generate questions: In 1898, Bell experimented with tetrahedral box kites and wings constructed of multiple compound tetrahedral kites covered in maroon silk.[N 23] The tetrahedral wings were named Cygnet I, II and III, and were flown both unmanned and manned (Cygnet I crashed during a flight carrying Selfridge) in the period from 1907–1912. Some of Bell's kites are on display at the Alexander Graham Bell National Historic Site.
What color silk covered Bell's kites? {sep_token} Who was on Cygnet I when it crashed? {sep_token} Bell's kits were flown from 1907 to what year? {sep_token} How many tetrahedral wings did Bell create? {sep_token} Some of the kites remain at what National Historic Site? {sep_token}