Amazing vortex photo

speedbird591 · Post by **speedbird591** » 10 Aug 2006, 13:41

Ha ha! That's brilliant! Patenting the winglet in 1897 and then waiting patiently for somebody else to invent the rest of the machine! A true Great Briton. Sad that he wouldn't have lived long enough to see his invention come into it's own

There is hope for us all! Thanks, Dan

Ian

TobyV · Post by **TobyV** » 10 Aug 2006, 14:14

Hi Ian,

Basically at the tip of a wing, or a rotating blade or pretty much anywhere really a fluid (liquid or gas) naturally flows from an area of high pressure to an area of low pressure.

Because of the curvature of the upper surface of the wing, the air has further to travel but 'arrives' at the same time it therefore has traded an increase in kinetic (motion) energy for a decrease in pressure energy.

At the wing tip, the higher pressure air below the wing has an opportunity to move around the tip towards the lower pressure area above the wing. Combined with the forward motion of the aircraft, this is what leaves the spiral vortex. Obviously theres a lot of 'wasted' energy in the vortex, so whats really happening is regarded in engineering terms as a "loss". The vortex adds drag to the wing (I think :think:

) and is obviously a nuisance for following aircraft. The whole point of the wingtlet is to make it harder for the air to generate this vortex. You can find similar things to prevent tip losses on modern turboprop, helicopter, compressor and even computer-fan blades, usually a sort of kined or twisted tip.

Sorry my engineering is a little rusty (pardon the possible pun), I hope that makes sense!

Toby

jonesey2k · Post by **jonesey2k** » 10 Aug 2006, 14:17

Like somebody posted on al.net: "Two places I wouldn't want to be in a 172"

speedbird591 · Post by **speedbird591** » 10 Aug 2006, 14:21

Yup. I followed all of that, Toby. You must be a born educator. Thanks for the insight

Ian

Post by **Garry Russell** » 10 Aug 2006, 14:34

I was always impressed at LHR watching B-747 come out out low rain clouds and pull the cloud down behind them almost to the ground.

Also a couple of times I have watched Concordes climbing up through the murk visible in the hole they had just made in the cloud and this sort of tunnel would form just briefly.

Garry

jonesey2k · Post by **jonesey2k** » 10 Aug 2006, 14:36

Actually you can hear them aswell. Standing just behind the threshold at liverpool when a 737 flys over for landing you can hear the air swirling around loudly for short while after the plane has landed.

Post by **Garry Russell** » 10 Aug 2006, 14:37

Yo Jonesy

146's are good for that as were Viscounts and Vanguards.

Garry

TobyV · Post by **TobyV** » 10 Aug 2006, 14:38

Garry, Concorde is a special case and the huge vortices are above the entire wing and integral to the way it generates lift.

Post by **Garry Russell** » 10 Aug 2006, 14:41

Hi Toby

Everything about Concorde was a bit special.

The edge of the tunnel had little swirls and it looked likeit had just entered a time tunnel

Garry

cstorey · Post by **cstorey** » 10 Aug 2006, 19:41

In addition to the pressure differential causing flow around the wingtip, there is also a considerable element of spanwise ( i.e outwards along the line of the wing , rather than fore and aft across it) flow which when it reaches the tip tends to detach and add to the vortex, and generate drag as Toby has said. This is the principal reason for the boundary layer fences on the VC10 which diminished the spanwise flow considerably, thus improving the lift/drag ratio of the wing and permitting the low approach speeds which were such a feature of it

Chris