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
Igor Sikorsky a naturalized citizen of the United States. The Sikorsky Manufacturing Company moved to Stratford, Connecticut in 1929. It became a part of the United Aircraft and Transport Corporation (now United Technologies Corporation) in July of that year. The company manufactured flying boats, such as the S-42 "Clipper", used by Pan Am for transatlantic flights. Meanwhile, Sikorsky also continued his earlier work on vertical flight while living in Nichols, Connecticut. On February 14, 1929, he filed an application to patent a "direct lift" amphibian aircraft which used compressed air to power a direct lift "propeller" and two smaller propellers for thrust.