> You can see this in a full-scale sailplane that has > both a ball-slip indicator on the instrument panel, and a yaw string taped > to the front of the canopy. In a really tight turn, particularly with a > light wing loading, the tail end of the yaw string will point a little bit > towards the outside of the turn when the ball-slip indicator is perfectly > centered. This makes perfect sense if you consider that the ball tells when > the turn is coordinated (and therefore the wings are lined up with the > airflow at their location), but the yaw string, located out on the nose, > well ahead of the wings, is seeing a distorted flow due to the curvature of > the turn.
I'm afraid I have to disagree with this a bit. BOTH "instruments" are used to determine if the turn is coordinated. And most full scale pilots will tell you that the yaw string is WAY more sensitive than the ball. Also consider that in many gliders the turn indicator is in the panel, usually very close to the yaw string, or at least not far enough away that it makes a difference. Now I'm not arguing with your analysis, only the line of evidence you are using to support it. I argue that the differences observed between the ball and the string are due to the fact that the string is simply more sensitive. When flying full size I never really watched the ball, I focused on the string as the primary and most sensitive indicator of a coordinated turn. I will comment that in the example you cited above the plane is NOT in a coordinated turn because of the fact that the yaw string in NOT centered, regardless of what the ball is telling you. Again, this is a manifestation of the sensitivity of the two. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Bill Malvey Ladera Ranch, California RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
