How do you explain why the A/S increases on thermal entry?

Hmmm...
I thought that if the CG is forward, a 'bump' in lift
is behind it (where the wing center of pressure is
maybe) and so the wing is accelerated up and the nose
pitches down.

Try it with drastically different CG. I tried it with
a 240# guy up front. Big difference from the 160#
guy up front.

Anyway, that's my take on it...

At 00:00 28 March 2005, Terry wrote:

Fred wrote:
Just got asked this question, didn't have a quick
and easy answer.
How
do you explain it?
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I'll stick my neck out on this.

In gliding flight, the horizontal component of lift
is our 'thrust'
that enables an airspeed, while the vertical component
is equal to the
weight of the glider.

Once the thermal is entered, there is an increase in
the total lift
vector equal to strength of the thermal. This results
in an imbalance
of forces which causes the glider to accelerate to
the new steady
state.

I flew for years on the east coast of the US and never
noticed this
effect until moving out west. Estrella has some strong
days were this
effect is very noticable, especially in clean ships.
The lowly 233
exhibits the same effect, just not as noticable.

Terry Claussen
Master CFI


Mark J. Boyd