And now for something completly different....

I should apologise for the lack of posts over the last few weeks, I am in the middle of my fourth year exams and the last few weeks before the semester finished I was run off my feet with a never ending list of coursework and reports. One of the modules had me doing some interesting programming of the vortex sheet produced by a wing to investigate the wing tip vortices's to see if the wake interfered with the tailplane. So while I have a few days between exams thought I'd write up a bit on this because having researched this topic, I know how tricky it was to model. The code is written in Matlab and a link to the scripts will be given at the bottom of the page. The mathematics behind computation of the vortical wake produced by a wing is too long for me to delve into for this mid-exam blog post, if there is enough interest I am more than happy to cover this in a future blog, but for now I will just gloss over the details and show the pretty pictures. After the last few weeks of non-stop revision digging out my notes and writing what would amount to another small report is the last thing on my mind. Besides, the UK is in the grip of a heatwave at the moment, it is nearly 28`C outside which reduces my desire to write up my derivations even more! For those of you who are reading this from sunnier climates it might sound like an average day for you, but for us it is almost unheard of on this rain drenched island.

Here is the classic NASA video of an experiment to show the vortex produced by the wing of an aircraft. These wing vortices's can interact with the empannage of the aircraft producing unpleasant effects as well as interfering with the behaviour of other aircraft. This is a well known phenomenon among large aircraft and most people know there are separation limits that govern take off and landings for commercial aircraft, but this video shows that the vortex sheet produced by an microlight aircraft is enough to interfere with a second microlight.

Here are a couple of screen shots from the my wake code that predicts the wake produced by a small aerobatic trainer type, aircraft which myself and several of my classmates designed for one of our uni modules. After finding the wake, the Matlab code will also plot the wing, fin and tailplane geometries to see if the wake produced any undesirable effects on the tail surfaces. 

The two files at the end of this post are the script 'wingwake.m' and function file 'vortex.m' for the wing vortex model. You'll need to download both into the same destination folder but only the 'wingwake.m' file needs to be run, and you will also of course, need a copy of Matlab. I will one day modify the code to add in the effects of flap deployment and tidy it up with a GUI, but I don't have the time yet. I never have the time for anything these days least of all the interesting projects. I haven't touched my gas turbine dashboard for a while and I'm itching to get back to it. 

Talking of interesting projects, fingers crossed I will start a PhD in a few weeks looking at CFD of ships with a view to improving the design process with respect to the handling qualities of a helicopter during deck operations.. I can't wait!

WingWake.m
Vortex.m