KittyHawk Software has a 10 part plane that I enjoyed. It may be the one that people are talking about as Paperparadise. It is very hackable, and the air scoop needs hacking. It was free when I got it, but I have not seen it since 2000 or so. The copyright is 1997, the web page goes to a German packing company, now
KHS – Filling and Packaging worldwide | KHS GmbH. Maybe this will ring a bell with someone.