Where is the next thermal?

On Sep 22, 2:00*am, Derek Copeland wrote:
Can I agree with Andy. In the UK we often seem to get really strong
thermals close to a large lake or reservoir such as Grafham Water. The
thermals are coming off the surrounding land of course, but the
temperature contrast between the hotter ground and the cooler water seems
to act as a trigger mechanism or a mini front. I have often found that
discontinuities such as the edge of a forest, a ridge line (especially if
pointing into sun), or a ploughed field next to one with crop often seem
to give thermals. Provincial towns and active power stations are also good
ground sources.

However the most reliable thermal markers are circling birds of prey such
as buzzards or kites, or insect eaters such as swallows and swifts.

Derek Copeland *

At 22:28 21 September 2009, Andy wrote:

On Sep 21, 1:52=A0pm, danlj *wrote:
I hope this turns into a thread on "How I keep going" - there must
be
scores of pilots more excellent than I who can say more than me.

I well remember that years ago when a visiting German pilot asked for
advice on finding thermals in Arizona I told him to look above and
downwind of cattle tanks. *These are known as stock ponds in other
places. *His reaction, that I must be a complete idiot for suggesting
that pools of water could trigger thermals, has made me cautious about
offering that advice to anyone. *I hoped he landed out but I don't
think he did.

Andy

Andy's observation is a secret well-known to cross-country pilots in
Arizona. Sometimes the most ridiculously small and almost dry water
holes will be the source of strong thermals. My theory is that water
holes inject enough moisture into the hot dry air to significantly
increase its buoyancy. We also have small hills consisting of black
volcanic rock that are also good sources. Dry river beds (called
washes in the southwest US) also can be useful sources.

Another issue with clouds here is that on fairly dry days the top of
the lift is often a thousand feet or more below cloud base. However,
a strong thermal will often continue for a short time above the top of
lift fueled by the extra heat released by condensation and eventually
form a cumulus. Once this short thermal pulse has decayed, the area
immediately below the cloud then has no lift, although the original
thermal may still be found a few thousand feet below. I call these
clouds "cumulus decoyus" - decoy cumulus!


Mike

On Sep 22, 11:40*am, Mike the Strike wrote:
On Sep 22, 2:00*am, Derek Copeland wrote:



Can I agree with Andy. In the UK we often seem to get really strong
thermals close to a large lake or reservoir such as Grafham Water. The
thermals are coming off the surrounding land of course, but the
temperature contrast between the hotter ground and the cooler water seems
to act as a trigger mechanism or a mini front. I have often found that
discontinuities such as the edge of a forest, a ridge line (especially if
pointing into sun), or a ploughed field next to one with crop often seem
to give thermals. Provincial towns and active power stations are also good
ground sources.

However the most reliable thermal markers are circling birds of prey such
as buzzards or kites, or insect eaters such as swallows and swifts.

Derek Copeland *

At 22:28 21 September 2009, Andy wrote:

On Sep 21, 1:52=A0pm, danlj *wrote:
I hope this turns into a thread on "How I keep going" - there must
be
scores of pilots more excellent than I who can say more than me.

I well remember that years ago when a visiting German pilot asked for
advice on finding thermals in Arizona I told him to look above and
downwind of cattle tanks. *These are known as stock ponds in other
places. *His reaction, that I must be a complete idiot for suggesting
that pools of water could trigger thermals, has made me cautious about
offering that advice to anyone. *I hoped he landed out but I don't
think he did.

Andy

Andy's observation is a secret well-known *to cross-country pilots in
Arizona. *Sometimes the most ridiculously small and almost dry water
holes will be the source of strong thermals. *My theory is that water
holes inject enough moisture into the hot dry air to significantly
increase its buoyancy. *We also have small hills consisting of black
volcanic rock that are also good sources. *Dry river beds (called
washes in the southwest US) also can be useful sources.

Another issue with clouds here is that on fairly dry days the top of
the lift is often a thousand feet or more below cloud base. *However,
a strong thermal will often continue for a short time above the top of
lift fueled by the extra heat released by condensation and eventually
form a cumulus. *Once this short thermal pulse has decayed, the area
immediately below the cloud then has no lift, although the original
thermal may still be found a few thousand feet below. *I call these
clouds "cumulus decoyus" - decoy cumulus!

Mike

Known in other parts of the world as "Cumulus no-liftus"

Craig

On Mon, 21 Sep 2009 15:28:09 -0700 (PDT), Andy
wrote:

On Sep 21, 1:52*pm, danlj wrote:
I hope this turns into a thread on "How I keep going" - there must be
scores of pilots more excellent than I who can say more than me.

I well remember that years ago when a visiting German pilot asked for
advice on finding thermals in Arizona I told him to look above and
downwind of cattle tanks. These are known as stock ponds in other
places. His reaction, that I must be a complete idiot for suggesting
that pools of water could trigger thermals, has made me cautious about
offering that advice to anyone. I hoped he landed out but I don't
think he did.

Andy

There was an article in S&G, a few years ago, about thermal origin and
how to guess their location.
It was under the title "Triggers and Feeders". Interesting reading
about the wide areas that collect warmer air, and features on the
ground that induce the bubbles to win adhesion and start soaring.

An antenna, a pond, a building, a moving object etc, all are excellent
triggers, but they're worth nothing without an adequate volume of warm
air being supplied by the feeder area.

Aldo Cernezzi

On Sep 22, 7:03*pm, cernauta wrote:
On Mon, 21 Sep 2009 15:28:09 -0700 (PDT), Andy
wrote:

On Sep 21, 1:52*pm, danlj wrote:
I hope this turns into a thread on "How I keep going" - there must be
scores of pilots more excellent than I who can say more than me.

I well remember that years ago when a visiting German pilot asked for
advice on finding thermals in Arizona I told him to look above and
downwind of cattle tanks. *These are known as stock ponds in other
places. *His reaction, that I must be a complete idiot for suggesting
that pools of water could trigger thermals, has made me cautious about
offering that advice to anyone. *I hoped he landed out but I don't
think he did.

Andy

There was an article in S&G, a few years ago, about thermal origin and
how to guess their location.
It was under the title "Triggers and Feeders". Interesting reading
about the wide areas that collect warmer air, and features on the
ground that induce the bubbles to win adhesion and start soaring.

An antenna, a pond, a building, a moving object etc, all are excellent
triggers, but they're worth nothing without an adequate volume of warm
air being supplied by the feeder area.

Aldo Cernezzi

Many times in strong conditions (especially down low) there will a
strong downdraft to be crossed before you hit that (thank you god)
strong thermal.

Bill Snead

I've heard pilots say that the departure of an aircraft will kick off a
thermal from the runway. Worth watching if you are relatively low over
the field and your timing is right to search it out.

At 00:03 23 September 2009, cernauta wrote:
On Mon, 21 Sep 2009 15:28:09 -0700 (PDT), Andy
wrote:

On Sep 21, 1:52*pm, danlj wrote:
I hope this turns into a thread on "How I keep going" - there must
be
scores of pilots more excellent than I who can say more than me.

I well remember that years ago when a visiting German pilot asked for
advice on finding thermals in Arizona I told him to look above and
downwind of cattle tanks. These are known as stock ponds in other
places. His reaction, that I must be a complete idiot for suggesting
that pools of water could trigger thermals, has made me cautious about
offering that advice to anyone. I hoped he landed out but I don't
think he did.

Andy

There was an article in S&G, a few years ago, about thermal origin and
how to guess their location.
It was under the title "Triggers and Feeders". Interesting reading
about the wide areas that collect warmer air, and features on the
ground that induce the bubbles to win adhesion and start soaring.

An antenna, a pond, a building, a moving object etc, all are excellent
triggers, but they're worth nothing without an adequate volume of warm
air being supplied by the feeder area.

Aldo Cernezzi

On Wed, 23 Sep 2009 01:45:02 +0000, Nyal Williams wrote:

I've heard pilots say that the departure of an aircraft will kick off a
thermal from the runway. Worth watching if you are relatively low over
the field and your timing is right to search it out.

Its well known in the free flight model flying world that in the right
conditions a few people running about flapping T-shirts can kick off a
thermal. I once made my own thermal just by running about circle towing
an F1A class competition glider in sparse foot-high dry grass on calm
early morning conditions. It wasn't strong though - just enough to make a
model with a 0.3 m/s min sink speed climb slowly.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

I think this rather depends on the degree of instability in the air. On
relatively stable days the usual thermal sources often don't seem to
work. You need a large area to remain undisturbed for some time until
enough hot air is available to give a decent thermal when triggered. Often
things like towns and motorways don't work because there is too much
trigger activity going on and only tiny weak thermals will form that go to
no great height.

Derek Copeland

At 14:01 23 September 2009, Martin Gregorie wrote:
On Wed, 23 Sep 2009 01:45:02 +0000, Nyal Williams wrote:

I've heard pilots say that the departure of an aircraft will kick off
a
thermal from the runway. Worth watching if you are relatively low
over
the field and your timing is right to search it out.

Its well known in the free flight model flying world that in the right
conditions a few people running about flapping T-shirts can kick off a
thermal. I once made my own thermal just by running about circle towing
an F1A class competition glider in sparse foot-high dry grass on calm
early morning conditions. It wasn't strong though - just enough to make
a
model with a 0.3 m/s min sink speed climb slowly.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

I have very good luck going right over the center of a town.

Flying in the Midwest farm country of the USA I find the vast majority
of thermals by simply blundering into them blindly.

Below 1500AGL ground clues MAY help you find lift but just as likely
not. In rocky mountainous terrain it's a different story.

Determine what altitude is half way to cloudbase (if there are
clouds); Below that ignore the clouds and just go, above that the
clouds MAY help you find lift.

Real cloudstreets DO exist as do lift streets with no clouds. Keep an
open mind at all times.

Many people fly too slow in sink or even turn in sink trying to decide
what to do. Even at 800agl if the vario says 500 or 1000 down go FAST
and go straight. You are much more likely to hit a thermal on your
way to your landing field than if you fly around maneuvering slow.

Fly SLOW in lift or zero sink. Pull back on the stick to min sink and
do it immediately. Many people turn too shallow and too late in
thermals. Circle just about as tight as you can fly slow in most
thermals for the best climb rate.

Keep a positive attitude. Keep a couple landing fields in sight but
keep a positive attitude. Many XC flights have been saved on
downwind. Once you turn base give it up. Hear the theme to Star Trek
in your mind and boldly go where no one has gone before.

Here is my methodology, most of which is found in Reichmann's
excellent book.

1. Develop testable 3-D models of the lift in your mind, based on
topography, wind, sun aspect and previous experience. This is my
version of "strolling along the ground to find where it is hot" in
Reichmann's definitive text.

2. Test the model by putting the glider in what you hypothesize as
the best energy lines.

3. Fly as precisely and efficiently as you can and in an direct
correlation to the intensity of lift/sink/turbulence: Smooth and easy
inputs in light, smooth lift. Firm and aggressive when it is rock-and
rolling. The flight paths of world-class pilots can appear as though
they are drunk or very sloppy as they weave about. This is in direct
opposition to wings lifting and can be used to locate in featureless,
cloudless terrain.

3. Adjust your mental image and flight path based on test results and
observation of other ships, birds, dust, etc. I believe AJ Smith and/
or Dick Schreder said that 90% of what you need to know is outside
the cockpit and if you have not made a decision in the last 5 minutes,
you are not working hard enough. Electron Slingers allow you to
direct your attention and energy where it matters: OUTSIDE THE
COCKPIT. A glance at the moving map periodically is all that is
required to affirm your location and that you have suitable fields in
a reasonable glide, how you are doing on task and what you need for
final glide.

3. Repeat this decision-action loop every 1/2 hour or so based on
changing wind direction and intensity, sun aspect, and terrain and
what is 20-50 miles down the road.

I would also echo what others have said:

When close to clouds, use them as the primary reference. And not just
"sort of under a cloud". You need to determine which side of the
cloud and what cloud phase is optimal and what height below base.
Target and test the clouds you select and adjust your selection
process. As one gets lower, lift hunting is more and more attached to
the terrain + wind + sun aspect.

Finally, be mentally Tough and never quit "soaring" until you commit
to landing. As someone said previously, many flights have been
"sucked off the ground", mostly due to the pilot's persistence and
willingness to fight until a safe landing is inevitably necessary.
"Giving up" is very seductive and absolutely ensures you will land.
Both of these behaviors are self-reinforcing; both become easier with
repetition. "Grinding it out" is where our hang glider brothers
really excel.

The paradoxical situation we find ourselves in when low and facing an
off-field landing is one of the many things I find interesting in X-C
soaring. Just when we are under maximum stress and with minimal
options, we need to be at our absolute technical best and most
creative. Gotta love it!