Losing time in Cloud-Streets?

All -

I've been flying with the assumption that flying slow in cloud-streets
is always a good idea. But in looking at some of my OLC flights I
wonder if my logic is faulty and I'm hurting my speed. Anyone with
lots of OLC or contest experience care to offer feedback? Details
below...

My thinking has always been that your forward speed in a circling
climb is effectively "0" (slightly more or less than 0, based on wind;
but call it 0 for the sake of argument). As a corollary, anything you
can do to maintain or gain altitude while retaining forward progress
on-course is a "win".

Therefore, I've always been slowing down in cloud-streets or under
large clouds with apparent extended areas of lift. If I'm anywhere
near cloudbase (say, less than 1000' or so), my logic has been that
I'm not gaining enough altitude to stop and circle with that zero
forward speed. Instead I try to maximize the lift by flying straight
ahead (or slightly curving my path to stay in the zone of lift) at
slow speed (say 50 kts).

Rough math to support my thoughts:
With a cruise speed of 75 knots and a time-in-climb around 25%,
average forward speed is roughly 56 knots (75% x 75 knots). This is
so close to the 50 knots (while flying in a cloud-street) that it
seems to support my behavior... But maybe I'm missing something?
Maybe the gains I'm getting are not enough to offset the slower cruise-
speed during these times? I should point out that I fly in pretty
strong thermal conditions at my local site (Ephrata, WA).

I could throw in all of my various caveats and details and thought-
processes, but rather than make this a really long post I'd love to
get some thoughts and feedback. Anyone have pointers, ideas, see
fallacies in my process, etc?

Thanks,

--Noel

On May 18, 4:33*pm, "noel.wade" wrote:
All -

I've been flying with the assumption that flying slow in cloud-streets
is always a good idea. *But in looking at some of my OLC flights I
wonder if my logic is faulty and I'm hurting my speed. *Anyone with
lots of OLC or contest experience care to offer feedback? Details
below...

My thinking has always been that your forward speed in a circling
climb is effectively "0" (slightly more or less than 0, based on wind;
but call it 0 for the sake of argument). As a corollary, anything you
can do to maintain or gain altitude while retaining forward progress
on-course is a "win".

Therefore, I've always been slowing down in cloud-streets or under
large clouds with apparent extended areas of lift. *If I'm anywhere
near cloudbase (say, less than 1000' or so), my logic has been that
I'm not gaining enough altitude to stop and circle with that zero
forward speed. *Instead I try to maximize the lift by flying straight
ahead (or slightly curving my path to stay in the zone of lift) at
slow speed (say 50 kts).

Rough math to support my thoughts:
With a cruise speed of 75 knots and a time-in-climb around 25%,
average forward speed is roughly 56 knots (75% x 75 knots). *This is
so close to the 50 knots (while flying in a cloud-street) that it
seems to support my behavior... *But maybe I'm missing something?
Maybe the gains I'm getting are not enough to offset the slower cruise-
speed during these times? *I should point out that I fly in pretty
strong thermal conditions at my local site (Ephrata, WA).

I could throw in all of my various caveats and details and thought-
processes, but rather than make this a really long post I'd love to
get some thoughts and feedback. *Anyone have pointers, ideas, see
fallacies in my process, etc?

Thanks,

--Noel

that sounds right to me. although i spend more like 30-40% of my time
thermalling. i always do my best to fly along at min sink or so
straight ahead in any sort of streetlike lift i find. not only do you
make forward progress but you also are gaining altitude. so now you
have gone say 5 or 10 miles in a street and you are at least at the
same altitude you started but probably 1000 or more feet higher. this
could be the equivalent climb that you would've had if you would've
stopped and circled right away except you have now made more progress
on course and still have the altitude to convert into speed.

On May 18, 2:33*pm, "noel.wade" wrote:
All -

I've been flying with the assumption that flying slow in cloud-streets
is always a good idea. *But in looking at some of my OLC flights I
wonder if my logic is faulty and I'm hurting my speed. *Anyone with
lots of OLC or contest experience care to offer feedback? Details
below...

My thinking has always been that your forward speed in a circling
climb is effectively "0" (slightly more or less than 0, based on wind;
but call it 0 for the sake of argument). As a corollary, anything you
can do to maintain or gain altitude while retaining forward progress
on-course is a "win".

Therefore, I've always been slowing down in cloud-streets or under
large clouds with apparent extended areas of lift. *If I'm anywhere
near cloudbase (say, less than 1000' or so), my logic has been that
I'm not gaining enough altitude to stop and circle with that zero
forward speed. *Instead I try to maximize the lift by flying straight
ahead (or slightly curving my path to stay in the zone of lift) at
slow speed (say 50 kts).

Rough math to support my thoughts:
With a cruise speed of 75 knots and a time-in-climb around 25%,
average forward speed is roughly 56 knots (75% x 75 knots). *This is
so close to the 50 knots (while flying in a cloud-street) that it
seems to support my behavior... *But maybe I'm missing something?
Maybe the gains I'm getting are not enough to offset the slower cruise-
speed during these times? *I should point out that I fly in pretty
strong thermal conditions at my local site (Ephrata, WA).

I could throw in all of my various caveats and details and thought-
processes, but rather than make this a really long post I'd love to
get some thoughts and feedback. *Anyone have pointers, ideas, see
fallacies in my process, etc?

Thanks,

--Noel

I've been thinking the same thing. I try hard to minimize the time I
spend circling. This year I'm going to slow down in lift, but not as
much as I have in the past...maybe to 60-65 knots. And I'm going to
strive harder to fly faster between thermals....say 75-80 knots on a
4-5 knot day. Ask yourself....Do I land out often? I'm guessing you
don't. I do think 50 knots is too probably too conservative under a
street. I may try to set my ring to the average expected lift under
the street, so that would be even faster than 60-65 knts....humm. Let
me know how it goes...

i guess it is worth noting that my average XC speed, no wind, is
slower than minimum sink speed for my glider.

On May 18, 4:33*pm, "noel.wade" wrote:
All -

I've been flying with the assumption that flying slow in cloud-streets
is always a good idea. *

I disagree. It's always MacCready theory, if correctly interpreted.

Suppose the cloudstreet offers 2 knots up everywhere with occasional 8
knot cores. (Uvalde). Option 1: fly 50 knots without losing altitude.
You average 50 knots = 57 mph. Option 2: fly 85 knots, (I.e. cruise at
Mc 4 or so) , slowly losing, but stopping to thermal in the 8 knot
cores. You average 80 mph. (Typical uvalde winning speeds) The latter
is much faster. Reichmann offers the same advice.

John Cochrane

On May 18, 5:33*pm, "noel.wade" wrote:
All -

I've been flying with the assumption that flying slow in cloud-streets
is always a good idea. *But in looking at some of my OLC flights I
wonder if my logic is faulty and I'm hurting my speed. *Anyone with
lots of OLC or contest experience care to offer feedback? Details
below...

My thinking has always been that your forward speed in a circling
climb is effectively "0" (slightly more or less than 0, based on wind;
but call it 0 for the sake of argument). As a corollary, anything you
can do to maintain or gain altitude while retaining forward progress
on-course is a "win".

Therefore, I've always been slowing down in cloud-streets or under
large clouds with apparent extended areas of lift. *If I'm anywhere
near cloudbase (say, less than 1000' or so), my logic has been that
I'm not gaining enough altitude to stop and circle with that zero
forward speed. *Instead I try to maximize the lift by flying straight
ahead (or slightly curving my path to stay in the zone of lift) at
slow speed (say 50 kts).

Rough math to support my thoughts:
With a cruise speed of 75 knots and a time-in-climb around 25%,
average forward speed is roughly 56 knots (75% x 75 knots). *This is
so close to the 50 knots (while flying in a cloud-street) that it
seems to support my behavior... *But maybe I'm missing something?
Maybe the gains I'm getting are not enough to offset the slower cruise-
speed during these times? *I should point out that I fly in pretty
strong thermal conditions at my local site (Ephrata, WA).

I could throw in all of my various caveats and details and thought-
processes, but rather than make this a really long post I'd love to
get some thoughts and feedback. *Anyone have pointers, ideas, see
fallacies in my process, etc?

Thanks,

--Noel

A few notes:
- the glider climbs much better going straight than circling, and can
fly slower
- you can fly through the cores when you fly straight, you circle
around them
- streets have narrower cores
- all this depends on the glider (harder to avoid circling as
performance decreases)

A few weeks ago I flew 440 miles, around 15% circling, mostly during
the beginning of the flight and digging out of one hole (flew under OD
at 2nd turn):
http://www.onlinecontest.org/olc-2.0...htId=502072323

Suggestion: Go look at the log files of the fastest pilots during last
years 18m nationals at Ephrata !

Hope this is helpful,
See ya, Dave "YO electric"

On May 18, 3:33*pm, "noel.wade" wrote:
All -

I've been flying with the assumption that flying slow in cloud-streets
is always a good idea. *But in looking at some of my OLC flights I
wonder if my logic is faulty and I'm hurting my speed. *Anyone with
lots of OLC or contest experience care to offer feedback? Details
below...

My thinking has always been that your forward speed in a circling
climb is effectively "0" (slightly more or less than 0, based on wind;
but call it 0 for the sake of argument). As a corollary, anything you
can do to maintain or gain altitude while retaining forward progress
on-course is a "win".

Therefore, I've always been slowing down in cloud-streets or under
large clouds with apparent extended areas of lift. *If I'm anywhere
near cloudbase (say, less than 1000' or so), my logic has been that
I'm not gaining enough altitude to stop and circle with that zero
forward speed. *Instead I try to maximize the lift by flying straight
ahead (or slightly curving my path to stay in the zone of lift) at
slow speed (say 50 kts).

Rough math to support my thoughts:
With a cruise speed of 75 knots and a time-in-climb around 25%,
average forward speed is roughly 56 knots (75% x 75 knots). *This is
so close to the 50 knots (while flying in a cloud-street) that it
seems to support my behavior... *But maybe I'm missing something?
Maybe the gains I'm getting are not enough to offset the slower cruise-
speed during these times? *I should point out that I fly in pretty
strong thermal conditions at my local site (Ephrata, WA).

I could throw in all of my various caveats and details and thought-
processes, but rather than make this a really long post I'd love to
get some thoughts and feedback. *Anyone have pointers, ideas, see
fallacies in my process, etc?

Thanks,

--Noel

Noel,

The best way to think about this is to do a few thought experiments.
First you need to say what is the average climb you expect for the day
that you are willing to take, lets say 5 knots. What is the speed you
can achieve with that if you were in pure MacCready flight mode.

There are side by side cloud streets one with a 5 knot thermal every
10 miles and one one where you can fly along at 50 knots for the whole
flight. Which one will get you home faster? What speed would you fly
between the thermals on the one street.

Now combine the two together. How would you fly differently? You can
fly faster than you have in the low lift under the street, but take
advantage of the stronger cores every few miles by being below the
clouds enough to make it worth while to stop and turn in the strong
stuff. If it is a really good street you fly faster but only pull up
in the strong cores and climb back to cloud base without turning.

Reichmann covers this well in the section on Dolphin flight models and
concludes:

"For dolphin flight a new theory results which contains the "classic"
theory as a special case. The speed ring and similar devices retain
their validity. Thus, according to the theory, the ring is set
exactly the same for "classic" flight (apart from possible tactical
considerations, of course). It has been proven that "force" dolphin
flight causes cruise-speed losses."

So you speed ring or speed to fly vario is going to tell you to slow
down in lift but not all the way to climb speeds if you are cruising
with a MC 5 and your in one knot lift.

A couple of things:

1) Thanks John, that's the kind of comparison/number-checking I was
looking for. I know that cloudbase/working-band/lift-strength play a
factor in determining whether the tradeoff is worth it; but didn't
think to do a straight MacCready comparison (the idea of pushing the
glider to high speed while still in spotty lift under a cloud-street
is just still feels awkward - discounting the few times where I've
approached cloudbase and needed to "bug out")!

2) I thought flying "energy lines" was the consensus these days, and
"Dolphin flying" was out - given that variometers lag and its
incredibly hard to time your pushes and pulls when flying through
alternating narrow cores and strong sink. If your strong cores are
separated by a couple of miles, their miniscule contribution (say a 50
- 150 foot height gain) when you fly straight through them doesn't
seem worth it (especially when you start considering the risks of
hitting nasty sink before accelerating back up to cruise speed;
possibly wiping out all of your gains). I've always been much more
tempted to slow down under weak spread-out lift (for example, under a
cloud thats about to OD).


Now just to turn this around and look at it from a different
perspective: For the fast guys out there, when (if ever) *do* you
start slowing down a lot while flying straight ahead? What're the
combination of factors that encourage you to switch into this mode?

Thanks,

--Noel

On May 18, 5:33*pm, "noel.wade" wrote:
All -

I've been flying with the assumption that flying slow in cloud-streets
is always a good idea. *But in looking at some of my OLC flights I
wonder if my logic is faulty and I'm hurting my speed. *Anyone with
lots of OLC or contest experience care to offer feedback? Details
below...

My thinking has always been that your forward speed in a circling
climb is effectively "0" (slightly more or less than 0, based on wind;
but call it 0 for the sake of argument). As a corollary, anything you
can do to maintain or gain altitude while retaining forward progress
on-course is a "win".

Therefore, I've always been slowing down in cloud-streets or under
large clouds with apparent extended areas of lift. *If I'm anywhere
near cloudbase (say, less than 1000' or so), my logic has been that
I'm not gaining enough altitude to stop and circle with that zero
forward speed. *Instead I try to maximize the lift by flying straight
ahead (or slightly curving my path to stay in the zone of lift) at
slow speed (say 50 kts).

Rough math to support my thoughts:
With a cruise speed of 75 knots and a time-in-climb around 25%,
average forward speed is roughly 56 knots (75% x 75 knots). *This is
so close to the 50 knots (while flying in a cloud-street) that it
seems to support my behavior... *But maybe I'm missing something?
Maybe the gains I'm getting are not enough to offset the slower cruise-
speed during these times? *I should point out that I fly in pretty
strong thermal conditions at my local site (Ephrata, WA).

I could throw in all of my various caveats and details and thought-
processes, but rather than make this a really long post I'd love to
get some thoughts and feedback. *Anyone have pointers, ideas, see
fallacies in my process, etc?

Thanks,

--Noel

Check out this site by Bob Hanson. He made a java app that directly
deals with your question with a cloud street strategy feature.
To get to that feature, look for the dropdown menu that says "These
Conditions" and choose the option at the very bottom "Cloud Street
Flight Strategy Comparison".
http://www.stolaf.edu/people/hansonr/soaring/spd2fly/

Essentially, it brute forces a lot speed to fly calculations to try to
find the optimum theoretical speed. With the given conditions it
finds the best results out of the batch it then takes the
corresponding airspeed and outputs it to the table. Some interesting
numbers it comes up with... Of course the results are subject to
interpretation based on real life results, like MacCready theory.

~Andrew

Read Reichmann, he explains everything.

While real life tactics may have changed, the mathematical basics are
still the same, and it's still good advice to start with strict McCready
and adopt only later when you have understood and mastered the basics.