Sikorsky X2 Sikorsky X2 The Sikorsky X2 is an experimental high-speed compound helicopter with coaxial rotors developed by Sikorsky Aircraft. Sikorsky developed the X2 helicopter on a $50 million budget. The design includes expertise gathered from several earlier design projects. The S-69/XH-59A Advancing Blade Concept Demonstrator had shown that high speed was possible with a coaxial helicopter with auxiliary propulsion (two jet engines), but that vibration and fuel consumption was excessive; the Cypher UAV expanded the company's knowledge of the unique aspects of coaxial flight control laws with a fly-by-wire aircraft; and the RAH-66 Comanche developed expertise in composite rotors and advanced
Sikorsky S-9 completion the S-9 was found to be substantially heavier than anticipated and the engine only delivered 80% of its rated horsepower. Initial flight tests revealed very poor performance. The engine was replaced by a Gnome Monosoupape and further flights showed only a nominal increase in speed. The machine was eventually scrapped. Sikorsky S-9 The Sikorsky S-9 "Kruglyj" (Rounded One) was a Russian single engine prototype aircraft completed in the spring of 1913 by the Russian Baltic Railroad Car Works while Igor Sikorsky was the chief engineer of the aircraft manufacturing division. The S-9 was a three-seat mid-wing monoplane with constant-chord