In 1898, Bell experimented with tetrahedral box kites and wings constructed of multiple compound tetrahedral kites covered in silk. The tetrahedral wings were named Cygnet I, II and III, and were flown both unmanned and manned - Wikipedia via Retronaut

In 1898, Bell experimented with tetrahedral box kites and wings constructed of multiple compound tetrahedral kites covered in silk. The tetrahedral wings were named Cygnet I, II and III, and were flown both unmanned and manned

- Wikipedia via Retronaut