Development of a Test Rig for the Assessment of Remotely Piloted Aircraft Systems (RPAS) in Icing

As the everyday use of flying small to medium size Remotely Piloted Aircraft System (RPAS) continues to evolve, so does the need to fly them in icing environments. To investigate an RPAS’ ability to fly in these conditions, an outdoor test rig has been developed at the National Research Council Canada (NRC) in which a range of RPAS have been tested in icing environments. This rig has an available test area of 3.05 m × 3.05 m, and is 5.1 m high. An array of spray nozzles installed at the top of the test rig provides a cloud that, when operated at sub-zero temperatures, enables simulation of in-flight icing conditions. The spray cloud is calibrated to provide water concentration and drop size distributions consistent with Appendix C, freezing drizzle and freezing rain conditions. Six RPAS were tested and their performance under icing conditions has been monitored via video and, where available, data provided by the on-board acquisition system was downloaded to enable flight information such as motor power and positional stability to be examined. It is shown that above a certain LWC, the time at which the systems could sustain flight in icing plateaus and no further increase in water content results in a reduction in the operational envelope. It was also found that the operational limits of the RPAS were independent of the median volumetric diameter (MVD).