I’ve put scans of a 1968 Popular Science article on the Lockheed AH-56 Cheyenne attack helicopter and a Boeing-Bell brochure on the JVX tiltrotor (which became the V-22) on the APR Patreon dropbox, in the 2016-02 folder.
The Pop Sci article featured cover art by Robert McCall. Just cuz, I tinkered with the cover art, attempting to scrape off the text and restore it to just the painting. Perhaps not a 100% success, but not too bad. The JVX is not *quite* the final V-22 design; a notable difference is the inclusion of a .50 caliber gatling gun in the nose and a rocket launcher hanging off the side the cockpit.
If interested in getting these, please consider signing up for the APR Patreon. The “Extras” are available to all $4 patrons. Quite a pile of high-rez stuff is available now.