The Flying Nun's order was completely fictional. Their habit was modeled - sort of - on that of the Daughters of Charity of St. Vincent de Paul, an order founded by St. Vincent in France in mid-1600s. I do some work for Providence Hospital in Michigan - which was a Daughters of Charity hospital until a couple of years ago when it merged with a health system sponsored by the Sisters of St. Joseph. Anyway, the cornette was the winged wimple you're thinking about. No time to find a photo right now; will come back and do so.
Edit: Can't believe there are no pictures out there; we have a million in the hospital archives. Well, the first page of this newsletter has a drawing of a Daughter of Charity that will give you the idea of what the cornette looked like.
http://www.dochs.org/who_we_are/caritas_spring_2003.pdf
