Sharing a thermal

"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

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

I fly into it and continue until the trend of the vario reverses to
down, then begin a turn into the lifted wing with between
30-45 degrees of bank. I've tried up to 60 degrees, and have
seen only worse climb from over 45 degrees. This in commonly
4-6 knot thermals.

Less than 30 degrees and I'm not sure I could stay in any of the thermals,
more than 45 and I think the loss of upward lift due to bank angle
exceeds any benefit from a tighter core, at least
in thermals around here.

I also tend to stay in the middle third of the thermal altitude,
so if it tops out at 9000ft agl, I'l stay between 3000-6000 ft agl,
although sometimes a little higher over unlandable or known thermal-free
terrain.

In article ,
Jim Vincent wrote:
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



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Mark J. Boyd