ASK OCE — April 4, 2006 — Vol. 1, 1 Issue 7

Highlights of Recent Publications and Awards

LaRC Team Uses GPS for Measurement of Earth’s Surface Reflectivity

Langley researchers Stephen J. Katzberg, Omar Torres, and Michael S. Grant and Dallas Masters of Colorado University published the results of the first use of calibrated GPS signals for the measurement of surface reflectivity in Utilizing Calibrated GPS Reflected Signals to Estimate Soil Reflectivity and Dielectric Constant: Results from SMEX02 (Remote Sensing of Environment, Vol. 1, 100, Issue 1, January 15, 2006, pp.17-28). Findings indicate that GPS shows promise as a novel tool for the remote sensing of moisture levels in soil. The reflected GPS technique had its genesis at Langley Research Center in the late 1990s, when it was found that GPS can be employed to measure surface wind speeds and sea state over the ocean.

Revolutionary Systems Concepts for Aeronautics (RSCA) 2005 Study Results

Results of the 2005 Revolutionary Systems Concepts for Aeronautics (RSCA) studies were presented January 26, 2006, at Langley Research Center. The RSCA project focuses on the development and analysis of future air transportation and vehicle concepts and on the identification of high-value technology R&D needs.

• John Melton (Ames Research Center) presented a study of new guidance and navigation strategies that use atmospheric energy to increase UAV range and endurance.
• Susan Cliff (Ames Research Center) presented a study of methods for improving terminal efficiencies for commercial flight operations, and outlined several novel concepts designed to improve the passengers traveling experience.
• Curtis Hanson (Dryden Flight Research Center) presented results of his investigation of natural atmospheric thermals and wingtip vortices generated by other aircraft to increase the time aloft for a group of small UAVs.
• Hyun Dae Kim (Glenn Research Center) and Ronald Kawai from Boeing’s Technology/Phantom Works in Huntington Beach presented results of a conceptual design that focused on cruise efficient short take-off and landing with distributed propulsion to determine the potential flyover noise benefits of such a concept.
• Andrew Hahn (Langley Research Center) and Daniel DeLaurentis of Purdue University presented analytical results of an architectural concept linking the deterministic and non-deterministic subsystems of the air transportation system.
• Dennis Bartlett (Langley Research Center) and Paul Gelhausen from AVID LLC, presented conceptual design and analysis results of a new and advanced unmanned airborne vehicle to be used for border patrol and interdiction.

The NASA Headquarters Aeronautics Research Mission Directorate began the Revolutionary Systems Concepts for Aeronautics (RSCA) initiative in 2002 with the stated goal of supporting long-range visions and bolstering plans for aeronautical research and development (R&D) investments.

Langley Researchers Paper Wins Award

Hypersonic Wind Tunnel Calibration Using the Modern Design of Experiments (PDF) written by Matthew N. Rhode and co-authored by Richard DeLoach, was named Outstanding Paper at the 41st IAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit in Tucson, Arizona on July 10-13, 2005.

Mr. Rhode’s paper outlined the calibration of the Langley 20-Inch Mach-6 wind tunnel using Modern Design of Experiment (MDOE) methods. This methodology requires significantly fewer data points than prior calibrations of this facility, while meeting all precision and resolution requirements and also revealing subtle interactions among independent variables that had previously gone undetected. The MDOE approach demonstrates that high-quality tunnel calibrations are achievable with a marginal impact on competing research and production testing schedules.

LaRC/ODU Team Examine Methods to Estimate Noise Scattering

Langley Research Center’s C. H. Gerhold and L. R. Clark, and M. Dunn and J. Tweed of Old Dominion University examine the use of the Equivalent Source Method to estimate the noise scattering by complex shapes in “Investigation of Acoustical Shielding by a Wedge-shaped Airframe,” (PDF), which will be published in an upcoming issue of the Journal of Sound and Vibration.

The theoretically-derived noise scattering through use of the Equivalent Source Method is validated by comparison with measured scattering data gathered on a scale model wedge-shape airfoil in the Anechoic Noise Research Facility Anechoic Chamber. The findings show agreement between measured and estimated scattering. The effects of frequency of the noise source and source location are also investigated. The goal of this research is to craft the tools to improve aircraft noise propagation analytic models for the prediction of aircraft flyover noise and assessment of noise control methods.