Performance Evaluation of an OH-58A+ With Dimpletape Installed

This flight test investigates the performance benefits of a recently developed vortex generator, called Dimpletaperegistered, on an OH-58A helicopter rotor blade. This product employs the aerodynamic concepts that are used to reduce the drag on a golf ball. The manufacturer claims significant performance benefits with the product applied to airplane wings and propellers however, no flight-testing has been conducted on commercial helicopter rotor blades. Four different Dimpletaperegistered lengths where flight-tested on an OH-58A to determine the optimum Dimpletaperegistered length and cordwise placement on the main rotor blades for the greatest performance gain. The flight-testing consisted of a quantitative performance evaluation including hover performance free hover method, level flight performance Wsigma, weight over density ratio test method, and autorotative performance flight tests The flight test results show that there is an insignificant reduction in power when Dimpletaperegistered is applied to the outboard 10 19.5 inches of the rotor blade at the maximum camber point optimum Dimpletaperegistered length and position tested. In most of the tests Dimpletaperegistered increased the power requirements of the rotor system.