Development of a Probability of Hover Analysis Capability to Support Rotorcraft Conceptual Design

The capability to hover has served as a defining characteristic of rotorcraft ever since the first flight. However, assuming fixed power and gross weight for a specific configuration, the capability to hover is directly dependent on the desired environment – the latter a function of the ambient pressure, altitude, and temperature. Following previous studies, it has been shown that a rotorcraft’s capability to hover in various environments can be represented by a single metric, the probability of hover. Therefore, an initial methodology has been developed that works with the rotorcraft design code NDARC [6] to determine said probabilities of hover for candidate aircraft in four example countries: Afghanistan, Iran, South Korea, and West Germany. This initial paper has specifically chosen to evaluate an advanced active rotor helicopter design at various gross weights and compute the corresponding probabilities of hover.