Deletion or keep
My opinion in short: Keep.
While this FDM was used only for a handful of aircraft, it was for a long time distributed with FlightGear (it might have been along as far as 2.8.0, though it is hard to tell).
Since older versions of FlightGear is available it might be a good idea to keep this page as well as making it clear that UIUC is not a part of the current distribution (preferably stating from which version it was removed).
I have read somewhere, probably on the forum, that there is still options to compile it into the current FlightGear. If someone have details on that it might be worth mentioning. As well as that one could expect problems doing so.
- Mm yes I guess that's a good reason. In the end, it's not a troublesome page. I'll remove the template.