Dehydration

Bob Greenblatt wrote:
Aren't we trying to puncture the edge of the cylinder very near its
bottom at maximum speed?

Got to thinking about your question, Bob and actually we shouldn't try
to hit the edge of the cylinder at red-line. Why? Because our
sailplanes are very inafficient at red-line, in fact they start coming
down like a stone at anything over 90 knots. We should climb the last
thermal to 500 over home + a smidgen and then fly the indicated M/C to
the edge of the cylinder. You should get there between 60 and 90 knots,
depending on conditions on the glide. If you get there at red-line,
that means you climbed too high in the last thermal and it cost you
(time).

The finish line, on the other hand, requires a finish at red-line, so
that we can exchange our excess speed for pattern altitude. I'm even
tempted to say the cylinder is the most efficient way to fly the final
glide, but if I did, OC would just fly off in another snit, and I would
be forced to look up all those big words, again...............
:) JJ

OC, You never did answer my question, "How many contests have you flown
using the finish cylinder?"
Your skepticism leads me to believe you havent flown that many. I know
you flew it at Montague, anywhere else? How about giving it a fair try
before condeming it?
JJ

Optimum is the same for either finish. Most of us just don't have the
guts to cut it that close with a line finish.

With a high cylinder finish, you can cut it close. You're risking points
if you end up a bit lower than you hoped. But your margin for momma and
the kids is built in to the optimum answer. Its then more a contest of
skill than nerve, at least for the final glide.

Since most pilots will try to fly efficiently, the range of speeds at
the cylinder is reduced, and lowered compared to the gate. Makes for a
nice orderly follow the leader to land, with a tad more time after the
race is over to sort it out.

That can degenerate when everyone finishes way too high and hot or just
squeaking in a rolling finish, but it does the same thing with a gate.

With a line everyone shoots for the sweet end of the line. There always
is one. With a cylinder, finishers will naturally be much more spread
out. Maneuvering will be less predictable, but also more uniformly
gentle. Given the blind spots in all our gliders, and the tendency to
fixate on the targets you see and know about, we really count on the big
sky theory more than we like to admit. A little more natural spacing
makes the sky bigger.

But the cylinder is an instrument approach since it is completely
invisible, which has to pull some of your attention into the cockpit.
Cutting the edge of the gate is, too, since its really defined by GPS
coordinates, not a ground feature. Not very comforting for either finish
in traffic.

If you think either one is really safe, you're nuts. Both can be
executed successfully, but the margins flying that close to so many
other gliders and the ground are just not that big. I think the cylinder
is a bit less risky, but a lot less fun.

A perfect final glide to the edge of the cylinder at 75 kts is so
anti-climactic after an epic adventure out on course. Nothing compares
to the good old assigned task and no minimum height gate.

But I can change... If I have to... I guess.

-Dave Leonard
ZL




wrote:
Bob Greenblatt wrote:
Aren't we trying to puncture the edge of the cylinder very near its

bottom at maximum speed?


Got to thinking about your question, Bob and actually we shouldn't try
to hit the edge of the cylinder at red-line. Why? Because our
sailplanes are very inafficient at red-line, in fact they start coming
down like a stone at anything over 90 knots. We should climb the last
thermal to 500 over home + a smidgen and then fly the indicated M/C to
the edge of the cylinder. You should get there between 60 and 90 knots,
depending on conditions on the glide. If you get there at red-line,
that means you climbed too high in the last thermal and it cost you
(time).

The finish line, on the other hand, requires a finish at red-line, so
that we can exchange our excess speed for pattern altitude. I'm even
tempted to say the cylinder is the most efficient way to fly the final
glide, but if I did, OC would just fly off in another snit, and I would
be forced to look up all those big words, again...............
:) JJ

At 01:30 29 March 2005, wrote:
Got to thinking about your question, Bob and actually
we shouldn't try
to hit the edge of the cylinder at red-line. Why? Because
our
sailplanes are very inafficient at red-line, in fact
they start coming
down like a stone at anything over 90 knots. We should
climb the last
thermal to 500 over home + a smidgen and then fly the
indicated M/C to
the edge of the cylinder.

I did an analysis of this and it would appear that
the minumum time solution is to dial in a finish altitude
equal to 500' minus the altitude you can gain in a
pullup from your McCready speed to minimum sink speed.
Just before the cylinder edge you pull up and hit the
bottom outside edge of the cylinder. Depending on your
McCready setting you will approach the edge of the
cylinder at somewhere between 0 feet (Mc = 6 or higher,
full ballast) and 350' (Mc = 2, dry). It's easy to
calculate that you save about 45 seconds over flying
the McCready speed to the cylinder at 500'.

Why is this? Because there is excess kinetic energy
that can be turned into altitude at all cruise speeds
(the higher the speed, the more excess energy - and
altitude). To optimize, you should not carry excess
energy through the cylinder but instead come in below
the cylinder floor and use the energy to make the minimum
altitude, in this case 500'.

Most of us carry some extra margin just in case of
unexpected sink. In this case you can wait until you're,
say, two miles from the edge of the cylinder, then
dive off even more excess energy in the last two miles.
Because you are flying off more excess energy in a
short distance, you pretty quickly get up to speeds
where you can be right on the deck and pull up to well
over 500'. In this case you are flying less efficiently,
so the time savings go down a bit, to 20-30 seconds
versus flying McCready speed to 500'.

I would add that I am not advocating that anyone do
this, since I don't want to be held responsible for
the consequences of this finishing technique. It's
only worth a handful of points per day, but then again
so is finishing at 50' versus 200-300' in a gate.

9B

JJ, I'm thinking back. Half a dozen sanctioned contests? We use the
cylinder at M-ASA for our Club tasks as well. You miss my point
though... It's not condemnation of the finish cylinder as a concept.
Whatever the rules, I'll follow them and use them to my best advantage.
It's an assessment of the forethought that has been applied to its
implementation. Many of the concerns you aptly apply to the finish line
can be transferred to the finish cylinder. While it answers some
concerns, it ignores others and raises still more. In my opinion, the
finish gate is most dangerous when sailplanes of different performances
and speed ranges are finishing together. This is why the cylinder is an
appropriate solution for the sports class. Under such circumstances,
there can be significant differences in the patterns pilots must fly
after the finish. And the cylinder raises greatest concerns during TATs
and ASTs, especially in weak or blue conditions, when gaggling is most
likely.

I've talked about the heads down aspect of the cylinder, the de facto
reduction of finish line width during ASTs, the reduced separation of
high and low speed traffic and the variables we're likely to encounter
once we enter the cylinder and proceed to the IP.

I keep asking for some regulation at the cylinder that will make it
easier for me to anticipate likely hazards. And the constant response
is density. I've flown the 1-mile "turn cylinder" for several seasons
now, and I've come to the conclusion that it does little to alleviate
congestion. There is some improvement under certain conditions, but by
and large there's typcally only one "best" way to round the turnpoint
at any given moment, and that's where sailplanes operate.

It comes down to this: I understand the finish gate. I know its hazards
and can anticipate them. The cylinder presents unaddressed variables.
And unlike some pilots, I prefer the advantages of going into a
hazardous environment with as much knowledge as I can. Right now I am
admitting my ignorance of how best to manage the cylinder. And I'm not
taking much confidence in the recommendations of those who purport to
understand its dynamics.

Racing is not inherently safe. And experience leaves me dubious about
rules changes that are predicated on improving the inherent safety of
any aspect of the sport. The density argument rings untrue. There is
clearly some value in elimination of head on traffic, but this can be
addressed in other ways as well, many of which have been offered but
not thoroughly explored because the cylinder is assumed to trump them
all.

You have to give me some credit here. I'm not addressing this as a
blunt-skull only. Sports Class... use the cylinder. MAT... the cylinder
might be appropriate... for the CD and his advisors to decide. Single
class of experienced pilots flying AST or TAT (Nationals), the line
serves very well. Perhaps even better. In either case, the safety of
cylinder versus line is determined solely by the knowledge and
practices of its users. I'd like to be knowledgable in both. If nothing
else, you've turned me pragmatist, JJ. The line serves me fine, but I
know I'll be presented with the cylinder more and more. So let's get on
with the business of putting some regulation on it.

wrote:
OC, You never did answer my question, "How many contests have you
flown
using the finish cylinder?"
Your skepticism leads me to believe you havent flown that many. I
know
you flew it at Montague, anywhere else? How about giving it a fair
try
before condeming it?
JJ

Morning Andy,
On the last day of the 18 meter nats at Montague, a few years back, the
fire base was activated and the County required us to arrive at or
above 1000 feet. Several pilots came to me and said, "If you don't
raise the finish cylinder to 1000 feet, some guys will drive hard and
then call a rolling finish, we need a big penalty for that". So, I
raised the 1 mile cylinder to 1000 feet and announced a 10 minute
penalty for making a rolling finish. Two top pilots did exactly what
wou described and BOTH missed the cylinder! They got their rolling
finish time + 10 minutes. There was ****ing & moaning & nashing of
teeth the like of which the world has seldom seen, complete with
threats of taking their protest to a higher power.

I don't recommend the procedure you described for several reasons, but
the big one I see is; It brings back the pull-up. I would be in favor
of a rule prohibiting hard pull-ups in the cylinder. Easy to enforce,
we have your GPS trace.
JJ

I did an analysis of this and it would appear that
the minumum time solution is to dial in a finish altitude
equal to 500' minus the altitude you can gain in a
pullup from your McCready speed to minimum sink speed.
Just before the cylinder edge you pull up and hit the
bottom outside edge of the cylinder. Depending on your
McCready setting you will approach the edge of the
cylinder at somewhere between 0 feet (Mc = 6 or higher,
full ballast) and 350' (Mc = 2, dry). It's easy to
calculate that you save about 45 seconds over flying
the McCready speed to the cylinder at 500'.

I don't recommend the procedure you described for several reasons,
but
the big one I see is; It brings back the pull-up. I would be in favor
of a rule prohibiting hard pull-ups in the cylinder. Easy to enforce,
we have your GPS trace.
JJ

But the rules DO recommend the procedure. It's the fastest way to
finish !

For any rule prohibiting hard pull-ups, how will the pilot know in
the cockpit, how hard can he pull up without violating the rule ?
Will g-meters be required equipment ?

I personnally have no fears of hard pullups, as long as I don't have to
do
them below 1000 ft AGL.

Todd Smith
3S

Hi Todd,
The rule could say something like, no sudden increase in altitude at or
near the finish cylinder, not to exceed, say 300 feet. I'm sure our
clever scoring programmer could measure time vs. altitude in the
pull-up and flag the trace for penalty consideration.

But the rules DO recommend the procedure. It's the fastest way to
finish !

For any rule prohibiting hard pull-ups, how will the pilot know in
the cockpit, how hard can he pull up without violating the rule ?
Will g-meters be required equipment ?

I personnally have no fears of hard pullups, as long as I don't have
to
do
them below 1000 ft AGL.

Yes, but this is where the near mid-air occurred at this years Seniors.
Several posters have pointed out the same potential exists in the
cylinder as in the line, hence my recommendation to basically prohibit
the pull-up in or near rhe cylinder. It's the guy in your blind spot
that gets you (or you get him)
JJ

Todd Smith
3S

wrote:

I keep asking for some regulation at the cylinder that will make it
easier for me to anticipate likely hazards. And the constant response
is density. I've flown the 1-mile "turn cylinder" for several seasons
now, and I've come to the conclusion that it does little to alleviate
congestion.

Morning Chris,
I think the problems in traffic separation can be solved with good
radio procedures like those we have adopted at Montague. The County
insists we use 122.8 for T/O and landing, so we tell all finishers to
call on 123.3 at 10 miles out, get the winds to see which way we are
landing and then switch to 122.8. They are instructed to call 4 miles
from the center, then in the gate (1 mile on DME) with direction and
condition, ie, JJ....In the gate.......from the S/W............high.
The finisher has been listening for 10 miles and knows who's in front
of him and their condition (low man gets priority). I have done this in
a contest with 80 ships at Reese. Charlie had similar procedures in
place and I never had even the hint of a problem.
I take that back, at Montague we did have a guy with a bad radio that
landed against traffic, thankfully we have a 200 foot wide rudway and
both pilots stayed to the right. His radio problems were a continuing
thing and I felt he should have dealt with it. He should have known his
radio wasn't working when he got no reply and heard nobody talking. We
gave him a hand-held for the remainder of the contest.
JJ

Ah, much better. Now we're going in the right direction. Is there some
way we can raise these from site specific to general practice? And in
the process, refine them to address conceptual (versus reported)
problems with the cylinder. And then do the same sort of thing for the
line. Let's make them both as safe as possible, then measure their
relative worth under the variety of finish scenarios we see. Your
contests will use the cylinder exclusively. That's fine. Others will
prefer the line. Each will attract its adherents, but in the long run,
there's no reason they can't co-exist, especially if each in its own
way contributes to improvements in traffic management at the finish (I
won't say safety in this case, because being safe is largely dependent
on individual practice and compliance with accepted procedures).

The good news, JJ, is that you're at least partly right. Maybe all
right. ;-) Time will tell. And it needn't be based on casuality
figures... just pilot preference.

Cheers,

Chris OC