Otto Lilienthal,1848–1896, a glider pioneer whose lifetime study of flight, gliding, and birds, was a big influence on the Wright brothers,

A German engineer who began his aeronautical research in 1871 by studying bird flight. After nearly two decades of imaginative experimentation and research, he produced the best and most complete body of aerodynamic data up to that time. He published his results in Der Vogelflug als Grundlage der Fliegekunst (Birdflight as the Basis of Aviation) in 1889. 

Following his program of data collection, Lilienthal constructed and tested a series of elegant, full-size gliders. Between 1891 and 1896 he made nearly 2,000 brief flights in 16 different glider designs based on his aerodynamic research.

An abrupt and tragic end, while flying one of his monoplane gliders, Lilienthal stalled and crashed (Aug 1896).

During a lucid moment, he spoke his last words to his brother, who had rushed to be by his side. His words translate to “Sacrifices must be made.”

 The Wright brothers later cited his death as the point when their serious interest in flight research began, and named Lilienthal as their inspiration.

https://airandspace.si.edu/exhibitions/wright-brothers/online/fly/1899/forefathers.cfm

https://disciplesofflight.com/otto-lilienthal-the-glider-king/