Rotating/Nonrotating Interface for Data and Power

Two systems, a roll ring and a rotating transformer, were developed to transmit data (30Mbps) and power (8kW) between the fixed and rotating interface of a helicopter with sufficient accuracy, quantity and reliability to support the new generation of on-rotor controls and sensors. A test stand was developed to evaluate performance and endurance of both units. The roll ring was run for 481 hours at speeds from 400 to 800 RPM with full data and power transfer (623 hours equivalent at 400 RPM). It weighed 20 pounds and met the data and power transfer requirements. The rotating transformer was run for 322 hours at 400 RPM with limited power transfer. It weighed 30 pounds, not including the weight of the drive electronics. It met the data transfer requirements and demonstrated power transfer. No wear or life issues were noted. The roll ring and the transformer represent significant improvements in transfer unit capability and endurance. The roll ring is a more mature technology, while the transformer represents promising non-contacting technology, especially in conjunction with on-blade actuation. Near term, both units should be considered for data transfer or de-ice applications. Long term, the transformer should be considered for on-blade actuation with hub-mounted amplifiers.