Description: “Weather-Tolerant Capability” is considered essential in the expanding urban air mobility vehicle industry. Erosion effects of rain, dust, and sand on vehicle surfaces, especially rotor surfaces, have a considerable effect on operational and maintenance costs. Another crucial environmental condition that heavily impacts flight safety is ice accretion. This project addresses a novel erosion shield system incorporating ice-protective technology that can be applied directly to helicopter blades. The innovation is based on the concept of Super Elasticity in certain metals known as Shape Memory Alloys (or SMA's) that allow the material to elastically deform over 4% strain, making them very durable and erosion resistant. The Phase I effort focused on the design of an SMA based erosion tape with natural durability qualities as well as the ability to change phase (strain) for anti-icing properties. Superior erosion resistance was demonstrated in the superelastic material Austenite phase. The material was also demonstrated to strain when activated by heat, and break the ice bond strength with a combination of surface strain and temperature, making this a very efficient electro-thermal de-ice mechanism. Its unique nature of high stress output rate and low power requirements is a promising material to meet the need for energy savings required for electric vertical take-off and landing (eVTOL) vehicles. Phase II will continue the development of an extremely efficient rotor blade de-icing actuator, with superior erosion resistance properties. Optimal actuator materials will be selected such that the SMA will self activate in the lower temp extremes, as well as be pulse activated electrically in a power assist mode, when the rotorcraft is in extreme icing environments. A final Proof of Concept demonstration will be perfromed at the Penn State AERTS Icing Faciity to evaluate SMA perfromance at representative temperature and cloud moisture (LWC) conditions.

Benefits: This proposal provides key technologies to support NASA’s Advanced Air Mobility mission objective for reliable and safe operations of UAM vehicles during weather-related challenges. The market/application of these vehicles will be in urban and rural locations and be expected to have high use (life) in a broad range of weather conditions.

An erosion shield with increased durability and built-in low-power ice protection capabilities gives it a significant market advantage over current rotor blade erosion systems. It is expected to have universal applications to new electric rotorcraft vehicles with limited available power. Other target applications include traditional helicopters and windmills.