According to the January 2017 issue of the Academy of Model Aeronautics' (AMA) Model Aviation magazine, the National Model Aviation Museum has acquired the right to the plans and articles published by Mr. Ed Sweeney's Potomac Aviation Publications, between July/August 1966 and March 1975. That includes American Modeler and American Aircraft Modeler magazines.
Interestingly, posted in the announcement is the provenance of titles for the AMA's official monthly magazine. I have collected many editions over the years through purchases on eBay, and have scanned, OCRed, and posted many articles with comments here on the AirplanesAndRockets.com website. I wrote to Mr. Sweeney probably 10 years ago asking whether it would be OK to do so. In respecting the AMA's right to help underwrite the expenses of the organization, I do not post high resolution scans of the plans, but suggest that anyone interested in building one of the models contact the AMA Plans Service. They will print and ship you a copy at any scale you want - not just the original size. That way if you want to build a 1/2A size version of an airplane that originally used a 60-size engine, just tell them the wingspan you want and you'll get it.
Here is that list of magazine names in alphabetical (not in chronological) order:
Posted January 8, 2017