B737-800 Winglets

[MilesDavis]

student pilot here just a quick question

Was reading about new winglets on FR's fleet, why would the addition of winglets impose a reduction in x-wind limitation by a couple of knots?

thanks

[Empty Cruise]

More vertical area, thus higher directional stability, thus more rudder required (for same airspeed) to straighten aircraft before impact.

Beech 1900C vs. D have same effect. Raising the cabin to standing height reduced the demonstrated crosswind from 25 to 22 kts.

...I...eeerrr...think :O

Brgds fm
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[Mad (Flt) Scientist]

Is it a "limitation" or a "demonstration"?

Often, even though it's in the "Limitations" section of the AFM a manufacturer will simply state the highest demonstrated crosswind, if they couldn't find the limiting conditions for controllability. If so in this case, it might just be a function of what winds they could find on a given day.

[Empty Cruise]

...or they may have obtained permission from the certifying body (FAA) to calculate the new, reduced "limit" based on the original set of wind data.

I refuse to believe that Boeing would put an effective limit to the warrenty of their aircraft just because they ran out of wind (or time). The increased directional stability can easily be calculated, so I'm not convinced that a new physical demonstration would be required - but ready to stand corrected :)

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