At 18:00 28 January 2004, Bill Daniels wrote:

'Jim' wrote in message
news
I think the recent threads on spinning have been wonderful.
I find
them a great help to focusing on such an important
issue.

Somewhere in my dark student-pilot experiences I was
shown that
coordinated flight, with the yaw string kept carefully
in the middle,
does not guarantee against spin entry. As I recall,
it was pointed
out to me that even with the string in the middle,
in a steep turn the
inside wing is flying at a higher angle of attack
than is the outer
wing. If a stall is induced in such a steep turn
the inside wing is
likely to stall before the outside wing and thus will
have higher drag
than the outer wing and the glider will likely fall
off over the
inside wing. If confusion or inadequate skill or
distraction get in
the way of an immediate recovery the higher drag of
the inside,
falling wing may initiate an autorotation and possible
spin entry.

Does this seem like a real possibility?

In any case, it instilled in me the knowledge that
the yaw string is
not an indicator of the relative angles of attack
on the two wings.

Your analysis is correct.

Dick Johnson makes a persuasive case for flying thermals
with the yaw string
deflected slightly toward the high wing. Dick says
this in not only safer,
it is aerodynamically more efficient.

Bill Daniels


The yaw string is ahead of the line of the center of
lift along the wing. This line is on the true radius
of the turn. Any yaw string not directly on this line
will be deflected to some extent in a turn. The two
yaw strings on a two-seater will not show the same
deflection in a turn; the one in front will be deflected
further.