losing proposition.

9B