Outer Aileron Yaw Damper

Actuators typically have large footprints and mass to meet the power output needed for operation, leading to design hurdles for aircraft and space applications. Innovators at NASA Glenn developed two novel actuators with different configurations of tubes of SMA to provide rotary output. The SMA tubes are deformed in their martensitic condition and when exposed to a thermal stimulus, the tubes will revert to their original state while providing rotary motion. One variation of the innovation nests the SMA tubes within a rotary actuator imparting several technical benefits. Nested SMA tubes can decrease the length of the actuator while achieving the same twist angle. For the same actuator length, a nested configuration of SMA tubes can multiply the twist angle and improve the power output. A second variation utilizes SMA components as transmission elements in a ring drive gear to enable continuous rotation in one direction. Previous similar SMA actuators rotate in one direction while heating and the other while cooling, which can limit the output of the rotary actuator. The innovation developed by NASA allows for continuous rotation in ANY direction, thereby allowing the rotational output capability to be independent from the amount of cyclic angular twist provided by the SMA tubes.

Glenn researchers have optimized how shape memory alloys (SMAs) are trained by reconceptualizing the entire stabilization process. Whereas prior techniques stabilize SMAs during thermal cycling, under conditions of fixed stress (known as the isobaric response), what Glenn's innovators have done instead is to use mechanical cycling under conditions of fixed temperature (the isothermal response) to achieve stabilization rapidly and efficiently. This novel method uses the isobaric response to establish the stabilization point under conditions identical to those that will be used during service. Once the stabilization point is known, a set of isothermal mechanical cycling experiments is then performed using different levels of applied stress. Each of these mechanical cycling experiments is left to run until the strain response has stabilized. When the stress levels required to achieve stabilization under isothermal conditions are known, they can be used to train the material in a fraction of the time that would be required to train the material using only thermal cycling. As the strain state has been achieved isothermally, the material can be switched back under isobaric conditions, and will remain stabilized during service. In short, Glenn's method of training can be completed in a matter of minutes rather than in days or even weeks, and so SMAs become much more practical to use in a wide range of applications.

According to the International Air Transport Association statistics, the annual fuel cost for the global airline industry is estimated to be about $140 billion in 2017. Therefore, fuel cost is a major cost driver for the airline industry. Advanced future transport aircraft will likely employ adaptive wing technologies that enable the wings of those aircraft to adaptively reconfigure themselves in optimal shapes for improved aerodynamic efficiency throughout the flight envelope. The need for adaptive wing technologies is driven by the cost of fuel consumption in commercial aviation. NASA Ames has developed a novel way to address aerodynamic inefficiencies experienced during aircraft operation. The real-time drag optimization control method uses an on-board, real-time sensor data gathered from the aircraft conditions and performance during flight (such as engine thrust or wing deflection). The sensor data are inputted into an on-board model estimation and drag optimization system which estimates the aerodynamic model and calculates the optimal settings of the flight control surfaces. As the wings deflect during flight, this technology uses an iterative approach whereby the system continuously updates the optimal solution for the flight control surfaces and iteratively optimizes the wing shape to reduce drag continuously during flight. The new control system for the flight control surfaces can be integrated into an existing flight control system. This new technology can be used on passenger aircraft, cargo aircraft, or high performance supersonic jets to optimize drag, improve aerodynamic efficiency, and increase fuel efficiency during flight. In addition, it does not require a specific aircraft math model which means it does not require customization for different aircraft designs. The system promises both economic and environmental benefits to the aviation industry as less fuel is burned.

Most spacecraft feature release, retention, and deployment devices as key components, because these devices achieve on-demand configurability of solar panels, probes, antennas, scientific instruments, fairings, etc. Until now, designing and using such devices in small spacecraft has been a challenge, because their mass, volume, and power requirements are significant and can impose design constraints. CubeSats, in particular, often need to deploy several structures (such as solar arrays) simultaneously, which prior-art deployment devices have not been able to manage effectively. Glenn's innovation embeds SMAs within the components so the structures can be retained during launch, then released and deployed in orbit. The release and retention device is controlled by an SMA activated pin puller to disengage the release plate from the hooks holding the solar arrays. Once released, the SMA hinge is passively enabled to the deployed state. When ready on orbit, the mechanism is commanded to release and electrical power is sent to the SMA actuator, releasing the component to its deployed state. The component is deployed to its final position through the use of hinges, which are activated passively with SMA spring strips. The retention and release device and hinge are substantially smaller and lighter than deployment mechanisms have ever been and can deploy simultaneously with great reliability. Having already been successfully deployed on a NASA mission, Glenn's innovation is a game-changing technology for CubeSats and other small satellites.

Distributed propulsion and lightweight flexible structures on air vehicles pose a significant opportunity to improve mission performance while meeting next generation requirements including reduced fuel burn, lower emissions, and enhanced takeoff and landing performance. Flexible wing-shaping aircraft using distributed propulsion enable the ability to achieve improved aerodynamic efficiency while maintaining aeroelastic stability. Wing shaping concepts using distributed propulsion leverage the ability to introduce forces/ moments into the wing structure to affect the wing aerodynamics. This can be performed throughout the flight envelope to alter wing twist, hence local angle of attack, as the wing loading changes with air vehicle weight during cruise. Thrust-induced lift can be achieved by distributed propulsion for enhanced lift during take-off and landing. For a highly flexible wing structure, this concept could achieve a 4% improvement in lift-to-drag ratio, hence reduced fuel burn, as compared to a conventional stiff wing. This benefit is attributed to a reduction in lift-induced drag throughout the flight envelope by actively shaping the spanwise lift distribution using distributed propulsion. Vertical tail size could be reduced by utilizing differential thrust flight-propulsion control. This will result in weight reduction to achieve further fuel savings. Aeroelastic stability is addressed in the design process to meet flutter clearance requirements by proper placement of the propulsion units. This technology enables synergistic interactions between lightweight materials, propulsion, flight control, and active aeroelastic wing shaping control for reducing the environmental impact of future air vehicles.