RSC, firstly welcome to Pprune and the FT forum.
Performance figures are not derived primarily from WT data, but what is not uncommon is to generate Cd/Cl/Cm curves from WT data and to then make a first stab at aircraft performance data from that. This is then validated and refined in FT. The same is true to a greater extend of aircraft handling data.
Now for an undergraduate thesis you need two elements for a good mark - theoretical and practical so here's one idea for you.
- Take a light aircraft with well documented performance data (plenty of those), make a model of it (I'd buy an airfix kit and modify it). Create some theory which would derive basic aircraft performance (don't shoot yourself in the foot trying to be too ambitious, just pick one thing - TORR for example). Then create wind tunnel tests to generate the data, and see how well the theory+WT match up with manufacturer's scheduled data. That, plus a good argument as to any inconsistencies could get you a good mark at BEng level.
- If you are still flying, do something similar with (say) glide performance at different speeds and flap settings, then do the same in an aeroplane. Generate the theory to cross-validate them.
There are a few other ideas, some of which might be more mechanical
here, which might be worth a look at.
G