On 14 Apr 2007 09:16:57 -0700, "Lou" wrote:

Correct me if I'm wrong, but doesn't a copywrite last for
a certain amount of time then it has to be renewed? If not
renewed in time, it becomes public domain.

Yes, but the period is at least 75 years past the death of the author.

The authors certainly can release them to public domain well before that. I
wrote a commercial flight simulator game about 25 years back, and upon a polite
query about five years ago, provided just such a written release. When another
guy asked for a PDF file of the manual, I put the release inside the front
cover:

http://www.wanttaja.com/IFR.pdf

It doesn't make any difference for a VIC-20 flight simulator, but I'm not sure
whether one can shed legal liability for an aircraft design by making it public
domain. However, IIRC, the canard folks market a CD-ROM with complete Long-EZ
plans on it, and I suspect that if Rutan was worried, he could easily stop them.

Ron Wanttaja