Lilienthal designed and built eighteen different hang-gliders; monoplanes mainly, but also biplanes. Lilienthal was without doubt the first successful flyer with his around 2,000 flights, even if their duration was always short. He was also a clever observer who put in paper with mathematical and engineer mind all he was doing. A capital figure in aviation, nothing could have been the same without him.
The simplicity and boldness of his gliders appears clearly in this superb photo of his very first monoplane (1891).