Aeronautics question

[happytraveller]

I was watching a film about the BAC 1-11 (flew many times in that as a passenger) and it got me wondering why wing fences went out of fashion. I read that slats can produce similar effects, but these are not used at high speeds, so does anybody know why wing fences are not used now??? Winglets, which are coming into fashion, have a similar function, but why not wing fences???

Any aeronautical experts out there can help on this one?

smooth landings

[ZK-MAT]

.. runs off to Google Wing Fences ...

[Ian Warren]

Wing fences were there to help with the layer barrier across the wing and to exited the air similar to vortex generators , this including today,s winglets , early design used more wind tunnel design were as today the data can be produced even more accurate on computers .
A good example of how , more fluke than planning is the rudder on the A4 , stopping tail flutter , basic a incomplete rudder (ribs only ), they just did not skin it , that solved the problem .

[pacblue]

Wing fences and winglets serve two very *different* functions.
Wing fences are used to inhibit the propagation of a stall, they help to stop the burbling and airflow separation that begins at the wing root and spreads towards the wingtips during incipient stalls.
The basic idea here is to protect the effectiveness of the ailerons during very slow speed regimes.
Winglets, on the other hand, exploit *high speed* aerodynamics.
So just to be perfectly clear, one would never choose between wing fences or winglets. They each address very specific aerodynamic problems.
alot of aircraft today still have both (off the top of my head pacblues 738) with the winglets and fences along the leading edge.