Tech Briefs

Aircraft Wing Flap Noise-Reducing Fins

Langley Research Center, Hampton, Virginia Two different modifications have been developed for the edges of aircraft wing flaps to reduce noise. Reactive Orthotropic Lattice Diffuser (ROLD) is a modification that consists of a honeycomb-like, interconnected structure added to the region of the flap that experiences the highest degree of sound-generating airflow instability. Flap Edge Noise Reduction Fins (FENoRFins) are modifications consisting of rigid fins on the edges of the aircraft flaps.

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Direct Multiple Shooting Optimization with Variable Problem Parameters

Lyndon B. Johnson Space Center, Houston, Texas Solving complex trajectory problems optimally is of vital importance to the success of future aerospace programs. Trajectory optimization research has been divided into two main categories: indirect methods and direct methods. Both methodologies have been tested and extensively applied to specific orbital trajectory problems.

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Constructing Composite Response Surfaces for Aircraft

The method combines neural networks with polynomial interpolation or estimation techniques. Ames Research Center, Moffett Field, California The design of aerodynamic components of aircraft, such as wings or engines, involves a process of obtaining the optimal component shape that can deliver the desired level of component performance, subject to various constraints, e.g., total weight or cost. Aerodynamic design can be formulated as an optimization problem that involves the minimization of an objective function over the design space, subject to constraints.

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Mars Relay CubeSat

Small relay stations can take the place of a small number of large ones. NASA’s Jet Propulsion Laboratory, Pasadena, California When NASA and other agencies send landers to Mars and other planets, they rely on existing orbiters to relay the data during the critical entry, descent, and landing (EDL) phase. The current orbiters are aging and there are no current NASA plans to replace them. Future landers have a critical challenge to communicate during a very risky mission phase. The InSight mission will land on Mars in September 2016 with no direct-to-Earth radio link. Instead, Insight expects the Mars Reconnaissance Orbiter (MRO) to be fully functional and placed in an orbit to be in view of the EDL time and place. MRO will take many hours to play back the data to Earth, leaving the project staff without knowledge if their valuable spacecraft has made it safely.

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Digitally Steered Phased Antenna Array for GPS Applications

This array improves GPS navigation at high altitude and in the presence of interference. Goddard Space Flight Center, Greenbelt, Maryland GPS signals are sparse and weak at high altitudes above the GPS constellation; this includes GEO and HEO orbit regimes. Spacecraft operating here need a high-sensitivity receiver capable of acquiring and tracking these weak signals throughout their orbits. Most space GPS receivers are designed to operate in the LEO regime below the GPS constellation and will perform poorly at high altitude. The Goddard Space Flight Center (GSFC) Navigator GPS receiver is designed for above-the-constellation applications and can provide adequate performance for many missions. The innovation described here provides large sensitivity increase through improvement of the receiver’s antenna gain. The technology can be applied to a standard LEO GPS receiver to enable adequate high-altitude performance, or to a specialized high-altitude receiver, like the GSFC Navigator, to further improve its high-altitude performance. The innovation can also be used to mitigate interference, including multipath and RF jamming signals for operation in any regime.

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Broadband Circularly Polarized Antenna Array for Mars Rover Direct-to-Earth Communications

Printed circuit board technology is used, which requires almost no hand assembly. NASA’s Jet Propulsion Laboratory, Pasadena, California Mars rovers and other landers typically use UHF relay to return their science and engineering data to Earth. Direct-To-Earth (DTE) communications are typically used for commanding. If future UHF relay capability becomes diminished, Mars landers may be forced to use DTE communications to meet their data return requirements. An augmented DTE capability with a high-gain antenna and a higher-power transmitter are required to support the relatively high data volume returned in a typical mission. The research for this innovation has developed an antenna architecture that can support such an augmented DTE capability. This antenna architecture comprises an array of microstrip patch subarrays fed by a waveguide corporate feed network, producing a net gain of 30 dBic at the array input.

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Robust, Low-Density Parity- Check Decoder Design to Mitigate Pulsed Radio Frequency Interference

Lyndon B. Johnson Space Center, Houston, Texas Low-Density Parity-Check (LDPC) codes are a class of forward error correction (FEC) linear block codes that provide near-capacity performance for power-efficient communications. Optimum decoding requires accurate combining ratio estimation to scale the input signal in an additive white Gaussian noise channel (AWGN). Test data and analysis show that the performance of the optimal LDPC decoding algorithm is severely degraded when encountering pulsed radio frequency interference (RFI) from sources such as ground-based radars.

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