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, 3:25*pm, John Cochrane
wrote:
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

Agree!

Reichmann called Option 1 "Forced dolphin flight" if I remember
correctly.

Unfortunately this is what I most often do and I should stop.

David (GJ)

On May 18, 6:25*pm, John Cochrane
wrote:
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

I would only add that the other important factor is the view ahead.
Sometimes slowing in moderate lift for a while- maybe to max l/d or
something as opposed to min sink, can keep you in contact with the
lift without having to circle. Modern gliders don't give up much
straight ahead climbing ability when flown a bit above l/d max.
Qualifier- if you slow down so much that you climb to where you can't
read the clouds effectively, you have made an important mistake.
You ask good questions.
UH

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 5/18/2010 3:28 PM, Dave Nadler wrote:
On May 18, 5:33 pm, 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...

snip

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 !
But keep in mind, a modern ballasted 18 meter glider will not have to
circle nearly as often as your unballasted DG 300 will!

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

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.