Hi,
from the same report about Lockheed Model-286,there is some old helicopters and convertiplanes
patents;
http://www.dtic.mil/dtic/tr/fulltext/u2/731493.pdf
from the same report about Lockheed Model-286,there is some old helicopters and convertiplanes
patents;
http://www.dtic.mil/dtic/tr/fulltext/u2/731493.pdf