Thermal Lift Dynamics

Hey Eric,

I flew out of EPH once about 6 years ago... Oh man, you have a
beutiful thing there! Dust devils and 10kt elevator lift that lasts
all day long. [sighh]

My conditions are very similar to the western half of the state (in
summer). I use the bank that's required to stay in the thermal. I
haven't found a thermal I can stay in with anything under a 45d bank.
If it's tight and peaky (which it usually is) I use more. I
continously move around the thermal re-coring and checking listening...
I think I'm getting "good" at it, but it's hard to tell without another
glider in the thermal for comparison.

Some day I'll move back somewhere with good conditions... but for now,
I'm taking what the good lord is giving and I'm happy to do it.
Besides anyone can stay up all day when conditions are good... It's a
good learning experiance to do it when the conditions are marginal.

If there's one thing I've learned... Thermals are absolutely
unpredictable. One minute their everywhere, next minute poof all gone!
Wait it out a few thousand feet, everywhere all over again. I've
definately notices patterns of stagnation. I imagine it's related
either to cloud shaddowing and or re-triggering.

-Bruce

Eric Greenwell wrote:
wrote:

I've gotten pretty good at keeping it up on marginal days. I
commonly ride the stall buffet (Vs+10kts) in a 60 degree bank satisfied
with 1kt average lift just to stay up a little longer.

I've not flown in your area, but may I suggest that this technique might
lead to seeing only 1 knot climbs?

Try flying at 35-45 degrees at your level flight minimum sink speed:
it's a lot easier to control the glider and feel the thermal, and the
sink rate is less. Weak thermals are usually plenty big for a glider
that flies as slowly as yours does without the need to bank so steeply.

In addition, a lot of gliders have a relatively high sink rate if you
fly near the stall buffet, thus the recommendation for "cruise minimun
sinnk", but check your manual for the proper thermalling speeds.

--
Change "netto" to "net" to email me directly

Eric Greenwell - Washington State, USA

www.motorglider.org - Download "A Guide to Self-launching Sailplane
Operation"

Bruce,

Wait until you read Renner's article on thermal life cycles and
convenction patterns throughout the day. He writes that thermals will
be more frequent and less strong early in the day, but as the day
unfolds and the lift patterens develop and consolidate, the thermals
become more powerful but farther apart, so by the time that happens you
want to be high already.

Of all the aspects of gliding and x/c soaring I've studdied to date,
nothing challenges (and frustrates) me more than weather and thermals.
The pilots who know how to do their own research and follow the
conditions in real time have a distinct advantage. I envy them!

If you ever get a chance, attend one of Carl Herold's camps at Ely. The
weather stuff alone is worth it!

~tuno

wrote:

I've gotten pretty good at keeping it up on marginal days. I
commonly ride the stall buffet (Vs+10kts) in a 60 degree bank satisfied
with 1kt average lift just to stay up a little longer.

I've not flown in your area, but may I suggest that this technique might
lead to seeing only 1 knot climbs?

Try flying at 35-45 degrees at your level flight minimum sink speed:
it's a lot easier to control the glider and feel the thermal, and the
sink rate is less. Weak thermals are usually plenty big for a glider
that flies as slowly as yours does without the need to bank so steeply.

In addition, a lot of gliders have a relatively high sink rate if you
fly near the stall buffet, thus the recommendation for "cruise minimun
sinnk", but check your manual for the proper thermalling speeds.

--
Change "netto" to "net" to email me directly

Eric Greenwell - Washington State, USA

www.motorglider.org - Download "A Guide to Self-launching Sailplane
Operation"

Where are you flying out of?

Mike Schumann

wrote in message
oups.com...
Hey Eric,

I flew out of EPH once about 6 years ago... Oh man, you have a
beutiful thing there! Dust devils and 10kt elevator lift that lasts
all day long. [sighh]

My conditions are very similar to the western half of the state (in
summer). I use the bank that's required to stay in the thermal. I
haven't found a thermal I can stay in with anything under a 45d bank.
If it's tight and peaky (which it usually is) I use more. I
continously move around the thermal re-coring and checking listening...
I think I'm getting "good" at it, but it's hard to tell without another
glider in the thermal for comparison.

Some day I'll move back somewhere with good conditions... but for now,
I'm taking what the good lord is giving and I'm happy to do it.
Besides anyone can stay up all day when conditions are good... It's a
good learning experiance to do it when the conditions are marginal.

If there's one thing I've learned... Thermals are absolutely
unpredictable. One minute their everywhere, next minute poof all gone!
Wait it out a few thousand feet, everywhere all over again. I've
definately notices patterns of stagnation. I imagine it's related
either to cloud shaddowing and or re-triggering.

-Bruce

Eric Greenwell wrote:
wrote:

I've gotten pretty good at keeping it up on marginal days. I
commonly ride the stall buffet (Vs+10kts) in a 60 degree bank satisfied
with 1kt average lift just to stay up a little longer.

I've not flown in your area, but may I suggest that this technique might
lead to seeing only 1 knot climbs?

Try flying at 35-45 degrees at your level flight minimum sink speed:
it's a lot easier to control the glider and feel the thermal, and the
sink rate is less. Weak thermals are usually plenty big for a glider
that flies as slowly as yours does without the need to bank so steeply.

In addition, a lot of gliders have a relatively high sink rate if you
fly near the stall buffet, thus the recommendation for "cruise minimun
sinnk", but check your manual for the proper thermalling speeds.

--
Change "netto" to "net" to email me directly

Eric Greenwell - Washington State, USA

www.motorglider.org - Download "A Guide to Self-launching Sailplane
Operation"

Mike,

I'm flying out of KCAR - Caribou, Maine

http://www.airnav.com/airport/KCAR

-Bruce

Mike Schumann wrote:
Where are you flying out of?

Mike Schumann