Pioneer aviation engineer (1889–1972) who developed the first four-engine airplane and the first modern helicopter to be put into widespread use. Six commemorative covers, five with stamped cachets honoring the first Canadian Air Mail flight from Toronto to Buffalo in 1929, and one with a stamped cachet honoring the first air mail flight from Tulsa, Oklahoma on July 5, 1928, Air Mail CAM 3, each signed on the front in fountain pen, “I. Sikorsky.” In very good condition, with scattered toning and soiling, several typed addresses or labels to covers, as well as collector’s stamps to reverse of the covers. RRAuction COA.
