Sikorsky Aircraft and soon increased prize money to US$25,000. In 2010, Sikorsky Aircraft pledged to increase the prize sponsorship to US$250,000. The Canadian engineers Dr. Todd Reichert and Cameron Robertson developed the world's largest ever human powered helicopter with a team from the [[University of Toronto]]. The first flight of AeroVelo Atlas was achieved in August 2012, the 64-second, 3.3-m-flight that won the prize on June 13, 2013. Sikorsky designates nearly all of its models with S-numbers; numbers S-1 through S-27 were designed by [[Igor Sikorsky]] in the Russian Empire. Later models, especially helicopters, received multiple designations by the military services using
Sikorsky S-5 during a country fair at Belaya Tzerkov, near Kiev. Between nine and ten flying hours were logged before the S-5 was lost in late fall. The crash was caused by fuel starvation due to debris (a mosquito) blocking the carburetor jet. Sikorsky S-5 The Sikorsky S-5 was an early Russian single seat biplane design by Igor Sikorsky, completed in late April 1911. The S-5 was powered by a Argus water-cooled engine turning a propeller Sikorsky designed and built himself. The fabric covering the wooden wings was tightened with pure alcohol and glue mixed with boiling water while the fuselage structure