What goes up – Pt.4 – Vortices

 

Wing vortices maybe a pain for aircraft and model designers alike, but it has to be said that they are sometimes very beautiful to look at! Because of this many photographers and video specialists have recorded them.

In the 70’s NASA did a number of full size experiments at Langley airfield aimed at understanding wing vortices better. This video is slightly slowed down as the clock in the corner shows. Whilst this is quite a good visualisation of the vortex it doesn’t really capture the power well.

Here’s another NASA test at Langley. This time the intensity of the vortex can seen much better.

What’s it like to follow “a heavy” in on landing and experience his wake? Well here you can see a light aircraft pilot cope well with the twists and turns in the air caused by a 737 that had used the same runway a little while earlier. I bet he just loved ATC for this one!

Here’s a rather “arty” video – but still technically very interesting. In the right weather conditions the vortices become visible as condensation trails. These videos are taken on landing so flaps down etc and the flap tips are effectively acting like mini local wing tips shedding beatiful vortices.

Here’s the other side of the coin from the previous video – the view from on board! Note that there are lots of little local vortices being formed. You should be able to work out what’s happening here. Take another look at figure 2 in the article. Now think about what happens at the trailing edge of the wing. You have the upper and lower surface flows going in “crossed” directions as the upper flow moves inwards and the lower surface flow moves outwards. When they reach the trailing edge they are traveling at an angle to each other and so they form a localised vortex when they mix.

http://www.youtube.com/watch?v=oq8bZlNZRe0&NR=1&feature=fvwp

Although it can't be embedded, the last video has absolutely nothing to do with wing vortices – but I make no apology for including it. It shows a couple of take offs from Manchester. Just take a look, it reminds me of all the reasons why I find aerodynamics so fasinating. The planes have all their lift aids deployed, leading edge slats and flaps. Then we see those enormous wings doings what they do best – absolutely magnificient, awe inspiring! Take a look at the pilot working the rudder on the second take off – just like a model!