Sure about that are we??:ok:

OK, let us agree to differ.

On big aircraft (see Falcon 20, if I remember) the fence is to reduce span-wise flow. There is no doubt.

If, on little aircraft, there is a hole to see if the light is on of not, or protect the pilots' vision, fair enuff.

It has little to do with aerodynamix, however.

Well the a/c in the original photo is a G/A Piper twin with non-swept wings, indeed if you look at the "fence" in question it measures just a few cm of chord so is no aero value whatsoever!! Not to confused with genuine wing fences especially on 1st/2nd generation swept wing jets which do indeed help to reduce span wise flow. Another solution used was the "dogtooth" or "sawtooth" leading edge. :ok:

I flew the Hunter; I know about that also.

Ha! This thread is hilarious

Most people didn't bother to click the link the OP has posted, so are talking about actual wing fences, when the OP is in fact asking about the very small piece of metal at the very edge of the wingtip on a typical light piper.

They are clearly not for any aerodynamic purpose, but to stop the glare from the Nav Lights and wingtip strobe, which would be blinding at night otherwise.

How lucky you were! So your deep, extensive knowledge and experience should tell you that the devices,in the original photo has the square root of sod all to do with span wise flow or any other aero phenomena :rolleyes:

A nav light is so designed as to be visible only from certain directions.

Specifically, you can see the problem should that green, starboard nav light be visible from left of the aircraft!

Nav lights are arranged so that when they can be seen from another aircraft, they convey certain positional info on the aircraft showing them.

From memory is it 140 degrees from parallel to the centreline?

That wee 'fence like' thing is to make sure you can't see the nav light from the 'wrong' side.

a wing fence keeps the wing demons from getting on the wing and ripping it apart...please see the Twilight Zone episode known as "Nightmare at 20,000 feet"...note that there is no WING FENCE on this plane...we learned from that one!