leading edge flap/slat thing......

[TIMTS]

On a few airliners I have seen a flap of some sort being folded down below and a little bit behind the leading edge of the wing. Its hinged in front.

As I fly helicopters I have a fairly good understanding of aerodynamics, but this one has me stumped. Is it some sort of speed brake? Lift dumping device?

Would like to know....

Timts
:confused:

[Md-driver]

Hi there!
Its is a leading edge flap, called a Krueger flap. Aerodynamically not very ellegant but effective enough. It is also a relatively simple construction and therefore light. Not as efficient as a slat.

Hope this answwers your question..

[John Farley]

TIMTS

As Md has said the Kreuger flap is simple and effective although it does not look right which is probably what has got to you! The way I have it in my head is that deploying the Kreuger lowers the stagnation point quite markedly. This means that the amount of airflow above the stagnation streamline is increased and has to travel further on its way over the upper surface and so Mr B works better.

If the stagnation streamline is new to you let me know and I could post a simple diag

[TIMTS]

Thanks guys

No..that makes perfect sense!

I guess it is the same Krueger that is behind the little metal strip on the trailing edge of the horizontal stabilizer on the Sikorsky S-76...

Any truth to the rumour that it was invented by accident by a nascar driver trying to win some races? A guy named Krueger...
Thats the story told at when I got my licenses

Thanks again guys
:ok:

[AhhhVC813]

Also, because it doesn't work as effectively as other leading edge devices, the stall occurs earlier on the section where the Krueger flap is located. That is why you will find it on the inboard section of the leading edge if the manufacturer has decided to utilise it.

[Right Stuff]

TIMTS - I believe you are confusing the Kruger with the Gurney. This is a surface normal to the flow, usually at the rear of an aerofoil. It has the effect of increasing the effective camber of the aerofoil and therefore lift/downforce.

It was first seen in F1 as a means to circumvent the rules on wing sizing. The team came up with some bizarre excuse to pass it off as nothing but the other teams caught up and 'borrowed' the idea too.

[john_tullamarine]

.. and, if my recollection is correct, a similar device was tried as a flight test fix on a light turboprop twin about 25 years ago to fix a long stab problem .. killing the two front seaters and critically injuring the FTE down the back ...

[Milt]

John Tullamarine

It wasn't at Tullamarine though. It was Avalon!!

I still see the surviving FTE.

[john_tullamarine]

aye .. and the FTE and I know each other extremely well ... had circumstances been a little different it could conceivably had been me in the aircraft instead of Pat ...

[L337]

This was a Kruger Flap thread a while back, and it has an interesting link as well.

Go here (http://www.pprune.org/forums/showthread.php?s=&threadid=82115&highlight=Krueger+flap)

L337

P.S. Sadly the link is broken

[TIMTS]

Gurney flap it is...

found a good quote
"Before it was tested every self-respecting aerodynamicist could name lots of reasons why it wouldn't work....after it was tested they all tried to explain why it did...":D