Envelope protection and atmospheric disturbances in icing encounters

Research is reported on aircraft performance and control in icing, related to the development of Smart Icing Systems for improved flight safety. Microburst and gravity wave atmospheric disturbances were modeled, and their effects on the aircraft performance and control were compared to that of an icing encounter. Simulations were run using a six degree- of-freedom computational flight dynamics model. The study showed that microbursts could easily be differentiated from icing encounters. On the other hand gravity waves are more difficult to differentiate. A plan was formulated for developing an envelope protection system effective in icing conditions. Two dimensional airfoil data were analyzed and showed promising results for prediction of envelope limit exceedence. Changes in unsteady hinge moments were especially effective in predicting stall. NOMENCLATURE Cd Airfoil drag coefficient Ch Airfoil hinge moment coefficient Ch,RMS Airfoil unsteady hinge moment coefficient Cl