Sharing a thermal

OK, this is going to get good.

Eric thinks wide fast turns work best for him. I think 45 degree turns are
best on average with steeper turns useful in small cores. If fly as slow as
I can without risking a stall.

Lets have a poll. Tell us how you thermal.

Bill Daniels

Bill,
I try to fly, if the conditions warrant it, a 45 deg. bank
my wing loading is 8.3 lb/ft/sq at that bank my turn will be 22 seconds.
My speed will be 52 kt. indicated.
Udo
PS. I will check some of my contest recordings to make sure my memory is
still ok. Also I open up the turn when more lift is indicated and tighten
when
less lift. I use the Borgelt and I react to the trend, that is when the
needle or sound just start coming out of the bottom or falling off. Works
for me like a charm.
Udo

"Bill Daniels" wrote in message
news:2bidd.499463$8_6.239366@attbi_s04...
OK, this is going to get good.

Eric thinks wide fast turns work best for him. I think 45 degree turns
are
best on average with steeper turns useful in small cores. If fly as slow
as
I can without risking a stall.

Lets have a poll. Tell us how you thermal.

Bill Daniels

Bill,
a small correction, wing loading remains 8.3 lb/ft/sq, average time around
the circle 25 second at 50 kt Ground speed. Bank of between 40 and 45 deg. I
use the Instrument screws as reference.
I have a number of recordings. If any body cares to look at them let me know
and I will send an http.
Udo
Bill,
I try to fly, if the conditions warrant it, a 45 deg. bank
my wing loading is 8.3 lb/ft/sq at that bank my turn will be 22 seconds.
My speed will be 52 kt. indicated.
Udo
PS. I will check some of my contest recordings to make sure my memory is
still ok. Also I open up the turn when more lift is indicated and tighten
when
less lift. I use the Borgelt and I react to the trend, that is when the
needle or sound just start coming out of the bottom or falling off. Works
for me like a charm.
Udo

"Bill Daniels" wrote in message
news:2bidd.499463$8_6.239366@attbi_s04...
OK, this is going to get good.

Eric thinks wide fast turns work best for him. I think 45 degree turns
are
best on average with steeper turns useful in small cores. If fly as slow
as
I can without risking a stall.

Lets have a poll. Tell us how you thermal.

Bill Daniels

Bill Daniels wrote:
OK, this is going to get good.

Eric thinks wide fast turns work best for him.

"Fast" is relative: at 8.2 lb/sq ft, going a slower is
counterproductive. I can slow down to 45 knots from the usual 50, but
the glider isn't very steady, feels "draggy", and it doesn't climb any
better, even in very smooth thermals (this measurement done when
circling with other gliders). In anything but very smooth thermals, the
50-52 knots is needed to have decent control, anyway.

I think 45 degree turns are
best on average with steeper turns useful in small cores. If fly as slow as
I can without risking a stall.

This may be appropriate for the Nimbus 2, but not for the ASH 26, where
the stall is noticeably lower than minimum sink. Waibel told me once
that he considers this a safety feature.


Lets have a poll. Tell us how you thermal.

And what, and where. These are likely important reasons for your bank
angle and speed preferences.


Bill Daniels



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

Eric Greenwell
Washington State
USA

"Eric Greenwell" wrote in message
...
Bill Daniels wrote:
OK, this is going to get good.

Eric thinks wide fast turns work best for him.

"Fast" is relative: at 8.2 lb/sq ft, going a slower is
counterproductive. I can slow down to 45 knots from the usual 50, but
the glider isn't very steady, feels "draggy", and it doesn't climb any
better, even in very smooth thermals (this measurement done when
circling with other gliders). In anything but very smooth thermals, the
50-52 knots is needed to have decent control, anyway.

I think 45 degree turns are
best on average with steeper turns useful in small cores. If fly as
slow as
I can without risking a stall.

This may be appropriate for the Nimbus 2, but not for the ASH 26, where
the stall is noticeably lower than minimum sink. Waibel told me once
that he considers this a safety feature.


Lets have a poll. Tell us how you thermal.

And what, and where. These are likely important reasons for your bank
angle and speed preferences.


I just examined some IGC traces of mine and, correcting for density
altitude, the IAS was about 43 mph in what looks like a 40 - 45 degree bank.
I'm still looking for a representative climb in a small, strong core but I
think I should have one from Moriarty, NM.

The Nimbus 2C ailerons become very ineffective at low IAS but it still
responds nicely to rudder inputs. I use Dick Johnson's slipping turn so the
ailerons stay neutral and I fly the bank with rudder. The big glider is
very stable in slow turns.

If there's a strong core, I'm not concerned with sink rate in slow, steep
turns. The strength of thermal cores will easily offset that.

Bill Daniels

Actual SeeYou measurements

ASW-27B dry (8.2 lbs/sf)
Altitude 13,000 ft
TAS/IAS: 71/53 mph
Measured radius: ~350 ft
Implied bank angle: 43.5 degrees
Stall speed (calculated): ~51 mph

ASW-27B wet (11.5 lbs/sf) -- prior day
Altitude 13,500 ft
TAS/IAS: 84/61 mph
Measured radius: ~515 ft
Implied bank angle: 42.5 degrees
Stall speed (calculated): ~57 mph

9B


At 03:06 20 October 2004, Eric Greenwell wrote:
Bill Daniels wrote:
OK, this is going to get good.

Eric thinks wide fast turns work best for him.

'Fast' is relative: at 8.2 lb/sq ft, going a slower
is
counterproductive. I can slow down to 45 knots from
the usual 50, but
the glider isn't very steady, feels 'draggy', and it
doesn't climb any
better, even in very smooth thermals (this measurement
done when
circling with other gliders). In anything but very
smooth thermals, the
50-52 knots is needed to have decent control, anyway.

I think 45 degree turns are
best on average with steeper turns useful in small
cores. If fly as slow as
I can without risking a stall.

This may be appropriate for the Nimbus 2, but not for
the ASH 26, where
the stall is noticeably lower than minimum sink. Waibel
told me once
that he considers this a safety feature.


Lets have a poll. Tell us how you thermal.

And what, and where. These are likely important reasons
for your bank
angle and speed preferences.


Bill Daniels



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

Eric Greenwell
Washington State
USA

"Bill Daniels" wrote in message
news:2bidd.499463$8_6.239366@attbi_s04...
Lets have a poll. Tell us how you thermal.

Bill Daniels


I do whatever it takes to make the averager number bigger! What that might
be depends on whether I am at Truckee or Ely or Williams; whether the lift
is turbulent or smooth, big or small core, alone or with other gliders, with
or without water, bugs on the wings, etc. The correct bank angle and speed
might change from one side of the circle to the other and is changing,
experimenting, trying to iterate the best possible lift.

When I see another glider climbing better in another part of the thermal, I
just go there!

It really matters that the climb rate is as high as possible in each climb
taken. When I fly with others in our DuoDiscus I am amazed at how carefully
many pilots follow the speed director (which is on a 30 second averager) in
cruise, but climb sloppily and lazily, accepting whatever comes and not
actively searching for the best thermals and using them to the max.
Maximizing climb and avoiding sink are the best ways to cover miles (or
km.). Interthermal glide speeds are relatively unimportant.

Of course, most of this is just experience -- many hours of flying and
thermalling -- and better learned in thermals than on Usenet...
-Bob Korves
5H DuoDiscus
5K LAK-17a

Won't SeeYou underestimate the thermalling speed because it is
calculating speed based on the straightline distance between different
points on a circle?


Andy Blackburn wrote:
Actual SeeYou measurements

ASW-27B dry (8.2 lbs/sf)
Altitude 13,000 ft
TAS/IAS: 71/53 mph
Measured radius: ~350 ft
Implied bank angle: 43.5 degrees
Stall speed (calculated): ~51 mph

ASW-27B wet (11.5 lbs/sf) -- prior day
Altitude 13,500 ft
TAS/IAS: 84/61 mph
Measured radius: ~515 ft
Implied bank angle: 42.5 degrees
Stall speed (calculated): ~57 mph

9B

Lets have a poll. Tell us how you thermal.

I don't believe in a shallow bank for 180 degrees. The trade off in efficiency
is more than offset by getting out of the sink and into the lift quicker.

Reichman's rules: Increase bank in sink, shallow bank as vario rises, increase
bank in lift. My numbers say min sink is 44 ktws, 30 degree min sink is 49, 45
is 52, and 60 is 63 kts.

If themals are tight and narly, then crank 45-60, decreasing with altitude as
thermals generally widen. Like many here, the screws on the instruments are
the 45 degree indicator (a golden nugget from a CSA instructor). I would
rather increase my airspeed than shallow the bank since the increase in
airspeed effectively increases the turn radius with minimal drag effects and
low time lag.

To me, crankin and bankin to get into the best lift is worth it...plus much
more fun!

Jim Vincent
N483SZ
illspam

I used to think that I could climb faster with steeper turns in the
strongest part of the thermal, but after flying with the some of the best
open class pilots in the USA, and seeing them outclimb me, it seems to me
that lower bank angles, 30-45 degrees, and slower speeds are better than
tightening up in the core and using steeper banks angles, and higher IAS.
Maybe this isn't as true with 15m wings.

I have seen days though, when you couldn't even climb if you didn't wrap it
up hard and use bank angles of at least 60 degrees or more.

It may not always be the most efficient, but I do think it's fun to circle
at very high bank angles for a few turns, or more once and a while. It is
such a rush to just stand a sailplane on it's wing., and climb at 3 or 4+
g's!

Gary Boggs

"Jim Vincent" wrote in message
...
Lets have a poll. Tell us how you thermal.

I don't believe in a shallow bank for 180 degrees. The trade off in
efficiency
is more than offset by getting out of the sink and into the lift quicker.

Reichman's rules: Increase bank in sink, shallow bank as vario rises,
increase
bank in lift. My numbers say min sink is 44 ktws, 30 degree min sink is
49, 45
is 52, and 60 is 63 kts.

If themals are tight and narly, then crank 45-60, decreasing with altitude
as
thermals generally widen. Like many here, the screws on the instruments
are
the 45 degree indicator (a golden nugget from a CSA instructor). I would
rather increase my airspeed than shallow the bank since the increase in
airspeed effectively increases the turn radius with minimal drag effects
and
low time lag.

To me, crankin and bankin to get into the best lift is worth it...plus
much
more fun!

Jim Vincent
N483SZ
illspam