Just some technical info. The posts here appear to be confusing patents, copyrights, and trademarks. Patents expire. If I recall correctly after 17 or 20 years the work is no longer protected and anyone can use the intellectual property. Trademarks also expire. I believe that you have to pay an annual fee to hold your trademark. Interestingly, work that can be copyrighted essentially does not expire.

So all of the folks who are making XYZ-Cubs are taking advantage of all of the above. In the case of Wag-Aero, they started making "cub clones" a long time ago so they might have run afoul of the rules in the early days and changed their names to avoid problems that cost $$.

In the case of publishing copies of other individual's works, that can indeed result in problems for the copier. Much safer legally and ethically to publish updates to the original plans. Or get the written blessing of the original author.

Best of luck,

Wes