What are all the demerits in having a winglet

[sakthivelzz]

Hi everyone! I'm new to this community ...I need to know few things about winglets..

1) what are all the demerits in having a winglet other than adding up wingloading,viscous drag ?

please reply only if ur sure about your answer as am working out for my thesis...

thank you...

 

[NobodySpecial]

1) what are all the demerits in having a winglet other than adding up wingloading,viscous drag ?

There is a fixed cost in buying them, especially as an after-market feature.
Plus the cost of taking the aircraft out of service to install them and the extra cost of routine inspections.

West-jet were trying them on their fleet and published some numbers showing the fuel savings had saved about 10% of the cost of installing them.
Mostly because they have very high fleet utilization - so aircraft out of service are very expensive, and they fly mostly commuter routes so spend proportionally less time at cruise where the fuel savings are greatest

 

[viscousflow]

Cons:
-Additional structure required to support them
-Thus additional weight to the aircraft
-Aeroelastic behavior changes

Just a few off the top of my head