Aviation and rotorcraft: What did Igor Sikorsky invent and pioneer in practical, modern form? Focus on his most famous contribution to powered flight technology. Choose the correct invention.

Given data

• We must identify Igor Sikorsky's key invention.

Concept / ApproachIgor Sikorsky is renowned for developing the practical helicopter, especially the single-main-rotor with tail-rotor layout (e.g., VS-300, R-4).

Step-by-step reasoningParachutes, jet engines, and rigid airships are associated with other inventors; Sikorsky's principal contribution is the helicopter.

Final AnswerHelicopter (practical single-rotor configuration).