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-42 span the oceans. The new design would need increased lifting capacity to carry enough fuel and 300 pounds of mail, but no passengers, for a 2,500 miles (4,023 kilometers) nonstop flight against a 30 mph (48 km/h) wind, at a higher cruising speed than the norm for similar flying boats at that time. Of the six companies tenders had been sent to, only Sikorsky and Martin provided submissions. Sikorsky offered the S-42. The other offer was the more ambitious Martin M-130. The new Sikorsky design, the S-42, had major aerodynamic improvements over the S-40. Igor Sikorsky said, "in its very